Five heterocyclic diarylethenes, 2,3-bis(1,2-dimethyl-3- indolyl)-2-butene (DF1), 2,3-bis(1,4-diphenyl-2-methyl-3-pyrryl)- 2-butene (DF2), 2,3-bis(1-p-methylphenyl-4-phenyl-2-methyl-3- pyrryl)-2-butene (DF3), 2,3-bis(1-p-bromophenyl-4-phenyl-2- methyl-3-pyrryl)-2-butene (DF4), and 2,3-bis(1-p-methoxyphenyl- 5-phenyl-2methyl-3-pyrryl)-2-butene (DF5), were synthesized. Their photochromic behaviour, especially photocolouration and photobleaching of DF1 and DF5, were discussed in detail.

Key words: PHOTOCHROMISM, ABSORPTION SPECTROMETRY