Blocking oriented monolayers of alkyl mercaptans on gold electrodes

Abstract

cess, was observed. This may be due to a side reaction during the irradiation with 254-nm light. The photodimer may produce photodimerization by another remaining double bond on prolonged irradiation. Thus, the absorption peak at 270 nm decreased gradually on continued irradiation. ConclusionsPrevious studies in the intermolecular reactions of LB films have been limited mainly to photopolymerization and photodimerization. In this study, the intermolecular photoreversible reaction in an LB films has been found for the first time, although the photoreversible reaction of cinnamylideneacetic acid has already been known in polymer film or in low-temperature glassy matrix. Originally, one might expect that these photoreversible systems are more favorable in LB films than in polymers. However, the reversibility was still low for the LB film of 2a, similarly to the polymer film of poly(vinyl cinnamylideneacetate). This is due to the overlapping of the absorption spectra of 2a and the photodimer of 2a and also to the side reaction arising from the chromophore containing two double bonds. Therefore, further investigations are required to find other chromophores for the improvement of reversibility.(41) MS IR, and *H and 13C NMR spectra for the compounds (four acids and their methyl or ethyl esters) in this work are saved in the Spectral Data Bank System (SDBS) constructed by our laboratory (NC-LI) in the Research Information Processing System (RIPS) of Tsukuba Research Center. The spectral patterns for the compounds are available on request.

Electron transfer dynamics across self-assembled N-(2-mercaptoethyl) octadecanamide/mycolic acid layers: impedimetric insights into the structural integrity and interaction with anti-mycolic acid antibodies

“…This is in agreement with the proposal by Finklea et al 38 that there are sites at which the redox couple can approach the underlying electrode surface more closely but not able to come into contact with it. a The value in parenthesis represents the relative percent error obtained from fitting the impedance spectrum using the proposed equivalent circuits (Fig.…”

“…The radius of the inactive domain surrounding the microelectrode (r b , i.e., half the distance between the centers of the neighbouring pinholes) is obtained from eqn (7) as: 38,47 1 À y app ¼ r where I 0 is the current obtained at the bare gold electrode, b is the electron-tunnelling coefficient (b = 1.05 per methylene group 50 ), and d is the thickness of the monolayer film. Under equilibrium conditions, eqn (8) may be expressed as eqn (9): 35…”

Carbon and gold electrodes as electrochemical transducers for DNA hybridisation sensors

“…Residual contaminants on bare gold can be removed by repeated cycling in diluted H 2 SO 4 (Hashimoto et al, 1994b) or diluted KOH (Aoki et al, 2000) until stable voltammograms are obtained. Clean gold shows a characteristic anodic peak current near +1.1 V (versus SCE) and a single cathodic peak near +0.9 V in dilute sulfuric acid solutions (Finklea et al, 1987).…”

“…Monolayers are stable in the potential range from −400 to +1400 mV (vs SCE) in dilute sulfuric acid solutions (Finklea et al, 1987), thus allowing electrochemical applications. The careful selection of the terminal functionalities of the monolayers and the proper surface chemistry allows a tremendous flexibility in biosensor design.…”

Selective Knockout of Gold Active Sites

“…Then the electrode was cycled between À0.3 V and 1.5 V (vs. Ag/AgCl) in H 2 SO 4 (0.1m) until a stable voltammogram typical of a clean gold electrode was obtained. [19] Then the electrode was washed with water and exposed to freshly prepared solutions of Fenton s reagent for 5 minute intervals. The exposure was repeated so that the overall exposure time ranged from 5 to 90 min.…”