Light-induced J-aggregation of merocyanine in Langmuir-Blodgett films

The structures and photoreactions of the Langmuir and LB films of an amphiphilic spiropyran, 1',3'-dihydro-3',3'-dimethyl-6-nitro--1' -octadecyl-8-(docosanoyloxymethyl)spiro[2H-1-benzopyran-2,2'-(2H)-indole] (SP) are investigated. Results indicate that the criteria of the J-aggregation of MC in Lagmuir and LB films are the presence of the bilayer domains and the nucleation sites with the mobility of the molecules large enough for the morphological change necessary for the J-aggregation.