February 2000

Oregon Academy of Science Meeting

February 26, George Fox University

Abstracts:

• Preparation of Ligand Stabilized, Water-Soluble Gold Nanoparticles through Ligand Exchange

Marvin G. Warner, Scott M. Reed, and James E. Hutchison, Dept. of Chemistry and Materials Science Institute, University of Oregon, Eugene, OR 97403-1253.

Ligand stabilized gold nanoparticles with a small core size (d_CORE< 2 nm) have generated a great deal of interest as possible building blocks for nanoelectronic devices that operate at room temperature. Traditionally, methods available to prepare gold nanoparticles produce only organic soluble species passivated by phosphine and chloride ligands (e.g. Au₅₅(PPh₃)₁₂Cl₆) or by thiol ligands (e.g. Au₆₄(SR)₃₄). It is our desire to prepare nanoparticles with a wider range of solubilities. A new approach employs a biphasic ligand exchange reaction in which an entering water-soluble thiol ligand (mercaptoethanesulfonic acid and (N,N-dimethylamino)ethanethiol hydrochloride) replaces the phosphine and chloride ligands of the Au₅₅(PPh₃)₁₂Cl₆ nanoparticles. This method provides a general approach to water-soluble gold nanoparticles containing a variety of passivant ligand shells. Characterization of these nanoparticles to determine composition, size, and dispersity involves a combination of ¹H and ¹³C spectroscopies, XPS, UV-visible spectroscopy, AFM, and TEM. The nanoparticles are seen to preserve the small core size of the phosphine parent and display marked stability over the phosphine stabilized starting nanoparticle. Future work discussing methods of rational assembly of these nanoparticles will be presented.

• The Environmentally-Benign (Green) Organic Chemistry Laboratory Curriculum at the University of Oregon.

James E. Hutchison, Kenneth M. Doxsee, Scott M. Reed, Marvin G. Warner and W. Brad Wan.

Green chemistry applies a set of principles that reduces or eliminates the use or formation of hazardous substances in the design, manufacture and application of chemical materials. Although green synthesis and manufacturing methods are beginning to find application in industry, few examples of green chemistry experiments are available for use in the organic teaching lab. We have developed a two-term series of experiments and supporting lecture material based upon the recent advances in green chemical methods. We will describe the curriculum and present the approach that we took in selecting, testing and optimizing the lab experiments for this course. In addition, the advantages of this curriculum will be emphasized, including improved laboratory safety, reduced wastestream, more realistic macroscale reactions, use of state-of-the-art green chemical concepts (e.g. recycling, hazard reduction, solvent reduction), and a platform for discussion of environmental issues in the classroom.

March 2000

Spring ACS Meeting

Scott Reed, Professor Hutchison, and Walter Weare will have posters. Reed will also give a talk.

Abstracts:

• Development of environmentally benign (green) laboratory experiments for an introductory organic lab course

Scott M. Reed, Marvin G. Warner, and James E. Hutchison.

Environmentally benign or green chemical techniques are growing in importance in academic and industrial research laboratories. Such chemistry has been slow to appear in teaching laboratories due, in part, to a lack of published material on this subject. We have been developing experiments for use in a green organic chemistry course, and present here the methods by which we selected, tested and optimized experiments for this course. As an example, we present a laboratory experiment for the synthesis of adipic acid that was developed from the primary literature. This synthesis utilizes green reagents (hydrogen peroxide as the oxidant), solvents (water) and methods (phase transfer catalysis, catalyst recycling). It provides students a first hand example of environmentally benign synthesis by demonstrating reuse of a product, synthesis using a non-hazardous solvent, elimination of deleterious by-products, and use of a recyclable catalyst.

Poster presentation in the Division of Chemical Education (General Posters)

• Electron transfer through peptide-containing alkanethiol assemblies

Scott M. Reed, Robert S. Clegg, Athena Klock, and James E. Hutchison.

