You missed us!
Here are some abstracts of talks that we have given.

Hybrid Approaches to Nanolithography and Chemical Patterning
C. Srinivasan, M. W. Horn, P. S. Weiss
Departments of Chemistry, Physics, and Engineering Science & Mechanics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Despite the impressive pace of innovations in photolithography, this technology faces fundamental physical and economic limitations for patterning sub-30-nm features.  We have combined photolithography, a top-down approach, synergistically with bottom-up chemical self-assembly to fabricate nanometer-scale features in a low-cost, scalable process - molecular-ruler nanolithography.^1,2  Here, we describe the strategies that have been developed to integrate this technique with CMOS-compatible materials and processes,³ patterns registered nanometer-scale features on quartz for use as the mold in nanoimprint lithography,⁴ with double the spatial frequency of features created by conventional lithographic techniques.⁵  We also use this methodology to fabricate connected device structures for ultranarrow channel length organic thin-film transistors and aligned metallic and semiconducting nanowires.

One of the limitations of photolithography is its inability to pattern chemical functionality on surfaces; chemically functionalized surfaces have applications ranging from biospecific recognition to molecular electronics.⁶  To address this issue, we developed lithography-assisted chemical patterning.  This technique utilizes a robust lithographic resist (LOR) that is capable of withstanding self-assembly deposition conditions to create high-quality chemical patterns.  The ability to pattern chemical functionalities without intercalation and with registered, parallel processing are some of its unique advantages.^7,8

1. A. Hatzor and P. S. Weiss, Science 2001, 291, 1019.
2. M. E. Anderson, L. P. Tan, M. Mihok, H. Tanaka, M. W. Horn, G. S. McCarty, P. S. Weiss, Adv. Mater. 2006, 18, 1020.
3. C. Srinivasan, M. E. Anderson, E. M. Carter, J. N. Hohman, S. S. N. Bharathwaja, S. Trolier-Mckinstry, P. S. Weiss, M. W. Horn, J. Vac. Sci. Technol. B 2006, 24, 3200.
4. C. Srinivasan, J. N. Hohman, M. E. Anderson, P. S. Weiss, M. W. Horn (submitted for publication).
5. C. Srinivasan, J. N. Hohman, M. E. Anderson, P. Zhang, P. S. Weiss, M. W. Horn, Proc. SPIE 2007, 6517, 65171I.
6. Y. Xia and G. M. Whitesides, Angew. Chem., Int. Ed. 1998, 37, 551.
7. M. E. Anderson, C. Srinivasan, J. N. Hohman, E. M. Carter, M. W. Horn, P. S. Weiss, Adv. Mater. 2006, 18, 3258.
8. C. Srinivasan, T. J. Mullen, J. N. Hohman, M. E. Anderson, A. A. Dameron, A. M. Andrews, E. C. Dickey, M. W. Horn, P. S. Weiss, ACS Nano 2007, 1, 191.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Precision Nanoscale Assemblies: Self-Assembled Monolayers, Clusters, and Nanoparticles
Rachel Smith, Materials Science Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA; WPI Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan

Extracting Quantitative Single-Molecule Dynamics from Scanning Probe Images
Patrick Han, Adam R. Kurland, Brent A. Mantooth, Amanda M. Moore, E. Charles H. Sykes, Vin H. Crespi and Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We measure these interactions and the electronic perturbations that underly them using scanning tunneling microscopy. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while still retaining all the single molecule and environmental information. This requires new automated tools for acquisition and analyses. We also use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Patterning and Measuring Molecules Inserted into Controlled Self-Assembled Monolayer Matrices
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We have devloped soft and hybrid lithographic strategies to pattern inserted single molecules. We use these surfaces to test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. We also use this control at the single-molecule level to prepare isolated small-molecule probes in well-defined chemical environments for biospecific capture for complex mixtures.

