Coordination-driven self-assembly of nanoZnO hybrids with tripodal zinc terpyridyl-viologen complex multilayers and their photochromic properties

Viologen (VIO) functionalized nanomaterials and supramolecular systems have attracted much attention because of their well reversible redox properties, unique photo-/electrochromic and radical-rich features that resulting in potential applications in the fields of coloration and memory devices, energy conversion and biomimetic chemistry . Here, a tripodal terpyridyl-viologen (TPyVIO) multidentate ligand was newly synthesized, which was then used as a linker, together with Zn 2+ ion as a connector, to construct Zn-TPyVIO multilayers on the surfaces of nanoZnO particles to produce nanoZnO@(Zn-TPyVIO) n hybrids by a layer-by-layer (LBL) technique. Luminescent emission of nanoZnO semiconductors was largely quenched in the nanoZnO@(Zn-TPyVIO) n hybrids, attributed to a quick electron transfer from the conduction band of excited nanoZnO particles to viologens; this electron transfer process resulted in the formation of colored monovalent viologen radical cations . Reversible redox couple was recorded for the glass carbon electrode modified by the nanohybrids , with the cationic and anionic potentials at approximately − 0.78–− 0.84 and − 0.63–−0.73 mV (vs Hg/Hg 2 Cl 2 ), respectively. Finally, it was revealed that the nanoZnO@(Zn-TPyVIO) n hybrids displayed well photochromic behaviors under light radiation.