Yushchenko Dmytro A, Shvadchak Volodymyr V, Bilokin' Mykhailo D, Klymchenko Andrey S, Duportail Guy, Mély Yves, Pivovarenko Vasyl G
Department of Chemistry, Kyiv National Taras Shevchenko University, 01033, Kyiv, Ukraine.
Photochem Photobiol Sci. 2006 Nov;5(11):1038-44. doi: 10.1039/b610054f. Epub 2006 Aug 16.
A representative of a new class of dyes with dual fluorescence due to an excited state intramolecular proton transfer (ESIPT) reaction, namely 1-methyl-2-(4-methoxy)phenyl-3-hydroxy-4(1H)-quinolone (QMOM), has been studied in a series of solvents covering a large range of polarity and basicity. A linear dependence of the logarithm of its two bands intensity ratio, log(I(N*)/I(T*)), upon the solvent polarity expressed as a function of the dielectric constant, (epsilon- 1)/(2epsilon + 1), is observed for a series of protic solvents. A linear dependence for log(I(N*)/I(T*)) is also found in aprotic solvents after taking into account the solvent basicity. In contrast, the positions of the absorption and the two emission bands of QMOM do not noticeably depend on the solvent polarity and basicity, indicating relatively small changes in the transition moment of QMOM upon excitation and emission. Time-resolved experiments in acetonitrile, ethyl acetate and dimethylformamide suggest an irreversible ESIPT reaction for this dye. According to the time-resolved data, an increase of solvent basicity results in a dramatic decrease of the ESIPT rate constant, probably due to the disruption of the intramolecular H-bond of the dye by the basic solvent. Due to this new sensor property, 3-hydroxyquinolones are promising candidates for the development of a new generation of environment-sensitive fluorescence dyes for probing interactions of biomolecules.
一类因激发态分子内质子转移（ESIPT）反应而具有双重荧光的新型染料的代表，即1-甲基-2-（4-甲氧基）苯基-3-羟基-4（1H）-喹诺酮（QMOM），已在一系列涵盖广泛极性和碱性的溶剂中进行了研究。对于一系列质子性溶剂，观察到其两个谱带强度比的对数log（I（N*）/I（T*））与以介电常数函数（ε - 1）/（2ε + 1）表示的溶剂极性呈线性关系。在考虑溶剂碱性后，在非质子性溶剂中也发现log（I（N*）/I（T*））呈线性关系。相比之下，QMOM的吸收峰和两个发射峰的位置并不明显依赖于溶剂极性和碱性，这表明QMOM在激发和发射时跃迁矩的变化相对较小。在乙腈、乙酸乙酯和二甲基甲酰胺中进行的时间分辨实验表明，该染料发生了不可逆的ESIPT反应。根据时间分辨数据，溶剂碱性的增加导致ESIPT速率常数急剧下降，这可能是由于碱性溶剂破坏了染料的分子内氢键。由于这种新的传感特性，3-羟基喹诺酮有望成为开发新一代用于探测生物分子相互作用的环境敏感型荧光染料的候选物。
