Emissive lanthanide dicyanoaurate coordination polymers with 2,2′-bipyridine dioxide antenna groups and their hydration states

Abstract

A series of lanthanide dicyanoaurate coordination polymers with 2,2′-bipyridine dioxide (OOBipy) has been created with the formula Ln(OOBipy)₂(H₂O)_x[Au(CN)₂]₃·yEtOH·zH₂O, where x and y = 0–2, and z = 0–4. It is possible to convert between these coordination polymers through the addition of heat (removing water, aqua ligands, or ethanol) or by exposure to water vapour (adding a full complement of aqua ligands and water molecules to a partially or fully dehydrated structure). The coordination polymers containing Sm, Eu, and Tb were emissive, with quantum yields between 0.43–0.66 and 0.09–0.72 for Eu- and Tb-containing materials respectively, depending on the solvation state. Atypically for emissive lanthanide materials, the highest quantum yields were found for the hydrated species, with a substantial drop in quantum yields as aqua units were sequentially removed. Eu/Tb-containing solid-solutions were prepared but only showed Eu-based emission, while Sm/Tb-containing solid-solutions had quantum yields of less than 0.02.