Ternary metal complexes of guaifenesin drug: Synthesis, spectroscopic characterization and in vitro anticancer activity of the metal complexes

•A series of M(II)/(III) complexes of GFS and Phen ligands were prepared and characterized.•It is found that all the chelates are octahedral geometrical structures.•The activity data show the complexes have antibacterial and antifungal activity more than the GFS.•ESR calculations support the characterization of the structure of the Cu(II) complex.•It is observed that the Cr(III) complex is more value of IC50 than the other complexes.

The coordination behavior of a series of transition metal ions named Cr(III), Fe(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with a mono negative tridentate guaifenesin ligand (GFS) (OOO donation sites) and 1,10-phenanthroline (Phen) is reported. The metal complexes are characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance, UV–vis spectral studies, mass spectroscopy, ESR, XRD and thermal analysis (TG and DTG). The ternary metal complexes were found to have the formulae of [M(GFS)(Phen)Cl]Cl·nH2O (M = Cr(III) (n = 1) and Fe(III) (n = 0)), [M(GFS)(Phen)Cl]·nH2O (M = Mn(II) (n = 0), Zn(II) (n = 0) and Cu(II) (n = 3)) and [M(GFS)(Phen)(H2O)]Cl·nH2O (M = Co(II) (n = 0), Ni(II) (n = 0) and Cd(II) (n = 4)). All the chelates are found to have octahedral geometrical structures. The ligand and its ternary chelates are subjected to thermal analyses (TG and DTG). The GFS ligand, in comparison to its ternary metal complexes also was screened for their antibacterial activity on gram positive bacteria (Bacillus subtilis and Staphylococcus aureus), gram negative bacteria (Escherichia coli and Neisseria gonorrhoeae) and for in vitro antifungal activity against (Candida albicans). The activity data show that the metal complexes have antibacterial and antifungal activity more than the parent GFS ligand. The complexes were also screened for its in vitro anticancer activity against the Breast cell line (MFC7) and the results obtained show that they exhibit a considerable anticancer activity.

Graphical abstractThe comparative analysis for biological activity of GFS, Phen ligands and GFS–Phen–metal complexes (1–8) shows that the Cu(II) and Cd(II) complexes (6 and 8) are more potent antibacterial than the other complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide