A μ-Bis(phosphino)ethane Gold(I) Dimer

Bis(bromo,cyano )-μ-[bis( dicyclohexylphosphino))ethane-P,P']-digold, [Au_2( C_(26)H_(48)P_2){Br_(1.16)(CN)_(0.84)}], M_r= 931.09, monoclinic, P2_1/n, ɑ = 9.772 (3), b = 15.366 (4), c = 20.973 (5) Å, β = 102.53(2)º, V = 3074.2 (15) Å^3, Z = 4, D_x = 2.01 g cm^(-3), λ(Mo Kɑ)= 0.71073 Å, μ = 111.2 cm^(-1), F(000) = 1774, room temperature (297 K), R = 0.029 for 2255 reflections with F_o > 3σ(f_o^2). A bis(dicyclohexylphosphino)ethane ligand bonds one Au atom at each P atom. The Au atoms are further bonded to Br^- or CN^- ions in a disordered manner, with the bromide populations being 0.532 (5) on Aul and 0.628 (5) on Au2

MICELLE FORMATION AND SURFACE INTERATIONS IN SUPERCRITICAL CO. FUNDAMENTAL STUDIES FOR THE EXTRACTION OF ACTINIDES FROM CONTAMINATED SURFACES.

We are examining the potential of water in CO? microemulsions as a new medium for the extraction of metal ions from contaminated surfaces with the ultimate goal of extracting actinides from heterogeneous waste to aid in decontamination and waste reduction

Design and applications of luminescent inorganic complexes

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. A series of Au(I) phosphine complexes were designed and synthesized to investigate the possibility of room temperature phosphorescence in solution from three different types of transitions: metal-to-ligand-charge-transfer in four coordinate monomers, [...] in Au(I) dimers, and [...] in two and three coordinate monomers. Solution emission was only observed from the three coordinate Au(I) complexes. The complex [...] (dcpe = 1,2-bis-dicyclohexylphosphinoethane) has two isolated AuP3 units and emits at 508 nm in acetonitrile solution with a lifetime of 21 [...] and a quantum yield of 0.8 (366 nm excitation). The emission has been assigned as a [...] transition with the corresponding absorption band at 370 nm. The excited state is a powerful reductant capable of reducing aryl halides. Electron transfer (ET) rates were studied from the excited [...] to a series of substituted pyridiniums (py+). The low excited state reduction potential (Au(II)/Au(I)) of -2.3 V made it possible to study ET rates at driving forces as high as 2.1 eV. High driving force, bimolecular ET rates were also studied with [Ir(cod)(pz)]2 (IR2; cod = cyclooctadiene, pz = pyrazole). The forward ET rates from Ir2 to py+ increase to the diffusion limit and remain diffusion limited at driving forces as high as 1.60 eV. The recombination ET rates from py to Ir2+ show inverted behavior (rates decrease as the driving force increases) at driving forces > 0.85 eV, representing the first observation of inverted behavior for a bimolecular system. The discrepancy between the forward ET and recombination ET rates is explained by ET to low lying excited states. On the basis of the emission observed from three coordinate Au(I) complexes, Au(I) was used as a probe for the coordination environment of the active site in Pseudomonas auruginosa azurin. The active site consists a copper center strongly bound to two histidines and a cysteine in a trigonal plane with a disputed axial interaction to [...] away. The Au(I)-WT-azurin is stable and emits at 580 nm, indicating that there is little or no interaction with the Metl2l

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

The goals of this research program included: (1) Study solubility of extractants and formation of micelles--(a) Do surfactants form micelles in scCO{sub 2} and what is the mechanism of their formation? (b) Can the pressure/density of scCO{sub 2} be used to alter surfactant solubility or micelle structure? (c) Can surfactant micelles be used to transport water based microphases? (2) Examine the solubilization of metals--(a) What influence does metal binding have on the surfactant solubility or micelle structure? (b) What is the selectivity of metal binding in promising systems? (c) Are all solubilized metals bound to surfactant ligands or is an entire aqueous micro-environment solubilized by the surfactant/micelle? (d) Can metal species, as charged ions or neutral complexes, be insulated by fluorinated surfactants to enhance solubility in scCO{sub 2}? (3) Explore surface interactions with the matrix and mobility of micelles.--(a) What factors affect wetting of heterogeneous matrices (i.e., ligand type, CO{sub 2} pressure); (b) How deep can surfactants penetrate materials such as concrete? (4) Explore surface interactions with the actinide contaminant--(a) Can surfactant based micelles be used to deliver acidic, aqueous microphases to the actinide surface? (5) Evaluate these new systems for metal extraction from a model contaminated surface containing radionuclides or surrogate metals--(a) What is the rate of extraction? (b) What ratio of ligand to metal is required

Micelle Formation and Surface Interactions in Supercritical CO2. Fundamental Studies for the Extraction of Actinides from Contaminated Surfaces.

We are examining the potential of water in CO2 microemulsions as a new medium for the extraction of metal ions from contaminated surfaces with the ultimate goal of extracting actinides from heterogeneous waste to aid in decontamination and waste reduction

Electronic Spectroscopy of Gold(I) Pseudomonasaeruginosa Azurin Derivatives

The trigonal (His_2Cys) coordination of blue copper sites in proteins favors Cu(I) over Cu(II), as reflected in the relatively high Cu^(II/I) reduction potentials; and the rigid polypeptide environment minimizes Cu^(II/I) nuclear reorganization, thereby facilitating long-range electron-transfer reactions with donor and acceptor molecules. Although blue Cu(II) sites exhibit rich spectroscopic and magnetic properties, the corresponding Cu(I) proteins do not; indeed, the methods that can be employed to investigate d^(10) metal sites are very limited. Because recent work has shown that Au(I) has geometry-sensitive d-p absorptions and emissions, we are using this 5d^(10) ion to probe ligand interactions in the Cu(I) sites of proteins. Here we report the electronic spectroscopy of Au(I)-substituted wild-type (WT) Pseudomonas aeruginosa azurin as well as the Au(I) derivative of a mutant in which the methionine at position 121 has been replaced with glycine (Met121Gly)