Synthesis, characterization, and theoretical study of new cocrystals and charge-transfer compounds

This study used single-crystal X-ray diffraction, elemental analysis, infrared (IR) spectroscopy, theoretical nuclear magnetic resonance (NMR), and theoretical ultraviolet spectroscopy to characterize 3 newly synthesized crystalline compounds. Additionally, the nonlinear optical, highest occupied molecular orbital energies, lowest occupied molecular orbital energies, band gap, molecular electrostatic potential, and thermodynamic parameters of the 3 crystalline compounds were examined. The strong correlation between experimental IR spectra and theoretical NMR chemical shifts confirmed the accuracy of computational predictions. The molecular formulas of the 3 newly synthesized crystalline compounds, each containing different ligand molecules, were: C₈H₁₄O₄·2(C₆H₄N₂), C₅H₇N₂·NCS, and Ni(CN)₄·2(C₅H₇N₂)·2(H₂O) for compounds 1, 2, and 3, respectively. Crystallographic analysis showed that the compounds crystallize in the space groups <i>P</i>1̄, <i>P</i>2₁/<i>n</i> and <i>C</i>2/<i>m</i>, respectively. Their molecular packing is stabilized by a network of hydrogen bonds (C-H···O, O-H···N, N-H···N, N-H···S, O-H···N, and N-H···O) and noncovalent interactions (C-H···μ and μ···μ). Computational studies using Gaussian 03 and CrystalExplorer further elucidated their structural, magnetic, electrooptic, and electrochemical properties.