Electrochrmoic properties of organic-metallo hybrid polymers synthesized by functional modular elements

Organic-metallic hybrid polymers attract considerable attention in terms of designing and fabricating materials since metals and ligands of polymer components can be easily changed. We are interested in terpyridine-metal hybrid polymers because terpyridine ligands possess an excellent ability to coordinate metal ions. Self-assembly of 1,4-bis(terpyridyl)benzene and Co(II) or Fe(II) results in metallosupramolecular polyelectrolytes (MEPEs). We have been studying the electrochromic property of MEPEs, which is one of the functions MEPEs possess. Thin films of MEPEs reversibly change their colors, based on redox chemistry of metal ions. Here, we report the multicolor electrochromic properties of MEPEs by developing a new MEPE containing both Co(II)and Fe(II) or combing MEPE with polyoxometallate (POM). Just mixing Co-MEPE and Fe-MEPE results in the formation of a block copolymer, which represents three different colors depending on the potential. Further, in order to expand the possible electrochromic potential window, MEPE (cationic) is combined with Eu-POM (anionic). The resulted thin film of this hybrid material shows multicolor electrochromic properties at larger potential range, between 1.0V and -1.0V.