Heterogeneous catalysis of water oxidation supported by a novel metallamacrocycle

Abstract

The rational design and syntheses of the new tetranuclear macrocycles [Cp*Ir(L)]₄(OTf)₄ (1) and [Cp*Rh(L)]₄(OTf)₄ (2) were successfully achieved through the reaction of pyridyl-substituted ligand 3-(pyridin-3-ylazo)-naphthalen-2-ol (HL) with [Cp*M(μ-Cl)Cl]₂ (M = Ir, Rh), which was preliminarily treated with AgOTf. The novel macrocycles 1 and 2 were structurally characterized by EA, IR and NMR to confirm their elementary components and frameworks. Further classification of their molecular structures via single crystal X-ray analysis has strongly proved their tetranuclear macrocyclic structures. The systematic investigation of the electronic properties of complex 1via cyclic voltammograms (CVs), clearly suggested that it had great potential application as a catalyst for water oxidation. Thus the use of complex 1 as a catalyst for water oxidation was performed in the presence of sacrificial chemical oxidation, and afforded a good efficiency of up to 2.47 min⁻¹.