Titanium-based tetrakis-2,3-[5,6-di(substituted)pyrazino]porphyrazine. Synthesis and characterization

Tetrapyrazinoporphyrazine (TPysPz) ligands and metal complexes find, generally, application as electronic materials and catalysts. Considering the limited application of Titanium (Ti), we prepared and characterized a family of ligands and Ti‐based complexes of tetrakis‐2,3‐[5,6‐di‐R8‐pyrazino]porphyrazine (R = H, 2‐Py, Ph). UV/Vis measurements in different solvents confirm molecular aggregation, which results more pronounced in the presence of 2‐pyridil and phenyl substituents on the macrocycle edge. Because of low solubility, solid state NMR was applied for structure characterization. Additional IR and MALDI‐TOF were carried out to complete the characterization. Cyclic voltammetry in DMSO/Bu4NBF4 0.1 m unveiled that our Ti complexes can take part in up to five redox events. The first two quasi‐reversible reductions involve Ti(IV), whereas the further to or three occur at the expense of the TPysPz macrocycle. To test the applicability of our compounds as catalytic materials, we performed a preliminary cyclic voltammetry investigation in the solid‐state, which showed typical peaks of hydrogen redox reactions.