Three Keggin-based complexes have been obtained with two N-heterocyclic carboxylic acids ligands.
Complex 3 shows an uncommonly double Cl-capped tri-nuclear CuI cluster.
The 1H,1′H-Biimdazole-4,4′-dicarboxylic acid ligand is firstly introduced to the POM field.
The electrochemical behavior of 2, 3 and photocatalytic properties and fluorescent properties of 1–3 are studied.