Donor-acceptor Stenhouse adducts (DASA) are new-generation photochromic compounds discovered recently. DASA exist normally in open form (blue/violet) and readily convert to cyclic (light yellow/colorless) zwitterionic form reversibly in the presence of green light in toluene/dioxane. In aqueous medium, the open form is not stable and converts to the cyclic zwitterionic form irreversibly. We report here
Michaeladditions of different aldehydes and ketones to β-nitrostyrene and 2-(β-nitrovinyl)thiophene in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6) were studied. β-Nitrostyrene was a better acceptor than 2-(β-nitrovinyl)thiophene, in terms of both reactivity and selectivity. Aldehydes proved to be better donors than ketones, which were themselves better than β-diketones. L-proline proved