Área de Química Física, Facultad de Química Bioquímica y Farmacia, Instituto Multidisciplinario de Investigaciones Biológicas (IMIBIO-SL) CONICET, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
Spectrochim Acta A Mol Biomol Spectrosc. 2014 Jan 24;118:112-9. doi: 10.1016/j.saa.2013.08.060. Epub 2013 Aug 29.
The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π(*)). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture.
采用紫外-可见光谱法和密度泛函理论（DFT）方法研究了磺胺甲恶唑（SMX）在纯溶剂和二元溶剂混合物中的溶剂化行为。该溶质的光谱位移与 Kamlet 和 Taft 参数（α、β和π（*））相关联。多元线性回归分析表明，特定氢键相互作用和非特定偶极相互作用都对吸收最大值在纯溶剂中的位置起着重要作用。使用 TD-DFT 方法模拟的吸收光谱与实验结果吻合良好。二元混合物由环己烷（Cy）-乙醇（EtOH）、乙腈（ACN）-二甲基亚砜（DMSO）、ACN-二甲基甲酰胺（DMF）以及含有 DMSO、ACN、EtOH 和 MeOH 共溶剂的水相混合物组成。优先溶剂化指数作为溶剂组成的函数进行计算，所有二元混合物均表现出非理想特性。在 ACN-DMSO 和 ACN-DMF 混合物中，结果表明具有较高极性和氢键供体能力的溶剂优先与溶质相互作用。在含有水的二元混合物中，SMX 分子在整个组成范围内被有机共溶剂（DMSO 或 EtOH）溶剂化。在 ACN-H2O 和 MeOH-H2O 中观察到协同效应，表明在某些浓度下，溶剂相互作用形成缔合配合物，其极性应比混合物中各溶剂的极性更强。
