水溶液中，糖ガラス中における2-(1-pyridinio)benzimidazolate の分子挙動
2019 年 64 巻 2 号 p. 91-95
詳細
2019 年 64 巻 2 号 p. 91-95
We report solvatochromic shift of the absorption spectrum and fluorescent red-edge effect (REE) of a betaine molecule, 2-(1-pyridinio)benzimidazolate (SBPa) in saccharide glasses. Interestingly, SBPa exhibits REE even in aqueous solution, where the microscopic environmental inhomogeneity is normally averaged over time by the solvent thermal fluctuation. We conclude that SBPa exists in an equilibrium state between betaine and protonated form in aqueous solution. Thus, frequency shift of absorption and fluorescence spectra of SBPa could be not only a measure of solvent polarity but also that of solvent acidity, and the data are reanalyzed by the new knowledge. Nevertheless, Stokes shift of SBPa in trehalose glass is the smallest compared to other saccharide glasses measured in this study, indicating significant suppression of molecular fluctuation by trehalose glass.
