Liana S. Gabrielyan

Dielectric relaxation study of diethylsulfoxide/water mixtures

Complex dielectric spectra of diethylsulfoxide (DESO)/water mixtures at 25°C over the entire concentration range of DESO, in the frequency range 0.2 ≤ ν/GHz ≤ 89 have been measured. In general, a description of the complex permittivity spectra requires a consideration of different types of relaxation processes depending upon DESO concentration. For the lower DESO concentration range the relaxation contribution to the spectrum is described by two Debye terms, whereas for higher concentration three Debye terms are used. For both at mol fraction equals to 0.9 and pure DESO as well Cole–Davidson type is valid. In addition, the data on the dimethylsulfoxide (DMSO)/water system obtained in this work well agree with those known from literature. The concentration dependent excess dielectric constant, excess inverse relaxation time and Kirkwood correlation factor of the mixtures have been determined.

Low temperature dielectric relaxation study of aqueous solutions of diethylsulfoxide

In the present work, dielectric spectra of mixtures of diethylsulfoxide (DESO) and water are presented, covering a concentration range of 0.2-0.3 molar fraction of DESO. The measurements were performed at frequencies between 1Hz and 10MHz and for temperatures between 150 and 300K. It is shown that DESO/water mixtures have strong glass-forming abilities. The permittivity spectra in these mixtures reveal a single relaxation process. It can be described by the Havriliak-Negami relaxation function and its relaxation times follow the Vogel-Fulcher-Tammann law, thus showing the typical signatures of glassy dynamics. The concentration dependence of the relaxation parameters, like fragility, broadening, and glass temperature, are discussed in detail.

FTIR and Ab Initio Studies of Diisopropylsulfoxide and its Solutions

Fourier transform infrared (FTIR) measurements, ab initio quantum chemical calculations at the restricted Hartree–Fock (RHF) level and density functional theory (DFT) calculations have been performed to study molecular interactions in pure diisopropylsulfoxide (DiPSO) and the binary mixtures DiPSO/CCl4 and DiPSO/water. The optimized molecular geometry, vibrational wavenumbers, dipole moments and several thermodynamic parameters of free DiPSO and DiPSO/water 1:1 complex in the ground state were calculated using the RHF and B3LYP methods with the 6-31G(d) basis set. A fitting procedure has been performed for both SO and CH stretching regions and a detailed spectral interpretation has been done based on the data obtained from ab initio calculations, infrared spectra and band deconvolution analysis.