Lanthanide dicyanoaurate coordination polymers containing 1,10-phenanthroline: Synthesis, structure, and luminescence

Abstract The synthesis of two novel lanthanide dicyanoaurates containing the bidentate ligand 1,10-phenanthroline (phen) have been carried out by reaction of select lanthanide nitrate salts with phen and potassium dicyanoaurate. The resultant compounds, [Ln(C12H8N2)(H2O)2{Au(CN)2}3] (Ln = Gd, Tb), are isostructural as established by single-crystal X-ray diffraction studies. Prominent structural features in these one-dimensional polymeric compounds are the existence of hexameric aurophilic interactions containing kinked Au6 units, π-stacking from partial phen ring alignment, and strong H-bonding interactions. Photoluminescence measurements illustrate that [Tb(C12H8N2)(H2O)2{Au(CN)2}3] displays enhanced Tb-based emission due to intramolecular energy transfer from the coordinated ligands while [Gd(C12H8N2)(H2O)2{Au(CN)2}3], which lacks low-lying electronic states, exhibits broad-band ligand-based emission.