Search

Abstract -- A simple, sensitive, and accurate spectrophotometric method has been developed for the assay of furosemide (FUR), which is based on the complexation of the drug with copper(II) at [...]

An attempt is made to evaluate the geometric and electronic structures of two mononuclear LCu[O.sub.2] systems using Cu K- and L-edge X-ray absorption spectroscopy (XAS) coupled with calculations. The XAS data, particularly the L-edge intensities, clearly demonstrates the Cu(II)-[O.sub.2-] and Cu(III)-[[O.sub.2].sup.2-] natures of [Cu[(O.sub.2)][HB[(3-Ad.5.Prpz).sub.3]]] and [Cu[(O.sub.2)]([beta]-diketiminate)] respectively.

Abstract -- The use of ram horn powder (RHP) as a new sorbent for the preconcentration of copper(II) was proposed. The procedure is based on the adsorption of copper(II) ions [...]

Reinvestigation of the vibrational and electronic spectra of the Cu atoms with NO during condensation in solid argon, and binary argon/neon mixtures is carried out. The molecule is bent in all electronic states with Cu-N-O bond angles varying slightly around 130(plusmn)10 degree, but the Cu-N bond force constants are substantially different, denoting larger differences in bond lengths.

The copper-monomethylamine and -dimethylamine complexes are produced in a supersonic jet and examined using single-photon zero kinetic energy (ZEKE) photoelectron spectroscopy and theoretical calculations. The adiabatic ionization potentials of the complexes and vibrational frequencies of the corresponding ions are measured from their ZEKE spectra.

The structure and stability of [Cu(aq)](super 2+) are investigated by the copper K-edge X-ray absorption (XAS) spectrum and by density functional theory (DFT) calculations. After this, the foundational assumption of rack-induced bonding in blue copper proteins is evaluated in light of the geometric and bonding preferences of the unconstrained aqua Cu(super II) ion.

Resonance Raman (rR) spectroscopic and density functional theory (DFT) computational studies on a trans-mu- 1,2-peroxo-bridged [Ni(super 2+)(sub 2)] complex, [{(tmc)Ni(super 2+)}(sub 2)(O(sub 2)](super 2+) where tmc = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane, are presented and discussed. These studies provide a quantitative comparison between Ni-peroxo and Cu-peroxo bonding.

A combined photoelectron spectroscopy (PES) and ab initio study is carried out on two copper carbide clusters in the gas phase, CuC2(super --) and Cu3Cu4(super --). For Cu3C4(super --1), two low-lying isomers are identified such as a sandwich structure containing a Cu3(super 3+) triangular group and two C2(super 2--) units and a linear structure in which two C2 units were separated by the Cu atoms.

The preparation, characterization, and photophysical properties of a series of Pt(super II)-M(super I) (M = Cu, Ag, Au) heterometallic complexes isolated by reactions of Pt(diimine)(edt) (edt = 1,2-ethanedithiolate) with M2(dppm)2(MeCN)(sub 2)(super 2+) (M = Cu, Ag, Au) are described. The study demonstrates that incorporating Pt(diimine)-(dithiolate) with [M2(dppm)2]2+ affords a feasible synthetic approach to attain heterometallic and multicomponent materials.

It is shown that spherical reverse micelles induce the spheres and also various other particle shapes like cubes, tetrahedral and ellipsoidal particles. A comparison of the HRTEM and transmission electron micrographs (TEM) results with the DNA simulations made for various shapes indicates that the additional resonance band is the proof of the presence of mainly decahedral nanocrystals with ellipsoidal particles and trigonal prisms.

The electronic structure of the wide band gap hole conductors CuI and CuSCN in contact with an organic dye cis-bis(4,4'-dicarboxy-2,2'-bipyridine)bis(isothiocyanato)ruthenium-(II)), (Ru(dcbpyH2)(sub 2)(NCS)2) are analyzed with photoelectron spectroscopy. The experiments revealed the specific interaction between the NCS groups of the dye molecules and the CuI and CuSCN surfaces.

Desorption of (R)- and (S)-propylene oxide and desorption of (R)-3-methylcyclohexanone from chiral (643) surface show enantiospecific desorption kinetics. The enantiospecific differences in desorption energies gives rise to enantiospecificity.

The Cu(II)-poly(propylene imine) dendrimer complexes with a diaminobutane core (DAB-Am(sub n)-Cu(II)(sub x), n = 4 to 64, x = n/2) are investigated by using an extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) spectroscopies. The transmission electron microscopy (TEM) and EXAFS studies shows that the size of the Cu(0) nanoclusters decreases with increased generation of the dedrimer.

Cuprous oxide photosplits in water under well defined, ultra high vacuum (uhv) conditions are investigated. The experimental uncertainties establish an upper limit of 2 x 10(sup-21) cm(sup-2) for the cross section of the photo processed sought.

