Yuan Huijuan, Feng Songyan, Wen Keke, Guo Xugeng, Zhang Jinglai
College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China.
College of Chemistry and Chemical Engineering, Henan University, Kaifeng 475004, PR China.
Spectrochim Acta A Mol Biomol Spectrosc. 2018 Feb 15;191:421-426. doi: 10.1016/j.saa.2017.10.048. Epub 2017 Oct 16.
Excited-state intramolecular proton transfer (ESIPT) reactions of a series of N(R)H⋯N-type seven-membered-ring hydrogen-bonding compounds were explored by employing density functional theory/time-dependent density functional theory calculations with the PBE0 functional. Our results indicate that the absorption and emission spectra predicted theoretically match very well the experimental findings. Additionally, as the electron-withdrawing strength of R increases, the intramolecular H-bond of the NS form gradually enhances, and the forward energy barrier along the ESIPT reaction gradually decreases. For compound 4, its ESIPT reaction is found to be a barrierless process due to the involvement of a strong electron-withdrawing COCF group. It is therefore a reasonable presumption that the ESIPT efficiency of these N(R)H⋯N-type seven-membered-ring H-bonding systems can be improved when a strong electron-withdrawing group in R is introduced.
采用含PBE0泛函的密度泛函理论/含时密度泛函理论计算方法，对一系列N(R)H⋯N型七元环氢键化合物的激发态分子内质子转移(ESIPT)反应进行了研究。我们的结果表明，理论预测的吸收光谱和发射光谱与实验结果非常吻合。此外，随着R吸电子强度的增加，NS形式的分子内氢键逐渐增强，沿ESIPT反应的正向能垒逐渐降低。对于化合物4，由于强吸电子COCF基团的参与，其ESIPT反应是一个无势垒过程。因此，可以合理推测，当在R中引入强吸电子基团时，这些N(R)H⋯N型七元环氢键体系的ESIPT效率可以得到提高。
