Co-2-Ions In A Low-Pressure Glow-Discharge Of Carbon-Dioxide

$CO_2^{-}$ ions have been detected in the gas phase and measured by a mass spectrometer with a flight time of 30 µs in the positive column of carbondioxide glow discharge.

Interaction of Metal Ions with 2'-Deoxyribonucleotides. Crystal and Molecular Structure of a Cobalt(l1) Complex with 2'-Deoxyinosine 5'-Monophosphate

The crystal structure of the cobalt( 11) complex with 2'-deoxyinosine 5'-monophosphate (5'- dlMP), [Co(5'-dlMP) (H,0),]-2H20, has been analysed by X-ray diffraction. The complex crystallizes in the space group P2,2,2, with a = 6.877(3), b = 10.904(2), c = 25.421 (6) A, and Z = 4. The structure was solved by the heavy-atom method and refined to an R value of 0.043 using 1 776 unique reflections. The cobalt ion binds only to the 6-oxopurine base of the nucleotide at the N(7) position, the octahedral co-ordination of the metal being completed by five water oxygens. The phosphate oxygens are involved in hydrogen bonding with the co-ordinated water molecules. The structure is closely similar to that of the corresponding ribonucleotide complex. The nucleotide has the energetically preferred conformation: an anti base, a C(3') -endo sugar pucker, and a gauche-gauche conformation about the C(4')-C( 5') bond. The significance of sugar puckering in the monomeric complexes of general formula [ M (5'-nucleotide) (H20),] is explained in terms of the structural requirements for metal-water-phosphate bridging interactions.

Interaction of metal ions with 6-oxopurine nucleotides. Part 2. X-Ray structures of ternary nickel(II) complexes with 2'-deoxyguanosine 5'-monophosphate or guanosine 5'-monophosphate

The ternary metal nucleotide complexes [Ni(en)1.3(H2O)1.4(H2O)2][Ni(5?-dGMP)2(en)0.7-(H2O)0.6(H2O)2]·7H2O (1) and [Ni(en)2(H2O)2][Ni(5?-GMP)2(H2O)4]·6H2O (2)(en = ethylenediamine, 5?-dGMP = 2?-deoxyguanosine 5?-monophosphate, 5?-GMP = guanosine 5?-monophosphate) have been prepared and their structures analyzed by X-ray diffraction methods. Both compounds crystallise in the space group C2221 with a= 8.810(1), b= 25.090(4), c= 21.084(1)Å, and Z= 4 for (1) and a= 8.730(1), b= 25.691(4), c= 21.313(5)Å, and Z= 4 for (2). The structures were deduced from the analogous CoIII complexes and refined by full-matrix least-squares methods to final R values of 0.087 and 0.131 for 1 211 and 954 reflections for (1) and (2) respectively. An interesting feature of the deoxyribonucleotide complex (1) is that en is not totally labilized from the metal centre on nucleotide co-ordination, as observed in corresponding ribonucleotide complexes. Apart from extensive intra- and inter-molecular hydrogen bonding, the structures are stabilized by significant intracomplex base�base and base�sugar interactions. The nucleotides in both complexes have an anti base, C(2?)-endo sugar pucker, and gauche�gauche conformation about the C(4?)�C(5?) bond.

A layered chlorophosphate, Na-3[Cd4Cl3(HPO4)(2)(H2PO4)(4)], containing Na+ ions in the interlamellar space

Reaction between CdCl2.H2O and NaH2PO4.H2O Under hydrothermal conditions gives rise to a new cadmium chlorophosphate of the formula Na-3[Cd4Cl3(HPO4)(2)(H2PO4)(4)] I. This material crystallizes in the orthorhombic system with space group Fmm2(no. 42). I has macroanionic layers of [Cd4Cl3(HPO4)(2)(H2PO4)(4)](3-) with Na+ ions in the interlamellar space. The discovery of such compounds suggests that metathetic reactions carried out under hydrothermal conditions may provide a novel route for the synthesis of new open-framework structures.

Effect of inorganic ions, H(2)O(2) and pH on the photocatalytic inactivation of Escherichia coli with silver impregnated combustion synthesized TiO(2) catalyst

The photocatalytic antibacterial activity of Ag impregnated combustion synthesized TiO(2) (0.25 g/L) was studied against Escherichia coil in presence of UV irradiation. The effect of various parameters, such as anions, canons, hydrogen peroxide and pH, on the photocatalytic inactivation was investigated. The addition of inorganic ions showed a negative effect on inactivation. Among anions, the presence of chloride ions was observed to have a maximum negative effect and reduced the inactivation considerably. Among cations, the bacterial inactivation reduced significantly in the presence of Ca(2+) ions. Hydrogen peroxide addition in combination with Ag/TiO(2) photocatalysis, however, improved the inactivation. Photocatalysis with high concentration of H(2)O(2) yielded complete bacterial inactivation within few minutes. The photocatalytic inactivation of E. coil was not affected by variation in pH. (C) 2011 Elsevier B.V. All rights reserved.

