STUDY ON THE AGGREGATION BEHAVIOR OF PORP HYRIN - VIOLOGEN MOLECULE EMBEDDED IN CADMIUM ARACHIDATE ACID MONOLAYER

The mixed LB films of porphyrin-viologen compound(diad) with arachidic acid(AA) are deposited on hydrophobic glass plates successfully. Pola rized-UV absorption measurement shows that the angle between porphyrin ring and substrate in mixed LB film is 5.9 degrees. Small angle X-ray diffraction pattern shows 3-grade Bragg diffraction peaks, indicating the mixed LB film has a periodic layered structure. UV-vis absorption spectrum suggests that a J-aggregate of diad is formed in mixed films . SEM results indicate that the uniform ''domain'' formed by aggregate s of diad can disperse evenly in the monolayer of cadmium arachidate b y adjusting the surface pressure of mixed monolayer; the size of ''dom ain'' becomes larger and the shape becomes uniform with increasing of surface pressure from 2mN/m to 30mN/m, and when surface pressure incre ases to 40mN/m(corresponding to the collapse pressure of mixed monolay er), the ''domain'' links and becomes larger ''domain'' with a variety of shapes. The electronic diffraction pattern also conforms that the phase separation exists in mixed monolayer, the two phases both have t he symmetrically ordered hexagonal structures. These results lay the f oundation of investigating the relationship between the structure and function of porphyrin diad, and realize to modulate the aggregation of molecules artificially.