Four Novel Coordination Polymers Based on a Flexible Zwitterionic Ligand and Their Framework Dependent Luminescent Properties

A new flexible bowl-shaped zwitterionic complex, 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tris(4-carboxypyridinium) tribromide (H3LBr3) was designed and synthesized, which was subsequently used as an efficient ligand to construct four interesting coordination polymers of [Cu2Cl2L2(H2O)2]·Cl·Br·4H2O (1), [ZnLBr]·NO3·H2O (2), [Cd2L2Br2]·2NO3·4H2O (3), and [Cd2L2(Inic)(H2O)4(MeOH)2]·Br·2NO3·3H2O (Inic = isonicotinlate, 4) by reaction of L ligand with corresponding metal salts or in the presence of isonicotinic acid. In these coordination polymers, L ligands link up metal nodes to form distinct linear networks. Two bowl mouths of two L ligands surround each other to form a ball-shaped building synthon in compounds 1 and 4, while the linear networks in 2 and 3 are in cylinder-shaped configurations. The luminescent spectra of L and compounds 1, 2, 3, and 4 suggested that the potential field around L ligand should be an important factor on the fluorescent emissions. The successful construction...