title: Stereochemical structure and intermolecular interaction of complexes of (-)-Gallocatechin-3-O-gallate and caffeine.
abstract: A suspension containing an equimolecular amount of (-)-gallocatechin-3-O-gallate (GCg) and caffeine in water was heated at 90 °C for 30 min to give a 1 : 2 complex of GCg and caffeine. X-Ray crystallographic analysis of crystal of the 1 : 2 complex showed that π-π interactions formed between the A, B' rings of GCg and the two six-membered rings of caffeine. Whereas, the same suspension was heated at 90 °C for 30 s to give a sticky substance, which contained GCg, caffeine, and water at a molar ratio of 1 : 1 : 22 based on measurement of the integral volume of (1)H-NMR signals. The sticky substance crystallized slowly to give a 2 : 2 complex of GCg and caffeine. X-Ray crystallographic analysis of crystal of the 2 : 2 complex showed that the A and C rings of GCg moieties faced each other, and face-to-face π-π interactions formed between the B ring of GCg and caffeine, the B' ring of GCg and caffeine.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsumi
authors.forename: Takashi
authors.initials: T
authors.lastname: Sato
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishizu
mesh_terms: D002110:Caffeine / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D013237:Stereoisomerism; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; C417940:gallocatechin gallate; D002110:Caffeine; D002392:Catechin