Synthesis and study of novel supramolecular nanocomposites containing aryl-imidazo-phenanthroline-based metallo-polymers (H-donors) and surface-modified ZnO nanoparticles (H-acceptors)

Four novel metallo-polymers (P1-P4) containing aryl-imidazo-phenanthrolines (AIP) ligands (incorporated with phenyl and fused-thiophene cores) were synthesized and characterized. Interestingly, P1-P4 exhibited electrochromism during the oxidation processes of cyclic voltammogram studies. In addition, P1-P4 were blended with surface-modified pyridyl-ZnO nanoparticles (ZnOpy as proton acceptors) to form nanocomposites, where P3-P4 were functionalized with carboxylic acid pendants (as proton donors) on the polymer backbones to study for the H-bonded effects on surface-modified ZnOpy nanoparticles. In order to investigate the nanocomposites containing metallo-polymers P1-P4 and surface-modified ZnOpy nanoparticles, nanocomposites P1-P4/ZnOpy were characterized by UV-visible (UV) absorption spectra, Fourier transform infrared (FT-IR), photoluminescence (PL) spectra, time-resolved photoluminescence decays, X-ray diffraction (XRD) measurements, and transmission electron microscopy (TEM) analyses. In contrast to nanocomposites P1/ZnOpy and P2/ZnOpy, higher crystallinities with a distinct layered-structure of H-bonded nanocomposites P3/ZnOpy and P4/ZnOpy in XRD measurements were induced by the introduction of surface-modified ZnOpy nanoparticles to metallo-polymers P3 and P4, correspondingly. Furthermore, due to the supramolecular interactions of surface-modified ZnOpy nanoparticles with metallo-polymers P3-P4, TEM images verified that ZnOpy nanoparticles were more homogeneously distributed in nanocomposites P3-P4/ZnOpy (with H-bonds) than those in P1-P2/ZnOpy (without H-bonds), respectively.