MgCl2/甲醇溶液的近红外光谱研究及量子计算

Study on MgCl_2 in Methanol by NIR Spectroscopy and Quantum Calculations

利用近红外光谱研究了MgCl2/甲醇溶液中的氢键种类及其变化和溶液离子化作用.近红外光谱结果分析表明,Mg2+与溶剂发生了强烈的相互作用导致溶液中的氢键发生变化.随着MgCl2浓度的增加,多聚体氢键(δ-OHs)减少,低聚体和二聚体氢键(γ-OHs)增加,OHs总数维持不变.通过对光谱曲线的分解拟合,定量地计算了不同浓度范围(0.21～0.62 mol·kg-1)内Mg2+的溶剂化数为5.5到5.0.并利用量子化学方法对溶剂化数为5和6的配合物结构进行优化及热力学性质的计算,通过光谱变化及理论计算推断Cl-可能会以氢键结合甲醇分子的形式存在.

The kinds and diversity of hydrogen bonds in MgCl2/CH3OH solutions have been investigated using NIR spectroscopy. It was found that the Mg^2＋ interacted with methanol, which mainly led to the diversity of hydrogen bonds in methanol solvent. The population of δ-OH bonds decreased and that of γ-OH bonds increased with rising the concentration of MgCl2, however the sum of OH bonds kept relatively constant. Based on the deconvolution and quantitative calculation on obtained spectra, apparent solvation numbers of 5.5-5.0 for Mg^2＋ have been inferred at different molalities of MgCl2. Moreover the optimized structures and some thermodynamic properties were obtained by DFT calculation. It was inferred that Cl^- should interact with methanol by hydrogen bonds.