Theoretical and experimental studies of Cu(II) and Zn(II) coordination compounds with N,O donor bidentate Schiff base ligand containing amino phenol moiety

• Two mononuclear coordination compounds were synthesized & characterized.
• Thermal degradation pattern of complexes were studied up to 1172 K.
• Non-isothermal kinetic parameters were calculated & proposed degradation mechanism.
• The CV studies were performed to examine their electrochemical behavior.
• DFT calculations were carried out to support the experimental findings.

We report here two mononuclear Cu(II) and Zn(II) coordination compounds of general formula [CuII(L)2].2H2O (1) and [ZnII(L)2].3H2O (2) derived from bidentate 2-chloro-6-{[(4-hydroxy-3-methoxyphenyl)methylidene]amino}-4 nitrophenol ligand (HL). These compounds were synthesized and characterized by elemental analysis, FT-IR, uv–vis, 1H NMR, molar conductance, thermal, PXRD, SEM-EDX and electrochemical studies. The PXRD and SEM analysis shows the amorphous/nanocrystalline nature of 1 and crystalline nature of 2. The diffraction peak broadening was explained in terms of domain size and the crystallite lattice strain. Thermogravimetric analysis in the range of 300–1172 K has been performed to determine the thermal stability of synthesized compounds. The non-isothermal kinetic parameters of degradation process were calculated using Coats-Redfern (C-R), Piloyan–Novikova (P–N) and Horowitz–Metzger (H–M) methods assuming first order degradation and proposed a random nucleation mechanism of thermal decomposition for both compounds. The cyclic voltammetric studies reveal the irreversibility of the oxidation/reduction process of synthesized compounds. To support the experimental findings theoretical calculations by means of DFT and TD-DFT at B3LYP level were incorporated. In addition; frequency calculations, HOMO–LUMO, energy gap (ΔE), molecular electrostatic potential (MEP), spin density and crystal packing were also computed at the same level of theory.

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