Department of Chemistry, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, China.
Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute for Advanced Study, Institute of Molecular Functional Materials, State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology , Clear Water Bay, Kowloon, Hong Kong, China.
J Am Chem Soc. 2017 Nov 15;139(45):16264-16272. doi: 10.1021/jacs.7b08592. Epub 2017 Nov 3.
π-Bonds connected with aromatic rings were generally believed as the standard structures for constructing highly efficient fluorophores. Materials without these typical structures, however, exhibited only low fluorescence quantum yields and emitted in the ultraviolet spectral region. In this work, three molecules, namely bis(2,4,5-trimethylphenyl)methane, 1,1,2,2-tetrakis(2,4,5-trimethylphenyl)ethane, and 1,1,2,2-tetraphenylethane, with nonconjugated structures and isolated phenyl rings were synthesized and their photophysical properties were systematically investigated. Interestingly, the emission spectra of these three molecules could be well extended to 600 nm with high solid-state quantum yields of up to 70%. Experimental and theoretical analyses proved that intramolecular through-space conjugation between the "isolated" phenyl rings played an important role for this abnormal phenomenon.
π 键与芳环相连通常被认为是构建高效荧光团的标准结构。然而，没有这些典型结构的材料仅表现出低荧光量子产率，并在紫外光谱区域发射。在这项工作中，合成了三种分子，即双(2,4,5-三甲基苯基)甲烷、1,1,2,2-四(2,4,5-三甲基苯基)乙烷和 1,1,2,2-四苯乙烷，它们具有非共轭结构和分离的苯基环，并系统地研究了它们的光物理性质。有趣的是，这三种分子的发射光谱可以很好地扩展到 600nm，固态量子产率高达 70%。实验和理论分析证明，“分离”的苯基环之间的分子内通过空间共轭对于这种异常现象起着重要作用。
