Silver complexes 2,2 -bipyridyl

Mono and bis 2,2 -bipyridyl and 1,10-phenanthroline complexes of silver(II) have been isolated as red-brown crystals by either peroxydisulfate, anodic or ozone oxidation techniques.497,519 No tris-chelated species have been substantiated,497 although it is worth noting that a 2,2, 2"-terpyridyl bis complex has been isolated and claimed to be a six-coordinate... 

Bipyridyl has been used to modify silver electrodes to overcome the sluggish response of proteins at the electrodes. Strong SERS is observed both at the oxidation (+0.45 V) and reduction (—0.6 V) potentials, indicating that the ligand remains adsorbed. The spectra observed as a function of potential show the presence of Ag1—bipy complexes, silver metal with adsorbed bipyridyl and, at —1.4 V, bipy -> bipy-.87... 

Haino and co-workers have reported the synthesis of a self-assembling dimeric capsule via metal-coordination utilizing two octadentate resorcin[4]arene cavitands possessing four bipyridyl groups (13) which complex four silver cations (Ag+) in a tetrahedral fashion (Fig. 4) [46, 47]. A detailed computational study of the dimeric metallo-capsule 14 revealed a large and elaborate three-dimensional inner capsular... 

The wider electrochemical potential windows associated with non-aqueous solvents than with water opens the way to a far richer field of reaction studies. A report of SERS of the tris(2,2-bipyridyl)-ruthenium(II) complex ion, [Ru(bpy)3]2+, adsorbed from acetonitrile solution on to a silver electrode [36] has been followed, independently, by a report [37] on an in situ SERS study of the electroreduction reaction to [Ru(bpy)3]+. It had been... 

Silver(n) complexes, 839-850 amino adds, 846 aqua,844,850 biguanides, 849 2,2 -bipyridyl, 843 carboxylates, 844 cinchomeronic acid, 842 dipicolinic acid, 842 dithiocarbamates, 845 isodnchomcronic add, 842 isonicotinates, 840 lutidinic acid, 842 N-heterocyclic ligands, 839 nicotinates, 840 1,10-phenanthroline, 843 phthalocyanines, 848 picolinates, 840... 

As discussed before in the case of nucleic acids the authors have also considered the incidence of the interfacial conformation of the hemoproteins on the appearance of the SERRS signals from the chromophores. Although under their Raman conditions no protein vibration can be observed, the possibility of heme loss or protein denatura-tion are envisaged to explain a direct interaction of the heme chromophores with the electrode surface in the case of the adsorl Mb. extensive denaturation of Cytc at the electrode appears unlikely to the authors on the basis of the close correspondence of the surface and solution spectra. Furthermore, the sluggish electron transfer kinetics measured by cyclic voltammetry in the case of Cytc is also an argument in favour of some structural hindrance for the accessibility to the heme chromophore in the adsorbed state of Cytc. This electrochemical aspect of the behaviour of Cytc has very recently incited Cotton et al. and Tanigushi et al. to modify the silver and gold electrode surface in order to accelerate the electron transfer. The authors show that in the presence of 4,4-bipyridine bis (4-pyridyl)disulfide and purine an enhancement of the quasi-reversible redox process is possible. The SERRS spectroscopy has also permitted the characterization of the surface of the modified silver electrode. It has teen thus shown, that in presence of both pyridine derivates the direct adsorption of the heme chromophore is not detected while in presence of purine a coadsorption of Cytc and purine occurs In the case of the Ag-bipyridyl modified electrode the cyclicvoltammetric and SERRS data indicate that the bipyridyl forms an Ag(I) complex on Ag electrodes with the appropriate redox potential to mediate electron transfer between the electrode and cytochrome c. 

When copper(i) oxide is treated in benzene with trifluoromethanesulphonic anhydride, the complex (Cu0 S02 CF3)2(C H,), which releases benzene only above 120 °C, is obtained. The trifluoromethanesulphonate ion does not compete with olefins for co-ordination sites on the copper cf. ref. 28, p. 2%) and cationic Cu complexes are formed. Oxidation of alkyl radicals by copper(ii) trifluoromethanesulphonate in acetic acid gives more of the alkyl acetate, by oxidative solvolysis, and less olefin, than oxidation by copper(ii) acetate, the difference in product ratio being due to the greater dissociation of the copper trifluoromethanesulphonate. Silver(ii) complexes Ag (bipy)2-(O3S CF,) (bipy = 2,2 -bipyridyl) may be prepared from the silver(i) complex either by electrolysis or by treatment with silver(ii) oxide and trifluoro-methanesulphonic acid. ... 

Direct Arylation of Thiophenes. For 2-substituted thiophenes, the C5 position is more reactive compared with the C4 position. Mechanistic studies were performed on the C4-selective direct C-H arylation of 2-substituted thiophenes. To study the effect of the counteranion on C4/C5 selectivity, stoichiometric amounts of arylpalladium bipyridyl complexes were reacted with 2-substituted thiophenes in the presence of various additives. Silver triflate showed high C4 selectivity with minimal amounts of biphenyl by-product (10%), whereas AgOAc and Ag2C03 favored the C5 product (eq 75). 

A number of recent papers report a dramatic increase in luminescence of diheptyl-bipyridyl-diol [45], organic dyes, and other species in the presence of silver [33,56-59], gold [60], and copper [61] NPs (plasmons) compared with the luminescence of the same complex without plasmons. The absorption coefficient of the NPs is six orders of magnitude higher than that of organic molecules. These papers provide a promising approach to increase the efficiency of LSCs. 

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