Saturday 8 March 2008
Pacific University Chemistry Symposium Honoring University Distinguished Professor James O. Currie, Jr.,
Pacific University, Forest Grove, Oregon

Imaging Single Molecule Polarizability and Buried Interface Dynamics
A. M. Moore, Y. Yao, J. M. Tour and P. S. Weiss
Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA
Department of Chemistry and Center for Nanoscale Science and Technology, Rice University

We have studied oligo(phenylene-ethylene) (OPE) molecules as candidates for molecular electronic switches. We previously determined the switching mechanism to rely on hybridization changes between the substrate and molecule. Here, we have determined which molecules will be more or less active in our samples using a custom-built alternating current scanning tunneling microscope (ACSTM). The polarizabilities of the OPE and host molecules are observed using the ACSTM magnitude signal. The stability of the ACSTM magnitude correlates to the stability of the switches in our samples. From this, we can determine which molecules are more likely to exhibit motion and/or switching events and which molecules will remain stable in our images.

Probing Single-Molecule Electronics and Dynamics
Amanda M. Moore, Department of Chemistry, The Pennsylvania State University, University Park, PA 16802-6300, USA

We have studied oligo(phenylene-ethylene) (OPE) molecules as candidates for molecular electronic switches using molecular engineering, scanning tunneling microscopy and spectroscopy. These molecules were inserted into host alkanethiolate self-assembled monolayers for isolation and individual addressability. Many different hypotheses and theoretical predictions have been put forth to describe conductance switching. We have assessed each through varying the molecular design of our switches and have concluded that the only mechanism consistent with all the switching data is changes in hybridization at the molecule-substrate bond. Furthermore, we have determined which molecules will be more or less active in our samples using a custom-built tunable microwave-frequency alternating current scanning tunneling microscope. The polarizabilities of the OPE molecules were observed using the microwave difference frequency magnitude signal. The stability of the difference frequency magnitude correlates to the stability of the switches in our samples. From this, we can determine which molecules are more likely to exhibit motion and/or switching events and which molecules will remain stable in sequential images.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Exploring and Controlling the Atomic-Scale World
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Selecting and Driving Nanoscale Assembly in Monolayer Films through Tailored Intermolecular Interactions
T. J. Mullen, C. Srinivasan, M. J. Shuster, S. E. Brunker, L. M. Dominak, J. N. Hohman, A. A. Dameron, M. W. Horn, C. D. Keating, A. M. Andrews, and P. S. Weiss, Departments of Chemistry, Engineering Science & Mechanics, Physics, and Veterinary & Biomedical Science, The Pennsylvania State University, University Park, PA 16802-6300, USA

Nanoscale Self- and Directed Assembly
T. J. Mullen, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Introducing ACS Nano
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Biocapture Surfaces and Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics and Anne M. Andrews, Department of Veterinary and Biomedical Science, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film.

We employ some of these approaches in directed assembly and chemical patterning to enable bioselective and biospecific binding. These probes are isolated in well-defined matrices and spaced at the sub-10-nanometer scale using combinations of soft lithography, conventional lithography, and self-assembly. We have developed the patterning tools, as well as the diagnostics and metrology tools for these new chemically patterned structures.

We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Creating and Probing Molecular Assemblies for Single-Molecule Devices
Amanda M. Moore, Department of Chemistry, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

How Can We Impact the Future with (New Materials,) New Methods and New Measurements?
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Biocapture Surfaces and Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, and Anne M. Andrews, Department of Veterinary and Biomedical Science, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film.

We employ some of these approaches in directed assembly and chemical patterning to enable bioselective and biospecific binding. These probes are isolated in well-defined matrices and spaced at the sub-10-nanometer scale using combinations of soft lithography, conventional lithography, and self-assembly. We have developed the patterning tools, as well as the diagnostics and metrology tools for these new chemically patterned structures.

