Multi-electron transformations in polymers derived from metal-salen complexes with four redox sites

• Applicant: Dr. Evgenia Dmitrieva
• Subject Area: Polymer Materials ; Synthesis and Properties of Functional Materials
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 469234593

Polymeric complexes containing transition metal ions and salen-type ligands are electrochemically active metallopolymers functionalized with multiple redox active units. They show a great potential because of their multi-electron nature of the oxidation-reduction processes, facile charge transport, electrochromic behavior, electrocatalytic activity and electrochemical stability for high performance in multiple fields such as energy storage and transformation, catalysis, chemical sensors, electronics or medicine. In the proposed project, we will attempt to elucidate the mechanism of charge injection and delocalization pathways in metal-salen type polymers during their n- and p-doping and develop strategies for tailoring main characteristics of redox conversions via modulation of polymer structure to enable advanced functional materials with easily tunable properties. We will synthesize and study a series of polymers, which are based on the metal-salen type complexes containing four redox active sites. The multi-electronic nature of redox processes in such polymers affords high values of specific capacitance and multicolor behavior and make them attractive candidates for energy storage applications. We will systematically probe the oxidation and reduction processes in the polymers with different molecular structure modulated by various metal centers and peripheral substituents in the ligand framework. This approach to modulating polymer structure will allow to uncover key structure-property relationships in metal-salen type polymeric materials. The polymer films will be investigated by using the in situ spectroelectrochemical methods including Electron Spin Resonance (ESR) spectroscopy, Ultraviolet-visible-Near Infrared (UV-vis-NIR) and Fourier Transform Infrared (FTIR) spectroscopy to define the type, localization and properties of charge carriers generated in the polymers, and the pathways for delocalization of these charged species. We will demonstrate that our findings can be used to design polymer-based materials with improved functional characteristics for use in energy storage, electrochromic devices and heterogeneous catalysis. Thus, the results of the proposed project will provide not only a contribution to the theoretical understanding of redox processes in electrochemically active metallopolymers but also grounds for a rational design of the next generation functional materials.

• DFG Programme: Research Grants