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Title: Monolayers in three dimensions: NMR, SAXS, thermal, and electron hopping studies of alkanethiol stabilized gold clusters

Abstract

Gold clusters stabilized by chemisorbed monolayers of octane-, dodecane- or hexadecanethiolate have been investigated in solution and in the solid phase. These materials can be pumped free of solvent to form a dark brown solid that can be re-dissolved in nonpolar solvents. Their exceptional stability suggests they be viewed as cluster compounds. High-resolution NMR spectra of cluster solutions display well-defined resonances except for methylenes nearest the gold interface; the absence of the latter resonances is attributed to a combination of broadening mechanisms based on the discontinuous change in magnetic susceptibility at the metal-hydrocarbon interface and residual dipolar interactions. Films of the dry, solid cluster compound on interdigitated array electrodes exhibit current-potential responses characteristic of electron hopping conductivity in which electrons tunnel from Au core to Au core. The electron hopping rate decreases and the activation barrier increases systematically at longer alkane chain length. The results are consistent with electron transport rate control being a combination of thermally activated electron transfer to create oppositely charged Au cores (cermet theory) and distance-dependent tunneling ({Beta} = 1.2 A{sup -1}) through the oriented alkanethiolate layers separating them. 23 refs., 11 figs., 5 tabs.

Authors:
 [1];  [2]; ; ; ;  [3]; ;  [4]; ;  [5]; ; ; ; ;  [6]
  1. Univ. of Illinois, Urbana, IL (United States)
  2. W.R. Grace and Co., Columbia, MD (United States)
  3. National Sun Yat-Sen Univ., Kaohsiung (Taiwan, Province of China)
  4. Univ. of Oregon, Eugene, OR (United States)
  5. Oak Ridge National Labs., TN (United States)
  6. Univ. of North Carolina, Chapel Hill, NC (United States)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
223600
DOE Contract Number:  
AC05-84OR21400
Resource Type:
Journal Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 117; Journal Issue: 50; Other Information: PBD: 20 Dec 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 40 CHEMISTRY; 66 PHYSICS; THIN FILMS; NMR SPECTRA; THERMAL GRAVIMETRIC ANALYSIS; CALORIMETRY; ELECTRIC CONDUCTIVITY; GOLD; ALKANES; CHEMISORPTION; SOLID CLUSTERS; THIOLS; ACTIVATION ENERGY; X-RAY DIFFRACTION; ELECTRON TRANSFER

Citation Formats

Terrill, R H, Postlethwaite, T A, Chen, C H, Poon, C D, Terzis, A, Chen, A, Hutchison, J E, Clark, M P, Wignall, G, Londono, J D, Superfine, R, Falvo, M, Johnson, Jr, C S, Samulski, E T, and Murray, R W. Monolayers in three dimensions: NMR, SAXS, thermal, and electron hopping studies of alkanethiol stabilized gold clusters. United States: N. p., 1995. Web. doi:10.1021/ja00155a017.
Terrill, R H, Postlethwaite, T A, Chen, C H, Poon, C D, Terzis, A, Chen, A, Hutchison, J E, Clark, M P, Wignall, G, Londono, J D, Superfine, R, Falvo, M, Johnson, Jr, C S, Samulski, E T, & Murray, R W. Monolayers in three dimensions: NMR, SAXS, thermal, and electron hopping studies of alkanethiol stabilized gold clusters. United States. doi:10.1021/ja00155a017.
Terrill, R H, Postlethwaite, T A, Chen, C H, Poon, C D, Terzis, A, Chen, A, Hutchison, J E, Clark, M P, Wignall, G, Londono, J D, Superfine, R, Falvo, M, Johnson, Jr, C S, Samulski, E T, and Murray, R W. Wed . "Monolayers in three dimensions: NMR, SAXS, thermal, and electron hopping studies of alkanethiol stabilized gold clusters". United States. doi:10.1021/ja00155a017.
@article{osti_223600,
title = {Monolayers in three dimensions: NMR, SAXS, thermal, and electron hopping studies of alkanethiol stabilized gold clusters},
author = {Terrill, R H and Postlethwaite, T A and Chen, C H and Poon, C D and Terzis, A and Chen, A and Hutchison, J E and Clark, M P and Wignall, G and Londono, J D and Superfine, R and Falvo, M and Johnson, Jr, C S and Samulski, E T and Murray, R W},
abstractNote = {Gold clusters stabilized by chemisorbed monolayers of octane-, dodecane- or hexadecanethiolate have been investigated in solution and in the solid phase. These materials can be pumped free of solvent to form a dark brown solid that can be re-dissolved in nonpolar solvents. Their exceptional stability suggests they be viewed as cluster compounds. High-resolution NMR spectra of cluster solutions display well-defined resonances except for methylenes nearest the gold interface; the absence of the latter resonances is attributed to a combination of broadening mechanisms based on the discontinuous change in magnetic susceptibility at the metal-hydrocarbon interface and residual dipolar interactions. Films of the dry, solid cluster compound on interdigitated array electrodes exhibit current-potential responses characteristic of electron hopping conductivity in which electrons tunnel from Au core to Au core. The electron hopping rate decreases and the activation barrier increases systematically at longer alkane chain length. The results are consistent with electron transport rate control being a combination of thermally activated electron transfer to create oppositely charged Au cores (cermet theory) and distance-dependent tunneling ({Beta} = 1.2 A{sup -1}) through the oriented alkanethiolate layers separating them. 23 refs., 11 figs., 5 tabs.},
doi = {10.1021/ja00155a017},
journal = {Journal of the American Chemical Society},
number = 50,
volume = 117,
place = {United States},
year = {1995},
month = {12}
}