Dual Luminescent Coordination Polymers Based on Flexible Aliphatic Carboxylate Ligands Supplementing by Rigid Bipyridyl Ligands for 2,4-Dinitrophenol (DNP) and Iron (III) Ion Detections

Based on flexible aliphatic carboxylate ligands supplementing by isomerized structure of rigid bipyridyl ligands, three novel Zn(II) coordination polymers, namely Zn 2 (dpe)(glutarate) 2 (H 2 O) 2 (1), Zn 2 (glutarate) 2 (tdpe) 2 (H 2 O) 2 (2), and Zn(H 2 O)(succinate)(tdpe) 2 (3) (dpe = 1,2-di(4-pyridyl)ethylene, tdpe = trans-1-(2-pyridyl)-2-(4-pyridyl)ethylene)), have been synthesized by appropriate methods. The crystallographic data of all complexes presented the diverse geometries of Zn(II) center such as two independent of square pyramidal and tetrahedral (in (1)), trigonal bipyramidal (in (2)), and octahedral (in (3)). Both the carboxylate ligands act as bridging ligands with the various coordination mode to build up the main structures. While bipyridyl ligand showed only 4-pyridyl site in coordination bond with metal center providing only dpe acted as bridging ligand to build up the principal framework in (1). Whereas tdpe ligand presented monodentate coordination mode in the other. All structures of complexes indicated that the coexistence of two ligand types could support the higher dimensionality in the complexes. Complex 1 was further used as nitro-aromatic compounds (NACs) and heavy metal ion sensors. It shows highly sensitive and selective sensing to 2,4-dinitrophenol (DNP), and Fe(III) ion, respectively based on fluorescence quenching effect.