The Cu(super 2+) binding characteristics of a dinucleating peptide, Ac-WGHGHGH-GPGHGHGH-NH2 (HGP) is designed and investigated. The peptide is unstructured in solution and binds copper in a 2:1 Cu(super 2+)/HGP ratio with a concomitant conformational change.

The article presents the formation of a new stable copper coordination scaffold, which is shown to consist of a four-standard [alpha]-helical coiled-coil structure. The protein bound copper site is shown to exhibit a blue color, UV-vis spectra.

The variable angle spectroscopic ellipsometry technique is employed to determine the dielectric functions and optical constants of the different [Cu.sub.2]ZnGe[S.sub.4] bulk crystals grown by the Bridgman method. An increase in the Ge-S hybridization in the system is shown to lead to a significant reduction in the first gap.

The Z-V (distance-voltage) spectroscopy is used in scanning tunneling microscopy in order to detect the linewidths of empty quantum-well (QW) states acquired from a Pb island grown on the Cu(111) substrate. The Fermi-liquid theory with the Fabry-Perot mode is applied to study the linewidths of the QW states and the electron-phonon coupling constant, the electron-electron coupling factor and the product of the electron reflectivities at the surface and interface of the Pb island are obtained.

The NMR spectroscopy technique is employed to explain the electronic characteristics of the different copper-based intermetallics with ZrCuSiAs-type structure. The lack of superconductivity observed in these structures is shown to be attributed to the low value of the density of states.

Several studies are conducted to explain the temperature-dependent photocurrent-spectra exhibited by the photoconductive CuGa[Se.sub.2] layers. The photocurrent signal in these layers is shown to highly get limited because of the trapping center, however this restriction is shown to decrease with temperature.

The low-temperatures structures of phosphoramidite complexes, the temperature-dependent equilibrium of different complex species and the ligand-dependent trend of these complexes to form homo- or heterochiral complexes are examined. The studies have shown that different preferences to build homo- or heterochiral complexes are detected for binaphthol and biphenol phosphoramidite complexes.

The kinetics of CuNB-OH formation is investigated in methanol by using rapid mixing techniques together with transient absorption spectroscopy. Equilibrium MALDI-TOF studies have shown that [Cu.sup.2+] rapidly binds to the PgCn followed by capsule formation.

Rapid injection NMR spectroscopy (RI-NMR) is used for preparing and characterizing the first examples of both [[eta].sup.1] [sigma]-allyl [Cu.sup.III] complexes and studying their reactions. Cis-cyano [sigma]-allyl [Cu.sup.III] intermediates are found in both the 1,4-addition reactions of [Me.sub.2]CuLi.LiCN (B)/TMSCl with 2-cyclohexenone and the [S.sub.N]2' reaction of B with dimethylvinylcarbinol acetate and hence these two types of conjugate addition are unified by a deep connection.

A new and facile process is described for cinnolines, dihydrocinnolines, and 1-aminoindolines by using diazo functionalities. The analysis of ultraviolet spectra has proved that 4-oxo-3-carboxylates have existed not as 4-hydroxycinnoline but as cinnolone.

A combination of X-ray absorption (XAS) and pulsed electron paramagnetic resonance (EPR) spectroscopies were employed to examine the nature of distinct well-ordered type II site formed by riboflavin binding protein (RBP) which binds copper in a 1:1 molar ratio. The XAS and EPR spectroscopy showed evidence for role of a single histidine ligand in binding of RBP with copper in an [O.sub.3]N type II site.

A combined experimental and computational method was developed to model and predict the reactivity of multistep processes of heterogeneous electron transfer. The approach could be applied to study the multielectron reduction of [[Cu.sub.2]L][Cl.sub.2] where L is the product of the [2+2] condensation of 2,6-diformyl-4-t-butylphenol and 1,3-diaminopropane.

The electronic and structural properties of copper phthalocyanine deposited onto multiwalled carbon nanotubes are analyzed as a function of the deposition thickness. The photoemission spectra have shown that the interaction between the organic molecules and the nanotubes is quite weak, thus determining very small effects on the spectra.

The evolution of the atomic-scale strain tensor of ductile [Zr.sub.64.13][Cu.sub.15.75][Ni.sub.10.12][Al.sub.10] bulk metallic glass under tensile loading is studied by using x-ray synchrotron radiation. The type and concentration of the constituent elements in the [Zr.sub.64.13][Cu.sub.15.75][Ni.sub.10.12][Al.sub.10] alloy have shown that Zr-Zr, Zr-Cu and Zr-Ni are the dominant atomic pairs, which have constituted the first coordination shell of the pair distribution functions (PDFs).