We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Application of Fluorescence Spectroscopy in the Development of Small-Molecule Capture Surfaces
Roya Nezarati, Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27607, USA

Neurotransmitters are small molecules that are responsible for communication between neurons. The focus of this research is to develop a small-molecule-functionalized surface for selective capture of each studied small molecule’s binding partners. These surfaces have been investigated for chemical functionalization using grazing angle Fourier-transform infrared spectroscopy (FT-IR). We developed a novel method based on surface functionalization on a thin gold film of 15 nm on a glass slide and further detect binding of large biomolecule binding partners using fluorescence spectroscopy. With this method, we obtained a biofunctionalized surface that was then exposed to primary antibody specific for serotonin followed by Alexa Fluor 488 tagged secondary antibody specific only to the serotonin antibody. Viewing the binding events using fluorescence spectroscopy revealed non-specific binding that was ameliorated by annealing the gold substrate for 20 hours at 215 °C. Incubating the functionalized surfaces in different molar ratios of immobilized rabbit anti-serotonin polyclonal antibody and rat monoclonal antibody demonstrated good specificity and selectivity of binding events. This research may have various applications ranging from the identification of important neuronal proteins and their binding partners and the development of drugs for various neurological diseases.

A new family of self-assembled monolayers: Carboranethiols on Au{111}
J. Nathan Hohman, Moonhee Kim, Elizabeth I. Morin, Viktor Balema, and Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

The self-assembly of carboranethiol derivatives on Au{111} represents an exciting new family of self-assembled monolayers (SAMs). Monolayers of these inorganic\organic hybrid molecules are well-ordered, displaying ad-vacancies and rotational domain boundaries. Carboranethiolate SAMs do not induce substrate vacancy islands characteristic of n-alkanethiolate SAMs. In addition, the carborane cage is amenable to a wide range of functionalization chemistries that opens the door to tailored intermolecular interactions¹ and post-adsorption modification. We have characterized the SAMs of structural isomers of several mono- and dicarboranethiols and associated defect modes by scanning tunneling microscopy; cyclic voltammetry; x-ray photoelectron spectroscopy; and grazing-angle Fourier transform infrared spectroscopy. Carboranethiolate SAMs are air stable and resist chemical exchange in the presence of n-alkanethiols. The behavior of carboranethiol SAMs in the presence of n-alkanethiol is in stark contrast to similarly-sized and labile adamantanethiolate SAMs.²

1. Smith et al., JPCB 105, 1119 (2001). Lewis et al., JPCB 105, 10630 (2001). Mullen et al., Materials Matters 1 (2), 8 (2006).
2. Dameron et al., JACS 127, 8697 (2005). Dameron et al., Nano Letters 5, 1834 (2005). Dameron et al., JVSTB 23, 2929 (2005).

Structural isomerism in self-assembled monolayers
Moonhee Kim, J. Nathan Hohman, and Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Self-assembly of adamantanethiols on metal surfaces provide valuable insight into the energetic and geometric factors of self-assembled monolayer (SAM) formation beyond n-alkanethiolates. These cage-tethered SAMs also generate unique molecular topologies and intermolecular interactions for advanced applications such as selective displacement. We have characterized SAMs of two adamantanethiol structural isomers, 1-adamantanethiol and 2-adamantanethiol on Au{111} using scanning tunneling microscopy and other techniques. These molecules generate different surface structures in order to optimize their intermolecular interactions. While adsorbed 1-adamantanethiol molecules maintain equal interaction strengths from the surrounding 6 molecules in hexagonal close-packed lattices, 2-adamantanethiol molecules must twist to orient themselves to increase van der Waals interactions between neighboring molecules. Both 1- and 2-adamantanethiol SAMs are labile in the presence of n-alkanethiols, resulting in their displacement. The different lattice structures of 1- and 2-adamantanethiolate SAMs dictate the kinetics and dynamics of the displacement process, and the unique lattice structure of 2-adamantanethiol drives n-alkanethiolates to adopt a similar pattern after displacement.

Quantitative Scanning Probe Measurements of Single Atoms, Molecules and Assemblies: Preserving and Understanding Heterogeneity
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We measure these interactions and the electronic perturbations that underly them using scanning tunneling microscopy. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while still retaining all the single molecule and environmental information.^1-3 This requires new automated tools for acquisition and analyses. We also use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means.^4,5 Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements.

