Effect of media polarity on the photoisomerisation of substituted stilbene, azobenzene and imine chromophores

King, N.R., Whale, E.A., Davis, F.J. ORCID: https://orcid.org/0000-0003-0462-872X, Gilbert, A. and Mitchell, G.R. (1997) Effect of media polarity on the photoisomerisation of substituted stilbene, azobenzene and imine chromophores. Journal of Materials Chemistry, 7 (4). pp. 625-630. ISSN 0959-9428 doi: 10.1039/A607980F

Abstract/Summary

The influence of substituents and media polarity on the photoinducedE→Z geometrical isomerisation of the stilbene, azobenzene and N-benzylideneaniline chromophores has been compared and assessed. The efficiency of the process in all three systems is markedly dependent on the presence and characteristics of electron-donor and electron-acceptor substituents at the 4- and 4′-positions. The results are discussed in terms of relaxation of the E-excited singlet state. In the absence of a nitro substituent, relaxation to the S1 orthogonal state competes effectively with non-productive intramolecular electron transfer; in the presence of a nitro substituent, the T1 orthogonal state is formed from inter-system crossing. For systems with a 4-nitro and a 4′-electron-donor substituent, access to the triplet state is inhibited by polar solvents promoting formation of the inactive charge-transfer state from the S1 state, and no isomerisation is observed. Similar effects are observed in both solution and polymer films. Such variations in behaviour have important implications for the utilisation of the chromophores in nonlinear optical phenomena including photorefractivity.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/26816
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Electron Microscopy Laboratory (CAF)
Publisher	Royal Society of Chemistry
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