Ru(II)-Based Metallo-Supramolecular Polymers

Abstract

This chapter introduces synthesis, properties, and device application of Ru(II)-based metallo-supramolecular polymer (polyRuL1-5) and the derivatives. Section 3.1 shows synthetic procedure of polyRuL1-5 by the 1:1 complexation of Ru(II) ions with bis(terpyridine)s (L1-5). Section 3.2 exhibits electrochemical and optical properties of polyRuL1-5. The polymers show red color due to the MLCT absorption around 520 nm. The polymer films exhibit reversible electrochromism, triggered by the electrochemical redox between Ru(II) and Ru(III). Sections 3.3 and 3.4 describe Fe(II)/Ru(II)-based heterometallo-supramolecular polymers (polyFeRuL1), synthesized by the stepwise complexation of Ru(II) and Fe(II) ions with L1. The polymers have both Fe(II) complex moieties and Ru(II) ones and show two MLCT absorptions in the UV-vis. spectra and two redox waves in the cyclic voltammograms. The polymer with same amount of Fe(II) and Ru(II) (polyFe_0.5Ru_0.5L1) exhibits multi-color electrochromism among purple, orange, and light green. Section 3.5 introduces flexible electrochromic devices using polyFeL1 and polyRuL1. The polymer films are prepared on a plastic substrate (ITO-PEN) using inkjet printing technique. The flexible devices show reversible electrochromism even in the bent state owing to the amorphous nature of the polymer. Sections 3.6 and 3.7 introduce luminescence of polyRuL1-5 and the electrochemical switching in the electrochemical device.