Interaction between gallocatechin gallate and caffeine in crystal structure of 1:2 and 2:2 complexes

A suspension of (-)-gallocatechin gallate (GCg) and caffeine in water afforded two kinds of complexes, the 1:2 and 2:2 complexes of GCg and caffeine. The crystal structures of the two complexes were determined by X-ray crystallography. The driving force for the formation of the 1:2 and 2:2 complexes was thought to be mainly pi-pi interactions between the A, B' rings of GCg and the six-membered rings of caffeines, and those between the B ring of GCg and caffeine, the B' ring of GCg and caffeine, and the A rings of GCgs, respectively. (C) 2009 Elsevier Ltd. All rights reserved.