Structural characterization, Hirshfeld surface analysis, optical properties, and DFT study of a new copper(II) complex

The reaction of copper acetate and 4,4'-dimethoxy-2,2'-bipyridyl in ethanol afforded a novel complex, 4,4'-dimethoxy-2,2'-bipyridyl Cu(II) acetate disolvate, whose structure was determined unambiguously by single-crystal X-ray diffraction (SC-XRD) analysis. The complex was found to crystallize with a space group of P21/n and in the monoclinic system. The crystal structure shows molecular tapes arising from strong intermolecular hydrogen bonding and two molecules of water within the crystal lattice. The intermolecular interactions were studied using Hirshfeld surface analysis and the role of water molecules in stabilizing the crystal packing was explored. BFDH and attachment energy (AE) models were used in the prediction of the crystal morphology of the complex. The results of these computational studies revealed that the (1 0 -1) face can be preserved with the most facet area due to its exceptionally slow crystal growth rate and minimal attachment energy. The DFT study of the complex shows that the complex is a direct semiconductor with an optical band gap energy of 1.8 eV. The study of the optical properties of the complex shows that it can be used in the solar cell device where the best absorption of about 6x104 cm-1 was shown along [001] direction with a reflectivity that does not exceed 13% along the same direction.