Abstract
The tridentate ligand L and its complexes with transition-metal ions have been prepared and characterized. The polycondensation reactions of transition-metal complexes with different dialdehydes led to the formation of transition-metal-complex-based polyazomethines, which have been obtained by on-substrate polymerization, and their electrochemical and electrochromic performance have been investigated. The most interesting properties are exhibited by polymers of Fe(II) and Cu(II) ions obtained by the reaction of the appropriate complexes with a triphenylamine-based dialdehyde. Fe(II) polymer P1 undergoes a reversible oxidation/reduction process and a color change from orange to gray due to the oxidation of Fe(II) to Fe(III) ions concomitant with the oxidation of the triphenylamine group. Its electrochromic properties such as long-term stability, switching times, and coloration efficiencies have been investigated, providing evidence of the utility of the on-substrate polycondensation reaction in the formation of thin films of electrochromic metallopolymers.
Highlights
Polymeric complexes of transition-metal ions have been attracting interest in many scientific and technological fields in recent years due to their multiple applications.[1−3] Complexes of transition-metal ions are known to be interesting materials for electrochromic applications, and the color change can be based on the redox reaction of the ligand molecule and/ or the metallic center
Metallosupramolecular polymers can be prepared by the complexation of metal ions with multidentate organic ligands or polymers[7−11] as well as by cross-coupling reactions,[12] radical polymerization,[13] or electropolymerization.[14−18] One of the methods of preparation of polymers is chemical linking of single or multiple kinds of monomers to form long chains, releasing water or a similar simple substance, called a polycondensation reaction
Hasanain et al described a synthesis via a polycondensation reaction and the electrochromic characterization of a dinuclear ruthenium complex incorporated into the polyimide polymer main chains.[19]
Summary
Polymeric complexes of transition-metal ions have been attracting interest in many scientific and technological fields in recent years due to their multiple applications.[1−3] Complexes of transition-metal ions are known to be interesting materials for electrochromic applications, and the color change can be based on the redox reaction of the ligand molecule and/ or the metallic center. The incorporation of transition-metal ions into the polymer backbone can change the electrochromic properties of polymeric materials. This is the result of the formation of additional absorption bands that change the color of the material, such as metal to ligand (MLCT) or ligand to metal charge transfer (LMCT) bands as well as d−d transitions that are characteristic for transitionmetal complexes.[4−6]. An example of the application of polycondensation to the preparation of metallopolymers was demonstrated by the synthesis of electrochromic Co(III)and Fe(III)-based metallosupramolecular polymers with aromatic azo ligands that conferred good solubility to the metal complex, and due to this the solubility issue has been overcome.[20]
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