Copper phenanthroline complex

Que BG, Downey KM, So AG (1980) Degradation of deoxyribonucleic acid by a 1,10-phenanthroline-copper complex the role of hydroxyl radicals. Biochemistry 19 5987-5991 Quintiliani M (1983) Cellular thiols and radiation response. In Balzani V (ed) Baxendale Memorial Symposium. Lo Scarabeo, Bologna, pp 81-108... 

Figure 5.1 Shortened chemical mechanism for DNA cleavage by 1,10-phenanthroline-copper complexes.

The distortions induced in the DNA double helix by the interstrand cross-links have been characterized by several techniques. As judged by chemical probes (diethyl pyrocarbonate, hydroxylamine, osmium tetroxide), antibodies to cisplatin-modified poly(dG-dC)-poly(dG-dC), natural (DNase I) and artificial (1,10-phenanthroline-copper complex) nucleases, the cytosine residues are accessible to the solvent, and the distortions are located at the level of the adduct [48-50]. From the electrophoretic mobility of the multimers of double-stranded oligonucleotides containing a single interstrand cross-link [50] it is deduced that the DNA double helix is unwound (79°) and its axis is bent (45°). 

The 1,10-phenanthroline-copper complex is usually generated in situ where it exhibits maximal cleavage efficiency at a copper to phenanthroline ratio of 1 4. This results from the smaller binding constant of the second phenanthroline in the complex. At high thiol concentrations where there is competitive binding between phenanthroline and the thiol this can be problematic. By covalently attaching two phenanthrolines using a short... 

Catalytic Oxidation of Sulfhydryl Groups by O-phenanthroline Copper Complex, BBA... 

Crystal stmctures of complexes of copper(II) with aromatic amine ligands and -amino acids " " and dipeptides" have been published. The stmctures of mixed ligand-copper complexes of L-tryptophan in combination with 1,10-phenanthroline and 2,2 -bipyridine and L-tyrosine in combination with 2,2 -bipyridine are shown in Figure 3.2. Note the subtle difference between the orientation of the indole ring in the two 1,10-phenanthroline complexes. The distance between the two... 

Pyridine-based N-containing ligands have been tested in order to extend the scope of the copper-catalyzed cyclopropanation reaction of olefins. Chelucci et al. [33] have carefully examined and reviewed [34] the efficiency of a number of chiral pyridine derivatives as bidentate Hgands (mainly 2,2 -bipyridines, 2,2 6, 2 -terpyridines, phenanthrolines and aminopyridine) in the copper-catalyzed cyclopropanation of styrene by ethyl diazoacetate. The corresponding copper complexes proved to be only moderately active and enantios-elective (ee up to 32% for a C2-symmetric bipyridine). The same authors prepared other chiral ligands with nitrogen donors such as 2,2 -bipyridines 21, 5,6-dihydro-1,10-phenanthrolines 22, and 1,10-phenanthrolines 23 (see Scheme 14) [35]. 

Despite numerous studies involving copper catalysts, only a few isolated copper complexes have been examined, including complexes (155)-(157). Bipyridine,397 phenanthroline,398 and pyridyli-mine cationic complexes399 all exhibit tetrahedral geometries, in which the copper center is bound to two ligands. 

Two stable bicarbonato complexes of bis(l,10-phenanthroline) copper(II) were reported for the first time by Mao et al. (44). These are akin to the Lipscomb and Lindskog structures of human carbonic anhydrase (HCA) (45). In the Lipscomb structure the bicarbonate acts as a bidentate ligand while in the Lindskog structure it is essentially coordinated to the metal center in unidentate fashion (Fig. 2). 

Figure 17.29 Structure of distorted tetrahedral copper complexes. SP is sparteine-TV./V, mint is maleonitriledithiolate, dmp is 2,9-dimethyl-1,10-phenanthroline, and phen is 1,10-phenan-throline. Reprinted with permission from Ref. 67. Copyright 2005 American Chemical Society.

L-histidine, L-glutamine, and L-histidine anhydride27 and by copper complexes of organic bases such as o-phenanthroline and a,a -dipyridyl has also been reported these complexes were more active than Cu++ ions alone.28... 

