Synthesis, Spectroscopic Analysis, Charge and Proton Transfer Interaction Studies, In-Vitro, and In-Silico Antimicrobial, Pharmacokinetics Studies of Piperazin-1-Ium 4-Aminobenzoate Monohydrate: A Density Functional Theory Approach

Abstract

Piperazin-1-ium 4-aminobenzoate monohydrate (PPAB) single crystals were grown by slow evaporation method. The grown crystal PPAB has been characterized by single-crystal X-ray diffraction, FTIR, FT-Raman, and UV-visible analysis. The B3LYP method and 6-311G (d, p) basis set were used to optimize the structure. The title compound was investigated theoretically and experimentally by FT-IR, FT-Raman, and UV-Vis spectral analysis. The presence of various functional groups in the structure was elucidated by FTIR and FT-Raman spectral studies. The intermolecular interactions within the crystal structure were investigated using Hirshfeld surface analysis. The crystal packing diagram reveals interesting non-covalent interactions involving C–H···O, N–H···O, and N–H···N hydrogen bonds, leading to the generation of 3D supramolecular architecture. The charge transfer within the molecule was deeply analyzed by using the NBO approach. The molecular electrostatic potential (MEP) and the local reactivity descriptors, such as Fukui function (fk +, fk −) analyses were performed to determine the reactive sites within the molecule. The HOMO and LUMO analysis was used to determine the chemical reactivity and bioactivity of the molecule. Hole-electron analysis was performed to analyze the charge transfer in an excited state. Based on the hole-electron analysis, the inter-fragment charge transfer (IFCT) analysis establishes the amount of charge transfer among different fragments. Topological analyses, such as AIM, RDG, and ELF were carried out to identify the non-covalent interaction within the molecule. The molecular docking studies of the molecule are performed to investigate the binding affinity of the ligand with the protein receptor. Drug-likeness properties, such as Lipinski’s rule of five, adsorption, distribution, metabolism, excretion, and toxicity (ADMET) have been investigated by in silico web-based tools like SwissADME and ADMETlab.