1. Imaging Substrate-Mediated Intermolecular Interactions, M. M. Kamna, S. J. Stranick, and P. S. Weiss, Science 274, 118 (1996).
2. Long-Range Electronic Interactions at High Temperature: Bromine Adatom Islands on Cu{111}, S. U. Nanayakkara, E. C. H. Sykes, L. C. Fernandez-Torres, M. M. Blake, and P. S. Weiss, Physical Review Letters 98, 206108 (2007).
3. Analyzing the Motion of Benzene on Au{111}: Single Molecule Statistics from Scanning Probe Images, B. A. Mantooth, E. C. H. Sykes, P. Han, A. M. Moore, Z. J. Donhauser, V. H. Crespi, and P. S. Weiss, Journal of Physical Chemistry C 111, 6167 (2007).
4. Molecular Engineering of the Polarity and Interactions of Molecular Electronic Switches, P. A. Lewis, C. E. Inman, F. Maya, J. M. Tour, J. E. Hutchison, and P. S. Weiss, Journal of the American Chemical Society 127, 17421 (2005).
5. Molecular Engineering and Measurements to Test Hypothesized Mechanisms in Single-Molecule Conductance Switching, A. M. Moore, A. A. Dameron, B. A. Mantooth, R. K. Smith, D. J. Fuchs, J. W. Ciszek, F. Maya, Y. Yao, J. M. Tour, and P. S. Weiss, Journal of the American Chemical Society 128, 1959 (2006).

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Exploring and Controlling the Atomic-Scale World: Life in the Weiss Group
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Neurotransmitter Chips
Ashley Gibb, Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802 USA

Switchable Lability of Self-Assembled Monolayers via an in situ Chemical Reaction
Christopher M. Thompson, Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802 USA

We describe the enhancement of the lability of two carboxylic acid terminated self-assembled monolayers via in situ Fischer esterification, which results in subtle chemical and structural defects within the monolayer that promote molecular exchange reactions to completion with n-dodecanethiol molecules. The complementary hydrolysis reaction was also employed to quench the reacted monolayers, returning them to their original non-labile state. The generality of the technique lends itself to serve as a resist layer for soft lithographic techniques such as mircodisplacement printing to fabricate complex functional surfaces.

Carboranethiol Dipoles May Direct Surface Chemistry
Elizabeth Morin, Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802 USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Quantitative Chemical Measurements at the Atomic Scale
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We use quantitative measurements of these interactions to illustrate approaches to making statistically significant data sets, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the single molecule and environmental information. This requires new automated tools for acquisition and analyses. This approach in combination with multiple modalities of atomic-resolution measurements enables new insights into surface chemistry, molecular function, and precise and hierarchical assembly.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We employ some of these approaches in directed assembly to enable bioselective and biospecific binding. We also selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We now apply these strategies to photo-driven, electrochemically-driven, and chemically-driven motion in single molecules and assemblies. This enables us to address how concerted nano-scale motions can be used to drive motion at larger scales. The atomic-scale details provide surprising and useful insights into the limitations and opportunities of cooperative motion.

Atomic-Scale Chemical, Physical and Electronic Properties of the Subsurface Hydride of Palladium
Adam R. Kurland, Patrick Han and Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We will elucidate the chemical, physical and electronic properties of the subsurface hydride of Pd, the key material and reactant, hypothesized to be critical both to hydrogenation reactions and metal embrittlement, and a model for hydrogen storage. We are able to create this species for direct measurement and for use as a chemical reagent. We will utilize our unique ultrastable scanning tunneling microscope (STM) for these studies. With insight gained from these STM measurements, we will develop more general methods for the preparation and study of this reagent. We will also determine how far such atomic manipulation techniques can be extended.

Exploring and Controlling the Atomic-Scale World
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Quantitative Measurements of Single-Molecule Dynamics: Intermolecular Potentials and Functional Properties
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We use quantitative measurements of these interactions to illustrate approaches to making statistically significant data sets, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the single molecule and environmental information. This requires new automated tools for acquisition and analyses. This approach in combination with multiple modalities of atomic-resolution measurements enables new insights into surface chemistry, molecular function, and precise and hierarchical assembly.

