Photochromic activity of dihydropyridine derivatives: energetics and kinetics of photochemically driven reactions in polycrystalline 1-methyl-2,4,4,6-tetraphenyl-1,4-dihydropyridine

Citation
A. Lewanowicz et al., Photochromic activity of dihydropyridine derivatives: energetics and kinetics of photochemically driven reactions in polycrystalline 1-methyl-2,4,4,6-tetraphenyl-1,4-dihydropyridine, J PHOTOCH A, 121(2), 1999, pp. 125-132
Citations number
27
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
ISSN journal
10106030 → ACNP
Volume
121
Issue
2
Year of publication
1999
Pages
125 - 132
Database
ISI
SICI code
1010-6030(19990226)121:2<125:PAODDE>2.0.ZU;2-H
Abstract
Kinetics of thermally driven reactions in a crystalline photochromic solid 1-methyl-2,4,4,6-tetraphenyl-1,4-dihydropyridine (DHP) has been studied. Th e processes have been monitored by measuring the isothermal bleaching of co loured species produced upon UV irradiation of DHP, and by measuring the he at flow in non-isothermal differential scanning calorimetry experiments. Si gnatures of two processes were detected; a combination of quantum-chemical calculations and spectroscopic measurements allowed us to attribute them to reactions occurring in the photochromic system. The model put forward in t he paper assumes that the primary photochemically driven reaction (intramol ecular phenyl shift) is irreversible; the photochromic cycle consists of tw o parallel processes: 2,4-ring closing and intramolecular hydrogen shift. ( C) 1999 Elsevier Science S.A. All rights reserved.