Self-assembly, crystal structure, computational studies, optical investigation, magnetic and biological properties of novel compounds based on methoxyphenyl piperazinium ligand

[Display omitted] •Two structures are obtained and confirmed by X-ray crystallographic analysis.•Thermal analysis was carried out to highlight the thermal stability of complexes.•antibacterial assets were investigated against different bacteria.•The chemical bond study occurred using the quantum theory of atoms in molecules.•The newly synthesized complexes are deemed to be effective NLO materials. Two novel methoxyphenyl-based piperazine compounds have been investigated. The crystal structures of [C11H18N2O][Co(SCN)4] (1) and [(C11H18N2O)4]Cl8·7H2O (2) have been determined using single crystal X-ray crystallography. However, (1) crystallizes in an orthorhombic system with the non-centrosymmetric space group P 212121 with the following lattice parameters: a = 8.4637(2) Å, b = 14.5848 (5) Å, c = 17.1847 (5) Å with V = 2121.3 (1) Å3 and Z = 4, otherwise (2) crystallizes in monoclinic system with P 21/c space group and the following lattice parameters: a = 7.2551 (2) Å, b = 9.0523 (4) Å, c = 22.3575 (8) Å, β = 95.998 (3)° with V = 1460.30 (9) Å3 and Z = 1. Different interactions packed the system through N-H…S hydrogen bonds for (1). The organic entities are grouped into dimers for (2) through weak interactions and N-H∙∙∙Cl, N-H∙∙∙O, and O-H∙∙∙Cl. The robustness of the crystals is also enhanced by C–H…π of the piperazine ring. Infrared spectrums were recorded to reveal the vibrational modes of the compounds, and to highlight the optical behavior, UV–visible analysis has been carried out. Thermal analysis was carried out to highlight the thermal stability of complexes. In addition, the antibacterial assets were investigated against different bacteria. The 13C Nuclear Magnetic Resonance was carried out to highlight the presence of primary reagents in the final product. Intermolecular interaction and stabilization of dimer complexes in the crystal packing are explored using Hirshfeld surface analysis to highlight the role of molecular interaction in the crystal packing. The more detailed quantum computation from crystallographic reported self-assembled dimer complexes occurred for comprehensive structure elucidation and showed good findings. The nature of dimer complexes has been assessed by strong and weak intermolecular interactions which were examined by NCI plots and analyzed by QTAIM calculation. Then, the thermal analysis was used to confirm the crystal thermal stability, Furthermore, biological behavior was performed for the compounds against different ant