Room temperature aqueous phase synthesis and characterization of novel nano-sized coordination polymers composed of copper(II), nickel(II), and zinc(II) metal ions with p-phenylenediamine (PPD) as the bridging ligand

Nanostructured metal-organic hybrid materials composed of nickel(II), copper(II), and zinc(II) metal ions and p-phenylenediamine (PPD) as the organic ligand were synthesized in aqueous medium at room temperature. The synthesized compounds were characterized by elemental analyses, powder X-ray diffraction (PXRD) spectra, Fourier transform infrared spectra, nuclear magnetic resonance (1H NMR) spectra, electronic spectra, scanning electron microscopy, N2 adsorption-desorption isotherm, and dynamic light scattering studies. N2 adsorption-desorption isotherm of copper(II)-PPD compound confirmed that it has mesoporous structure as it exhibits type-IV reversible isotherm with H1 hysterisis. Steep adsorption indicated that the mesopores possessing it are of uniform order. Barrett-Joyner-Halenda model showed an average pore diameter of 5.2 nm. The PXRD patterns of all the three compounds are identical and showed well-defined and highly intense diffraction peaks, thereby suggesting their nature as crystalline. The broadness of the diffraction peaks indicated that the particles are of nanometer dimensions.