Accurate measurement of electron transfer (ET) rates requires precise control of the distance between electron donor and acceptor. Measurement of ET through peptides is therefore complicated by the inherent conformational flexibility of proteins. We have developed a peptide-containing alkanethiol thin film model system that allows for the measurement of ET through different peptide fragments (1-3 amino acids in length) whose confirmations are constrained within a molecular assembly that is covalently attached to a gold electrode. We will present evidence from X-ray photoelectron spectroscopy, infra-red spectroscopy, contact angle measurements, and electrochemical experiments that these peptide-containing films possess the requisite order for accurate measurement of ET. We have recently synthesized two families of peptide-containing alkanethiols with pendant redox probes and will present electrochemical characterization of a series of these films containing one through three amides. Initial investigations suggest that the ET rate constant for amide material is higher than for alkanes.

Oral presentation in the Division of Inorganic Chemistry (Electron Transfer session)

• Metal nanoparticles chemically assembled on biomolecular scaffolds: Structure, stability, and electron-transport properties

James E. Hutchison, Martin N. Wybourne², Jana Mooster¹, Laura I. Clarke², Leif O. Brown¹, Scott M. Reed¹, and Mary E. Schmidt¹. (1) Department of Chemistry, University of Oregon (2) Department of Physics and Astronomy, Dartmouth College

The novel electronic properties (e.g., Coulomb blockade) of nanometer scale assemblies of metal nanoparticles make them potentially useful in nanoelectronic devices and extremely sensitive chemosensors. To date, no straightforward and reproducible methods are available for the fabrication of low-dimensional nanoparticle assemblies. Our method for nanofabrication of linear nanoparticle arrays involves the assembly of functionalized metal nanoparticles onto rigid biomolecular scaffolds cast upon an insulating substrate and bridged between narrowly spaced electrodes. Our previous investigations of unpatterned nanoparticle thin films provided clear evidence of Coulomb blockade at room temperature, but the response was unstable over time. In this paper we present a wet chemical approach to preparing one- and two-dimensional arrays of gold nanoparticles assembled onto a polypeptide (poly-L-lysine) scaffold layer. The assembly process provides a simple, chemical method to immobilize the particles and is found to stabilize the electrical response (Coulomb blockade) of the array compared with unpatterned samples.

To be presented in two different poster sessions:

(1) Division of Inorganic Chemistry Poster Session II: Organometallics, Ziegler-Natta, Catalysts, Materials, General
(2) Sci-Mix

• Large-scale synthesis of near-monodisperse, sub 2 nm, triphenylphosphine-stabilized gold nanoparticles

James E. Hutchison, Walter W. Weare, Scott M. Reed, Marvin G. Warner, and Mary E. Schmidt. Department of Chemistry, University of Oregon, 1253 University of Oregon, Eugene, OR 97403-1253, fax: 541-346-0487, hutch@oregon.uoregon.edu

Larger scale synthetic methods are needed if nanoparticles are to become important building blocks in the production of a wide range of technologically useful materials. We have developed a unique biphasic synthesis for triphenylphosphine stabilized gold nanoparticles that safely and easily produces gram quantities of nanoparticle material. Here we will present the synthetic scheme, characterization of the material, and comment on the implication of the synthesis on theories of nanoparticle formation and growth. Characterization of the nanoparticle products utilizes electron microscopy and powder X-ray diffraction for size analysis, with X-ray photoelectron spectroscopy and thermogravimetric analysis used to determine elemental composition. We will show the utility of this material in ligand exchange chemistry through the synthesis of thiol-stabilized derivatives for study in nanoelectronic materials.

To be presented in two different poster sessions:

(1) Division of Colloid and Surface Chemistry: Session on Surfactants, Colloids, and Applications

(2) Sci-Mix

Past Presentations (From January 1, 1999)

Seminars:

"Toward Molecular Electronics: New Approaches Toward the Preparation of Nanoscale Wires and Devices," Idaho State University, Pocotello, Idaho, January 21, 2000.

“Chemical Assembly and Electrical Characteristics of Biopolymer Templated Nanoparticle Structures,” Stanford University, Palo Alto, California, October 5, 1999.