X-ray adsorption near edge structure (XANES) analysis is used for a metal-to-ligand charge-transfer (MLCT) excited-state structure of a copper(I) diimine complex ([[Cu[(dmp).sub.2]].sup.+] (dmp = 2,9-dimethyl-1,10-phenanthroline)) in acetonitrile. The XANES calculations have allowed angular dependent structural parameters to be extracted, which is vital for imaging reaction coordinate of many photochemical reactions.

The synthesis, characterization and pulsed electron-electron double resonance (PELDOR) study of a copper(II) porphyrin/nitroxide model system is described. The effect of orientation selection and exchange coupling is examined.

The steric demands of a TMPA (tris(2-pyridylmethyl)amine) derived ligand possessing 6-pyridyl substituents on one of the three donor groups of the tripodal tetradentate ligand is discussed The TMPA regulates the preference for the formation of particular [Cu.sub.2][O.sub.2] isomer from (ligand-[Cu.sup.1]/[O.sub.2] reactivity.

The mixing of the spin-frustrated 2(S=1/2) and S=3/2 states by the Dzialoshinsky-Moriya (DM) exchange is employed to understand the [Cu.sub.3](II) clusters with strong DM exchange coupling. The in-plane DM exchange mixing of the excited 2(S=1/2) and the ground S=3/2 states in the ferromagnetic [Cu.sub.3] clusters results in the large negative DM exchange contribution 2[D.sub.DM'] < 0 to the axial zero-field splitting (ZFS) 2D of the ground S=3/2 state.

The results of the multiconfigurational g tensor calculations of three copper(II) complexes, [[Cu[Cl.sub.4].sup.2-], [[Cu[([NH.sub.3]).sub.4].sup.2+] and plastocyanin are discussed. The analysis also demonstrates the existence of covalency of the copper-ligand bonds present in these complexes.

Focused ion beam (FIB) microscopy and positron annihilation lifetime spectroscopy (PALS) were utilized to obtain the time dependent transformation fraction and analyze the vacancy-type defects in electroplated copper (Cu). PALS were found to be more effective than FIB to show the room-temperature microstructural evolution of electroplated Cu at the first state of self-annealing.

Pyridine-2-carbaldehyde thiosemicarbazones with Ru[(P[Ph.sub.3]).sub.3][Cl.sub.2] have formed mononuclear [Ru.sup.II] precursors for preparing trinuclear complexes. X-band electron spin resonance and ultraviolet-visible spectra have shown the presence of [Cu.sup.II] and the cyclic voltammetry studies have supported the [Ru.sup.II]/[Ru.sup.III] redox behavior of this metal in trinuclear complexes.

The syntheses and structural characterization of tetraisopropoxyaluminates and tetra-tert-butoxyaluminates of nickel(II), copper(I) and copper(II) are described. Copper(II) hydroxyaluminate is isolated, which has exhibited pentacoordinate copper by dimerization.

The desorption of [F.sup.-] ions from FCuPc films is used for monitoring damaging processes and accessing their nature under low-energy electron irradiation. The strong influence of energy redistribution is emphasized, which has quenched the long-lived negative ion resonances and has selected localized and strongly repulsive excitations.

High-resolution UV photoemission and near-edge X-ray absorption spectroscopy are used for examining the electronic properties of a single layer (SL) of pentacene molecules by either standing up on an aromatic self-assembled monolayer or planar on a bare Cu(111) substrate. The highest-occupied molecular orbital lineshape in the weakly interacting SL has shown a double structure, which is attributed to two nonequivalent molecules in the ordered configuration.

Several spectroscopic and kinetic studies of the perturbed trinuclear copper clusters (TNC) are conducted to analyze the function of protons in the reductive cleavage of the O-O bond in multicopper oxidase Fet3p.

Numerous solid-state [super 63]Cu and [super 65]Cu NMR spectroscopic studies of inorganic and organometallic copper(I) complexes with different Cu coordination complexes are conducted. These complexes are found to exhibit very large quadrupolar interactions.

The copper(I)-catalyzed reaction for the synthesis of 1,3-benzoselenazoles and 1,3-benzotellurazoles with heteroatom functionality at the second position is described.

The one-dimensional proton and the HMBC spectrum have provided evidence for a square planar coordination of the Cu(III) intermediate in solution. The presence of 4,4-dimethylcyclohexenone has increased the detectable amount of the trimethylcyano Cu(III) species, whereas in pure substitution reactions the proposed tetraalkyl Cu(III) species is more stable in diethyl ether.

The study describes the design and synthesis of a copper(II) ion-selective on-off type fluoroionophore based on the zinc porphyrin-dipyridylamino complex. The sensor has excellent photophysical properties and can be easily used in the development of fluorescent sensors for metal ions.

Time-resolved step-scan FTIR and density functional theory are used for probing the structural dynamics of [Cu.sub.B] in heme-copper oxidases at room temperature. The small variations in the v(CO) of [Cu.sub.B] are attributed to protein conformational changes in the vicinity of [Cu.sub.B].