An alternating chain of spider-like tris(peptides) stabilized by stacking and by N-H••• N and N-H••• O=C hydrogen bonding

The X-ray crystal structure of the novel spider-like trispeptide N,N',N"-tris(2-aminopyridine)benzene-1,3,5-tricarboxamide shows the unexpected formation of a new extended polymeric architecture. The structure is characterized by cooperative hydrogen bonding generating neighbouring pairs by self-assembly, and stacking between rings. Pairs of amide groups related by an inversion centre are connected into dimers via two N-(HOcarbonyl)-O-... and two N-(HNpyridyl)-N-... intermolecular hydrogen bonds. The offset-stacked layers are tightly inter-linked (spacing of 3.477 angstrom) by hydrogen bonding and aromatic pi-pi stacking interactions. These dimers are further linked into polymeric chains by hydrogen bonding through bridging methanol solvent molecules. The central aromatic rings of molecules in adjacent dimers are once again related by inversion symmetry, with a perpendicular separation of 3.619 angstrom. (c) 2005 Elsevier B.V. All rights reserved.