Bondarev Stanislav L, Raichenok Tamara F, Tikhomirov Sergei A, Kozlov Nikolai G, Mikhailova Tatyana V, Ivanov Anatoly I
B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Prospect Nezavisimosti 68, Minsk BY-220072, Republic of Belarus.
Institute of Physical Organic Chemistry, National Academy of Sciences of Belarus, Surganov str. 13, Minsk BY-220072, Republic of Belarus.
J Phys Chem B. 2021 Jul 29;125(29):8117-8124. doi: 10.1021/acs.jpcb.1c03745. Epub 2021 Jul 16.
An acridine-dione derivative (3,3,11,11-tetramethyl-8,16-diphenyl-3,4,8,10,11,12,13,16-octahydroacridino[4,3-]acridine-1.9(2,5)dion) with quadrupolar motif has been synthesized and its stationary and transient spectra have been measured. Stationary absorption and fluorescence spectra as well as nonstationary spectra show no signs of symmetry breaking (SB) in aprotic solvents, even of high polarity. The specific features of SB are revealed in alcohol solvents through a considerable red shift of stationary fluorescence spectra and the appearance of a new excited state absorption band in transient absorption spectra. SB is due to the formation of asymmetric strong hydrogen bonds, mainly on one side of the molecule. An unexpected regularity of symmetry breaking is found in mixtures of aprotic dimethylformamide and protic methanol, where methanol acts as a fluorescence quencher. It is revealed that there is no quenching as long as the methanol concentration is less than the critical value of 9 M. This leads to the conclusion that SB in such mixtures is possible only if the concentration of the protic solvent exceeds a certain threshold value.
已合成一种具有四极结构的吖啶二酮衍生物（3,3,11,11-四甲基-8,16-二苯基-3,4,8,10,11,12,13,16-八氢吖啶并[4,3-]吖啶-1,9(2,5)二酮），并测量了其稳态和瞬态光谱。在非质子溶剂中，即使是高极性的非质子溶剂，稳态吸收光谱、荧光光谱以及非稳态光谱均未显示出对称性破缺（SB）的迹象。通过稳态荧光光谱的显著红移以及瞬态吸收光谱中出现新的激发态吸收带，在醇类溶剂中揭示了SB的具体特征。SB是由于主要在分子一侧形成不对称强氢键所致。在非质子二甲基甲酰胺和质子甲醇的混合物中发现了对称性破缺的意外规律，其中甲醇起到荧光猝灭剂的作用。结果表明，只要甲醇浓度低于9 M的临界值，就不会发生猝灭。由此得出结论，只有当质子溶剂的浓度超过一定阈值时，此类混合物中才可能发生SB。
