Issue in Honor of Prof. Vladimir I. Minkin ARKIVOC 2005 (vii) 18-27
Solvation effect and aggregation of semipermanent spiro[indolephenanthrolinoxazines] in CH3CN / H2O binary solvent
Elena B. Gaeva,ab Anatoly V. Metelitsa,b Nikolai A. Voloshin,b Véronique Pimienta,a and Jean-Claude Miceaua
a Laboratoire des IMRCP, UMR CNRS 5623, Université P. Sabatier, F-31062 Toulouse Cedex, France E-mail: micheau@chimie.ups-tlse.fr b Institute of Physical Organic Chemistry, Stachki Av.194/2, 344090 Rostov on Don, Russia E-mail: photo@ipoc.rsu.ru
Dedicated to Professor Vladimir Minkin on his 70th birthday (received 20 Oct 04; accepted 23 Nov 04; published on the web 8 Jan 05)
Abstract
For three 5-alkyloxyspiro[indolephenanthrolinoxazines], the open form possesses a low- polarity semi-quinoidal structure. In acetonitrile-water binary solvent, the merocyanine is stabilized by a specific interaction with a water molecule. At high water content, the hydrated open form gives rise to H-aggregates.
Keywords: Spirooxazines, acetonitrile-water solvent, aggregates
Introduction
Photochromic materials are of considerable interest for their potential applications in variable transmission glasses and photo-switching devices.1 Among the best known photochromic molecules are spirooxazines which have been extensively investigated because they are expected to exhibit greater photostability than their spiropyran analogs.2 Another advantage is their versatility, allowing modulation of their properties by playing with the position and nature of the substituents.3 Among the various spirooxazine compounds available, those containing both a phenanthroline moiety and a long alkyl-chain are promising. The ionophoric properties of phenanthroline enable metal-ion complexation for the future development of light-controlled chemosensors.4 The presence of a hydrophobic long-chain substituent is able to promote aggregation leading to a sharp absorption band which could be used for independent erasing or reading in optical memory devices.5a-c Spirooxazine aggregation has received only a limited attention6a-b as association properties have mainly been described for spiropyrans.7a-g
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