Photochromism of Spiropyran Nanocrystals Embedded in Sol−Gel Matrices

Spectroscopic and kinetic properties of a new photochromic medium, consisting of nanocrystals of spyropyran molecules (1,3-dihydro-1,3,3,5‘,6‘,pentamethyl-spiro[2H-indole-2,2‘-[2H]pyrano [3,2-b]pyridinium] iodide) embedded in an organo-silicate sol−gel film, are presented and compared to microcrysta...

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Bibliographic Details
Published in:The journal of physical chemistry. B 2005-05, Vol.109 (18), p.8587-8591
Main Authors: Spagnoli, Sylvie, Block, Dominique, Botzung-Appert, Estelle, Colombier, Isabelle, Baldeck, Patrice L, Ibanez, Alain, Corval, Anne
Format: Article
Language:English
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Summary:Spectroscopic and kinetic properties of a new photochromic medium, consisting of nanocrystals of spyropyran molecules (1,3-dihydro-1,3,3,5‘,6‘,pentamethyl-spiro[2H-indole-2,2‘-[2H]pyrano [3,2-b]pyridinium] iodide) embedded in an organo-silicate sol−gel film, are presented and compared to microcrystals obtained by slow evaporation of a solvent. High photoconversion efficiencies for both kinds of crystals have been observed. In microcrystals, the photomerocyanine form absorbs at 570 nm with a fading rate of 5 h, in nanocrystals the photomerocyanine form absorbs at 535 nm with a fading rate of 41 h. Therefore, the crystalline structure of nanocrystals is different from the microcrystal one.
ISSN:1520-6106
1520-5207
DOI:10.1021/jp046792r