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Mechanisms of Photoisomerization of Polyenes in Confined Media: From Organic Glasses to Protein Binding Cavities †
Author(s) -
Liu Robert S. H.,
Yang LanYing,
Liu Jin
Publication year - 2007
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/2006-01-27-ra-786
Subject(s) - photoisomerization , polyene , bacteriorhodopsin , chromophore , chemistry , isomerization , photochemistry , rhodopsin , relaxation (psychology) , chemical physics , organic chemistry , retinal , psychology , social psychology , biochemistry , membrane , catalysis
Photochemical reactivities of model organic systems (stilbene and diphenylbutadiene) in organic glasses were first examined and compared with those in solution and in organized media. These observations were in turn compared with reactivities of polyene chromophores in protein binding cavities (specifically PYP, rhodopsin and bacteriorhodopsin). The obvious conclusion is that the preference for the most volume‐conserving Hula‐twist mechanism isomerization in organic glasses is because of the close interaction between the guest and the host molecules. In organized media (zeolites, crystals and protein binding cavities), the residual empty space coupled with any specific guest–host interactions that are characteristic of a given system, could lead to involvement of the more volume‐demanding one‐bond‐flip ( i.e. torsional relaxation) or bicycle‐pedal or an extended HT process in photoisomerization.