Ligational behaviour of (E)-2-amino-N ` -1-(2-hydroxyphenyl) ethylidene]benzohydrazide towards later 3d metal ions: X-ray crystal structure of nickel(IV) complex

Ligational behaviour of (E)-2-amino-N'-1-(2-hydroxyphenyl)ethylidene]benzohydrazide (Aheb) towards later 3d metal ionscopper(II), cobalt(II), manganese(II), zinc(II), cadmium(II) and nickel(IV)] has been studied. Their structures have been elucidated on the basis of spectral (IR, H-1 NMR, UV-Vis, EPR and FAB-mass), elemental analyses, conductance measurements, magnetic moments, and thermal studies. During complexation Ni(II) ion has got oxidized to Ni(IV). The changes in the bond parameters of the ligand on complexation has been discussed by comparing the crystal structure of the ligand with that of its Ni(IV) complex. The X-ray single crystal analysis of Ni(aheb)(2)]Cl-2 center dot 4H(2)O has confirmed an octahedral geometry around the metal ion. EPR spectra of the Cu(II) complex in polycrystalline state at room (300 K) and liquid nitrogen temperature (77 K) were recorded and their salient features are reported. (C) 2014 Elsevier B.V. All rights reserved.

Spectroscopic investigations of manganese ions in microwave-prepared NaPO3-PbO glasses

The EPR spectra of microwave-prepared 70NaPO(3):30PbO glasses containing different weight percentages of manganese ions have been studied. The EPR spectra exhibit a well-resolved hyperfine pattern at g(eff) approximate to 2.0. Optical absorption, fluorescent emission and excitation spectra of the glasses have been examined. The absorption spectrum exhibits a peak near 500 nm and this has been attributed to the spin-allowed E-5(g) --> T-5(2g) transition of Mn3+ ions. The emission spectrum shows a band at 595 nm which has been assigned to the T-4(1g)(G) --> (6)A(1g)(S) spin-forbidden transition of Mn2+ ions in octahedral coordination. Concentration quenching of fluorescence was found to occur above 0.75 wt% of Mn2+ ions. The excitation spectra exhibit four bands characteristic of Mn2+ ions in octahedral coordination. From the observed band positions of the excitation spectra, the crystal field parameter D-q and the Racah interelectronic repulsion parameters, B and C have been calculated. A structural model is proposed based on the IR, Raman and MASNMR studies according to which Mn2+ ions are likely to occupy sites similar to Na+ ions in these glasses.

Synthesis, structure and spectroscopic studies on hydroxo-bridged heterotrinuclear complexes of cobalt(m) with ethane-l,2-diamine and ammonia as terminal ligands

Hydroxo-bridged homo- and hetero-trinuclear cobalt(III) complexes of the type [MII(H2O)2{(OH)2CoIII(N4)}2]X2·nH2O [MII= a divalent metal ion such as CoII, NiII or ZnII; N4=(en)2(en = ethane-1,2-diamine) or (NH3)4; X = SO4 or (ClO4)2; n= 3 or 5] have been prepared and spectroscopically characterized. The structure of [Cu{(OH)2Co(en)2}2][SO4]2·2H2O 1 has been determined. The geometry around copper atom is a pseudo-square-based pyramid, with the basal sites occupied by four bridging hydroxide oxygens and the apical site is occupied by a weakly co-ordinated sulfate anion [Cu–O 2.516(4)Å]. The hydroxo groups bridge pairs of cobalt(III) ions which are in near-octahedral environments. The ethylenediamine chelate rings have the twist conformation. In the crystal structure of [Cu{(OH)2Co(en)2}2][ClO4]4·2H2O 2 the perchlorate ion is not co-ordinated and the en ligands have envelope conformations. The sulfate ion in [Cu{(OH)2Co(NH3)4}2][SO4]2·4H2O 3 is not co-ordinated to the central copper ion. Electronic, infrared and variable-temperature EPR spectral data are discussed.

Structure of nonactin-calcium perchlorate, C40H64O12.Ca(ClO4)2, and a comparative study of metal-nonactin complexes

M r= 975.9, orthorhombic, Pnna, a = 20.262 (3), b= 15.717 (2), c= 15.038 (1)A, V= 4788.97 A 3, z = 4, D x = 1.35 Mg m -3, Cu Kct radiation, 2 = 1.5418 A, /t = 2.79 mm -1, F(000) -= 2072, T = 293 K, R = 0.08, 3335 observed reflections. The molecular structure and the crystal packing are similar to those observed in the nonactin complexes of sodium thiocyanate and potassium thiocyanate. The eight metal-O distances are nearly the same in the potassium complex whereas the four distances involving carbonyl O atoms are shorter than the remaining four involving the tetrahydrofuran-ring O atoms in the Na and the Ca complexes. This observation can be explained in terms of the small ionic radii of Na + and Ca 2+, and leads to a plausible structural rationale for the stronger affinity of nonactin for K + than for the other two metal ions.

