Synthesis, structural characterization, antibacterial activity, DFT computational studies and thermal analysis of two new thiocyanate compounds based on 1-phenylpiperazine

Abstract

Two hybrid materials, (HPhPip)2[Co(NCS)4] (I) and (HPhPip)(NCS)•PhPip (II), were grown using the slow evaporation method. The characterization of both compounds was accomplished by means of different analytical techniques such as IR, TGA–DTA, and single X-ray diffraction. XRD showed that compounds (I) and (II) crystallized into triclinic and noncentrosymmetric orthorhombic systems, respectively. In Compound (I), the Co(II) ion is surrounded by four NCS−anions and shows a distorted tetrahedral coordination geometry. Crystal packing analysis indicates that the [Co(NCS)4]2−anion and 1-phenylpiperazinium cation are linked together through N–H…S to form a graph set. Compound (II) presents an interesting 3-D network via N–H…N, C–H…S, and C–H•••π intermolecular interactions between HPhPip+, NCS−, and PhPip, consolidating the stacking of the crystal. FT-IR was used to explore the modes of vibration of the different functional groups present in two compounds. A theoretical investigation has also been performed via DFT on the molecular structure of compounds, allowing the determination of the Mulliken charge distribution, the Molecular Electrostatic Potential maps, and the HOMO–LUMO diagrams. The Hirshfeld surface, two-dimensional fingerprint plots and enrichment ratio were investigated to indicate the important role of intermolecular interactions. The robust thermal stability of the two crystals was ensured by thermogravimetric–differential thermal analysis. Finally, the bacterial potency of two compounds has been surveyed.