Electrochemical and photophysical properties of various Au38 nanoparticles protected by mixed-monolayer ligands

ANYL 44

Jai-Pil Choi, jpchoi@email.unc.edu, Kenan Laboratories of Chemistry, University of North Carolina, Chapel Hill, NC 27599, Balasubramanian Ramjee, ramjee@email.unc.edu, Kenan Laboratories of Chemistry, University of North Carolina at Chapel Hill, CB 3290, Chapel Hill, NC 27599, Joseph M. DeSimone, desimone@unc.edu, NSF Center for Environmentally Responsible Solvents and Processes, Department of Chemistry, University of North Carolina, CB# 3290, Venable Hall, Chapel Hill, NC 27599-3290, and Royce W. Murray, rwm@email.unc.edu, Kenan Laboratories of Chemistry and NSF Science & Technology Center for Environmetally Responsible Solvents and Processes, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
We report that the fundamental properties of Au38 nanoparticles could be affected by their surface protecting ligands. Five different types of Au38 nanoparticles protected by mixed-monolayer ligands were prepared by ligand exchange reactions, and ~ 50 % of original ligands, phenylethanethiolate, were exchanged with incoming ligands, HS-(CH2CH2O)n-CH3 (n = 1 ~ 5). In electrochemistry, the redox-peak potentials of these nanoparticles were changed as n increased (more polar). HOMO-LUMO gap energies measured by both differential pulse voltammetry and electronic absorption increased with increase of n. In photoluminescence, Au38 nanoparticles of mixed-monolayer ligands produced broad near-IR emission (900 ~ 1100 nm), and their quantum efficiencies increased with increase of n. Electron transport properties were investigated by estimating electron-hopping rate constants (kHOP) obtained from impedance of drop-cast nanoparticle films. Electron transport became faster as n increased up to 4, and then somewhat decrease in kHOP was observed at n = 5.
 

General Papers
7:00 PM-9:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster

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8:00 PM-10:00 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Sci-Mix

Division of Analytical Chemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006