Copper complexes spectroscopy

The treatment of LB films of copper behenate (10-50 layers) with H2S gas resulted in formation of the semiconductor CU2S [177]. In this case, the LB films of behenic acid alone were formed and then exposed to solutions of copper chloride. Conversion of the carboxyl groups to carboxylate groups upon copper complexation was confirmed by infrared spectroscopy. Resistivity measurements versus temperature confirmed the formation of semiconducting CU2S in one case, and showed a linear increase in log(R) versus IT K). All of the samples became insulators on exposure to air maintaining the conductivity required storage under vacuum. The formation of CuiS sheets in some of the sample was concluded from optical microscopy and resistivity data. 

Infrared spectra were recorded on a Perkin Elmer model 680 spectrophotometer as mulls in nujol or fluorolube. The magnetic susceptibility of the copper complexes was measured from 4.2 to 300 K by the Faraday method . X-ray photoelectron spectroscopy (XPS) was performed with a Perkin Elmer hemispherical spectrometer. 

Le Bihan and Courtot-Coupez [202] used the copper complex and flameless atomic absorption spectroscopy to determine anionic detergents. Crisp [200]... 

Recently, hf structure associated with the copper signal of cytochrome c oxidase has been reported by Frondsz et al.210 which used octave bandwidth S-band EPR spectroscopy (2-4 GHz). The observed structure has been attributed to copper hfs and to an additional magnetic interaction. Data obtained from powder simulation of the EPR spectra at 2.62 GHz and 3.78 GHz are collected in Table 12.2. In a subsequent paper Frondsz and Hyde211 have shown that in S-band EPR spectra of copper complexes in frozen solutions, improved spectral resolution can be achieved. This new technique, which allows a proper selection of the microwave frequency between 2 and 4 GHz, is therefore recommended for studying powder EPR spectra of these types of compounds. 

The P5000 Acorga extraction reagents contain as the major complexing agent 5-nonylsalicyl-aldoxime, the copper complexes of which were studied in 1983 by electronic and ESR spectroscopy.72... 

The d-d absorption of the copper complex differs in each step of the catalysis because of the change in the coordination structure of the copper complex and in the oxidation state of copper. The change in the visible spectrum when phenol was added to the solution of the copper catalyst was observed by means of rapid-scanning spectroscopy [68], The absorbance at the d-d transition changes from that change the rate constants for each elementary step have been determined [69], From the comparison of the rate constants, the electron transfer process has been determined to be the rate-determining step in the catalytic cycle. 

The additional insight from UV-vis spectra also proved useful in an investigation of the homogeneous oxidation of benzyl alcohol to benzal-dehyde in which copper complexes were employed as catalysts (Mesu et al., 2005 Tinnemans et al., 2006). It was shown that the synchrotron radiation used for XAFS spectroscopy affected the reacting solutions besides a thermal effect, reduction of copper was induced. This effect was investigated in detail for a number of ligands (Mesu et al., 2006). 

The intriguing structure of the GAOX active site has raised a challenge to the held of bioinorganic chemistry and inspired the synthesis of an array of molecular models. Models for the isolated Tyr-Cys side chain have yielded important information on the chemistry and spectroscopy of the dissected cofactor, as described earlier (Section VI) (Whittaker <2/., 1993 lioh etal., 1993, 1997 Gerfen <2/., 1996). More recently, attention has been directed at mimicking the complex structure, spectroscopy, and even the catalytic reactivity of the intact radical-copper complex in model chemistry. 

Although the focus of this section has primarily been on iron and copper complexes, probably the most important transition metals biologically studied by the MCD technique, variable temperature and field dependence studies have also been carried out for complexes of other transition metals such as cobalt and manganese and the techniques described for iron and copper can easily be applied to other metals based on the nature of the ground state. MCD spectroscopy has the key advantage, over other techniques used to study bulk magnetic properties of an entire sample, that spectral bands associated with specific mefal cenfers can be sfudied in isolation. 

Kaim W, Wanner M, Knodler A, Zalis S (2002) Copper complexes with non-innocent ligands probing CuVcate-cholato-CuVo-semiquinolato isomer equilibria with EPR spectroscopy. Inorg Chim Acta 337 163-172... 

Copper-containing molecular sieve materials are very important catalysts in many liquid-phase oxidation reactions. The analysis of metal content is usually obtained using atomic absorption spectroscopy (AAS) but this provides no information on the distribution of the metal within the material. In this paper, we report on the characterisation of a siliceous MCM 41 material postmodified with a Schiff base copper complex by x-ray photoelectron spectroscopy (XPS), AAS and other standard techniques. Quantitative estimations of the copper concentrations and chemical states and its distribution within the material have been made using XPS. The effect of modification by the Schiflf base copper complex on the surface characteristics of the MCM 41 was investigated by nitrogen sorption at 77 K. 

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