Studies on the syntheses, structural characterization, antimicrobial-, and DPPH radical scavenging activity of the cocrystals caffeine:cinnamic acid and caffeine:eosin dihydrate

Abstract Two organic cocrystals namely, caffeine:cinnamic acid [(caf)(ca)] ( 1 ) and caffeine:eosin dihydrate [(caf)(eos)]·2H 2 O ( 2 ) were synthesized and studied by FT-IR, TGA/DTA, and single crystal XRD. The crystal system of cocrystal 1 is triclinic with space group P - 1 and Z  = 2 and that of cocrystal 2 is monoclinic with space group P 2 1 / C and Z  = 4. An imidazole–carboxylic acid synthon is observed in the cocrystal 1 . The intermolecular hydrogen bond, O–H⋯N and π–π interactions play a major role in stabilizing 1 whereas the intermolecular hydrogen bonds, O–H⋯O, O–H⋯N, and intramolecular hydrogen bond, O–H⋯Br; along with π–π interactions together play a vital role in stabilizing the structure of 2 . The antimicrobial- and DPPH radical scavenging activities of both the cocrystals were studied.