Combined NMR, SERRS, and DFT study of photochemical and thermal reactions of acetylene- and thienylacetylene-substituted chromenes

Autor:	Gaston Vermeersch, T. Couesnon, Jean Aubard, Stéphanie Delbaere, François Maurel, S. Lau Truong, R. Dubest
Rok vydání:	2007
Předmět:	Chemistry Organic Chemistry Substituent Resonance Nuclear magnetic resonance spectroscopy Photochemistry Spectral line symbols.namesake chemistry.chemical_compound Photochromism Acetylene symbols Density functional theory Physical and Theoretical Chemistry Raman scattering
Zdroj:	Journal of Physical Organic Chemistry. 20:944-952
ISSN:	1099-1395 0894-3230
DOI:	10.1002/poc.1212
Popis:	Nuclear Magnetic Resonance (NMR), Surface-Enhanced Resonance Raman Scattering (SERRS), and Density Functional Theory (DFT) were used to study 8-substituted acetylene- and thienylacetylene-diphenylnaphthopyran photochromic compounds. The purpose of this work is to determine the effect of the 8-acetylene substituent on the photochromic equilibrium. NMR spectroscopy shows that photocoloration by UV irradiation at low temperature leads to a mixture of transoid isomers (TC and TT) and a small amount of an allenyl-naphthol structure. The mixture is further enriched in this latter isomer by subsequent visible irradiation. Some photoproducts are identified by analysis of the changes in the SERRS spectra of an irradiated solution with time. To assist spectral assignment, the vibrational frequencies of compounds (1) and (2) and their photoproducts were computed at optimized geometries and compared with the observed Raman bands. Copyright © 2007 John Wiley & Sons, Ltd.
Databáze:	OpenAIRE
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