“Chemical Assembly and Electrical Characteristics of Biopolymer Templated Nanoparticle Structures,” Colorado State University, Fort Collins, Colorado September 14, 1999.

“Chemical Assembly and Electrical Characteristics of Biopolymer Templated Nanoparticle Structures,” University of Wyoming, Laramie, Wyoming, September 10, 1999.

“Chemical Assembly and Electrical Characteristics of Biopolymer Templated Nanoparticle Structures,” Northwestern University, Evanston, Illinois, May 21, 1999.

“Toward Biomolecular Lithography: Synthesis, Functionalization and Biomolecule-Assisted Assembly of Gold Nanoparticles,” Boise State University, Boise, Idaho, March 5, 1999.

“Toward Biomolecular Lithography: Synthesis, Functionalization and Biomolecule-Assisted Assembly of Gold Nanoparticles,” Eastern Oregon State University, La Grande, Oregon, February 2, 1999.

Presentations:

“Functionalized Gold Nanoparticles; a Study on the Effect of Incorporating a Protein Binding Ligand into an Alkanethiol Passivated Nanoparticle,” W. W. Weare, S. M. Reed, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Synthesis of Peptide Containing Alkanethiols,” A. Klock, S. M. Reed, R. K. Smith, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Investigations of Stability in Hydrogen-Bonding Self-Assembled Monolayers,” R. K. Smith, R. S. Clegg, A. Klock, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Synthesis of Regioregular Poly(4-Substituted-2,2-Bithiophene)S: Potential Precursors to Organized Conjugated Polymer Solids,” B. D. Straw, S. C. Rasmussen, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Biomolecular Templating of Gold Nanoparticles,” S. M. Reed, W. W. Weare, L. O. Brown, M. G. Warner, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Measurement of the Material Dependence of Electron Transfer Upon Peptide Material,” R. S. Clegg, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Principles for Design of Ordered, Stratified, Self-Organized Supramolecular Assemblies,” R. S. Clegg, S. M. Reed, R. K. Smith, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Assembly of Nanoparticles on Biomolecular Scaffolds: The Influence of Polypeptide Scaffolds on Assembly Stability and the Characteristics of Electron Transport,” L. Clarke, M. N. Wybourne, J. Mooster, L. O. Brown, S. M. Reed, J. E. Hutchison, 54^th Northwest Regional Meeting of the American Chemical Society, Portland, Oregon, June 20-23, 1999.

“Thermal and Solvent Stability of Self-Assembled Monolayers Cross-Linked by Hydrogen Bonds,” R. S. Clegg, R. K. Smith, A. Klock, J. E. Hutchison, 73^rd American Chemical Society Colloid and Surface Science Symposium, Cambridge, Massachusetts, June 13-16, 1999.

“Assembly of Nanoparticles on Biomolecular Scaffolds: The Influence of Polypeptide Scaffolds on Assembly Stability and the Characteristics of Electron Transport,” L. Clarke, J. Mooster, L. O. Brown, S. M. Reed, M. N. Wybourne, J. E. Hutchison, 73^rd American Chemical Society Colloid and Surface Science Symposium, Cambridge, Massachusetts, June 13-16, 1999.

“Electron Transfer Through Peptide Backbones in Self-Assembled Monolayers,” R. S. Clegg, J. E. Hutchison, 73^rd American Chemical Society Colloid and Surface Science Symposium, Cambridge, Massachusetts, June 13-16, 1999.

“Ligand Exchange Reactions of Phosphine-Stabilized Gold Nanoparticles: Controlled Particle Functionalization and Growth,” J. E. Hutchison, L. O. Brown, S. M. Reed, 73^rd American Chemical Society Colloid and Surface Science Symposium, Cambridge, Massachusetts, June 13-16, 1999.

“Electron Transfer Through Peptide Chains in Monolayer Assemblies,” R. S. Clegg, J. E. Hutchison, 195^th Meeting of the Electrochemical Society, Inc., Seattle, Washington, May 2-6, 1999.

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