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Switching behavior and optical absorbance of azobenzene-functionalized alkanethiols in different environments

Paper ID Volume ID Publish Year Pages File Format Full-Text
27436 44023 2009 8 PDF Available
Title
Switching behavior and optical absorbance of azobenzene-functionalized alkanethiols in different environments
Abstract

Photoswitching of an azobenzene-functionalized alkanethiol has been investigated in different environments. It is found that in solution, in a polymer matrix, in thin layers adsorbed on quartz or silica gel, and in a self-assembled monolayer (SAM) on a rough gold surface the azo compound shows reversible trans to cis photoisomerization. In contrast, molecules in microcrystalline films are optically inactive. In these systems we observe a blue-shift of the π,π*-absorption band from about 350 nm to 308 nm, which is attributed to H-aggregate formation. This was confirmed by investigation of the compound in different aqueous ethanolic solutions. When the water content is high enough the absorption pattern and maxima of the H-aggregates are identical to those of the non-switching systems. Furthermore, it is shown that both trans and cis isomers of the azo derivative exist in an equilibrium with the H-aggregates which depends on the solvent composition. These findings suggest that also in well-ordered SAMs of azobenzene-functionalized alkanethiols formation of aggregates impedes photoswitching by intermolecular coupling.

Keywords
Self-assembled monolayers; Azobenzene thiols; Photoswitching; Aggregation; Medium effects; UV/Vis spectroscopy; Surface properties
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Switching behavior and optical absorbance of azobenzene-functionalized alkanethiols in different environments
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 204, Issues 2–3, 20 May 2009, Pages 102–109
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
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