Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
J Phys Chem A. 2010 Dec 16;114(49):12875-80. doi: 10.1021/jp108064x. Epub 2010 Nov 17.
We report on the rotational diffusion dynamics of the anionic chromophore resorufin in water and N-octyl-2-pyrrolidone (NOP) solutions as a function of solution electrolyte concentration. Our data show that resorufin exhibits a single exponential anisotropy decay in aqueous solutions containing up to 0.1 M lithium perchlorate (LiClO(4)). In contrast to the observed behavior of resorufin in pure NOP, where biexponential decay occurs, we also observe a single exponential anisotropy decay for resorufin in NOP with the addition of up to 0.1 M tetrabutylammonium bromide (TBAB) or tetraoctylammonium bromide (TOAB). For resorufin in NOP, the reorientation time constant increases with increasing electrolyte concentration, consistent with complexation between the resorufin anion and the electrolyte ammonium cation. We observe a qualitatively different trend in the aqueous resorufin solutions and understand these data for both solvent systems in the context of interactions between the chromophore and cationic species present.
我们报告了阴离子生色团 Resorufin 在水和 N-辛基-2-吡咯烷酮（NOP）溶液中的旋转扩散动力学，作为溶液电解质浓度的函数。我们的数据表明，Resorufin 在含有高达 0.1 M 高氯酸锂（LiClO4）的水溶液中表现出单指数各向异性衰减。与在纯 NOP 中观察到的 Resorufin 的双指数衰减行为相反，我们还观察到在添加高达 0.1 M 的四丁基溴化铵（TBAB）或四辛基溴化铵（TOAB）的 NOP 中，Resorufin 也表现出单指数各向异性衰减。对于 NOP 中的 Resorufin，重取向时间常数随电解质浓度的增加而增加，这与 Resorufin 阴离子与电解质铵阳离子之间的络合一致。我们在水溶液 Resorufin 溶液中观察到一种定性上不同的趋势，并根据发色团和阳离子物种之间的相互作用，理解了这两种溶剂体系的数据。