Molecular Motion Driven by Electric Field, Light, and Charge
Dongbo Li, Ajeet Kumar, and Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

There has been significant interest and activity in understanding and mimicking nature's complex molecular machines. Artificial molecular machines are capable of performing mechanical movements at the atomic and molecular scales in response to external stimuli, thereby opening the potential for fabrication of nanoelectromechanical devices. Based on self-/directed assembly techniques, we have developed various types of single-molecule motors, which can be triggered by light, electric field, and charge, in precise nanoscale assemblies on a substrate. Using the combination of scanning tunneling microscopy (STM) and a variety of microscopic methods, we have measured the motions of the isolated molecules and assemblies at the nanometer scale.

We show here three examples of molecular machines, which have the capability to convert electrical, optical, and chemical energy into mechanical motion. Oligo(phenylene ethynylene) molecules are shown to undergo stochastic and driven switching in the highly localized electric field of the STM tunnel junction.¹ Azobenzene-functionalized molecules, which are isolated in tailored alkanethiolate monolayer matrices, exhibit reversible conformational changes under irradiation by UV/visible light.² In the case of redox-controllable palindromic bistable rotaxane molecules (artificial molecular muscles), microscale motions are generated in a cantilever actuator by oxidation/reduction in an electrochemically controlled system.³

1. Lewis, P. A.; Inman, C. E.; Maya, F.; Tour, J. M.; Hutchison, J. E.; Weiss, P. S. Molecular Engineering of the Polarity and Interactions of Molecular Electronic Switches. J. Am. Chem. Soc. 2005, 127, 17421-17426.

2. Kumar, A. S.; Ye, T.; Takami, T.; Yu, B.-C.; Flatt, A. K.; Tour, J. M.; Weiss, P. S. Reversible Photo-Switching of Single Azobenzene Molecules in Controlled Nanoscale Environments. Nano Lett. 2008, 8, 1644-1648.

3. Juluri, B. K.; Kumar, A. S.; Liu, Y.; Ye, T.; Yang, Y. W.; Flood, A. H.; Stoddart, J. F.; Weiss, P. S.; Huang, T. J. A Nanomechanical Actuator Driven Electrochemically by Artificial Molecular Muscles. Submitted for publication.

New Families of Molecules for Self-Assembly and Three-Dimensional Superstructures
J. Nathan Hohman,¹ Moonhee Kim,¹ Hector M. Saavedra,¹ Pengpeng Zhang,¹ Elizabeth I. Morin,¹ Viktor Balema,² and Paul S. Weiss¹

¹Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA. http://www.nano.psu.edu/
²The Sigma Aldrich Corporation, St. Louis, MO 63103, USA.

The self-assembly of cage molecules on metal surfaces provides valuable insight into the energetic and geometric factors of self-assembled monolayer (SAM) formation. Molecules such as adamantanethiols and carboranethiols generate similar three-dimensional superstructures, but the intermolecular interactions between the molecules lead to striking differences in their behavior within monolayers. We have characterized SAMs of structural isomers of several mono-carboranethiols and 1- and 2-adamantanethiol. In each case, their defect modes are investigated by scanning tunneling microscopy, cyclic voltammetry, and grazing-angle Fourier transform infrared spectroscopy. While all these SAMs are air stable and form well-ordered hexagonal lattices on Au{111}, we see large differences in the stabilities of the monolayers in competitive binding and exchange environments. The adamantanethiolates are susceptible to displacement by n-alkanethiols, while the carboranethiolates are not. We discuss the effects of defect modes and intermolecular forces in order to understand the differences in behavior for these structurally similar monolayers.

The Importance and Surprising Roles of Contacts in Molecular Electronics
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We find that the contacts and substrate play critical roles in the switching. Switching of rigid, conjugated molecules is due to changes the molecule-substrate bonds, which involves motion of the molecules and also motion of substrate atoms. We are able to measure the coupling of the electrons of the molecules to those of the substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.

