EMISSION BEHAVIOR OF LANTHANOID COMPLEXES IN MONOLAYER ASSEMBLIES

Monolayers of newly synthesized complexes of lanthanoids, such as sama rium(III), europium(III), and terbium(III), containing two long alkyl chains and their mixtures with arachidic acid or octadecane were inves tigated. These complexes can form stable condensed monolayers having m olecular areas of 104-111 Angstrom(2) at the air-water interface. Octa decane molecules in the mixed monolayers assist close packing not only of long alkyl chains but also for large head groups. The mixed monola yers were deposited on quartz plates by the Langmuir-Blodgett method a nd a horizontal lifting technique. It has been found that in the monol ayer assemblies of europium(III) complexes, the emission probability f rom the higher excited singlet state D-5(1) and the Symmetric forbidde n transition D-5(0) --> F-7(0) is enhanced in comparison with that in solution, and further the emission of D-5(0) --> F-7(0) splits into tw o peaks. These results are ascribed to the fact that the thermal deact ivation of the higher excited state is decreased and the symmetries of these complexes are slightly distorted in the monolayer assemblies. C haracteristic emission behavior for the samarium(III) and terbium(III) complexes was observed depending on the different molecular assembly systems, though these effects were not as significant as in the case o f the europium(III) complex.