7-二芳氨基香豆素类荧光染料的合成及光谱性能

Synthesis and Spectral Property of 7-Diarylamino Coumarin Fluorescent Dyes

摘要:

以7-二芳氨基香豆素为电子给体，联噻吩和联苯噻吩为π桥，氰乙酸为电子受体设计合成了两个“D-π-A”型香豆素类光敏染料，通过核磁共振氢谱及高分辨质谱测定，确认其化学结构，测定了其紫外-可见吸收光谱、荧光发射光谱。采用密度泛函理论-高斯密度泛函（DFT-B3LYP/6-31G(d)）对化合物进行几何优化，并进一步用TD-DFT方法计算得到吸收光谱和发射光谱，分析了构效关系。结果表明，与二苯氨基香豆素光敏染料相比，二芴氨基香豆素光敏染料的基态能级差分别由2.49 eV和2.62 eV减小至2.31 eV和2.49 eV；激发态能级差也相应减小了0.52 eV和0.42 eV；与以联苯噻吩为π桥的光敏染料相比，以联噻吩为π桥的光敏染料具有更好的分子平面性，最大吸收波长分别红移19 nm和4 nm，发射波长则分别红移16 nm和9 nm。

Abstract:

Two “D-π-A” type coumarin photosensitizers were synthesized with 7-diarylamino coumarin as the donor, dithiophene or phenylthiophene as the π-bridge, and cyanoacetic acid as the acceptor. Their structures were confirmed by 1H NMR and HRMS and their UV-vis absorption spectra and fluorescence emission spectra were measured. The geometric structures of these dyes were optimized using density functional theory (DFT) in conjunction with the d-polarized 6-31G(d) basis set. Time-dependent density functional theory (TD-DFT) was further used to calculate the absorption spectra and the emission spectra and the structure-property relationship was analyzed. The results showed that 7-difluorenylamino coumarin photosensitizers exhibited relatively smaller energy gap at the ground state (2.31 eV and 2.49 eV) than 7-diphenylamino coumarin photosensitizers (2.49 eV and 2.62 eV) and their energy gap of the excited state was also reduced by 0.52 eV and 0.42 eV respectively. Compared with photosensitizers with phenylthiophene π-bridge, photosensitizers with dithiophene π-bridge had better molecular planarity and their maximum absorption wavelength was shifted bathochromically by 19 nm and 4 nm respectively and the maximum emission wavelength was shifted bathochromically by 16 nm and 9 nm respectively.