Dimethyl sulfoxide heavily extends homogeneous regions of the Propionitrile/DMSO/Water mixtures

Abstract

The ternary mixtures exhibit peculiar solvation properties thanks to simultaneously possessing a few functional groups. The preparation of such systems opens a wide avenue to fine-tune the physicochemical properties of the medium and, therefore, obtain designer solvents to match specific problems in applications. Understanding the mutual affinities of the components and structural features of the mixtures is a key prerequisite to enriching the treasury of available solvents. Water, propionitrile (PN), and dimethyl sulfoxide (DMSO) are three polar liquids. Yet, their polarities are of different degrees that prevent infinite mutual miscibilities. We hereby report that significant contents of DMSO permit one to prepare PN/DMSO/water mixtures with any coveted molar fraction of PN. By using densitometric measurements over wide ranges of compositions and supportive computer simulations, we have identified that xDMSO/xwater ≥ 1 is sufficient for the ternary homogeneous mixture incorporating any contents of PN from 298.15 to 323.15 K. The numerical simulations suggest that the partially amphiphilic nature of DMSO represents a paramount factor to make a successful interface between PN and water workable. The paper, for the first time, discusses binary and ternary complexes in the PN/DMSO/water single-phase mixtures in the context of their relative thermodynamics stabilities. The reported new physical insights boost the progress in the ongoing development of modern on-demand solvents and promise evident practical applications in biomedical fields.