吡啶基团的对称性和离子化对分子双光子吸收截面的影响

采用超快速激光光谱方法研究了含吡啶基团的四个联苯乙烯衍生物及两个杂环分子(A: 4,4’-二(2-(4-吡啶基)乙烯)联苯; B: 4,4’-二(2-(2-吡啶基)乙烯)联苯; C: 1-甲基-4-(2-(4’-(2-(4-吡啶基)乙烯基)-4-联苯)乙烯基)吡啶碘盐; D: 1-甲基-2-(2-(4’-(2-(2-吡啶基)乙烯基)-4-联苯)乙烯基)吡啶碘盐; E: 4-(2-(9-丁基-9氢-3-咔唑)乙烯基)-1-甲基吡啶碘盐; F: 4-(2-(9-丁基-9氢-3-咔唑)乙烯基)-1-甲基喹啉碘盐)的结构-性能关系. 实验结果显示双光子吸收截面最大的是分子E, 高达617.3 GM; 最小的是分子B, 为19.3 GM(1 GM=10^-50 cm⁴·s·photon^-1). 实验研究结果表明, 分子中吡啶基团的对称性及其离子化对分子双光子吸收截面起很重要的作用; 进一步用理论计算证实了以上实验结论并对其机制进行了分析讨论.

Two-Photon Absorption Properties Dependent on Symmetry of Pyridinium Group and Cationic Structure

Structure-property relationships of four divinyl-biphenyl derivatives and two heterocyclic molecules (A: 4,4’-bis(2-(pyridin-4-yl)vinyl)biphenyl, B: 4,4’-bis(2-(pyridin-2-yl)vinyl)biphenyl, C: 1-methyl-4-(2-(4’-(2-(pyridin-4-yl)vinyl) biphenyl-4-yl)vinyl)pyridinium iodide, D: 1-methyl-2-(2-(4’-2-(pyridin-2-yl)vinyl) biphenyl-4-yl)vinyl) pyridinium iodide, E: 4-(2-(9-Butyl-9H-carbazol-3-yl)vinyl)-1-methyl-pyridinium iodide, and F: 4-(2-(9-butyl-9H-carbazol-3-yl)vinyl)-1-methyl-quinolinium iodide) that contain pyridinium groups were studied by laser spectroscopy. The largest two-photon absorption cross-section is 617.3 GMfor molecule E, and the smallest is 19.3 GM(1 GM=10^-50 cm⁴·s·photon^-1) for molecule B. Our research demonstrates that two-photon absorption cross-sections of compounds A-F are evidently dependent on both the pyridiniumgroup symmetry and the cationic structure.