Quantitative Measurements of Adsorbate Interactions and Dynamics: Intermolecular Potentials and Functional Properties
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Biospecific Recognition of Serotonin-Functionalized Materials
Mitchell Schuster and Amit Vaish, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

New Families of Molecules for Self-Assembly
Nate Hohman, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Effects of Embedded Dipoles on the Electrical Response of Self Assembled Monolayers
P. P. Zhang, O. M. Cabarcos, T.A. Daniel, Paul S. Weiss, and D. L. Allara, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

There has been recent interest in the use of polar molecules assembled at electrodes for tuning work functions and engineering charge injection barriers in organic electronic devices. With this in mind we have been investigating the electrostatic properties of simple model systems prepared from self-assembled alkanethiolate monolayers on Au{111} with the incorporation of an embedded ester moiety [-(CO2)- = E] in the adsorbate molecules. The intrinsic static dipole moment of the ester moiety of ~1 Debye magnitude leads to the formation of a strong, highly organized, planar electric dipole layer in the SAM. From our previous X-ray photoelectron spectroscopy data we observe a consistent shift of the C 1s photoelectron kinetic energies between the top and bottom alkyl segments, defined as -(CH2)-E-(CH2)_nCH3, regardless of the relative lengths m and n. This shift correlates well with the value of the electrostatic potential across the E layer. Our recent surface potential AFM measurements, however, reveal an apparently anomalous strong dependence of surface potential on the sizes and ratios of m and n, in contrast to the constant electrostatic potential observed in XPS measurements. Mechanisms underlying these effects will be discussed, with possible implications for the electrostatic behavior of more complicated organic and biological systems.

In search of brain nanobiosensors: Small-molecule recognition and biomolecule capture as critical first steps
Anne M. Andrews, Department of Veterinary & Biomedical Sciences, Amit Vaish, Mitchell J. Shuster, Paul S. Weiss, Departments of Chemistry and Physics, and The Pennsylvania State University, University Park, PA 16802-6300, USA

To explore interneuronal signaling in the central nervous system at length and time scales pertinent to its intrinsically encoded information, and to relate this information to complex behavior, as well as brain disorders and new treatment and prevention strategies, chemically specific in vivo nanobiosensors are needed that approach the sizes of synapses (ca. 20 nm) and respond in milliseconds. Using highly specific functionalization chemistries and nanoscale self-assembly and patterning strategies, we demonstrate that large biomolecules, including antibodies or membrane-associated receptor proteins with high affinity for serotonin or dopamine, can be selectively captured from solution by tethered small-molecule neurotransmitters or closely related molecules with minimal nonspecific binding. We are using neurotransmitter-functionalized surfaces to capture and to identify high-affinity molecular-recognition elements for future use with semiconductor nanowire or carbon nanotube platforms to create ultrasmall, multiplexed sensing devices to revolutionize in vivo sensing and functionally directed proteomics.

Nanoscale Chemical Patterning
Paul S. Weiss, Departments of Chemistry and Physics, and Anne M. Andrews, Department of Veterinary & Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802-6300, USA

We exploit our ability to control self- and directed assembly at the sub-nanometer scale in order to extend and to enhance soft and hybrid lithographies. The interactions between molecules can be tailored, controlled, and directed. The complex chemical patterns created include isolated molecules placed in high-quality matrices with designed interactions and environments. These can be used to control molecular function, biospecificity and other properties. We have prepared monolayers that are labile, so as to enable selective displacement, and have elucidated the mechanistic details of displacement. Isolating molecules has significant advantages in preserving patterned nanostructures during further functionalization. We also describe new metrology tools being developed for patterning and chemistry at this scale.

Precise Clusters, Superatoms, and Cluster-Assembled Materials
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We examine single, isolated atomically precise assemblies in order to elucidate their properties. Specifically, we use self-assembly and insertion strategies to place and to tether atomically precise clusters; then, we use ultrastable, low-temperature, extreme high vacuum scanning tunneling microscopy and spectroscopy to measure these cluster assemblies. Surprisingly, we find that such assemblies can have unstable electronic properties. We use these same strategies to prepare other cluster-capture surfaces, and to test the chemistry and stability of superatom clusters. We build precise clusters into cluster-assembled materials. We compare the properties of the bulk materials to their component parts. These enable us to tune component properties, lattice parameters, and thus coupling and materials properties through the careful selection and assembly of building blocks. We seek to address the key question as to the extent of coupling between clusters, and thus the tunability of the properties in these cluster-assembled materials.

