Anion-dependent crystallization of four supramolecular cadmium complexes: Structures and property studies

Solvothermal reactions of 4,4 '-meth ylene-bis(3-hydroxy-2-naphthalene carboxylic acid) (H(4)mbna), heterocyclic bidentate ligands, and Cd(II) salts yielded four zero- to two-dimensional coordination complexes, [Cd(phen)(2)(H2O)(2)](H(2)mbna) center dot (H2O) (1), ([Cd-4(H(2)mbna)(8/2)(phen)(4)] center dot 2DMF}(n) (2), [Cd(H(2)mbna)(bipy)(H2O)](n) (3), and (Delta,Delta)-[Cd(H(2)mbna)(bipy)(2)](n) (4). Crystal structural analyses revealed that the zero-dimensional units of 1 are connected by hydrogen-bond interactions forming a two-dimensional double-layer with hollow structure. The dinuclear units in 2 are bridged by the carboxylate groups of H2mbna producing a two-dimensional nanoporous layer with the size about 11 x 15 angstrom(2). The zigzag chains in 3 are linked by hydrogen bonds constructing the nanotube structure with the size about 11 x 13 angstrom(2). The chiral chain in 4 is formed by the introduce of the Delta-configuration 2,2 '-bipyridine ligands. The differences in the structures of the four complexes indicate that the anion of the metal salts might act as a template in the formation of the solid product. The thermal property studies show that all of the four complexes are thermally stable. The title complexes also displayed structure-related photoluminescence properties in the solid state.