Structural diversity of copper(II) complexes with three dimensional network: Crystal structure, Hirshfeld surface analysis, DFT calculations and catalytic activity

Three new copper(II) complexes containing benzoic acid (2-hydroxy-3-methoxy-benzylidene)-hydrazide (HL) viz., [Cu(L)(H2O)]NO3∙H2O 1, [Cu(L)(NO3)(H2O)] H2O 2 and [Cu4(L)4](ClO4)4 3 have been synthesized and characterized using physicochemical and spectroscopic methods. Complexes 1 and 2 are mononuclear while 3 is tetranuclear. In these complexes the center Cu(II) ions are four, five and six-coordinated in 1–3, respectively. All complexes involve hydrogen bonds and π⋯π interactions which develop supramolecular assemblies of different dimensionalities and architectures. The Hirshfeld surface analysis with 2D fingerprint plots revealed the short-range possible intermolecular interactions in these complexes. The molecular geometries in the ground state have been calculated using density functional theory (DFT) method with 631G(d) and 6–311++G(d,p) basis sets. The natural population analysis (NPA) and Mulliken charge distribution analysis showed the different electron donors which coordinate with copper. Some global reactivity descriptors like chemical potential (μ), electronegativity (χ), hardness (η) and electrophilicity index (ω) were also evaluated using DFT method. Additionally, antioxidant superoxide catalytic activity was also measured. The results of catalytic measurements exhibited that 2 provide an effective and selective catalytic system for dismutation of superoxide anion (O2∙-).