Designing, Measuring, Assembling, and Operating Synthetic Molecular Motors
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We study motion in single synthetic molecules and assemblies driven by electric fields, light, electrochemical potentials, or chemical interactions. We control the motions of individual molecules and determine the underlying phenomena responsible for motion or actuation, as well as the related factors that limit motion. Each of these measurements requires specialized nanoscale analysis tools. We also use new acquisition and analysis tools to acquire and to mine statistically significant functional data sets on driven motion. We are thereby able to vary molecular designs, environmental conditions, measurement conditions, and other aspects in order to understand and to optimize driven motion. We assemble these systems to understand concerted operation, in analogy to hierarchical assemblies of biomolecular motors enabling motion in living systems. We address how concerted nanoscale motions can be used to drive motion at larger scales in synthetic systems. The nanoscale details provide surprising and useful insights into the limitations of and opportunities for cooperative motion.

5-Hydroxytryptophan-functionalized self-assembled monolayers capture native membrane-associated serotonin receptors
Amit Vaish, Mitchell J. Shuster, Paul S. Weiss, Departments of Chemistry and Physics, and Anne M. Andrews, Department of Veterinary & Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802-6300, USA

We have developed methods to tether small molecules to self-assembled monolayers (SAMs) at necessarily low surface coverages so as to retain sufficient chemical functionality for recognition by large biomolecules. We chose the neurotransmitter serotonin as a prototypical small molecule because of its importance in psychiatric disorders. The amino acid precursor of serotonin, 5-hydroxytryptophan (5-HTP) was covalently bound to oligoethyleneglycol alkanethiol SAMs by carbodiimide coupling chemistry. Surface chemistry was analyzed by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Using quartz crystal microgravimetry, we demonstrate that 5-HTP-functionalized surfaces show low nonspecific binding. They selectively capture anti-5-HTP antibodies or recombinant receptors that natively recognize free serotonin vs. receptors for other neurotransmitters with similar structures. Previously studied serotonin-functionalized surfaces fail to show binding of membrane-associated serotonin receptors. Our findings suggest that the lack of recognition of tethered serotonin itself is due to masking of primary amines by the tethering chemistry.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We look at how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We demonstrate the importance of these junctions in conductance switching of single molecules. We find that the contacts and substrate play critical roles in the switching. Switching of rigid, conjugated molecules is due to changes the molecule-substrate bonds, which involves motion of the molecules and also motion of substrate atoms. We are able to measure the coupling of the electrons of the molecules to those of the substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.

Eyes of the 21st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Eyes of the 21st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Exploring and Controlling the Atomic-Scale World
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Nanoscale Chemical Patterning
Paul S. Weiss, Departments of Chemistry and Physics, and Anne M. Andrews, Department of Veterinary & Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802-6300, USA

We exploit our ability to control self- and directed assembly at the sub-nanometer scale in order to create nanoscale chemical patterns, as well as to extend and to enhance soft and hybrid lithographies. The interactions between molecules can be tailored, controlled, and directed. We have designed and assembled new families of molecules for patterning, and have tested the properties that affect their interactions, quality, and controllability. We have prepared molecular monolayers that are labile, so as to enable selective displacement, and have elucidated the mechanistic details of displacement. The complex chemical patterns created include isolated molecules placed in high-quality matrices with designed interactions and environments. These can be used to control molecular function, biospecificity and other properties. Isolating molecules has significant advantages in preserving patterned nanostructures during further functionalization. We also describe metrology tools being developed for patterning and chemistry at this scale.

Quantitative Measurements of Adsorbate Interactions and Dynamics: Intermolecular Potentials and Functional Properties
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We use quantitative measurements of these interactions to illustrate approaches to making statistically significant data sets, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the single-molecule and environmental information. This requires new automated tools for acquisition and analyses. This approach in combination with multiple modalities of atomic-resolution measurements enables new insights into surface chemistry, molecular function, and precise and hierarchical assembly.

Quantitative Measurements of Adsorbate Interactions and Dynamics
Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We use quantitative measurements of these interactions to illustrate approaches to making statistically significant data sets, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the single-molecule and environmental information. This requires new automated tools for acquisition and analyses. This approach in combination with multiple modalities of atomic-resolution measurements enables new insights into surface chemistry, molecular function, and precise and hierarchical assembly.