EPR observation of phase transitions in calcium cadmium acetate hexahydrate: Using Mn2+ and Cu2+ ions as probe

Results of temperature dependence of EPR spectra of Mn2+ and Cu2+ ions doped calcium cadmium acetate hexahydrate (CaCd(CH3COO)4•6H2O) have been reported. The investigation has been carried out in the temperature range between room temperature ( 300 K) and liquid nitrogen temperature. A I-order phase transition at 146 ± 0.5 K has been confirmed. In addition a new II-order phase transition at 128 ± 1 K has been detected for the first time. There is evidence of large amplitude hindered rotations of CH3 groups which become frozen at 128 K. The incorporation of Cu2+ and Mn2+ probes at Ca2+ and Cd2+ sites respectively provide evidence that the phase transitions are caused by the molecular rearrangements of the common coordinating acetate groups between Ca2+ and Cd2+ sites. In contradiction to the previous reports of a change of symmetry from tetragonal to orthorhombic below 140 K, the symmetry of the host is concluded to remain tetragonal in all the three observed phases between room temperature and liquid nitrogen temperature.

A 1h And 13c Magnetic Resonance And Infrared Spectroscopic Study Of Coordinated 2-Aminocyclopentene-1-Dithiocarboxylic Acid And Its S-Methyl Ester

The ligating properties of 2-aminocyclopentene-1-dithiocarboxylic acid and its S-methyl esters were investigated. Complexes with Zn(II), Cd(II) and Hg(II) halides were synthesized and characterized by infrared and proton and carbon-13 NMR studies. The results are concordant with a bidentate coordination of the -CS2 group to the metal ions

Lanthanide perchlorate complexes of 4-nitroquinoline-1-oxide and 5-nitroisoquinoline-2-oxide

Novel complexes of lanthanide perchlorates with 4-nitroquinoline-1-oxide (NQNO) and 5-nitroisoquinoline-2-oxide (NIQNO) have been prepared and characterized. The complexes have the general formulaeLn(NQNO)8(ClO4)3 (whereLn=La-Nd), Ln(NQNO)7(ClO4)3 (whereLn=Gd-Yb),Ln(NIQNO)9(ClO4)3 (whereLn=La-Nd), andLn(NIQNO)7(ClO4)3 (whereLn=Gd-Yb). The IR, proton NMR spectral data indicate the coordination of the N—O group of the ligands to he lanthanide ions.

Molecular complexes of metallo tetraphenyl porphyrins with 2,4,5,7-tetranitro fluorenone

The interactions of mesotetraphenyl porphyrin and its metallo derivatives with 2,4,5,7-tetra nitrofluorenone have been studied using spectroscopic methods. The association constants (K) for 1:1 complexes in Ch2Cl2Cl2 follow the order Pd+2>Co+2> Cu+2>VO+2>Ni+2>Zn+2. The values of K are accounted in terms of stereochemistry of MTPPs and the electronic configuration of the metal ions. The magnitude and direction of the proton NMR shifts of the acceptor and donor in the complexes and their ESR parameter furnish information as to the possible structures of these complexes in solution.

Ammonium ions prevent methylation of uridine to ribothymidine in Azotobacter vinelandii tRNA

It was shown that tRNA from Azotobacter vinelandii grown in the presence of ammonium chloride lacks ribothymidine while that grown in the absence of the ammonium salt contains this modified nucleoside. [32P]-Labelled tRNA from this organism grown in a medium containing the ammonium salt was digested with RNase T1 and the pseudouridinecontaining tetranucleotide, common to all tRNAs was isolated and analysed for the nucleoside replacing the ribothymidine. It was found to be uridine. Cells previously labelled with [32P]- phosphate in the ammonium salt medium were washed and incubated in the ammonium saltfree medium to test whether ribothymidine would be formed upon removal of the ammoniumions. Methylation of the uridine did not take place.

Complexes of lanthanide nitrates with 2-N-(6-picoIyl)-benzamide

New complexes of lanthanide nitrates with 2-N-(6-picolyl)-benzamide of the formulae Ln2[6-pic-BA], [NO3l6 (Ln = Y and La-Yb) have been prepared and characterised by chemical analysis, infrared, molar conductance and electronic spectral data. Molar conductance data along with IR data point to the presence of co-ordinated nitrate groups. IR spectra prove the bidentate co-ordination of the ligand to the metal ion, through the oxygen of the secondary amide and the nitrogen of the heterocyclic ring. Electronic spectral studies in the visible region suggest an eight co-ordinate geometry around the metal ions.