20200-62-8Relevant articles and documents
Photochromism of spirobenzopyranindolines and spironaphthopyranindolines
Chibisov,Goerner
, p. 424 - 431 (2007/10/03)
The photocolouration of five spiro[2H-1-benzopyran-2,2′-indoline] compounds (1-5) and two spironaphthopyranindolines (6, 7) to give the ring-opened merocyanine(s) and the subsequent thermal relaxation back to the closed form was studied. A trans-merocyanine but no cis-photoisomer were detected for 1-7 using λexc = 308 nm and a singlet pathway accounts for photocolouration. In contrast to nitrospiropyrans the yield of colouration of spiropyrans is essentially independent of solvent polarity. The relaxation times at 25°C range from 0.01 s for 6 in methylcyclohexane to 17 s for 5 in ethanol, which is due to differences in both activation energies (65-80 kJ mol-1) and the pre-exponential factor (1012-1014 s-1). The photomerocyanine yield is substantially increased upon naphthalene- or acetone-sensitized excitation, where otherwise the same spectral changes, relaxation time and activation parameters were found. Upon excitation of the trans-merocyanine (λexc = 530 nm), a cis-merocyanine with lifetime in the sub ms range could be detected at lower temperatures. Deactivation of the excited trans-merocyanine occurs mainly in the excited singlet state. For 4 and 5, due to an internal heavy-atom effect of bromine substituents, and for 1, a triplet state as a precursor of the cis- and trans-merocyanines could be observed. The effects of structure and medium properties on the photoprocesses are described and the mechanisms of photochromism and thermal decolouration are discussed.
Photo-polymerizable composition containing an acid salt of an indolinobenzospiropyran
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, (2008/06/13)
A photo-polymerizable composition comprising (A) a photopolymerization initiator comprising at least one inorganic or organic acid salt of an indolinobenzospiropyran represented by the following general formula (I): SPC1 wherein R1 represents an alkyl group, substituted alkyl group or a phenyl group; R2 and R3 each represents an alkyl group or a phenyl group or, when taken together, R2 and R3 form a methylene chain CH2 wherein n is an integer of 4 or 5; X represents a hydrogen atom, a nitro group, a halogen atom, a carboxy group; and Y represents one or more substituents selected from the group consisting of a hydrogen atom, a nitro group, a halogen atom, a formyl group and an alkoxy group, and (B) at least one cationically polymerizable substance.