Geminally diaurated μ₂-aryl complexes have been prepared where gold(I) centers were bridged by the semirigid diphosphine ligands bis(2-diphenylphosphinophenyl)ether (DPEphos) and 4,6-bis(diphenylphosphanyl)dibenzo[b,d]furan (DBFphos). Diaurated complexes were synthesized in ligand redistribution reactions of the corresponding di-gold dichlorides with di-gold diaryls (six of them new) and silver(I) salts. Diaurated complexes were isolated as salts of the minimally coordinating anions SbF₆⁻ and ReO₄⁻. Efforts to prepare salts of the tetraarylborate [B(3,5-(CF₃)₂C₆H₃)₄]⁻ led to transmetalation from boron, with crystallization of the fluorinated aryl complex. The new complexes were characterized by multinuclear NMR, absorption and emission spectroscopies, 77 K emission lifetimes, and by combustion analysis; three are crystallographically characterized. Structures of geminally diaurated aryl ligands are compared to those of mono-aurated analogues. Both crystal structures and density-functional theory calculations indicate slight but observable disruptions of aryl ligand aromaticity by geminal di-gold binding. An intermolecular aurophilic interaction in one structurally authenticated complex was examined computationally.

Fundamental study of enzymatic nucleoside transport suffers for lack of optical probes that can be tracked noninvasively. Nucleoside transporters are integral membrane glycoproteins that mediate the salvage of nucleosides and their passage across cell membranes. The substrate recognition site is the deoxyribose sugar, often with little distinction among nucleobases. Reported here are nucleoside analogues in which emissive, cyclometalated iridium(III) complexes are “clicked” to C-1 of deoxyribose in place of canonical nucleobases. The resulting complexes show visible luminescence at room temperature and 77 K with microsecond-length triplet lifetimes. A representative complex is crystallographically characterized. Transport and luminescence are demonstrated in cultured human carcinoma (KB3-1) cells.

One gold(I)-substituted styrylbenzene, six digold(I) distyrylbenzenes, one tetragold distyrylbenzene, and four digold distyrylnaphthalene complexes were synthesized using base-promoted auration, alkynylation, triazolate formation, and Horner–Wadsworth–Emmons reactions. The gold(I) fragments are either σ-bonded to the aromatic system, or they are attached through an alkynyl or triazolate spacer. Product formation was monitored using ³¹P{¹H} NMR spectroscopy. Systems in which gold(I) binds to the central benzene ring or the terminal phenyl rings were designed. All of these complexes have strong ultraviolet absorptions and emit blue light. The position of the gold(I) attachment influences the luminescence efficiency. Complexes with two gold(I) fragments attached to the ends of the conjugated system have fluorescence quantum yields up to 0.94, when using 7-diethylamino-4-methylcoumarin as the emission standard. Density-functional theory calculations on three high-yielding emitters suggest that luminescence originates from the distyrylbenzene or -naphthalene bridge.

A series of di(gold(I) aryls), L(AuR)₂ (L=DPEphos, DBFphos, or Xantphos; R=1-naphthyl, 2-naphthyl, 9-phenanthryl, or 1-pyrenyl), have been prepared. The complexes were characterized by multinuclear NMR spectroscopy, static and time-dependent optical spectroscopy, mass spectrometry, microanalysis, and X-ray crystallography. In addition, DFT calculations on model dinuclear gold complexes have been used to examine the electronic structures. Photophysical properties of the dinuclear complexes have been compared to mononuclear analogues. Low-temperature excited-state lifetimes for both the mononuclear and dinuclear complexes in toluene indicate triplet-state emission. Time-resolved DFT calculations suggest that emission originates from aryl-ligand transitions, even if the LUMO resides elsewhere.

A series of phosphane- and (N-heterocyclic carbene)gold(I) complexes were prepared by deprotonation of terminal alkyne precursors and reaction with the corresponding gold(I) chlorides. Some ten new compounds are reported; these are characterized by multinuclear NMR, optical spectroscopy, and elemental analysis. Crystallographic characterization is reported for five complexes. Organogold species bearing conjugated aryl substituents on the alkynyl ligand are luminescent. Density-functional theory calculations on a model complex suggest that emission and the first several absorption transitions result from excited states dominated by the arylacetylide ligand. Excited-state geometry optimization finds that the lowest-energy triplet state bears linear, two-coordinate gold(I) with a miniscule lengthening of the alkynyl carbon–carbon bond. An unusual triplet excited state having a bent geometry at gold lies at higher energy in arylacetylide complexes. For the model terminal acetylideMe₃PAuC≡CH, the calculations find this bent state to be the lowest-energy triplet.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)