Cu2+ complex

Entry 3 involves a catalyst derived from (/ , Trans-cyclohexane- 1,2-diamine. The square planar Cu2+ complex exposes the re face of the dienophile. As with the BOX catalysts, this catalyst has c2 symmetry. 

NucleosilChiral-1 L-hydroxyproline Cu2+ complexes bonded on sihca gel [33] Macherey-Nagel... 

In addition to the 1 1 square planar Cu2+ complex azo dyes, 2 1 Cr3+, Co3+, and, to a lesser extent, Ni2+ complex azo dyes are important commercially. Such 2 1 octahedral complex azo dyes generally adopt the meridial (mer) stereochemical structure (18) rather than the facial (fac) structure (19).7... 

A new imidazole-functionalized calix[4]arene ligand, able to form a dinuclear Cu2+ complex, has been reported to hydrolyze HPNP and ethyl p-nitropheny lphosphate [70]. The dinuclear complex was found to be 22-and 330-fold more reactive than the corresponding monomer towards the above substrates, respectively. Dinuclear Cu2+ complexes of linked triazacyclononane ligands are reported to promote the hydrolysis of the monoribonucleotide GpppG, a model for the 5 -cap structure of mRNA [71]. The dinuclear complexes offer some 100-fold higher reactivity compared to the mononuclear Cu2+-triazacyclononane system. 

In most of the above-cited studies, it was assumed that the increase of toxicity was due to enhanced uptake of the metal, and that overall toxicity is only due to metal toxicity. However, stable complexes may exhibit specific toxicity by themselves. The Cu2+ complex of 2,9-dimethyl-l,10-phenanthroline has been shown to react with H2C>2 in the cell, thereby producing radicals [221], Cu(Ox)2 exhibits a specific toxic effect on photosynthesis [230]. Cu-ethylxanthogenate enhances respiration and ATP production [230]. 

The interpretation of the ESR of Cu2+ complexes in terms of molecular orbitals has been discussed at length in Sec. V and will not be discussed here. 

Other chiral immobilised stationary phases are available commercially, for example covalently bonded bovine serum albumin or chemically bonded l-hydroxyproline-Cu2 complexes to wide-bore Nucleosil (both from Macherey-Nagel). 

Albumine-Cu2+ complexes are similarly reduced by thiols and then react with H202 (Ozawa et al. 1993). The OH radical thus formed has been detected by spin trapping. 

The DNase activity of o-phenanthroline-Cu2+ complex bound to DNA in the presence of H202 is also triggered by thiols (Chap. 12). 

As a rule many of these dyes only have moderate lightfastness on paper. To improve this metal complexes are used, particularly with the blue azo dyes. Because planarity of the dye molecule is advantageous for a good dyeing, virtually only Cu2+ complexes such as C.I. DirectBlue 218,24401 28407-37-6] (18) are of interest for paper. 3.3 -Dimcthoxy-4,4 -biphcnyldiaminc (o-dianisidine) has proved particularly suitable, because after coupling with a 1-naphthol derivative demethylative copperization can take place. 

Wellmann and coworkers give some interesting features for aminoacid complexes in solution38. They conclude from the quasi-enantiomeric shape of the CD-spectra of the Cu2+-complexes with L-histidine and L-1-CH3-histidine that the equilibrium state of the system 7a 7b is strongly in favor of 7a in the case of bidentate amino-... 

Figure 23.11 UV-vis analysis of photocontrolled ion-binding, (a) Regeneration of spiropyran and meiocyanine—Co2+ complex in acetonitrile through the following steps (1) spiropyran, (2) merocyanine, (3) complex, (4) spiropyran, (5) complex, (b) Cycling of spiropyran to merocyanine and generation of merocyanine-Cu2+ complex on SP-modified surface, 560 nm (dashed line) and 431 nm (full line).

We have added to the table EPR parameters for Cu2+ complexes with the same ligands frozen at 77 K in vitreous solutions for easier comparing with analogous values of the adsorbed species. 

Fig. 2 SEM images of DNA-metal ion fiber of DNA-Cu2+ fiber and DNA-A13+ complex. The structure of the DNA-A13+ complex is more regular than that of DNA-Cu2+ complex...

The absorption and rotatory dispersion of the complexes of ovotransferrin and serum transferrin with Mn3+ and Cu2+ were compared to those of the ferric complexes (Fig. 5 and Fig. 9). The Mn3+ complexes absorbed maximally at 429 mp and gave rise to positive Cotton effects closely similar in both transferrins. The Cu2+ complexes absorbed maximally at 436 mp but this absorption, in contrast to those of the Fe3+ and Mn 3+ complexes, was not optically active. It was concluded that copper does... 

In the case of PVA, spectrophotometric and potentiometric titrations showed that two kinds of Cu2 + complexes may be present in aqueous solution a simple complex, Cu-PVA, and a hydroxo complex. The latter occurs at pH values 2 7. In the Cu-PVA complex the Cu2+ ion seems to coordinate four —NH2 groups. As a consequence, the shape of the macromolecule is deeply modified upon chelation, as confirmed by conductometric and viscosimetric measurements61. The initial viscosity of the PVA solution, in the presence of Cu2+ ions is reduced by a factor of about 10 at a pH corresponding to about 50% chelation. The same results are obtained in the presence of Ni2+ and Zi2+ ions 61 ... 

The stability constants of the Cu2+ complexes with poly(4-vinylpyridine), and with partially quatemized poly(4-vinylpyridine) have been determined by potentiometric... 

Ligand (L) Ability to form Cu2+ complexes in aqueous solution Reaction Stability Constants Electronic spectra 103 cm-1... 

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