Neocuproine copper complexes

NdjlCufpballj 23H2O, 43 208-210 Negative ion spectra, 28 7 Neocuproine copper complexes, 45 289 Neodymium carbides, 11 200 dibromide, 20 4 dichloride, 20 4 preparation of, 20 8 properties of, 20 15-18 diiodide, 20 4... 

A lipophilic copper complex with neocuproine has been found to increase the toxicity of a trichlorophenol in bacteria, probably due to increased transport of Cu over the membrane [229],... 

D. Cu+ reacts with neocuproine to form the colored complex (neocuproine)2Cu+, with an absorption maximum at 454 nm. Neocuproine is particularly useful because it reacts with few other metals. The copper complex is soluble in 3-methyl-1-butanol (isoamyl alcohol), an organic solvent that does not dissolve appreciably in water. In other words, when isoamyl alcohol is added to water, a two-layered mixture results, with the denser water layer at the bottom. If (neocuproine)2Cu+ is present, virtually all of it goes into the organic phase. For the purpose of this problem, assume that the isoamyl alcohol does not dissolve in the water at all and that all the colored complex will be in the organic phase. Suppose that the following procedure is carried out ... 

Fig. 10. Structure of terpyridyl (6), bipyridyl (7), and neocuproine (8) copper complexes.

The lower efficiency of the bipyridine complex compared to its ter-pjTidine analogue was proposed to be due to its dimerization at neutral pH. A related complex that cannot dimerize, [Cu"(neocuproine) (H20)2] (8, Fig. 10), was proved to be much more efficient than both bpy and tpy complexes (334). The half-life of ApA with respect to the trans-esterification step was 3 min (ApA, 0.5 mM complex, 10 mM) at neutral pH and 37°C. The reaction is first order with respect to the copper complex and, as in the two previous examples, a pH dependence of rate constants is observed (optimal reactivity at pH 7). The... 

A few reactions of aryl chlorides catalyzed by ligated copper complexes have been reported. The reaction of phenyl chloride with diphenylamine to form triarylamines catalyzed by the complexes of CuL(PPh3)Br in which L is 1,10-phenanthroline, neocuproine, or 2,2 -bipyridine occurred in about 50% yield. The favorable effect of potentially coordinating ortho substituents on the rates of Ullmann reactions has been exploited to couple o-chlorobenzoic acids with anilines to form N-arylanthranilic acids in aqueous or DMF solutions in the presence of pyridine. ... 

The first copper-mediated C—S coupling of aiyl boronic acids with alkyl thiols was reported in the presence of an organic base, pyridine (Scheme 20.54) [163]. Copper complexes, Cul-neocuproine [164], Cul-ethylene glycol [165], Cul-bipyridine/air [166], and CuSO -l,10-phenanthroUne/O, [167], have been subsequently explored for the coupling of aryl halides and boronic acids with... 

In the preceding iron determination, the results would be about 10% high because serum copper also forms a colored complex with ferrozine. Interference is eliminated if neocuproine or thiourea is added. These reagents mask Cu+ by forming strong complexes that prevent Cu+ from reacting with ferrozine. 

Cuproine (2,2 -biquinolyl, formula 19.2), neocuproine (2,9-dimethyl-1,10-phenanthroline, formula 19.3), and bathocuproine (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, formula 19.4) react with copper(I) to form coloured cationic complexes. The methods using these reagents are specific for copper, but are of relatively low sensitivity. 

Figure 19.2 shows the absorption spectra of the copper(I) complexes with cuproine, neocuproine, and bathocuproine in isoamyl alcohol. 

Fig. 19.2. Absorption spectra of copper(l) complexes with cuproine (1), neocuproine (2), and bathocuproine (3) in isoamyl alcohol...

Neocuproine reacts with copper(I) within the pH range 3-10, to form an orange complex extractable with -amyl and isoamyl alcohols, -hexanol, and MIBK. Neocuproine is added to the sample as an ethanol solution, and the complex formed is extracted with CHCI3 [29]. The molar absorptivity of the complex in isoamyl alcohol at Xmax = 545 nm is 7.9-10 (a = 0.12). 

The bathocuproine method for the determination of copper(I) [30,31 ] is about twice as sensitive as those based on cuproine and neocuproine. The molar absorptivity of the copper-bathocuproine complex in isoamyl alcohol at max = 479 nm is 1.42-10 (a = 0.22). 

Copper can be determined by use of ion associates, formed by the cationic complexes of Cu(I) with cuproine [63-65], neocuproine [65], bathocuproine [66] and thio-crown ethers [67,68], associated with the acid dyes such as Rose Bengal (e = 7.8-10 ) [63,65,66], the ethyl ester of eosin (e = 9.4-10 ) [64], and Erythrosin [63]. These ion-associates are extracted into chloroform [65,66], 1,2-dichloroethane [64,67,68], and other solvents. The ion-associates of cyanide [69] and chloride [70,71] complexes of Cu(I) with Methylene Blue (1,2-dichloroethane, = 9.8-10 ) [69], and Ethyl Violet (toluene, = 9.6-10 ) [70] are also worth mentioning. The halide complexes of Cu(I) with azo dyes have also been extracted. 

Extraction and stripping of copper(I) as a neocuproine complex in a surfactant medium was used to determine Cu in steel [4], Solid-phase extraction based on the preconcentration of the complex with neocuproine on a preconditioned membrane disc containing octadecyl-bonded silica followed by extraction of Cu and elution with isopentyl alcohol was applied to the determination of copper in distilled, tap and spring waters [5]. 

The contribution of the copper during the DNA degradation can be revealed by the addition of neocuproine or bathocuproine, which trap copper to form non-redox active Cu complexes unable to oxidize DNA. 

Although 1,10-phenanthroline and 2,9-dimethyl-1,10-phenanthroline (neocuproine) will each chelate both copper and iron, the effect on the redox chemistry of the two metal ions are distinct Cu(I) chelated to 1,10-phenanthroline reacts readily with H2O2 to form HO (Goldstein and Czapski 1986), whereas reaction of the Fe(II) complex is inhibited (Mello-Filho and Meneghini 1991). Neocuproine inhibits the reaction of Cu(I) with H2O2 (Czapski and Goldstein 1986) but appears to have... 

The cupric reducing antioxidant capacity (CUPRAC) method [82], which involves the use of copper(II)-neocuproine reagent, has been modified to assay both lipophilic and hydrophilic antioxidants simultaneously, including PG and DG [83]. The modification makes use of methyl-P-cyclodextrin, which forms inclusion complexes, increasing the solubility of lipophilic antioxidants and avoiding the turbidity of alcohol-water solutions. 

Tutem et al. (1997) reported another spectrophotometric method for vitamin E (a-tocopherol) in pharmaceutical preparations using copper(II)-neocuproine reagent in neutral medium, that is, ammonium acetate buffer (pH 7, 0.1 mol/E) and obeyed Beer s law between 2.4 x 10 and 9 x 10 mol/E a-tocopherol with a correlation coefficient (R ) of 0.996. The absorbance of the copper(I)-neocuproine complex as a result of vitamin E oxidation was stabilized after 30 min (monitored at 450 nm against the reagent blank) and was stable for at least a further 90 min. 

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