Synthesis, Hirshfeld surface analysis, DFT calculations, spectroscopic studies and biological investigation of a newly synthesized organic cocrystal of theophylline and pyrazinecarboxylic acid

The potential of cocrystals in drug research and development is substantial, as their creation is associated with changes in the intermolecular interactions between the constituent materials. This enhancement can improve the physicochemical properties of active pharmaceutical ingredients (APIs). A new organic cocrystal, theophylline pyrazinecarboxylic acid (TPPCA), was grown using the slow evaporation technique. The structure of TPPCA was analyzed using the SCXRD method. Hirshfeld surface analysis reveals that H center dot center dot center dot H (30.4%) and O center dot center dot center dot H/H center dot center dot center dot O (28.0%) interactions are the primary contributors to the stabilization of TPPCA. The functional group vibrations within TPPCA have been investigated using FTIR spectroscopy and the DFT/B3LYP-D3/6-311++G(d,p) method. The electronic properties of TPPCA were investigated using UV-Vis absorption spectroscopy and the TD-DFT method. The optical band gap and thermal stability of TPPCA are found to be 4.35 eV and up to 172 degrees C, respectively. The HOMO-LUMO analysis revealed a smaller bandgap value (4.47 eV), which suggests that TPPCA may possess pharmaceutical activity. The MEP map indicates the most favorable binding sites within TPPCA. Further, a biological study was conducted to examine the antibacterial activity of TPPCA using the disc-diffusion method. Additionally, a molecular docking analysis was conducted to investigate the antibacterial property of the cocrystal utilizing the AutoDock software.