Synthesis, structures, and photoluminescence properties of lanthanide dicyanoaurates containing dimeric aurophilic interactions

摘要

The synthesis of a series of lanthanide dicyanoaurates containing the ancillary ligand 2,2':6',2''-terpyridine (terpy) have been carried out by reaction of Ln~(3+) nitrate salts with terpy and potassium dicyanoaurate. The resultant compounds, [Ln(C_(15)H_(11)N_3)(H_2O)(NO_3)_2Au(CN)_2] (Ln = Eu, Tb, Dy, Ho, Er, Yb), form an isostructural series as established by single-crystal X-ray diffraction studies. These studies reveal the existence of two important non-covalent interactions in these compounds. Dimeric aurophilic interactions and terpyridine π-stacking are both present with distances of ~3.5 ? for each. Photoluminescence measurements illustrate that the Eu~(3+) and Tb~(3+) compounds display enhanced Ln-based emission due to intramolecular energy transfer from the coordinated terpy ligands. Additionally, a [Au(CN)_2~-]_2 dimeric excimer produces a broad, green emission band in this class of compounds, albeit reduced in intensity in several of the compounds where a reasonable energy match exists with Ln~(3+) excitation bands.