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International Journal of Photoenergy
Volume 6, Issue 4, Pages 215-220

NMR studies of the polyphotochromic behaviour of biphotochromic compounds

1Laboratoire de Physique et LARMN, UMR CNRS 8009, Faculté de Pharmacie, Université de Lille 2, BP 83, Lille cedex 59006, France
2GCOM2, UMR CNRS 6114, Université de la Méditerranée, Marseille Cedex 9 13288, France
3Laboratoire IMRCP, UMR CNRS 5623, Université Paul Sabatier, Toulouse F-31062, France

Copyright © 2004 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


NMR spectroscopy has been used to investigate the photochromism of four biphotochromic molecules in both the spirooxazine and naphthopyran families. The thermal evolution of photoproducts and their structural identification made it possible to observe polyphotochromic behaviour: photocoloration, thermal bleaching, photo and thermal isomerisation, photoelectrocyclisation and thermochromism.