N-芳基吡啶盐染料的一阶超极化率性质

First hyperpolarizabilities of N-aryl pyridinium dyes

在纳秒激光器上通过超瑞利散射(HRS)技术测定了具有推拉结构的N-芳基取代吡啶盐类化合物的一阶超极化率,研究了它们的二阶非线性光学性质。结果表明,当吡啶环中N原子上的取代基由烷基变成芳基时,化合物的荧光发射强度急剧降低,但是一阶超极化率却明显增加。该系列化合物中两个相连的六元环破坏了吡啶盐的共轭平面结构,降低了化合物的荧光量子效率;另一方面,吡啶环上的取代芳基相对于烷基而言,其共轭体系增大,推拉电子能力增强,分子内电荷转移程度增大,从而提高了吡啶盐化合物的一阶超极化率。

First hyperpolarizability（β） values of a series of N-aryl pyridinium dyes with ＂push-pull＂ structure were measured by hyper-rayleigh scattering（HRS） technique with an Nd：YAG nanosecond laser.The result showed that fluorescence of these compounds decreased intensively but β values increased when alkyl was replaced with aryl at pyridine N atom.The simulative geometrical structure indicated that aryl substitute directly linked to pyridine ring broke the planarity of the conjugated system which decreased the fluorescence quantum field greatly.The increase of β might be mainly attributed to the enhanced electron-withdrawing abilities of corresponding aryl substitute.