title: Structure and emissive properties of heterobimetallic Ln-Au coordination polymers: role of Tb and Eu in non-aurophilic [nBu4N]2[Ln(NO3)4Au(CN)2] versus aurophilic Ln[Au(CN)2]3·3H2O/3D2O chains.
abstract: This investigation is focused on comparing photophysical properties between two series of lanthanide-dicyanoaurate coordination polymers that contain and lack aurophilic interactions, respectively. Luminescence and crystallographic studies have been carried out on five different coordination polymer chain frameworks: the non-aurophilic [(n)Bu4N]2[LnxGd1-x(NO3)4Au(CN)2] (Ln = Eu, Tb; x = 0.01, 0.02, 0.04, 0.08) and[(n)Bu4N]2[EuxTb1-x(NO3)4Au(CN)2] (x = 0.25, 0.5, 0.75), as well as the analogous solid-solutions of aurophilic LnxGd1-x[Au(CN)2]3·3H2O and EuxTb1-x[Au(CN)2]3·3H2O. The single-crystal structures of M[Au(CN)2]3 ·3H2O (M = Eu, Gd) are also reported for comparison. In the aurophilic frameworks the close proximity of gold(I) centers on neighboring chains allows for Au-Au interactions to take place that facilitate energy transfer between lanthanides. Terbium- and europium-doped aurophilic frameworks show energy transfer between one of the lanthanide ions and dicyanoaurate centers as observed via luminescence measurements. In the non-aurophilic frameworks the [(n)Bu4N] cations separate the Au-Au chains, thereby preventing interaction between them, and preventing energy transfer. By preparing the aurophilic EuxTb1-x[Au(CN)2]3·3D2O frameworks, it was shown that the O-H vibrational energy in the hydrated (aurophilic) samples can partially quench the Ln signal.
authors: Department of Chemistry, University of Maine , Orono, Maine 04469, United States.
authors: John C
authors: JC
authors: Ahern
authors: Ryan J
authors: RJ
authors: Roberts
authors: Philip
authors: P
authors: Follansbee
authors: Jeffrey
authors: J
authors: McLaughlin
authors: Daniel B
authors: DB
authors: Leznoff
authors: Howard H
authors: HH
authors: Patterson