Cu-phenanthroline complex

Electrophilic activation can occur by both metal coordination and hydrogen bonding, and it is common for enzymes to combine these effects. Less common are synthetic systems that combine these, but one particularly simple example is the use of the diaminophenanthroline-Cu(II) complex shown below. This compound accelerates the hydrolysis of 2, 3 -cAMP(cAMP = cyclic adenosine monophosphate) approximately 20,000-fold compared to a Cu-phenanthroline complex with the amino groups replaced by methyls. 

Oxidation of ethylbenzene catalyzed by the Cu(II) complex with o-phenanthroline was found to occur with the rate depending on the dioxygen concentration [170]. 

The oxidation of butanone-2, catalyzed by complexes of pyridine with cupric salts, appeared to be similar in its main features [191]. Butanone-2 catalytically oxidizes to acetic acid and acetaldehyde. The reaction proceeds through the enolization of ketone. Pyridine catalyzes the enolization of ketone. Enole is oxidized by complexes of Cu(II) with pyridine. The complexes Cu(II).Py with n = 2,3 are the most reactive. Similar results were provided by the study of butanone-2 catalytic oxidation with o-phenanthroline complexes, where Fe(III) and Mn(II) were used as catalysts [192-194],... 

The oxidation of alcohols in a basic solution catalyzed by Cu(II) o-phenanthroline complexes has been recently studied by Sakharov and Skibida [305-309], The copper-phe-nanthroline complex is stable in a basic solution and appears to be a very efficient catalyst for the oxidation of alcohols to carbonyl compounds. The reaction rate increases with an increase in the partial pressure of dioxygen. The solvent dramatically influences the reaction rate (conditions 348 K, [MeOH] = 20%vol, [Cu—(o—phm)] = 0.01 mol L-1). 

The NO reduction of the Cu(II) complex Cu(dmp)2(H20)2+ (dmp = 2,9-dimethyl-l,10-phenanthroline) to give Cu(dmp)2 plus nitrite ion (Eq. (20)) has been studied in aqueous solution and various mixed solvents (42a). The reduction potential for Cu(dmp)2(H20)2+ (0.58 V vs. NHE in water) (48) is substantially more positive than those for most cupric complexes owing to steric repulsion between the 2,9-methyl substituents that provide a bias toward the tetrahedral coordination of Cu(I). The less crowded bis(l,10-phenanthroline) complex Cu(phen)2(H20)2+ is a weaker oxidant (0.18 V) (48). 

Mixed-ligand Cu(II) complexes with salicylato and phenanthroline derivatives as ligands can also be highly cytotoxic (231). Mixed-ligand Cu(II) amino acid phenanthroline complexes (Casiopeinas) such as [Cu(L-Ser)(phen)(H20)]+ 52 are reported to be effective anticancer agents (232). It is possible that a complex in this class will soon enter clinical trials. 

Enzyme-stabilized single-stranded DNA (known as the open complex) is the first intermediate formed in transcription initiation of RNA polymerases its formation is the rate-limiting step. Designing molecules which bind specifically to the open complex is a strategy for generating potent transcription inhibitors. The redox-stable complex of Cu(I) with 1,2-dimethyl- 1,10-phenanthroline is an example of such a strategy (405). The Cu(I) complex binds specifically to the single-stranded DNA of transcriptional open complexes and is an effective inhibitor of eukaryotic and prokaryotic transcription. 

Abstract A new thiourea ligand, N-[l,10-phenanthroline]-N -[(benzo-15-crown-5)yl]thiourea has been synthesized from the reaction of 5-amino-1,10-phenanthro-line with 15-isothiocyanatobenzo[15-crown-5] and its Cu(I) complex has been prepared. The stmctures of the ligand and its complex have been characterized by elemental analysis, UV-vis, FTIR, H NMR (DMSO-dg), NMR (DMSO-dg) and MS spectra (LC-MS). 

A semi-synthetic metalloenzyme that catalyses the enantioselective hydrolysis of simple amino acid esters has been reported. Iodoacetamido-l,10-phenanthroline (238) was interacted with a cysteine residue in adipocyte lipid binding protein (ALBP) to produce the conjugate ALBP-Phen (239), which was converted into its Cu(II) complex. The ALBP-Phen-Cu(II) was found to catalyse the enantioselective... 

Figure 6.22 Stmctural formula of dendrimer 28 consisting of a Cu(I) bis-phenanthroline complex as core, linked to four dendrons, each one containing two fullerene moieties appended at the periphery.77...

Several tetrahedral cuprous phenanthroline complexes, known inhibitors of transcription, were tested against integrase and shown to be reasonably effective inhibitors [56] IC50 values in the range of 1-10 jiMwere determined (for example, the neocuproine-Cu+ complex, XII). Analyses of the mode of inhibition demonstrated that these compounds act noncompetitively, and that inhibition does not correlate with inhibition of DNA binding. Thus, it has been proposed that these metal chelates may act at a site distant from the active site, or perhaps in the context of an enzyme-DNA complex. 

Substituent effects in 1,10-phenanthrolines have been comprehensively investigated201,202 from their pA s, stability constants in Fe(III) and Cu(II) complexes, and redox potentials the Ni(II) complexes have also been examined,203 as have other metal complexes.204 p- Values have been obtained for the three successive proton losses (1, 2, 3, respectively) from 4-substituted dications of 10-hydroxy- 1,7-phenanthrolines (23).205... 

Bauerle and coworkers have synthesized a re-conjugated catenane, utilizing Cu(I) templation and a newly developed method for acetylenic homocoupling based on the reductive elimination of platinum to generate the desired C-C bond formation (Scheme 6.16) [65,66]. The C-shaped 57 was first preorganized around Cu(I), resulting in the homoleptic bis-phenanthroline complex 58. After removal... 

Fallis and Heuft have used a metal-templated synthesis to form the helical 1,10-phenanthroline-capped metal-complexed SPMs 87 and 88 (Scheme 6.20) and their demetalated analogs (not shown). The addition of [Cu(OAc)2] (0.5 equiv) to a solution of 89 in pyridine and diethyl ether templated the formation of intermediate 90. Following the addition of excess [Cu(OAc)2] (5.5 equiv), the Cu(I)-complexed SPM 87 was isolated in an excellent yield of 84%. Treatment of 87 with aqueous KCN then provided the Cu-free SPM in 70% yield (not shown). The N,N-dibutylamine substituted analog 88 was formed in an analogous manner and taken on directly to the Cu-free SPM (39%) in a one-pot procedure. It was shown by variable temperature 13C NMR spectroscopy that the helical Cu(I) complex 88 had a barrier to racemiza-tion of 4 kcal mol 1 higher than that of the Cu-free analog [83]. 

To our knowledge, topologically chiral molecules have not yet been resolved into enantiomers. However, we may anticipate that their energy barrier to racemization will be extremely high, compared to Euclidean chiral molecules. Therefore they are expected to be useful in enantioselective interactions or reactions. For example, it has been shown that tetrahedral copper(I) bis-2,9-diphenyl-l,10-phenanthroline complexes (which form the catenate subunits) are good reductants in the excited state [97] therefore the chiral Cu(I) catenates could be used for enantioselective electron-transfer reactions. Alternatively, the resolution of topologically chiral molecules would allow to answer fundamental questions, such as what are the chiroptical properties of molecular trefoil knots ... 

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). 

Cu(I)-complexed [2]-rotaxane 96 was synthesized as follows (Figure 2.32)16f 67 2-rnethy l-9-(p-anisy I)-1, 10-phenanthroline 91 was deprotonated (lithium diisopropylamide) and the resulting anion was alkylated with the... 

---