MONOLAYER ASSEMBLIES AND OPTICAL-PROPERTIES OF EUROPIUM(111) COMPLEXES WITH BETA-DIKETONES CONTAINING VARIOUS SUBSTITUENTS

Europium(III) complexes with P-diketones containing various substituen ts were newly synthesized and their monolayer behaviors on the water s urface were studied in situ by a Brewster angle microscopy (BAM) toget her with surface pressure-area isotherms. Some BAM images look like a thin soap him on the flat surface, consisting of gas and liquid phases . The monolayer assemblies of these complexes could be deposited by bo th LB and horizontal lifting techniques. The emission probability from the excited singlet state D-5(1) increased in the film as compared to the lowest excited state D-5(0), and the symmetrically forbidden tran sition D-5(0)-->F-7(0) was enhanced in comparison with those in the so lutions and the crystallines. This effect on the fluorescence was obse rved significantly for the complex with an asymmetrically substituted ligand rather than that with a symmetrically substituted one. These re sults can be ascribed to the fact that the thermal deactivation of the higher excited state is decreased and also the symmetries of these co mplexes are slightly distored in the monolayer assemblies. (C) 1997 Ac ademic Press.