论文部分内容阅读
通过考察2-羟基-1-萘甲醛半碳酰腙(HNLSC)在不同极性溶剂中的吸收光谱和荧光光谱,详细研究了HNLSC分子在不同溶剂及酸、碱条件下的不同构型,证实了HNLSC具有典型的ESIPT特性。在非极性溶剂中分子主要以分子内氢键的闭式构型存在,这种闭式构型使分子具有ESIPT特性,在环己烷溶剂和高酸度极性溶剂中分子均表现出～415nm的正常荧光和～435nm处的反常ESIPT荧光。在极性质子溶剂中,因溶质和溶剂之间形成了分子间的氢键以及进一步去质子化,HNLSC形成了基态的溶剂化开式构型和离子构型,在吸收光谱中表现出～395nm的离子构型特征吸收。开式构型和离子构型阻断了分子内质子转移途径,因而在荧光光谱中仅表现出一个特征峰。实验进一步通过三乙胺和稀硫酸调节溶液体系的极性和酸度环境,证明在不同溶剂极性和酸度环境下,HNLSC分子不仅存在萘环上羟基变化引起的多种互变异构体间的转化平衡,同时存在—CHN—NH—CO—NH2结构域的烯醇式和酮式结构的相互转化。
By investigating the absorption and fluorescence spectra of 2-hydroxy-1-naphthaldehyde semicarbazone (HNLSC) in different polar solvents, the different configurations of HNLSC molecules in different solvents and acids and bases were investigated in detail. HNLSC has typical ESIPT features. In a non-polar solvent, the molecule exists mainly in the closed intramolecular hydrogen bond configuration. This closed configuration gives the molecule ESIPT properties, both in cyclohexane solvent and in highly polar solvents show ~ 415 nm Of normal fluorescence and abnormal ESIPT fluorescence at -435 nm. In polar protic solvents, HNLSC forms solvated open and ionic configurations in the ground state due to the formation of intermolecular hydrogen bonds between solute and solvent and further deprotonation, exhibiting ~ 395 nm in the absorption spectrum Ion configuration characteristic absorption. The open configuration and the ionic configuration block intramolecular proton transfer pathways and therefore show only one characteristic peak in the fluorescence spectrum. The experiment further adjusted the polarity and acidity environment of the solution system by triethylamine and dilute sulfuric acid to prove that the HNLSC molecules not only exist between the various tautomers caused by the change of the hydroxyl groups on the naphthalene ring under different solvent polarities and acidity conditions Conversion equilibrium, while the existence of -CHN-NH-CO-NH2 domain enol and keto structure interconversion.