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摘要
For a binary mixture of xN-methylimidazole (hereafter abbreviated to N-mim) + (1-x) water, over a full molar fraction range, the mass density, sound velocity, refractive index, viscosity, mixing enthalpy, conductivity, and pH at (298.15, 308.15, 318.15) K and 0.1 MPa, and H-1 NMR and C-13 NMR at room temperature combined with Ab initio calculations, were measured and carried out. The excess molar volume (V-m(E)), sound deviation (Delta u), refractive index deviation (Delta n(D)), viscosity deviation (Delta eta), excess Gibbs energy of activation of viscous flow (Delta G*(E)), molar mixing enthalpy (Delta H-mix(m)), H-1 NMR chemical shift changes of N-mim and water protons (Delta delta(H)),C-13 NMR chemical shift change of N-mim (Delta delta(C)), sum of the chemical shift changes (Sigma Delta delta(H(N-mim)), Sigma Delta delta(C)), and the interaction energy, hydrogen bond length, second-order perturbation stabilization energy, electron density, and the electronic energy density of the trimer hydrogen-bonded complexes were calculated. The values of V-m(E), Delta u, Delta n(D), Delta eta, Delta G*(E), and Delta H-mix(m), were fitted to a Redlich-Kister equation. The extreme positions of these quantities and the chemical shift changes were compared and discussed with regard to the intermolecular interaction between N-mim and water, and a possible molecular interaction scheme was suggested for N-mim added to water. There occurs an ionization process and hydrogen-bonded interactions between N-mim and water. The ionization process may not be neglected at an infinite dilution of water, and hydrogen bonds predominate the primary interaction in the mixture. The predominant hydrogen-bonded complex in the mixture transforms with increasing x, which is consistent with the calculation results.
