Isoniazid Based Zn(II) Coordination Compound for Potential Energy Applications: Synthesis, Structure, Topology and Theoretical Interpretation

{[Zn(L)₂]}_n(1) [HL= N'-(propan-2-ylidene)isonicotinohydrazide], is characterized by single crystal X-ray diffraction measurement. The HL acts as monoanionic bridging ligand consisting of pyridyl-N coordination to one Zn(II) centre and hydrazine-N,O chelation to neighboring Zn(II) centre to form Zn(N,O, N^/)₂ coordination sphere (N = Pyridyl-N; N^/ = hydrazide-N and O = hydrazide-O). Zn(II) lies at the centrosymmetric position. Thus, chelatative bridging of two L^- to Zn(II) propagate almost perpendicularly to form two-dimensional coordination polymer (2D CP). Various non-covalent interactions in the coordinated ligand frame contribute to building a 3D supramolecular network, which has been supported by Hirshfeld surface analysis. The density functional theory (DFT) computation of the monomeric unit, using crystallographic parameters of the compound 1, yielded a calculated band gap (E_HOMO – E_LUMO) (HOMO = highest occupied molecular orbital and LUMO = lowest unoccupied molecular orbital) of 1.36 eV. Bader's Quantum Theory of "Atoms in Molecules" (AIM) was employed at bond critical points (BCPs), providing insight into electron density distribution and bonding characteristics between the chelating ligand and the metal center. Additionally, principle interacting orbital (PIO) analysis further elucidates the nature and strength of the orbital interactions within the compound.