Fe(II)-Based Metallo-Supramolecular Polymers
This chapter introduces synthesis, properties, and device application of Fe(II)-based metallo-supramolecular polymer (polyFeL1-5). Section 2.1 shows synthetic procedure of bis(terpyridine)s (L1-5) and preparation of polyFeL1-5 by the 1:1 complexation of Fe(II) ions with L1-5. Section 2.2 exhibits electrochemical and optical properties of polyFeL1-5. It is revealed that introduction of electron-releasing or -withdrawing groups to the ligand varies their polymer properties. Section 2.3 explains blue electrochromic properties of the polymers. PolyFeL1-5 have the metal-to-ligand charge transfer (MLCT) absorption from the Fe(II) ion to the terpyridine moiety at around 580 nm. Therefore, the color of the polymers is bluish, as the complementary color of the MLCT absorption. Authors found that the polymer film changes the color from blue to colorless upon applying an oxidative potential and the blue color recovered again upon applying a reductive potential. Section 2.4 introduces an electrochromic device fabrication using polyFeL1. Sections 2.5 show a hyperbranched structure formation by the further addition of Fe(II) ions and tris(terpyridine) to a solution of polyFeL1 and the improvement of electrochromic properties. Sections 2.6 exhibit another hyperbranched structure of metallo-supramolecular polymers and their ionic conductivity. Section 2.7 demonstrates electrochemical emission control of dye anions in an electrochemical device of polyFeL1.
KeywordsFe(II)-based metallo-supramolecular polymer Metal-to-ligand charge transfer absorption Blue electrochromism Hyperbranched structure Ionic conductivity Electrochemical emission switching
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