Recognition-directed supramolecular assemblies of metal complexes of terpyridine derived ligands with self-complementary hydrogen bonding sites

The synthesis and X-ray structures of three metal complexes with terpyridin e-derived ligands that contain amino-pyrimidine and amino-pyrazine moieties are presented. They have been designed in view of directing their self-ass embly into specific supramolecular arrays through molecular recognition int eractions. The solid-state structures indeed reveal extensive hydrogen-bond ed networks. The Co complex 4a with PF6- counterions builds a two-dimension al infinite interwoven grid through strong double hydrogen bonds (d(N-H-N) =2.918-3.018 Angstrom) between the amino groups and the N atoms of the ring s, with all H-bonding sites saturated. Changing the anions to BF4- in 46 le ads to a similar infinite but partially broken grid with a quarter of the H -bonding sites unsaturated (d(N-H-N)=2.984-3.206 Angstrom). In the case of the Zn complex 12 with triflate anions, half of the hydrogen bonds are form ed. Only one of the two orthogonal ligands has hydrogen bonds (d(N-H-N)=3.0 82, 3.096 Angstrom) to the neighbouring complexes and thus builds linear, s upramolecular, polymeric chains. These structural differences are mainly at tributed to crystal-packing effects caused by the different anions. The dat a presented here may also be regarded as a prototype for the generation of organised arrays through sequential self-assembly processes.