Synthesis, structural, spectral characterization, DFT analysis and antimicrobial studies of aquabis(L-ornithine)copper(II) picrate

• Preparation and characterization of aquabis(L-ornithine)copper(II) picrate.
• Crystal data showed a distorted square-pyramidal geometry for studied complex.
• Complex exhibits antimicrobial activities against Gram-positive and Gram-negative bacteria.
• DFT/B3LYP level is capable to provide satisfactory results for predicting optimized geometry and vibrational data.

The present work consists of synthesis, spectroscopic, DFT studies and crystal structure investigation of complex [Cu(L-orn)2(H2O)](PIC)2 (where L-orn = L-ornithine, PIC = picrate anion). The molecular structure of complex was determined by X-ray crystallography and refined by three-dimensional least squares techniques. Copper atom is five coordinate and two molecules of L-ornithine are coordinating with it through their carboxylate oxygens and amine nitrogens whereas the fifth site is occupied by water molecule. Both of the picrate anions are present outside the coordination sphere of metal ion resulting in formation of charge-separated type complex. EPR spectrum suggests about the distorted square-pyramidal geometry of the complex and is confirmed by X-ray crystallography. The optimized structure of the present complex has been studied using the DFT/B3LYP/6-31G*(d,p)/LANL2DZ level of theory. The vibrational assignments and HOMO–LUMO were theoretically examined by means of the hybrid DFT method. Also the antimicrobial properties of the title complex have been explored in the present work.

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