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Monomolecular Langmuir-Blodgett films at electrodes. Electrochemistry at single molecule gate sites
| Content Provider | Semantic Scholar |
|---|---|
| Author | Bilewicz, Renata Sawaguchi, Takahiro Chamberlain, Richard V. Majda, Marcin |
| Copyright Year | 1995 |
| Abstract | The Langmuir-Blodgett (L-B) technique is used to coat electrode surfaces with bifunctional monolayer films that are designed to carry out two functions : passivation and gating. We demonstrate that incorporation of ubiquinone (Q 50 ) in otherwise passivating L-B monolayer films allows us to control access to the electrode surface via a controlled number of single molecule gate sites. The electrode passivation is accomplished with mixed octadecanethiol/octadecanol(C 18 SH/C IB OH) monolayers, as described previously (Bilewicz, R. ; Majda, M. Langmuir 1991, 7, 2794). A detailed characterization ofthe passivating properties of these L-B monolayers is provided in view of the Amatore-Saveant-Tessier (A-S-T) theory (Amatore, C. ; Saveant, J.-M. ; Tessier, D. J. Electroanal. Chem. 1983, 147, 39). The incorporation of low levels (10 -12 -10 -17 mol/cm 2 ) of ubiquinone allows electroreduction of probe species such as Ru(NH 3 ) 6 3+ . At Q 50 concentrations below 10 -15 mol/cm 2 , these monolayers behave as a random array of individual, 5-A-radius disk microelectrodes each created by a single ubiquinone molecule. We postulate that a loose conformation of the ubiquinone's isoprenoid chain creates a channel that allows for a direct approach ofRu(NH 3 ) 6 3+ ions to the electrode surface. Electrochemical results are evaluated on the basis ofA-S-T theory using direct comparison of the experimental and calculated cyclic voltammetric responses. Negative deviations in the observed voltammetric response compared with the theory at the Q 50 concentrations higher than 10 -15 mol/cm 2 are explained by postulating aggregation and loss of Q 50 during L-B transfer. |
| Starting Page | 2256 |
| Ending Page | 2266 |
| Page Count | 11 |
| File Format | PDF HTM / HTML |
| DOI | 10.1021/la00006a065 |
| Volume Number | 11 |
| Alternate Webpage(s) | http://www.cchem.berkeley.edu/mmmgrp/Publications/Langmuir1995.pdf |
| Alternate Webpage(s) | https://doi.org/10.1021/la00006a065 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
