Dept of Pharmaceutical Chemistry, Faculty of Pharmacy University of Ibadan, Orita UI, Ibadan, Oyo State, Nigeria.
Spectrochim Acta A Mol Biomol Spectrosc. 2010 Feb;75(2):719-27. doi: 10.1016/j.saa.2009.11.045. Epub 2009 Nov 24.
Comprehensive electronic absorption spectra of a new dye series, 4-carboxyl-2,6-dinitrophenylazohydroxynaphthalenes have been investigated in solvents of varying polarities. The solvent dependent UV-vis spectral shifts were analysed using some solvent physical parameters such as refractive index, dielectric function, hydrogen bonding acceptor ability, orientation of polarization and others. The observed spectral shifts were correlated with different solute-solvent interaction mechanisms using simple and multiple linear regression analyses. The results of the curve fitting coefficients enabled us to classify the various interactions of solvents with the dyes and relate the solvatochromic behaviours to the substituent effects on the dye molecules. Charge-transfer complexation occurring between one of the congeners and N,N'-dimethylformamide was extensively studied and discovered to be both concentration- and temperature-dependent. The electronic character and the chemical nature of the solvents as well as the chemical nature of the other substituents, apart from the common hydroxyl group, are important factors for the observed solvatochromic properties of the 4-carboxyl-2, 6-dinitrophenylazohydroxynaphthalenes.
已研究了一系列新的染料，即 4-羧基-2,6-二硝基苯偶氮羟基萘在不同极性溶剂中的综合电子吸收光谱。使用折射率、介电常数、氢键接受能力、极化方向等一些溶剂物理参数分析了溶剂依赖性 UV-vis 光谱位移。使用简单和多元线性回归分析，将观察到的光谱位移与不同的溶质-溶剂相互作用机制相关联。曲线拟合系数的结果使我们能够对溶剂与染料的各种相互作用进行分类，并将溶剂致变色行为与染料分子上的取代基效应相关联。对一种同系物与 N,N'-二甲基甲酰胺之间发生的电荷转移络合进行了广泛的研究，发现其既依赖于浓度又依赖于温度。溶剂的电子性质和化学性质以及除常见的羟基以外的其他取代基的化学性质是观察到的 4-羧基-2,6-二硝基苯偶氮羟基萘溶剂致变色性质的重要因素。
