Luminescent Coordination Polymers of Naphthalene Based Diamide with Rigid and Flexible Dicarboxylates: Sensing of Nitro Explosives, Fe(III) Ion, and Dyes

A naphthalene based diamide, 3-pyridin-3-yl-N-[5-(3-pyridin-3-yl-acryloylamino)-naphthalen-1-yl]-acrylamide ligand (L) with four dicarboxylates were shown to form Cd/Zn(II) coordination polymers under solvothermal conditions. Three of these coordination polymers (CPs) were found to have 2D-networks, while one of them contains a 3D-network. The Cd(II) centers exhibited bimetallic and trimetallic secondary building units to link the dicarboxylates and ligands. The CPs displayed high luminescence given the presence of electron rich moiety in the ligand. This luminescent property of CPs has been exploited for the detection of nitro aromatics and Fe(III) ions from aqueous solutions of 0.69 mu M (0.16 ppm) and 1.29 mu M (0.52 ppm) of picric acid and ferric ion, respectively. Further, all the CPs have shown propensity to adsorb dyes such as methylene blue, while eosin-Y is adsorbed by only one of the four CPs. The dye sorption was found to influence the emission profiles in terms of absorption maxima.