Interactions between Diatrizoic acid and water in pre-nucleation clusters

The formation of water containing crystal forms, so-called hydrates, is a real problem for the pharmaceutical industry. Hydrates show thermodynamically the lowest solubility in water and thus in bodily fluids, and can thus jeopardise the efficiency and safety of a medicine. We are investigating the aggregation of drug molecules with water in pre-crystallisation solution to evaluate the existence of strong interactions between solute and water in solution leading to hydrate formation. Diatrizoic acid (DTA) forms a very stable dihydrate from DMSO in the presence of water, and we could show pre-nucleation interaction by FTIR and NMR spectroscopy. To structurally elucidate this system, we have measured DTA in DMSO/H2O but could not obtain data on DTA in pure DMSO due to crystallisation. In this continuation, we propose to measure DTA in DMSO solution in quartz cells to complete the study.