高等学校化学学报 ›› 2019, Vol. 40 ›› Issue (7): 1425.doi: 10.7503/cjcu20190127

• 物理化学 • 上一篇    下一篇

溶剂效应和取代基效应对2-(2-氨基苯基)苯并噻唑光谱性质及激发态分子内质子转移的影响

李庆, 易平贵(), 陶洪文, 李洋洋, 张志于, 彭文宇, 李玉茹   

  1. 湖南科技大学化学化工学院, 理论有机化学与功能分子教育部重点实验室,精细聚合物可控制备及功能应用湖南省重点实验室,分子构效关系湖南省普通高校重点实验室, 湘潭 411201
  • 收稿日期:2019-02-28 出版日期:2019-07-10 发布日期:2019-07-12
  • 作者简介:易平贵, 男, 博士, 教授, 博士生导师. 主要从事分子构效关系与理论计算化学研究. E-mail: pgyi@hnust.edu.cn
  • 基金资助:
    国家自然科学基金(批准号: 21172066)和湖南省教育厅重点科研项目(批准号: 17A065)资助.

Solvent and Substituent Effects on Spectral Characteristics and Excited-state Intramolecular Proton Transfer of 2-(2-Aminophenyl) Benzothiazole

LI Qing, YI Pinggui*(), TAO Hongwen, LI Yangyang, ZHANG Zhiyu, PENG Wenyu, LI Yuru   

  1. School of Chemistry and Chemical Engineering, Key Laboratory of Theoretical Organic Chemistry and Functional Molecules of Ministry of Education, Hunan Provincial Key Laboratory of Controllable Preparation and Functional Application of Fine Polymers,Hunan Province College Key Laboratory of QSAR/QSPR, Hunan University of Science and Technology,Xiangtan 411201, China
  • Received:2019-02-28 Online:2019-07-10 Published:2019-07-12
  • Contact: YI Pinggui E-mail:pgyi@hnust.edu.cn
  • Supported by:
    † Supported by the National Natural Science Foundation of China(No.21172066) and the Key Scientific Research Project of Hunan Provincial Department of Education, China(No.17A065).

摘要:

合成了多种2-(2-氨基苯基)苯并噻唑(APBT)氨基氢原子被供电子及吸电子基团取代的衍生物, 并用紫外光谱﹑荧光光谱等方法和密度泛函理论(DFT)计算研究了溶剂效应和取代基效应对衍生物的光谱性质及激发态分子内质子转移(ESIPT)的影响规律. 结果表明, 相比于非极性溶剂环己烷, 随溶剂极性的增加及APBT-溶剂分子间氢键的形成, APBT的紫外-可见最大吸收峰和荧光最大发射峰均发生了一定程度的红移, 并对APBT的ESIPT产生了影响. 在APBT分子的氨基氮原子上引入不同的吸电子或斥电子取代基, 对氮原子的电荷性质有较大的影响. 在环己烷溶剂中, 甲基取代后的APBT仅有单重荧光发射峰, 体系未发生ESIPT过程; 而COCH2Cl等吸电子基团能促进APBT的ESIPT, 其荧光发射光谱出现了明显的双重峰, 表明体系发生了激发态分子内质子转移反应. 量子化学的理论计算较好地验证了光谱实验结果.

关键词: 质子转移, 溶剂效应, 取代基效应, 量子化学计算

Abstract:

A group of 2-(2-aminophenyl)benzothiazole(APBT) derivatives was synthesized with electron-donating or withdrawing substituent introduced at the nitrogen atom in amino. Solvent and substituent effects on their spectral characteristics and excited state intramolecular proton transfer(ESIPT) were further investigated by ultraviolet absorption spectrum, fluorescence emission spectrum and density functional theory(DFT) calculations. The results showed that, compared to non-polar solvent cyclohexane, the increase of solvent polarity and the formation of hydrogen bond between APBT and solvent molecule cause the maximum absorption peaks and fluorescence emission peaks of APBT red-shift a few nanometers. The ESIPT of APBT was also influenced to some extent by solvent effects. It was found that the charge distributions of nitrogen atom in amino be changed when substituent were introduced in APBT molecules. There were only a single fluorescence emission peak of APBT and its electron-donating substituent derivatives. The peaks were generated by enol tautomer and no ESIPT happened. However, the electron-withdrawing substituent, such as COCH2Cl, would make the APBT derivatives to occur ESIPT reaction and the dual fluorescence peaks with different wavelength appeared in cyclohexane solution, which should be respectively assigned to enol and keto tautomers. The theoretical calculation of quantum chemistry agreed well with the spectral experimental results.

Key words: Proton transfer, Solvent effect, Substituent effect, Quantum chemical computation

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