DFT–Assisted Structure Determination from Powder X-ray Diffraction Data of a New Zonisamide/ϵ-Caprolactam Cocrystal

Abstract

The crystal structure of a new zonisamide cocrystal, an anticonvulsant drug used to treat the symptoms of epilepsy and Parkinson’s disease, with ϵ-caprolactam is reported herein. The structure has been solved by direct space methodologies from powder X-ray diffraction data. The refinement of the structure was conducted by the Rietveld method assisted by the dispersion-corrected density-functional theory (D-DFT) calculations and periodic boundary conditions. Further analysis of the structure reveals several H-bonded synthons and self–assembled dimers that have been further analyzed by DFT calculations and other computational tools such as molecular electrostatic potential (MEP) surfaces and the quantum theory of “atom-in-molecules” (QTAIM).

Structural features, dissolution performance and anthelmintic efficacy of multicomponent solid forms of fenbendazole with maleic and oxalic acids

“…Thus, the process of structure determination from powder XRD is usually complemented by periodic DFT-D calculations, which improve metric parameters of covalent bonds and non-covalent interactions as well as reconcile the proton sites with an actual crystalline environment. [73][74][75][76][77][78] The latter aspect is essential for discrimination between cocrystals and salts in multicomponent structures where the extent of proton transfer is uncertain. 68,79 In this study, the PBE-D3 geometry optimization (with fixed unit cell) was applied to enhance the accuracy of the structural models obtained via powder XRD data.…”