An experimental and computational investigation of the elusive anhydrous form of Oxyma-B

We report the crystal structure of the anhydrous form of Oxyma-B, a relevant racemization suppressor for peptide synthesis, solved by direct space methodologies with X-Ray Powder Diffraction data. The structure had remained elusive since only monohydrate crystals are readily obtained from slow crystal growth experiments. An extensive combined experimental and computational study has allowed us to obtain deeper insight into the solid-state landscape of Oxyma-B and its tendency for hydration. The singular network of H-bonds and energetically relevant OMIDLINE HORIZONTAL ELLIPSIS pi interactions formed by the two symmetrically independent molecules of anhydrous Oxyma-B has been analysed by using the quantum theory of "atoms-in-molecules" (QTAIM) and the noncovalent interaction plot (NCIplot). We report a combined crystallographic and computational study on the important peptide synthesis reagent Oxyma-B. It has provided deeper insight into its solid-state landscape and its tendency for hydration.