Synthesis, characterization, crystal structure, Hirshfeld surface analysis and DFT of 1,2-benzothiazine metal (II) complexes

Abstract

In the present study, the mononuclear complexes of oxicam precursor with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) metal ions have been prepared. The UV/Vis, FT-IR, 1H NMR spectroscopies, elemental analysis and magnetic susceptibility measurements were used to confirm successful synthesis of transition metal complexes. The square planar coordination geometry of the Cu(II) complex 5 was confirmed by XRD analysis. The spectroscopic data indicated that two mono anionic bidentate ligands act as chelating agents and attached with metal center via enolate oxygen and carbonyl oxygen of the ester group present in 1,2-benzothiazine. The molar conductance indicated the non-ionic nature of the Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes. The octahedral geometry is proposed for the Mn(II), Co(II) and Zn(II) complexes, respectively and square planar geometry for Ni(II) and Cu(II) complexes is proposed on the basis of obtained data. The reported basis sets with ligand and its Cu(II) complex were used to conduct DFT studies. The synthesis of the targeted compounds was also confirmed by energy gap calculations between HOMO and LUMO. The Hirshfeld surface analysis of the copper complex was carried and 2D contacts were drawn. Furthermore, COX-I and COX-II inhibition studies for the targeted compounds were carried out by applying molecular docking study. The docking results revealed that these molecules have potential to inhibit the cyclooxygenases and may reduce the inflammation in the body.