Cu(II)-Based Metallo-Supramolecular Polymers

Abstract

This chapter introduces synthesis and green electrochromism of Cu(II)-based metallo-supramolecular polymers (polyCuL10-15) and synthesis and multi-color electrochromism of Cu(I)/Fe(II)-based heterometallo-supramolecular polymer (polyCuFeL16). To introduce Cu(II) ions with a tetrahedral structure into metallo-supramolecular polymers, 5,5′-linked bis(1,10-phenanthroline)s (L10-15) are synthesized by a Suzuki-type cross-coupling reaction. Section 6.1 introduces optimization to the synthetic conditions (catalyst, based, solvent, and temperature) of L10-15 and the detailed synthetic procedure for polyCuL13 by the 1:1 complexation of L13 and Cu(ClO₄)₂·6H₂O. Section 6.2 shows stepwise complexation behavior of L13 with Cu(II) ions and green electrochromism of polyCuL13. The green color of polyCuL13, which is caused by the MLCT absorption of the Cu(II) complex moieties, disappears upon applying a negative potential because of the electrochemical reduction of Cu(II) to Cu(I). Section 6.3 describes synthesis of Cu(I)/Fe(II)-based heterometallo-supramolecular polymer (polyCuFe16) by one-pot complexation of Cu(I), Fe(II), and an asymmetrical ligand (L16). L16 has both bidentate phenanthroline and tridentate terpyridine moieties. Cu(I) and Fe(II) ions are preferentially complexed with the bidentate phenanthroline and tridentate terpyridine moieties of L16, respectively, based on the different (tetrahedral or octahedral) coordination geometries. Section 6.4 shows multi-color electrochromism (from purple to blue to colorless) in a solid-state device with a polyCuFeL16 film.