title: Gated photochromism and acidity photomodulation of a diacid dithienylethene dye.
abstract: The present study quantitatively analyses the gated photochromism and the acidity photomodulation properties of a diacid dithienylethene compound. Photoisomerisation between the open and closed isomers was investigated by UV/visible and (1)H NMR spectroscopy. It was found that the photocyclisation quantum yield of the diacid form was remarkably high (around 90%). Partial neutralisation of the open isomer revealed a gated photochromism as the photocyclisation quantum yield of the mono- and dianion were 50 and 67%, respectively. A considerable photomodulation of the acidity was observed: the closed isomer is more acid than the open one by more than one pK(a) unit. This effect has been shown to be exploitable for a reversible photo-acid generation. This is the first time that a complete quantitative investigation that allows for the determination of the main photochromic, spectral and thermodynamic parameters of a base-sensitive photochromic diarylethene has been carried out.
authors.affiliation: University Paul Sabatier, UMR CNRS 5623, IMRCP, 31062 Toulouse, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Massaad
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Micheau
authors.forename: Christophe
authors.initials: C
authors.lastname: Coudret
authors.forename: Rafael
authors.initials: R
authors.lastname: Sanchez
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Guirado
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Delbaere