表面增强拉曼光谱研究基于轴向配位键结合的金属卟啉自组装膜

选择一种金属卟啉有机物(5-对-烷氧基苯基-10,15,20-三苯基卟啉羟基稀土化合物, HoOH)和4,4'-联吡啶(44BPY)作为自组装膜的基本构筑单元, 利用金属配位作用, 成功地将HoOH单分子膜组装到44BPY修饰的银表面. 采用紫外-可见吸收光谱、表面增强拉曼光谱研究了金属卟啉自组装膜的形成并且探索其结构和取向的变化. 结果表明, 底层的44BPY通过4位的N原子垂直吸附到银表面, 另一端的吡啶环上的N原子与HoOH的金属中心配位形成化学键. 从而在44BPY长轴向方向上将HoOH连接到44BPY自组装膜上, 并形成了新的交替膜. 之后, 底层的44BPY取向发生变化, 更向基底倾斜, 而上层的HoOH的分子平面则近乎平行于基底.

SERS Spectroscopy Studies on the Self-assembled Films of Metalloporphyrin Based Axial Ligation

We select a 5-para-alkyloxyphenyl-10, 15, 20-tri(m-ethoxyphenyl)]porphyrin hydroxy rare earth complexes(HoOH) and 4, 4'-bipyridine(44BPY) as the blocking units, and successfully assemble a HoOH monolayer on the 44BPY-modified silver surface based on axial ligation. The structure and orientation of the SAMs were studied by UV-Vis and SERS spectroscopy. The results reveal that 44BPY is assembled onto the silver surface with an end-on adsorption via 4-position nitrogen. The other side pyridine groups coordinate into the central metal ions of HoOH. Therefore, a HoOH monolayer is ligated to the underlying 44BPY layer along its axial direction, forming new alternative films. In the alternative films, the oblique angle between the molecular long axis of 44BPY and the normal of the substrate increased, while the molecular plane of HoOH was nearly parallel to the substrate.