A series of metal–organic coordination polymers containing multiple chiral centers

Two new trifunctional amino acid derivatives, (S-2-(pyridine-4- ylmethylamino)succinic acid (L1) and S-2-(pyridin-4-ylmethylamino)pentanedioic acid (L2)), containing carboxylate, achiral amine and pyridine groups, were used as effective bridging ligands for the synthesis of six homochiral coordination networks of [ZnL1(H2O)2]·H2O (1), [CoL1(H2O)2]·H2O (2), [ZnL2(H2O)2] (3), [NiL1(H2O)]·H2O (4), [Cd2L122(H2O)]·3H2O (5) and [CdL2]·H2O (6). Compounds 1, 2 and 3 adopt 1D polymeric linear networks, and compound 4 presents a 2D lattice framework, while compounds 5 and 6 comprise 3D networks containing small voids occupied by water molecules. The achiral amine groups within all six compounds are induced by the neighbouring chiral carbon centres into homochiral units to coordinate transition metal cations. Hydrogen bonding contacts play very important roles for the formation and stabilization of these homochiral coordination networks. The magnetic properties of 2 and 4, and the photoluminescent properties of 1, 3, 5 and 6 in solid state were investigated.