The photophysical behavior of 9-(2-(4-(N,N-dimethylamino)phenyl)ethynyl)anthracene-10-carbonitrile (CNAacDMA) was investigated with absorption and steady-state fluorometry. Studies have shown extremely interesting properties of the analyzed derivative. The studied molecule is characterized by dual fluorescence and bidirectional fluorescence. These two observed phenomena are interrelated. Dual fluorescence analysis (part 1) explains bidirectional fluorescence. The compound in polar solvents shows only one emission band, however in moderate polar solvents shows dual emission. The appearance of the long-wavelength CT band in moderate polar solvents and its lack in polar solvents leads to bidirectional solvatofluorochromism. The solvatochrome analysis was performed in a wide range of 24 solvents. To determine the contribution of specific and nonspecific interaction of this compound with solvents linear and multi-parametric correlation of the solvent polarity were analyzed. The novelty and innovation in this article is to carry out such an analysis separately for two different individuals occurring in the excited state. Single-parameter scale with ET(30) as a solvent polarity parameter and multi-parameter scales such as the Catalán four-parameter solvent scale were used. The excited state dipole moment was determined based on solvatochromic method. The hydrogen bond energy change after excitation in the Franck-Condon and relaxed excited state were estimated.
Keywords: acetylene derivatives; bidirectional solvatofluorochromism; fluorescence spectroscopy; fluorophores; polarity scale.
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