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Combined NMR, SERRS, and DFT study of photochemical and thermal reactions of acetylene‐ and thienylacetylene‐substituted chromenes
Author(s) -
Maurel F.,
Delbaere S.,
Truong S. Lau,
Coues T.,
Dubest R.,
Vermeersch G.,
Aubard J.
Publication year - 2007
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1212
Subject(s) - chemistry , acetylene , photochromism , substituent , photochemistry , raman spectroscopy , irradiation , density functional theory , resonance (particle physics) , proton nmr , carbon 13 nmr , nuclear magnetic resonance spectroscopy , spectroscopy , computational chemistry , organic chemistry , particle physics , quantum mechanics , nuclear physics , optics , physics
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.