μ-phenoxide bridged mixed ligand Cu(II) complex: Synthesis, 3D supramolecular architecture, DFT, energy frameworks and antimicrobial studies

Abstract

As an essential class of heterocyclic derivatives, 8-hydroxyquinoline(HQ) and 4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione (TFTB) have a broad range of pharmaceutical applications and they are found to be excellent precursors for metal complexes and crystal engineering. The novel mixed ligand Cu(II) complex [Cu2(C8H4O2SF3)2(C9H6NO)2] has been synthesized using a metal salt and the above ligands in a 1:1:1 M ratio and characterized by FT-IR, UV–visible, SEM and EDAX techniques. Single crystal X-ray structure analysis reveals a centrosymmetric dinuclear form of the Cu(II) complex, linked by the obtuse phenolate oxygen atom, and the central Cu(II) ion adopts a distorted square pyramidal coordination geometry. The Cu(II) complex exhibits various intermolecular interactions, leading to the construction of R22(16), R22(10) and R22(20) supramolecular synthons. The existence of intermolecular interactions is supported by Hirshfeld surface analysis and quantified by 2D fingerprint plots. In addition, the 3D topology of the molecular packing is visualized through energy frameworks, which reveal the predominance of dispersion energy over other interaction energies. DFT calculations have been performed for the mixed ligand Cu(II) complex to study the optimal geometry, related reactive parameters and the HOMO-LUMO energy gap (0.8232 eV). Further, the Cu(II) complex was evaluated against MRSA and showed an MIC value of 15 μg/mL. A time-killing assay for the Cu(II) complex was performed to study the antimicrobial effect with respect to time. A molecular docking study revealed the binding affinity of the Cu(II) complex to penicillin-binding protein 2, with an excellent binding score of −8.0 kcal/mol.