Gold complexes sensitizers

Hydroarylation can also be mediated by Au(I) and Au(III) (Scheme 33) (384). In the case of aryl substituted alkynes, the Au(III) Ji complex undergoes electrophilic aromatic substitution with the electron-rich arene to give aLkenyl-Au(III) complex, which is immediately protonated by the H generated upon C C bond formation. For the Au(I)-catalyzed hydroarylation, the cationic gold complex k coordinates the alkyne, with subsequent nucleophilic attack by the arene from the opposite face leading to an alkenyl-gold complex, which is protonated to the desired products. The nature of the reaction causes the regioselectivity of this reaction to be sensitive to electronic rather than steric factors. 

For whatever reasons, gold biochemistry is not well understood. Any attempt to improve the situation seemed to require the introduction of a new, more sensitive technique for the characterization of gold complexes in a biological milieu. X-ray absorption spectroscopy, XAS, (12,13,14) offered such a tool. This type of spectroscopy has enjoyed a recent revitalization due to the advent of intense new sources... 

Bunz, U. H. F. and Rotello, V. M. Gold Nanoparticle-Fluorophore Complexes Sensitive and Discerning Noses for Biosystems Sensing. Angewandte Chemie International Edi-tion,49(19), 3268-3279, (2010). 

U. H. F. Bunz and V. M. Rotello 2010 Angew. Chem. 49, 3268 Gold nanoparticle-fluorophore complexes sensitive and discerning noses for biosystems sensing... 

The mutual adsorption of the ultramicrons results in the gold hydrosol losing its characteristic properties, viz., irreversible dehydration and sensitiveness to electrolytes, while the complex particles assume the properties and show all the reactions of the protective colloid. If the protective colloid can be precipitated by a given. reagent, so can the gelatin gold complex. On the contrary if the protective colloid is unaffected by the electrolyte in question, the complex will also be exempt from the influence. 

The silver perchlorate [7783-93-9] salt, AgClO, is dehquescent and forms a light-sensitive monohydrate that can be dehydrated at 43°C and is soluble in a variety of organic solvents. Explosions of silver perchlorate have been reported (40—42). Gold forms organic perchlorate [42774-61-8] complexes as well as complexes with silver, eg, (CgH )2AgAu(CgF )2C104. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

Trends in Au-X and Au-P bond lengths in complexes (PPh3) AuX should be noted (Table 4.10) the Au-Cl bond length varies more with changes in coordination number than does the Au-P bond and is, therefore, more sensitive to the decrease in s character as the hybrid orbitals used by gold change from sp to sp3. 

Novel boron-gold bonds containing complexes are realized in two borido clusters. Addition of [HFe4(CO)i2BH] ppn to xs (PPhjIAuCl in CH2CI2 forms the green-brown, air-sensitive Fe4(CO) 2(AuPPh,)2BH ... 

Table 2.2 IC50 values of selected gold(lll) complexes against the human ovarian carcinoma A2780 cell lines sensitive (S) or resistant (R) to cisplatin. Adapted from Ref [47],...

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