Lin S, Struve W S
Department of Chemistry, Iowa State University, Ames 50011.
Photochem Photobiol. 1991 Sep;54(3):361-5. doi: 10.1111/j.1751-1097.1991.tb02028.x.
The fluorescence kinetics of the nitrobenzoxadiazole (NBD) chromophore were studied at low concentrations in solvents with varying polarity and hydrogen-bonding donor strength. The emission decay was essentially single exponential in all solvents studied. While the absorption and fluorescence solvatochromism is determined largely by the solvent polarity, the S1 state decay kinetics are strongly modulated by the solvent H-bonding capacity. The NBD emission lifetime, generally approximately 7-10 ns in the aprotic solvents, is reduced to 0.933 ns in water. The solvent deuterium isotope effect on the fluorescence decay is substantial in D2O and in methanol-d4, but is insignificant in DMSO-d6. These results are consistent with acceleration of S1----S0 internal conversion through an accepting vibrational mode created by intermolecular hydrogen-bonding of the NBD chromophore to an H atom-donating solvent. This work bears on the practically of using NBD as a fluorophore in assays for estrogen and progesterone receptors.
在具有不同极性和氢键供体强度的溶剂中，研究了低浓度下硝基苯并恶二唑（NBD）发色团的荧光动力学。在所研究的所有溶剂中，发射衰减基本上是单指数的。虽然吸收和荧光溶剂化显色主要由溶剂极性决定，但S1态衰减动力学受到溶剂氢键能力的强烈调制。NBD发射寿命在非质子溶剂中通常约为7 - 10 ns，在水中降至0.933 ns。溶剂氘同位素对荧光衰减的影响在D2O和甲醇-d4中很大，但在DMSO-d6中不显著。这些结果与通过NBD发色团与供氢原子溶剂的分子间氢键形成的接受振动模式加速S1----S0内转换一致。这项工作与在雌激素和孕激素受体测定中使用NBD作为荧光团的实用性有关。
