Photochromic systems succinic anhydrides

Groups of reportedly photochromic systems which deserve further study include (a) disulfoxides (123,124), (b) hydrazones (125-129), (c) osazones (130-133), (d ) semicarbazones (134-143), (e) stilbene derivatives (144), (/) succinic anhydrides (145-148), and (g) various dyes (149,150). A number of individual compounds also remain unclassified as to their mechanism of photochromic activity. These include o-nitro-benzylidine isonicotinic acid hydrazide (151), 2,3-epoxy-2-ethyl-3-phenyl-1-indanone (152), p-diethyl- and p-dimethyl-aminophenyli-minocamphor (153), brucine salts of bromo- and chloro-nitromethionic acid (154), diphenacyldiphenylmethane (155,156), 2,4,4,6-tetraphenyl-1,4,-dihydropyridine (155,156), 2,4,4,6-3,5-dibenzoyltetrahydropyran (155,156), o-nitrobenzylidenedesoxybenzoin (157), p-nitrobenzylidene-desoxybenzoin (157), N-(3-pyridyl)sydnone (158,159), tetrabenzoyl-ethylene (160), and the oxidation product of 2,4,5-triphenylimidazole (161,162). 

Source Based on P. J. Darcy, R. J. Hart, and H. G. Heller, overcrowded molecules. Part 14. Photochromic systems involving (Z)-1 -methylpropylidene (diphenylmethylene)-succinic and (E)-3,5-dimethoxybenzylidene (alkyl- substituted methylene) succinic anhydrides, J. Chem. Soc., Perkin Trans. 1, 1978, 571-576. 

H. G. Heller and R M Megit, Overcrowded molecules. Part IX. Fatigue-free photochromic systems involving (E)-2-isopropylidene-3-(mesitylmethylene)-succinic anhydride andiV-phenylimide, J. Chem. Soc., Perkin. Trans. 1, 1974, 923—927. 

P. A. Davidse, J. L. M. Dillen, A. M. Heyns, T. A. Modro, and P. H. van Rooyen, Photochromic systems. Part 1. Structural and spectroscopic study of photochemically active products of Stobbe condensation. 2,3-dibenzylidene-succinic acid and its anhydride, Can. J. Chem., 68, 741-746 (1990). 

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