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Query: UNIPROT:P06889 (Mol)
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Complexes of Co(II), Ni(II) and Cu(II) with substituted phenylazo-6-aminouracils containing (-H, p-OH, p-CH(3), p-OCH(3) p-COOH) have been synthesized and characterized by elemental analysis, magnetic measurements and spectral measurements (IR, UV-Vis, ESR). Infrared spectra assigned the fundamental bands of the major groups, O-H, N-H, C-H, C=O, C=N, N=N, C-N and C-O (nu, delta and gamma modes of vibrations). The absence of nu(OH) and the appearance of nu(C=O) in the infrared spectra of the free ligands of 5-(p-tolyl and p-anisylazo)-6-aminouracil, assigned the keto structure, whereas in cases of 5-(phenyl, p-hydroxyphenyl and p-carboxyphenylazo)-6-aminouracil ligands, the data showed strong nu(OH) and nu(C=O) bands to assign keto-enol tautomerisms. The modes of interactions between the ligands and the metals were discussed, where oxygen and nitrogen atoms (of amino-amide groups) are involved in chelation. The azo group was not involved in chelation for all the prepared complexes except those of copper complexes derived from 5-(phenyl, p-tolyl, p-hydroxyphenyl and p-carboxyphenylazo)-6-aminouracils. The room temperature effective magnetic moment values, the Nujol mull spectra and ESR proved that all the prepared complexes were of octahedral geometry, except the nickel complex derived from 5-(phenylazo)-6-aminouracil and cobalt complex derived from 5-(p-carboxy-phenylazo)-6-aminouracil were square planar.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Jan
PMID:Spectral and magnetic properties of phenylazo-6-aminouracil complexes. 1467 Apr 63

[CuBr(2)(pMA)(2)] and [CuBr(2)(mMA)(2)] complexes (pMA: p-methylaniline, mMA: m-methylaniline) have been prepared and characterized by elemental analyses, thermogravimetric analyses, magnetic moment measurements, and IR, Raman and EPR spectroscopic studies. Coordination effects on the vibrational spectra of the ligands have been investigated. The room temperature EPR spectra of the complexes and their simulated spectra are also discussed in detail. The vibrational and EPR spectral studies suggest that the coordination sphere around Cu(II) consist of a distorted tetragonal structure.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Jan
PMID:Thermal, vibrational and EPR studies of Cu(II) bromide bis(p-methylaniline) and bis(m-methylaniline) complexes. 1467 Apr 92

Bacterial translation initiation factor IF2 was localized on the ribosome by rRNA cleavage using free Cu(II):1,10-orthophenanthroline. The results indicated proximity of IF2 to helix 89, to the sarcin-ricin loop and to helices 43 and 44, which constitute the "L11/thiostrepton" stem-loops of 23S rRNA. These findings prompted an investigation of the L11 contribution to IF2 activity and a re-examination of the controversial issue of the effect on IF2 functions of thiostrepton, a peptide antibiotic known primarily as a powerful inhibitor of translocation. Ribosomes lacking L11 were found to have wild-type capacity to bind IF2 but a strongly reduced ability to elicit its GTPase activity. We found that thiostrepton caused a faster recycling of this factor on and off the 70S ribosomes and 50S subunits, which in turn resulted in an increased rate of the multiple turnover IF2-dependent GTPase. Although thiostrepton did not inhibit the P-site binding of fMet-tRNA, the A-site binding of the EF-Tu-GTP-Phe-tRNA or the activity of the ribosomal peptidyl transferase center (as measured by the formation of fMet-puromycin), it severely inhibited IF2-dependent initiation dipeptide formation. This inhibition can probably be traced back to a thiostrepton-induced distortion of the ribosomal-binding site of IF2, which leads to a non-productive interaction between the ribosome and the aminoacyl-tRNA substrates of the peptidyl transferase reaction. Overall, our data indicate that the translation initiation function of IF2 is as sensitive as the translocation function of EF-G to thiostrepton inhibition.
J Mol Biol 2004 Jan 23
PMID:The translation initiation functions of IF2: targets for thiostrepton inhibition. 1469 86

The interaction between homocysteine (HCysSH) and Cu(II) leads to the formation of a yellow complex [Cu(I)(HCysS-SCysH)2]Cl (1) after redox processes in the Cu(II)-homocysteine system resulting in dimerization of the ligand and formation of a mononuclear Cu(I) complex with two dimers. The structure of (1) was obtained by IR-LD spectral analysis of a solid amorphous sample oriented in nematic liquid crystal medium. The original technique for orientation developed here and the polarized IR spectra thus obtained, permit the determination of the complexation sites and coordination mode of diamagnetic complexes. In the complex (1), Cu(I) is coordinated through the two O atoms of one COO- group of each of the ligands and the metal ion coordination sphere represents a distorted tetrahedron.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Mar
PMID:Linear-dichroic infrared spectral analysis of Cu(I)-homocysteine complex. 1503 96

