ESIPT inspired fluorescent 2-(4-benzo[d]oxazol-2-yl)naphtho[1,2-d]oxazol-2-yl)phenol: experimental and DFT based approach to photophysical properties

ESIPT inspired fluorescent 2-(4-benzo[d]oxazol-2-yl)naphtho[1,2-d]oxazol-2-yl)phenol was synthesized from 1-amino-3-(1,3-benzoxazol-2-yl)naphthalen-2-ol. Photophysical behavior of the synthesized compound was studied using UV–visible and fluorescence spectroscopy in polar and non-polar solvents. The synthesized naphthoxazolyl benzoxazole is fluorescent and very sensitive to the micro-environment. It shows a single absorption and dual emission in non-polar solvents with large Stokes shift originating from Excited State Intramolecular Proton Transfer while in polar solvents only a single short wavelength emission is observed. Experimental absorption and emission wavelengths are in good agreement with those predicted using the Time-Dependent Density Functional Theory (TD-DFT) [B3LYP/6-31G(d)]. The largest wavelength difference between the experimental and computed absorption maxima was 16 nm (acetonitrile) and 7 nm (ethyl acetate, THF, and 1,4-dioxane) in the short and long wavelength regions, respectively. A largest difference of 25 nm was observed for the short wavelength emission in DMF and 22 nm for the longer wavelength emission in chloroform.     

一步法2-氨基-1-苯乙酮盐酸盐、醛和巯基乙酸三组分反应高效合成噻唑烷酮

采用一步法在二异丙基乙胺存在下由2-氨基-1-苯乙酮盐酸盐、芳香醛和巯基乙酸三组分反应高效合成了噻唑烷酮。该反应显示出很好的化学选择性。首先2-氨基-1-苯乙酮的N原子与芳香醛选择性反应生成席夫碱,然后巯基乙酸的S原子亲核进攻席夫碱的C原子,最后N原子与羧酸基团环加成生成噻唑烷酮。合成的化合物用光谱技术进行了表征。