Special features strongly related to the compactness of the phenylene-bridged knots were also observed during the photophysical studies. All die compounds, as usual for copper complexes with phenanthroline-type ligands [116, 117], exhibit MLCT luminescence in CH2C12 at room temperature. Only one emission band, assigned to the lowest MLCT excited state, is observed even for the complexes con-... 

Bis( 1,10-phenanthroline)copper(I) has an absorption spectrum which is a function of concentration. This has been attributed to oligomerization, possibly via n—K intermolecular stacking interactions. The tendency to oligomerize has a marked effect on the electrochemistry of the complex. For example, the complex exhibits extensive adsorption on the surface of a graphite electrode. The multilayers exhibit good electron mobility and the layers probably grow by reduction of surface copper(II). Rotating disc voltammetric measurements of the reduction of... 

Dithio-oxamide (LH2) and its dimethyl and dicyclohexyl derivatives form polymeric [CuL]n probably with S2N2 co-ordinated copper.405 The copper complexes of l,10-phenanthroline-2-carbothiamide, CuLX2 (X = Cl, Br, or NCS), are six-co-ordinate with X-bridges. The N-phenyl-l,10-phenanthroline-2-carbothiamide complexes of copper are similar to those of Co111, in that only species containing the deprotonated ligand can be obtained, Cu(L - H)X (X = Cl, Br, or N03). 

Our own work in the area of aerobic oxidations was inspired by the exquisite research performed on the structure and reactivity of the binuclear copper proteins (7), hemocyanin and tyrosinase, and by the seminal contribution of Riviere and Jallabert (8). These two authors have shown that the simple copper complex CuCl - Phen (Phen = 1,10-phenanthroline) promoted the aerobic oxidation of benzylic alcohols to the corresponding aromatic aldehydes and ketones (Fig. 2). 

Patra AK, Dhar S, Nethaji M, Chakravarty AR. Visible light-induced nuclease activity of a ternary mono-phenanthroline copper(II) complex containing L-methionine as a photosensitizer. Chem Commun 2003 1562-3. 

Not many reduction potentials are known for copper complexes. That of the Cu2+/Cu+ couple is 0.16 V Since lo(Cu+/Cu°) is 0.52 V, the disproportionation of Cu+ to Cu° and Cu2+ is favourable. This reaction does indeed occur, which makes is impossible to study stable copper(I) solutions. Reduction potentials of copper(II)-/copper(I)-(l,10-phenanthroline)2 and a few derivatives have been calculated from a kinetic analysis of appropriate rate constants values range from 108 mV for the 5-methyl-l, 10-phenanthroline complex to 219 mV for the complex with a nitro group at the 5 position [52], Values of 0.17 V and 0.12 V are given by Phillips and Williams [53] for the phenanthroline and bipyridine complexes, respectively. Such complexes can thermodynamically catalyse both the superoxide dismutation and the one-electron reduction of hydrogen peroxide (see below). 

Because the copper complexes with 2,2/-bipyridine, 1,10-phenanthroline, and their derivatives have a triplet MLCT excited state like that of [Ru(bpy)3]2+, the copper complexes exhibit similar photocatalyses to those of [Ru(bpy)3]2 + for instance, the trans-cis isomerization of stylbene through energy transfer [48] and the photoreduction of viologen compounds [9b,c,e,49,50] were successfully carried out with the copper complexes. Also, a Gratzel-type solar cell was constructed with the copper complexes, recently [51,52]. 

Since the copper complexes, [Cu(NN)2]+ and [Cu(NN)(PR3)2]+ (NN = 1,10-phenanthroline, 2,2 -bipyridine, and their derivatives) were applied to stoichiometric and catalytic photoreduction of cobalt(III) complexes [8a,b,e,9a,d], one can expect to perform the asymmetric photoreduction system with the similar copper(l) complexes if the optically active center is introduced into the copper(I) complex. To construct such an asymmetric photoreaction system, we need chiral copper(I) complex. Copper complex, however, takes a four-coordinate structure. This means that the molecular asymmetry around the metal center cannot exist in the copper complex, unlike in six-coordinate octahedral ruthenium(II) complexes. Thus we need to synthesize some chiral ligand in the copper complexes. 

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