Multicomponent cystals of selected Hydroxycinnamic Acids

Abstract

The solid-state modification of a given active pharmaceutical ingredient is a desired way to alter its physicochemical properties, such as solubility or bioavailability. Multicomponent crystals constructed with p-coumaric acid (pCA) and trans-ferulic acid (TFA) were investigated with the amines (2-amino-4-picoline (2A4MP), 2-amino-6-picoline (2A6MP), 4,4’-bipyridine (BIPY) and pyridine (PYR)) and 1,4-dioxane (DX). Eight compounds were prepared using the slow evaporation technique. pCA formed one co-crystal, two salts and two solvates while TFA formed a co-crystal, a salt and a solvate. The crystal structures were determined using single crystal Xray diffraction crystallography. Further characterisations were done using thermal analysis and FTIR spectroscopy. Z’ > 1 was observed for some of the crystal structures of pCA. The solvent assisted grinding method for preparation of these compounds was not successful as they all resulted in unknown compounds. The Hirshfeld analysis confirmed that the crystal structures generated in this study were dominated by hydrogen bonding (O-H•••O, O-H•••N and C-H•••O) and the π-π stacking had minimal contribution in the packing arrangement of the new solid forms.