Eyes of the 21st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Constructivist Education at the Interdisciplinary Borders and Frontiers
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.

Keywords: Molecular Devices, Self-Assembly, Scanning Tunneling Microscopy, Scanning Tunneling Spectroscopy.

Eyes of the 21st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, all the way to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.

Eyes of the 21st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, all the way to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.

Eyes of the 21st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, all the way to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA

Photo-switching of single-molecule and one-dimensional assemblies of azobenzene molecules in precise nanoscale environments
Ajeet S. Kumar, Bala K. Pathem, David A. Corley, James M. Tour, and Paul S. Weiss, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802-6300, USA, Department of Chemistry, Rice University

Molecules that control position and conduction at the nanometer scale have great promise for future devices. Azobenzene molecules having two conformational isomers (trans- and cis-) are well-known candidates for optoelectronic switches. We drive reversible photo-induced switching of single azobenzene-functionalized molecules isolated in tailored alkanethiolate monolayer matrices on Au{111}. Control over photo-switching was achieved by appropriately designing the tether and tuning the rigid assembly of the molecule to limit surface quenching and non-photo-induced switching effects. Trans and cis conformations were imaged using the scanning tunneling microscope (STM). Features in the images were assigned to ON (trans) and OFF (cis) states of the molecule, respectively. Control over single-molecule switching is attractive, but integration of such single-molecule switches into larger circuits and assemblies remains a major challenge for molecular devices. We assembled precisely defined 1D linear chain structures of azobenzene-functionalized molecules using directed self-assembly. We controlled in situ photo-switching of these linear chains and studied the effects of local environments and coupling on switching efficiency.

1. Kumar et al., Nano Lett. 8, 1604 (2008).

Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function [1]. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.

References
[1] P. S. Weiss: Acct. Chem. Res. Vol. 41 (2008), p. 1772

Designing, Measuring, and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

We use molecular design, tailored syntheses, intermolecular interactions and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function [1]. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules with predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.

References
[1] P. S. Weiss: Acct. Chem. Res. Vol. 41 (2008), p. 1772

Eyes of the 21^st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, all the way to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.

Eyes of the 21^st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, all the way to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.

Eyes of the 21^st Century: Precise and Hierarchical Control of Chemical Functionality from the Wafer Scale Down to Single Molecules and Supramolecular Complexes
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA

New and Upcoming Views from the Nanoscale: Precise and Hierarchical Control of Molecular Assemblies, Function, and Interactions
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA

Controlling Adsorbate Interactions for Advanced Chemical Patterning
H. M. Saavedra, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

Scanning Tunneling Microscopy and Spectroscopy of Nanoscale Assemblies
M. Blake, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

Controlling the Placement and Environments of Molecules at All Scales: New Strategies and Chemistries
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies.

Controlling the Placement and Environments of Molecules at All Scales: New Strategies and Chemistries
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA; Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA

We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies.

Directed assembly and subsequent photomodulation of anthracene-terminated phenylethynylthiolate molecules provide a means to control charge transfer in molecular switches. These fully conjugated molecules were selectively inserted as lone molecules, or in pairs, into defect sites of n alkanethiolate monolayers on Au{111}. Control of the assembly and a fixed molecular conformation on the surface allow a regioselective [4+4] cycloaddition between adjacent anthracene moieties under ultraviolet illumination. This photodimerization breaks the delocalized ¥ð network of the anthracene, which results in a dramatic conductivity decrease, observed as a photomodulated ¡°off¡± state. The reaction between molecules also reduces stochastic conductance switching.

We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies.

Interactions within and between surface adsorbates can be designed, directed, measured, understood, and exploited at unprecedented scales. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the single-molecule and environmental information. This requires new automated tools for acquisition and analyses. This approach, in combination with multiple modalities of atomic-resolution measurements, enables new insights into precise and hierarchical assembly, as well as function at the nanoscale.

Controlling the Placement and Environments of Molecules at All Scales: New Strategies and Chemistries
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA

We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies.

We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This, in turn, is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies.

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9 February 2010
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