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

Abstract

A new flexible bowl-shaped zwitterionic complex, 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tris(4-carboxypyridinium) tribromide (H 3 L Br 3 ) was designed and synthesized, which was subsequently used as an efficient ligand to construct four interesting coordination polymers of [Cu 2 Cl 2 L 2 (H 2 O) 2 ]·Cl·Br·4H 2 O ( 1 ), [Zn L Br]·NO 3 ·H 2 O ( 2 ), [Cd 2 L 2 Br 2 ]·2NO 3 ·4H 2 O ( 3 ), and [Cd 2 L 2 (Inic)(H 2 O) 4 (MeOH) 2 ]·Br·2NO 3 ·3H 2 O (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 of the four novel coordination polymers based on the flexible zwitterionic L ligand should provide valuable information for further generation of novel topological networks with interesting properties.