Combination of CuI and tetrahydrothiophene (THT) in MeCN or neat THT produces various phases depending upon experimental conditions. Green luminescent product (CuI)4(THT)2 (1) consists of Cu4I4 cubane units knit into a 3-D network by 2-THT ligands. Yellow luminescent (CuI)10(THT)7(MeCN) (2) contains {[Cu4I4(THT)](2-THT)2(Cu2I2)(2-THT)2[Cu4I4(NCMe)]} "rungs" linked into 1-D ladders by pairs of 2-THT ligands. Two molecular (CuI)4(THT)4 phases were found: 2 orange luminescent 3a and dull yellow luminescent 3b. Triclinic 3b is the more stable phase at 25 °C, but undergoes endothermic transformation to monoclinic 3a at 38 °C. 3a transforms to a triclinic phase (3a') that retains orange emission at −60 °C. Non-emissive (CuI)3(THT)3•MeCN (4) is a 2-D sheet structure in which Cu3(THT)3 rings are linked in trigonal directions by rhomboid Cu2I2 dimer units. The previously reported (CuI)2(THT)4 (5) is a molecular dimer. Temperature and mixing ratio domains for the formation of the CuI-THT phases from MeCN are presented. Luminescence in 1, 2, 3a, and 3b is rationalized based on varying degrees of halide-to-metal charge transfer (XMCT) and metal-centered (MC) behavior. Low temperature spectra reveal reversible changes, including modest red shifts for 1 and 2, and splitting into two excitation/emission band pairs for 3a and 3b.

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.

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New members of the Ln[Au(CN) 2 ] 3 ·3H 2 O and [nBu 4 N] 2 [Ln(NO 3 ) 4 Au(CN) 2 ] series Ln = Ce (CeAu 3 and CeAu respectively) are reported herein where their synthesis, structure and photoluminescence properties are discussed. The first is a 3-D coordination polymer with aurophilic interactions of 3.35 Å and the latter is a 1-D coordination polymer that lacks them. At 293 K both CeAu 3 and CeAu display characteristic Ce III -based emission at λ max = 393 nm (5d→ 2 F J ), however in CeAu 3 Au I -

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