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

Two organic cocrystals namely, caffeine:cinnamic acid [(caf)(ca)] (1) and caffeine:eosin dihydrate [(caf)(eos)]center dot 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 P2(1)/C and Z = 4. An imidazole-carboxylic acid synthon is observed in the cocrystal 1. The intermolecular hydrogen bond, O-H center dot center dot center dot N and pi-pi interactions play a major role in stabilizing 1 whereas the intermolecular hydrogen bonds, O-H center dot center dot center dot O, O-H center dot center dot center dot N, and intramolecular hydrogen bond, O-H center dot center dot center dot Br; along with pi-pi 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. (C) 2013 Elsevier B.V. All rights reserved.