Structural, spectroscopic (FT-IR, FT-Raman) and theoretical studies of the 1:1 cocrystal of isoniazid with p-coumaric acid

The 1:1 cocrystal of isoniazid (INH) with p-coumaric acid (pCA) has been prepared by slow evaporation method in methanol, which was crystallized in monoclinic P21/n space group having four molecules in the asymmetric unit. The cocrystal has been characterized by single crystal X-ray analysis, FTIR, FT Raman and DFT calculations. The crystal structure was stabilized by OHphenol⋯Npyridine, NH⋯OC, COOH⋯NH and CH⋯O hydrogen bonding interactions. The geometry optimized structure of the cocrystal at the B3LYP/6-31G(d,p) level of theory has been used to calculate the vibrational frequencies.

► This research paper describes the experimental and theoretical studies on a co-crystal-which are usually prepared to enhance the physiochemical property of a molecule (usually an active pharmaceutical ingredient). ► Here the API is an anti-tuberculosis drug (Isoniazid) and the cocrystal former is a nutraceutical (p-coumaric acid). This combination can be termed as a “synergistic pharmaceutical co-crystal” as p-coumaric is sure to add its inherent anti-oxidant property, etc. ► Instead of using a GRAS listed compound (as a co-crystal former)- a molecule with well documented pharmacological property has been used. This can also be programmed in such a way that the side-effects of the API can be reduced by the co-crystal former.