Department of Chemistry and Material Science, College of Science, Nanjing Forestry University, Nanjing, 210037, People's Republic of China.
Photochem Photobiol Sci. 2021 Apr;20(4):533-546. doi: 10.1007/s43630-021-00036-8. Epub 2021 Mar 31.
The photophysical properties and excited-state intramolecular proton transfer (ESIPT) processes for 2-(2'-hydroxyphenyl)-4-chloromethylthiazole (1), 2-(2'-hydroxyphenyl)-4-phenylthiazole (2), 2-(2'-hydroxyphenyl)-4-hydroxymethyl-thiazole (3) were studied at the TD-B3PW91/6-31 + G(d, p)/IEFPCM level. The structures of 1-3 were fully optimized and the corresponding structural parameters, infrared spectra and electron densities in the ground (S) and the first excited (S) states were analyzed. The calculated absorption and fluorescence wavelengths of 1-3 reproduced the experimental data. The potential energy curves of the S and S states were built and the ESIPT processes were clarified. Our results showed that the intramolecular H-bonds of 3 and 2 in the S state were the strongest and the weakest, respectively, and then the ESIPT potential barriers of 3 and 2 were the lowest and highest, respectively. Among the three phenol-thiazole type probes, the compound 2 with phenyl ring group at the 4 position of the thiazole ring had the larger π-conjugation, and had the higher ESIPT potential barrier at the same time. The corresponding compound 1 and 3 with CHCl and CHOH had the lower ESIPT barrier.
研究了 2-(2'-羟基苯基)-4-氯甲基噻唑（1）、2-(2'-羟基苯基)-4-苯基噻唑（2）、2-(2'-羟基苯基)-4-羟甲基噻唑（3）的光物理性质和激发态分子内质子转移（ESIPT）过程。在 TD-B3PW91/6-31 + G(d, p)/IEFPCM 水平上对 1-3 进行了全优化，并分析了其基态（S）和第一激发态（S）的结构参数、红外光谱和电子密度。计算得到的 1-3 的吸收和荧光波长与实验数据吻合。构建了 S 和 S 态的势能曲线，阐明了 ESIPT 过程。结果表明，3 和 2 在 S 态时分子内氢键最强和最弱，ESIPT 势垒最低和最高。在三种苯酚噻唑型探针中，噻唑环 4 位带有苯基环的化合物 2 具有较大的π共轭，同时具有较高的 ESIPT 势垒。相应的化合物 1 和 3 带有 CHCl 和 CHOH，ESIPT 势垒较低。
