Synthesis, characterization, crystal structure and biological activities of supramolecular compounds of Mn(II) and Zn(II) with dipicolinic acid and 8-hydroxyquinoline

Abstract

Two compounds, (8-H2Q)2[Mn(dipic)2] · 6H2O (1) and (8-H2Q)2[Zn(dipic)2] · 6H2O (2) (8-HQ = 8-hydroxyquinoline (oxine), H2dipic = dipicolinic acid), have been prepared and characterized by elemental, spectroscopic (IR and UV–Vis), and thermal analyses, magnetic measurements and single crystal X-ray diffraction techniques. Compounds 1 and 2 consist of two 8-hydroxyquinolinium cations, one bis(dipicolinato)M(II) anion (M = Mn(II) and Zn(II)) and six uncoordinated water molecules. Both 1 and 2 crystallize in the monoclinic space group C2/c. In the complex anion, each dipic ligand is tridentate through N of pyridine and oxygens of the carboxylate groups. Crystal packing of 1 and 2 is a composite of intermolecular hydrogen bonding interactions. The in vitro antibacterial and antifungal activities of 1 and 2 were evaluated by the agar well diffusion method by MIC (Minimal Inhibition Concentration), looking for compounds which display high-inhibitory effect against gram positive bacteria and fungi. No growth inhibition was observed against tested gram negative bacteria.