含有二芳基乙烯的新型分子荧光性质的理论研究

Theoretical analysis of a novel fluorescent molecule synthesized by non-symmetry diarylethene

采用DFT/TDDFT下的PBE0/6-31G(d)方法研究了由二芳基乙烯DE与荧光基团二萘嵌苯双酰亚胺PBI合成的新型荧光分子的一系列吸收以及发光性质.利用内稟反应坐标(IRC)以及频率分析对三重态副反应过程进行验证,得到相对应的反应路径.计算结果表明,实验中PBI的芳香环修饰有效地降低了跃迁能级差,引起吸收光谱的红移,从而避免副反应发生.使用Rehm-Weller公式对光激发电子转移过程进行热力学评估,以解释在二芳基乙烯为闭环的情况下发生荧光猝灭的原因.

PBE0 functional based on DFT/TDDFT method and 6-31G（d） basis set are adopted to study the reaction mechanism, absorption, and fluorescence properties of a novel molecule synthesized by diarylethene（DE） and perylenebisimide（PBI）. Intrinsic reaction coordinate（IRC） and frequency analysis are utilized to verify the side triplet-state ring-opening reaction pathway. The purpose of modification to PBI by aromatic nucleus is to decrease the energy gap and make the absorption spectrum red-shift, which averts the side reaction. Rehm-Weller equation is also used to make a thermodynamic evaluation to the photo-induced electron transfer（PET） process and explain the fluorescence quenching when diaryletnene is ring-closed.