Four of the coordination compounds of the general formula, [M(DPPP)(APY)(H2O) Cl2].xH2O, where M = Ni(II), Cu(II), Mn(II), and Fe(II) and x = 0, 1, or 2 molecules of H2O, DPPP = 1,3-bis(diphenylphosphino)propane, and APY = 2-aminopyridine, have been prepared and characterized. The structure of the complexes has been confirmed by elemental analysis, FT-IR, and UV-Vis spectral data. Thermal analysis (thermogravimetry, derivative thermogravimetry, and differential thermal studies) has been used to study the thermal decomposition stages. Biological activity of all synthesized complexes was tested against five bacterial strains and three fungal strains. Bacteria and fungi strains are common contaminants of the environment in Saudi Arabia, some of which are frequently reported from contaminated water, soil, and food.

Nano-sized manganese oxide and cadmium oxide were formed quantitatively via chemical routes, using calcination from an aqueous solution containing metal chloride as a precursor, to create polyvinyl alcohol and para-aminobenzoic acid complexes with the following formulae: [Mn (PVA)(P-ABA) (H2O)3] H2O and [Cd (PVA)(P-ABA) (H2O)3]. The synthesized complexes and metal oxide nanoparticles were characterized using elemental analysis, thermal analyses (TGA and DTA), FT-IR spectroscopy, XRD analysis, UV-vis spectra, and SEM and TEM electron microscopes. The kinetic and thermodynamic parameters (∆H*, ∆G* and ∆S*) for the Mn(II) and Cd(II) coordination compounds were calculated. The antimicrobial properties of the samples were assessed using five bacterial strains and three fungal strains. Three strains of (G+) bacteria, two strains of (G−) bacteria, one stain of yeast-like fungi, and two molds were used in this study.