给体和受体取代的苯乙烯衍生物的π-π相互作用

π-π Interactions of Donor and Acceptor SubstitutedBenzylidene Derivatives

具有电子给体(D)和电子受体的给-受体(D-π-A)分子, 由于在光诱导下可以产生分子内电荷转移(ICT)激发态, 可作为非线性光学和光电转换等材料[1,2]. D-π-A分子由于共轭体系一端是推电子取代基, 另一端是吸电子取代基, 所以其HOMO能级较高, LUMO能级较低[3,4], 在基态容易发生HOMO-LUMO非定域化作用(π-π相互作用). 为进一步研究不同取代基对π-π相互作用的影响, 我们设计合成了以不同长度烷基链的氨基[(CH3)2N, (C12H25)2N, (C18H37)2N]作为给体、弱的受体吡啶基和强的受体吡啶盐基取代的6种苯乙烯衍生物, 利用稳态电子光谱研究了这些给-受体分子的聚集行为. 结果发现, D-π-A分子除了ICT激发态的特殊电荷分离功能外, 在基态有很强的聚集作用.

Six benzylidene derivatives with dialkylaniline substituents as the electron donor and pyridine orpyridinium substituents as the acceptor were synthesized and their intermolecular π-π interactions werestudied. It is found that the derivatives with dialkylaniline substituent as donor and pyfidine group as ac-ceptor tended to form J-aggregates in solution and solid state and their electronic configurations of excitedstates were subjected to great changes, while the derivatives with diakylaniline substituent as donor andpyridinium group as acceptor tended to form H-aggregates and the configurations were subjected to smallchanges. The strength of the π-π interactions can be mediated by the length of the alkyl substituents.