Synthesis, structure, Hirshfeld surface analysis, and molecular docking studies of the cocrystal between the Cu(II) complex of salicylic acid and uncoordinated piracetam.

The cocrystal (or supramolecular complex) between the Cu(II) complex of salicylic acid and uncoordinated piracetam has been synthesized. Its structure is characterized by elemental analysis, FT-IR, UV-Vis spectroscopy, and X-ray crystallography. Spectroscopic methods confirm the formation of the metal complex, while X-ray crystallography establishes the molecular and crystal structure of the obtained compound. The Cu(II) complex of salicylic acid (complex molecule) is a symmetric binuclear compound in the form of a "Chinese lantern" and contains 4 salicylic acid and 2 water molecules. It interacts with uncoordinated piracetam through a complicated system of hydrogen bonds. However, according to Hirshfeld surface analysis, the contribution of the O•••H/H•••O contacts is only 24.9%, while H•••H and H•••C/C•••H contacts account for 67.5%, indicating that intermolecular interactions are mainly hydrophobic. In silico (molecular docking) studies of the cocrystal, the complex molecule, and piracetam's antifungal, antibacterial, and antiviral activities confirm that the complex molecule demonstrates enhanced biological activities; practically, the inactive piracetam improved all tested types of bioactivities through cocrystal formation. For example, the binding energy in the case of anti-COVID activity is improved from -10.34 to -11.40 kcal/mol. Thus, cocrystal formation based on metal complexes and inactive organic compounds may be promising in drug design.