多支结构的吡嗪衍生物的合成及其双光子吸收性质

摘要

合成了一系列含有双支、三支和四支的吡嗪衍生物,测定了它们的线性吸收和发射性质以及双光子吸收和发射性质.随着吡嗪环上侧链数目的增加(支链数目从2到4),吸收光谱(吸收峰位于290～390 nm)、荧光谱(发射峰位于400～510 nm)和双光子荧光谱(激发波长720 nm)都发生红移,荧光量子产率也逐渐增强(从0.13增大到0.25).另外,从双支到四支结构,双光子吸收截面σ按照1:2.8:3.7的比例增加,接近于支链数目的平方之比(1:2.25:4),表明多支结构的双光子吸收存在显著的增强效应,其中四支结构的σ值为1007 GM.实验中还发现,对于具有相同支链数目的化合物,邻、对位的取代模式比间位取代模式具有更强的单光子和双光子荧光性质.%A series of multi-branched pyrazine derivatives with two,three and four branches have been synthesized.The linear absorption (peak position: 290～390 nm) and emission spectra (peak position: 400～510 nm) along with the two-photon excited fluorescence (TPEF) spectra (excited at 720 nm) showed regular red-shifts as the branch number increased,and the fluorescence quantum yields of the pyrazine derivatives increased (from 0.13 to 0.25).In addition,the two-photon absorption (TPA) cross section σ non-linearly increased with a ratio of 1:2.8: 3.7,which is near to the ratio of the square of branching number n~2 (1 : 2.25 :4),indicating a remarkable cooperative enhancement of a in the multi-branched pyrazine derivatives.The σ value of the four-branched compound is 1007 GM.It was also found that the ortho-/para-branching pattern took great advantage over the meta-branching pattern in the linear fluorescence and TPEF.