Dimethyl sulfoxide (DMSO) is a widely used chemical in synthetic chemistry and also has unique and important biological applications. In the pure liquid, DMSO forms chain like structures of alternating sulfur and oxygen atoms due to its high self-association. However, it is known that DMSO/water mixtures form solutions with unique physical characteristics depending on the mole ratio. For instance, at a 1:2 ratio of DMSO/water a eutectic mixture forms with a freezing point of-70 C. Vibrational spectroscopy allows us to study the effects of noncovalent interactions when water and DMSO interact in solution. Spectral shifts can be analyzed in order to give a clearer picture of the structure of DMSO in DMSO/water mixtures and also in solutions with other hydrogen bond donors that cannot form as extensive hydrogen bonded networks. The anomalous properties of DMSO/water mixtures have been the subject of a large number of studies. It has been previously established that the reason for the unique properties of such solutions lies in the formation of strong hydrogen bonds between water and DMSO. Despite the many studies there is still no clear picture of the structure of DMSO in the water mixture. When a DMSO/water mixture is formed there is great increase in temperature of the solution. This suggests a significant perturbation of water’s hydrogen bond network due to interactions with DMSO. Here, the hydrogen bonding geometries of DMSO/water mixtures are studied using Raman spectroscopy and computational chemistry
