The Nature of Charge Carriers in Polymeric Complexes of Nickel with Schiff Bases Containing Electron-Withdrawing Substituents

Russian Journal of Electrochemistry - The data on polymeric complexes of nickel with salen-type Schiff bases containing electron-withdrawing nitro groups in ligand’s aromatic fragments are...     

Nickel(II) Complex of N4 Schiff Base Ligand as a Building Block for a Conducting Metallopolymer with Multiple Redox States

Metal–ligand interactions in monomeric and polymeric transition metal complexes of Schiff base ligands largely define their functional properties and perspective applications. In this study, redox behavior of a nickel(II) N₄-anilinosalen complex, [NiAmben] (where H₂Amben = N,N′-bis(o-aminobenzylidene)ethylenediamine) was studied by cyclic voltammetry in solvents of different Lewis basicity. A poly-[NiAmben] film electrochemically synthesized from a 1,2-dichloroethane-based electrolyte was investigated by a combination of cyclic voltammetry, electrochemical quartz crystal microbalance, in situ UV-Vis spectroelectrochemistry, and in situ conductance measurements between −0.9 and 1.3 V vs. Ag/Ag⁺. The polymer displayed multistep redox processes involving reversible transfer of the total of ca. 1.6 electrons per repeat unit, electrical conductivity over a wide potential range, and multiple color changes in correlation with electrochemical processes. Performance advantages of poly-[NiAmben] over its nickel(II) N₂O₂ Schiff base analogue were identified and related to the increased number of accessible redox states in the polymer due to the higher extent of electronic communication between metal ions and ligand segments in the nickel(II) N₄-anilinosalen system. The obtained results suggest that electrosynthesized poly-[NiAmben] films may be viable candidates for energy storage and saving applications.     

Adsorption-electrochemical modification of nanoporous carbon materials by nickel complexes with Schiff bases

Adsorption and subsequent polymerization of nickel(II) complexes with Schiff bases were studied in a porous carbon material used to manufacture electric double-layer capacitors (supercapacitors). The optimal modification conditions of the carbon material with polymeric complexes to obtain the maximum effect as regards the accumulation of electric energy in the supercapacitor were determined and substantiated. An effective and cost-efficient technique for modification of supercapacitor electrodes with electrically active polymers was suggested.