Sensing and photocatalytic properties of a new 1D Zn(II)-based coordination polymer derived from the 3,5-dibromosalicylaldehyde nicotinoylhydrazone ligand

Abstract

A new 1D coordination polymer, [Zn(dsn)(HO2CCH3)]n (1), has been synthesized by reacting the Schiff base ligand 3,5-dibromosalicylaldehyde nicotinoylhydrazone (H2dsn) with Zn(O2CCH3)2·6H2O. The polymer has been characterized using FTIR spectroscopy and single crystal X-ray diffraction analysis. The single crystal X-ray analysis reveals that the immediate geometry around the Zn(II) ion is five-coordinate, that is satisfied by a pyridyl nitrogen atom of one dsn ligand, the imine-N, carbonyl-O and phenoxo-O atoms of the other dsn ligand, as well as the acetate oxygen atom, which generate a trigonal bipyramidal geometry. Furthermore, the dsn ligand coordinated by the pyridyl nitrogen atom also coordinates to another Zn(II) ion by its imine-N, carbonyl-O and phenoxo-O atoms to generate a zig-zag lD polymer chain. The 1D chain is held by weak non-conventional interactions in the solid state to engender a 2D supramolecular layer. The photoluminescent (PL) property of 1 has been investigated and the polymer has been exploited as a sensitive and selective fluorescent sensor to detect metronidazole (MDZ) with limit of detection (LOD) of 9.39 × 10−7 M amongst a variety of related antibiotics. Also, 1 has been used as a photocatalyst and displays excellent photocatalytic degradation of methylene blue (MB), decomposing 86.3% in 100 min under UV light irradiation. The plausible mechanisms which polymer 1 executed for the sensing of MDZ and photodegradation of MB have been explained with the aid of theoretical calculations.