N-oxide-4,4′-bipyridine, a forgotten ligand in coordination chemistry: structure–photoluminescence property relationships in 2D and 1D lead-coordination polymers

In the strong orange luminescent material of [Pb(bp4mo)Cl2], two different types of octahedra, namely PbCl4N2 and PbCl4O2, are bridged by the N-oxide-4,4′-bipyridine (bp4mo) ligand, while its protonated form, Hbp4mo+, coordinates to Pb2+ center only with the N-oxide group in [Pb(Hbp4mo)2Cl2](NO3)2. Important relationships between structures and luminescence properties are revealed.