A Cocrystal of Baicalein and 4,4′-Bipyridine with Zipper-Type Architecture

A new cocrystal of baicalein, possessing three A-ring-hydroxyl groups and without B-ring-hydroxyl groups and 4,4′-bipyridine (BE·2BPY·H2O) has been prepared and characterized. The structural analyses and Hirshfeld surfaces show that baicalein is hydrogen-bonded to co-crystallized solvent water molecules featuring for example motifs that can be described with graph set R44(8) similar to those reported for the cocrystal of myricetin with 4,4′-bipyridine. A zipper-type architecture is observed in cocrystal BE·2BPY·H2O linking a baicalein, two 4,4′-bipyridine and a solvent water molecules via classical O–H⋯N and O–H⋯O and non-classical C–H⋯O hydrogen bonds into 2D sheets. Additionally, the cocrystal shows better solubility in 0.1 M HCl in comparison to pure baicalein. Cocrystal of baicalein with zipper-type architecture shows improved solubility compared to baicalein.