Photoisomerization and photodimerization in self-assembled monolayers of cis- and trans-4-cyano-4`-(10-mercaptodecoxy)stilbene on gold
- Univ. of Texas, Austin, TX (United States)
Thin films of cis-4-cyano-4`-(10-mercaptodecoxy)stilbene (1) and trans-4-cyano-4`-(10-mercaptodecoxy)stilbene (2) on quartz or self-assembled monolayers of these substrates on optically transparent gold undergo photoisomerization and photodimerization reactions when irradiated with >350 nm visible light. The quantum yield for cyclodimerization in a monolayer of 1 is {Phi}=1.0{+-}0.5x10{sup -6}, whereas that observed in the solid-state thin film was {Phi}{sub cis{yields}trans} =4{+-}1x10{sup -3} and {Phi}{sub cis{yields}dimer}=6{+-}2x10{sup -4} Two photodimers are isolated by irradiation of melts of the derivatives cis-4-cyano-4`-(10-(acetylthio)decoxy)stilbene (3) and trans-4-cyano-4`-(10-(acetylthio)decoxy)stilbene (4). Irradiation of 3 resulted in photoisomerization to 4 as well as dimerization, where as irradiation of 4 resulted only in photodimerization. A monolayer of 1 on gold blocks the electrochemical oxidation of decamethylferrocene (DMFc) dissolved in CH{sub 3}CN in the potential region from -0.5 to +0.5 V vs Ag wire. After scanning between -0.5 and +1.0 V vs Ag, the monolayer no longer blocks the oxidation of DMFc present in the contacting electrolyte solution. Cycling of the potential of monolayers of 1 or 2 on Au in 0.1 M KOH between 0 and -1.2 V vs Ag results in the reductive stripping of the monolayer from the electrode surface. 50 refs., 12 figs.
- OSTI ID:
- 226750
- Journal Information:
- Langmuir, Journal Name: Langmuir Journal Issue: 4 Vol. 12; ISSN 0743-7463; ISSN LANGD5
- Country of Publication:
- United States
- Language:
- English
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