Rapid microwave synthesis of tetrahedral pyrazole/Co(II) complex: [NH···Cl] synthon, XRD/HSA-interactions, DFT/TD-DFT, physiochemical, antifungal, antibacterial, and POM bio-calculations

•Under microwave mode of vibration, a new CoCl2(NNH)2 complex was prepared with an excellent yield.•XRD was used to determine the structure, while DFT and HSA analyses were used to compute it.•Numerous spectra, including IR and UV–Vis, as well as their associated DFT calculations, were also studied.•The complex experimental antibacterial/antifungal and the theoretical POM were carried out. A new coordination complex, CoCl2(NNH)2, was synthesized by complexation of the pyrazole (NNH) ligand with CoCl2 in less than 5 min with a high yield (>85%). The synthesis was done using microwave radiation in water solvent where no side products were detected. The complexation was confirmed using UV–visible, CHN-analysis, and FT-IR analysis and compared to theoretical IR, DFT and TD-DFT calculations. CoCl2(NNH)2 crystallizes in a C2/c space group with distorted tetrahedral center as shown by single-crystal X-ray diffraction, two types of heteromeric [NH···Cl] synthons have been recorded, such interactions type and ratios were confirmed also via Hirsfield surface analysis (HSA). The desired complex was evaluated for its antibacterial activity against four classes of gram-positive and gram-negative bacteria, and its antifungal activity against four types of fungi. The complex's physio-chemical properties, toxicity risk, lipophilicity, and pharmacophore sites were studied using the POM (Petra-Osiris-Molinspiration) bio-computational theory.