Monolayer Assemblies and Optical Properties of Europium(III) Complexes with beta-Diketones Containing Various...

Europium(III) complexes with beta-diketones containing various substituents were newly synthesized and their monolayer behaviors on the water surface were studied in situ by a Brewster angle microscopy (BAM) together with surface pressure-area isotherms. Some BAM images look like a thin soap film on the flat surface, consisting of gas and liquid phases. The monolayer assemblies of these complexes could be deposited by both LB and horizontal lifting techniques. The emission probability from the excited singlet state 5D1 increased in the film as compared to the lowest excited state 5D0, and the symmetrically forbidden transition 5D0-->7F0 was enhanced in comparison with those in the solutions and the crystallines. This effect on the fluorescence was observed significantly for the complex with an asymmetrically substituted ligand rather than that with a symmetrically substituted one. These results can be ascribed to the fact that the thermal deactivation of the higher excited state is decreased and also the symmetries of these complexes are slightly distored in the monolayer assemblies. Copyright 1997 Academic Press. Copyright 1997Academic Press