Synthesis, Structural Analysis, and DFT optimization of Novel Zn(II) coordination polymer derived from N'-(pyridin-2-ylmethylene)nicotinohydrazide

Abstract

In this work, we report one-pot synthesis and structural characterisation, based on elemental analysis, IR spectroscopy, and single-crystal X-ray diffraction analysis, of a new Zn(II) coordination polymer {[Zn2(L)2(SCN)2]·0.5H2O}n (1) synthesized from the ligand N'-(pyridin-2-ylmethylene)nicotinohydrazide (HL) and thiocyanate as an ancillary ligand. The solution-state properties of the Zn(II) complex 1 were investigated by UV-vis spectroscopy in different solvents. In the solid state of Zn(II) complex 1, the asymmetric unit contains two crystallographically independent Zn(II) atoms, two deprotonated ligands (L-), two SCN- anions and half of a lattice water molecule. The Zn(II) cations are in a pentacoordinated environment and adopt a distorted square pyramidal coordination geometry formed by the N2O tridentate chelating ligand HL and the nitrogen atoms of the thiocyanate anions. In the crystal packing of 1, the thiocyanate ancillary ligands mediate all other short contacts, and the bridging ligands form a zig-zag coordination polymer, which is additionally stabilized by pyridine π-stacking interactions. Furthermore, a DFT study was conducted to analyze the charge distribution and different intermolecular interactions in the Zn(II) complex 1, along with HOMO to LUMO electronic transitions. These findings highlight the role of nicotinoyl hydrazone-based ligands and thiocyanate as an ancillary ligand in the generation of a coordination polymer.