title: Investigation of ultrafast photoinduced processes for salicylidene aniline in solution and gas phase: toward a general photo-dynamical scheme.
abstract: Photodynamics of 2-hydroxybenzylideneaniline (photochromic salicylidene aniline SAOH) and N-(2-methoxybenzylidene)aniline (SAOMe) are studied by steady state and transient optical spectroscopy in solution and gas phase at different excitation wavelengths (266, 355 and 390 nm). Two competitive processes are observed from the enol* excited state: on one hand a rotation to get a twisted-enol, and on the other hand an excited state intramolecular proton transfer (ESIPT) followed by a cis-trans isomerisation to get the trans-keto photochromic product. For the first time both processes are characterized at an ultrashort time scale for salicylidene aniline. Resolution of the spectrokinetic data is achieved by multivariate curve resolution and attribution of the intermediate species recovered is performed in comparison with the results obtained for SAOMe, which can only undergo enol rotational isomerisation. It shows that ESIPT and rotation to the twisted-enol for SAOH occur within 100 fs, as predicted by recent quantum dynamical simulations, with an efficiency ratio dependent on the excitation wavelength. Therefore a general photoinduced mechanism for salicylidene aniline is drawn.
authors.affiliation: Laboratoire de Spectrochimie Infrarouge et Raman (UMR 8516 CNRS), Université de Lille 1 Sciences et Technologies, Bât. C5, 59655, Villeneuve d'Ascq Cedex, France. michel.sliwa@univ-lille1.fr
authors.forename: Michel
authors.initials: M
authors.lastname: Sliwa
authors.forename: Nicolas
authors.initials: N
authors.lastname: Mouton
authors.forename: Cyril
authors.initials: C
authors.lastname: Ruckebusch
authors.forename: Lionel
authors.initials: L
authors.lastname: Poisson
authors.forename: Abdenacer
authors.initials: A
authors.lastname: Idrissi
authors.forename: Stéphane
authors.initials: S
authors.lastname: Aloïse
authors.forename: Ludovic
authors.initials: L
authors.lastname: Potier
authors.forename: Julien
authors.initials: J
authors.lastname: Dubois
authors.forename: Olivier
authors.initials: O
authors.lastname: Poizat
authors.forename: Guy
authors.initials: G
authors.lastname: Buntinx