blies of the complexes with various ligands would be possi-Europium(III) complexes with b-diketones containing various ble to tune the relative intensities of the emission behaviors substituents were newly synthesized and their monolayer behaviors to the desired purposes.
on the water surface were studied in situ by a Brewster angle Previously the authors studied the monolayer assemblies microscopy (BAM) together with surface pressure-area isoof samarium(III), europium(III), and terbium(III) comtherms. Some BAM images look like a thin soap film on the flat plexes with thienyltrifluoroacetone (4-6), and it was found surface, consisting of gas and liquid phases. The monolayer assemthat the monolayer assemblies with the highly ordered and blies of these complexes could be deposited by both LB and horiclosely packed arrangement of the complex molecules led to zontal lifting techniques. The emission probability from the excited a decrease in the thermal deactivation of the excited states singlet state 5 D 1 increased in the film as compared to the lowest excited state 5 D 0 , and the symmetrically forbidden transition as well as a slight distortion in the symmetry of the complex. 5 D 0 r 7 F 0 was enhanced in comparison with those in the solutions In the present work, europium(III) complexes with different and the crystallines. This effect on the fluorescence was observed b-diketone ligands have been newly synthesized to obtain significantly for the complex with an asymmetrically substituted information for the mechanism of the intramolecular energy ligand rather than that with a symmetrically substituted one. transfer. Those monolayers of some europium(III) com-These results can be ascribed to the fact that the thermal deactivaplexes with different b-diketone ligands and long alkyl tion of the higher excited state is decreased and also the symmetchains and their mixed monolayers with arachidic acid, octaries of these complexes are slightly distored in the monolayer asdecane, or methyl stearate on the water surface have been semblies. ᭧ 1997 Academic Press investigated by surface pressure-area isotherms as well as Key Words: monolayer assemblies; Eu(III) complexes; BAM in situ Brewster angle microscopy (BAM). With regard to images; emission behaviors.
the physical states of a monolayer on the water surface, the liquid-expanded, intermediate, liquid-condensed, and solidcondensed states at relatively higher pressure regions have EXPERIMENTAL Lanthanoid oxides (99.99%) were purchased from Yue