Alloxazine-Based Ligands Appended with Coordinating Groups: Synthesis, Electrochemical Studies, and Formation of Coordination Polymers

Abstract

Three new ligands based on the alloxazine core appended with pyridyl coordinating groups have been designed, synthesized, and characterized. The ligands are revealed to be redox-active in DMF solution, as attested to by CV and combined CV/EPR studies. The spin of the reduced species appears to be delocalized on the alloxazine core, as attested to by DFT calculations. The coordination abilities of one of the ligands toward Cu²⁺ or Ni²⁺ 3d cations revealed the formation of the first alloxazine-based 3D coordination polymers, presenting strong π-π stacking and substantial cavities. Preliminarily charge/discharge experiments in Li batteries evidence Li⁺ insertion in such systems.