Solvent effects on the absorption spectra of arginine–salicylaldimine
作者:S. Hisaindee、J. Graham、M.A. Rauf、M. Nawaz
DOI:10.1016/j.molliq.2012.02.020
日期:2012.5
Arginine–salicylaldimine was synthesized, characterized and its absorptionspectra were studied in various solvents. The molecule can exist either as keto or enol forms. These forms can be stabilized by the nature of the solvent. The results revealed that intramolecular hydrogen bonding is responsible for stabilizing the keto form in non-polar solvents whereas intermolecular hydrogen bonding favors the enol
合成了精氨酸-水杨基亚胺,对其进行了表征,并在各种溶剂中研究了其吸收光谱。该分子可以酮或烯醇形式存在。这些形式可以通过溶剂的性质来稳定。结果表明,分子内氢键负责稳定非极性溶剂中的酮形式,而分子间氢键则有利于烯醇形式。同时,在分子的酸性和碱性形式之间可以存在平衡,这影响探针分子的溶剂化。发现水溶液中存在三种不同的物质,它们的平衡态存在,它们的p K a值得到确定(p K a1 = 5.13,p K a2 = 8.11,和p Ka3 = 10.88)。在由甲醇和二氯甲烷组成的混合溶剂系统中,精氨酸-水杨醛亚胺的优先相互作用显示出在低浓度甲醇下吸收能的急剧变化,这表明探针分子非常希望与甲醇相互作用。随时间变化的密度泛函理论(TD-DFT)计算用于将在370-440 nm范围内观察到的电子跃迁分配为酮和烯醇形式的π - π *跃迁,并在溶液中进行区分。