Hybrid Electrochromic Multilayer Films Based on Fe(II)-Metalloviologens and TiO_2 Nanoparticles

Metallosupramolecular coordination polyelectrolyte, Fe（II）-metalloviologen（FEN）, was prepared by the reaction of Fe（II） with a novel bisterpyridine ligand. As active components, FENs could be assembled into electrochromic multilayer films with negative charged polystyrene sulfate（PSS） by the sequential deposition layer-by-layer technique. Numerous analytical instruments, such as UV-Vis spectroscopy, atomic force microscopy（AFM）, tunneling electron microscopy（TEM）, zeta-potential measurement and electrochemical measurement have been utilized to characterize their morphology, optical and electrochromic properties. It has been observed that as-prepared films exhibited multi-colour changes by triggering with different potentials. However, the low optical contrast of multilayer films would limit their further applications. In order to overcome this problem, semiconductor TiO2 nanoparticles（TiO2） were incorporated into FEN multilayers by layer-by-layer approach. By carefully optimizing the film structure, as-resulted hybrid films containing FEN, TiO2 and PSS exhibited high optical contrast, suitable response time and long-term stability. Such hybrid films should be promising candidates to meet the requirements for developing flexible displays and electrochromic devices.

Synthesis,Photochromism and Switchable Photoluminescence of a Cd-based Metalloviologen Complex

A novel metalloviologen complex{[Cd(PhSQ)(HTBC)(H_(2)O)_(2)]·1.25 H_(2)O}n(1)based on N-(4-sulfophenyl)-4,4’-bipyridinium(PhSQ)and monoprotonated trimesic acid(HTBC)has been prepared and structurally characterized.Complex 1 has been characterized by elemental analysis,IR,thermogravimetric analyses,UV-Vis spectra and X-ray crystallography.The coordination geometry of Cd(Ⅱ)ion is a pentagonal bipyramid.Complex 1 displays a zigzag chain along the b axis,and such chains are extended into a 2 D layer supramolecular network through hydrogen bonding and π…π interactions.Moreover,complex 1 exhibits reversible photochromic and switchable luminescent behaviors via UV light irradiation at room temperature induced by the photogenerated radicals via a photo-induced electron transfer(PET)mechanism.