The synthesis, spectroscopy (IR, UV-Vis, ESR), magnetic and thermal behaviors, as well electrochemistry and reactivity towards PPh3 of alkyl-substituted bis(2-nitrosophenolato)copper(II) complexes, CuLx2, where Lx = 4,6-di-t-Bu-2-nitrosophenolato (L1), 4-CH3-6-t-Bu-2-nitrosophenolato (L2), 4-t-Bu-2-nitrosophenolato (L3) mono-anion ligands, are presented. The solid-state and solution ESR spectra showed an axially symmetric g-tensors with gII > g 2.03 indicating that the unpaired electron is located in the dx2 - y2orbital. When CuLx2 complexes were treated with an excess of PPh3 in air or under vacuum in toluene (or other solutions) at 300K, as confirmed by UV-Vis and ESR examination, without formation of PPh3 adduct of the complexes, the immediately generation of semiquinone type radical species and reduction of Cu(II) to Cu(I) were observed. In the case of CuL(1)(2) the further conversion of the generated primary radical species to secondary bis(PPh3)2(phenoxazinolato)Cu(I) semiquinone type radical was detected. The cyclic voltammetry (CV) of CuLx2 exhibited two successive quasi-reversible ligand centered reductions and two irreversible metal and ligand centered oxidation processes. Electrochemical behaviors were interpreted in terms of the existence two-valence tautomeric nitroso and oximato isomers of CuLx2 in solution.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Mar
PMID:Synthesis, spectroscopy and redox behaviors of 4,6-di-t-Bu-, 4-Me-6-t-Bu- and 4-t-Bu-2-nitrosophenolato copper(II) complexes; Characterization of radical species generated by PPh3. 1503 3

New polymeric complexes of Cu(II), Co(II), Ni(II) and UO2(II) with 5-(2(1)-carboxyphenylazo)-8-hydroxyquinoline (LH2) have been prepared and characterized on the basis of analytical, magnetic, 1H NMR, EPR and electronic spectral studies. Tentative structures for the polymeric complexes are proposed. The important infrared (IR) bands and the main 1H NMR signals are assigned and discussed relative to the molecular structure. EPR spectrum of copper(II) complex has been studied with a view to assigning their stereochemistries. Various EPR parameters have been calculated. Each metal has six-coordinates in an octahedral environment. The ligand acts as a dibasic (bis-bidentate chelating agent coordinating through CN, N=N, COOH and OH groups by replacement of a proton from the two latter groups. Considerable interest has also been focused on the synthesis of the azo compounds and its polymeric metal complex due to its wide potential applications. The thermal decomposition behavior of the complexes is also discussed.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Mar
PMID:Stereochemistry of new nitrogen containing heterocyclic compounds.; X. Supramolecular structures and stereochemical versatility of polymeric complexes. 1503 10

The importance assigned to chelating agents in diverse areas has impelled studies concerning their development as related to metal ions representing a biological concern. The synthesis of di-isopropyliminodiacetoamide (D) is presented in this work. The acidity constant obtained for D was pKa = 5.79 +/- 0.04 with the aid of program SUPERQUAD. The equilibrium constants for D with Cu(II) were obtained with the aid of program SQUAD for CuD2+ and CuD2(2)+ species giving log beta1 = 4.795 +/- 0.002 and log beta2 = 8.374 +/- 0.004, respectively.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Apr
PMID:Speciation of the new ligand di-isopropyliminodiacetoamide with Cu(II) using computational processing and graphical methods. 1508 25

A new polydentate Schiff base (H3L) was synthesized from the condensation of 2,6-diformyl-4-methylphenol and S-methylhydrazine-carbodithionate. The 1:1 metal complexes were obtained from the interaction of H3L and the metal ions Cr(III), Co(II), Ni(II), Cu(II), Cd(II) and Hg(II). The complexes were characterized by elemental analysis and IR spectroscopy. Detailed studies of the thermal properties of the complexes were investigated by thermogravimetry techniques.
Spectrochim Acta A Mol Biomol Spectrosc 2004 Apr
PMID:Synthesis, characterization and thermal analysis of some new transition metal complexes of a polydentate Schiff base. 1508 38

Charge-transfer (CT)-photolysis of Cu(II) dithiocarbamate mixed-ligand complexes Cu(II)(Et2dtc)X (X = Cl-, Br-) and Cu(II)(Et2dtc)(+)...Y- (Y = ClO4-, NO3-) has been studied in toluene/ROH and compared with our previous data obtained in chloromethane/ROH solutions, where chloromethane = CCl4, CHCl3 or CH2Cl2 and ROH = MeOH, EtOH, i-PrOH or i-BuOH. An EPR evidence is obtained about the formation of a new copper(II) dithiocarbamate mixed-ligand complex during simultaneous photolyses of Cu(II)(Et2dtc)+ and Cu(II)(Et2dtc)2 species in toluene/ROH. The role of the solvent is discussed from the combined analysis of spectrophotometric and EPR data and quantum yield results.
Spectrochim Acta A Mol Biomol Spectrosc 2004 May
PMID:Charge-transfer photolysis of copper(II) dithiocarbamate mixed-ligand complexes in toluene/alcohol solutions. 1513 26

The composition of the co-ordination sphere of Cu(II) dithiocarbamate mixed-ligand complexes Cu(Et2)dtc)X (X = Cl-, Br-) and Cu(Et2)dtc)(+)...Y- (Y- = ClO4-, NO3-) is studied from the combined analysis of spectrophotometric and EPR data. The results obtained about CT-photolysis of the complexes in EtOH and i-PrOH are compared with our previous data of photolysis in chloromethane/ROH solutions. Reaction mechanism and the role of alcohol are discussed on the ground of electronic and EPR spectra and quantum yield results.
Spectrochim Acta A Mol Biomol Spectrosc 2004 May
PMID:Structure of copper(II) dithiocarbamate mixed-ligand complexes and their photoreactivities in alcohols. 1513 27


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