嵌入花生酸镉单层中的卟啉-紫精分子聚集行为的研究

本文制备了卟啉-紫精与花生酸镉混合LB膜, 用紫外可见光谱研究了膜中卟啉基团的聚集及取向, X射线衍射说明混合LB膜具有层状有序的周期结构。扫描电镜结果表明: 通过调节膜的表面压可使聚集成"微畴"的卟啉-紫精均匀分布在花生酸镉单分子层中, 随膜表面压的增大, 小的"微畴"相互连接形成更大的"微畴"。电子衍射说明混合膜中两组份分相存在, 且都为六角对称的有序结构。

Study on the aggregation behavior of porphyrin-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. Polarized-UV absorption measurement shows that the angle between porphyrin ring and substrate in mixed LB film is 5.9°. 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 aggregates of diad can disperse evenly in the monolayer of cadmium arachidate by adjusting the surface pressure of mixed monolayer; the size of "domain" becomes larger and the shape becomes uniform with increasing of surface pressure from 2mN/m to 30mN/m, and when surface pressure increases to 40mN/m (corresponding to the collapse pressure of mixed monolayer), 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 the symmetrically ordered hexagonal structures. These results lay the foundation of investigating the relationship between the structure and function of porphyrin diad, and realize to modulate the aggregation of molecules artificially.