Octahedral cobalt(III) complexes of the chloropentammine type. XXI. The preparation, properties, and reactions of some Chloro(amine)bis(ethylenediamine)cobalt(III) salts containing unidentate glycinenitrile and glycinamide as influencing ligands

1970 ◽  
Vol 23 (6) ◽  
pp. 1175 ◽  
Author(s):  
SC Chan ◽  
FK Chan
Keyword(s):  
Aqueous Solution ◽  
Pure State ◽  
The Other ◽  
Base Hydrolysis ◽  
Other Hand ◽  
Kinetics Of

Salts of one isomeric series of chloro(amine)bis(ethylenediamine)cobalt(111) type of cations have been prepared from trans-dichlorobis(ethy1enediamine)-cobalt(111) chloride by replacing one of its chloro ligands with either glycinenitrile or glycinamide. These complexes have been assigned a cis-configuration on the basis of spectral observations. For the glycinenitrile system, the cis-chloro(cyano-methylamine)bis(ethylenediamine)cobalt(111) cation rearranges to the trans-chloro(aminoacetonitrile) isomer in aqueous solution at rates very much higher than those for the aquation of both forms. This isomerization is retarded by acid and accelerated by base. The kinetics of base hydrolysis are also reported. On the other hand, for the glycinamide system, the corresponding isomerization proceeds at rates comparable to those of chloride release, the latter leading to the formation of the chelated N,O-glycinamidebis(ethylenediamine)cobalt(111) species. Consequently, it has not been possible to isolate the other linkage isomer in the pure state. Furthermore, although the aquo(glycinamide)bis(ethylenediamine)cobalt(111) species is not formed in non-basic spontaneous chloride release, its hydroxo counterpart can be readily obtained by base hydrolysis. The mechanistic implications of these observations are discussed.

Synthesis of ZrO2 Nanotubes by Anodization of Zr Foil

2015 ◽  
Vol 799-800 ◽  
pp. 125-129
Author(s):  
Mary Donnabelle L. Balela ◽  
April Alexa S. Lagarde ◽  
Stephen Jann A. Tamayo ◽  
Nikko S. Villareal ◽  
Ann Marielle Parreno
Keyword(s):  
Aqueous Solution ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Surface Preparation ◽  
The Other ◽  
Preparation Methods ◽  
X Ray ◽  
Anodization Time ◽  
Other Hand ◽  
Scanning Electron

Zirconia (ZrO2) nanotubes were synthesized by anodization of zirconium (Zr) foil in NH4Fand (NH4)2SO4 aqueous solution. Different surface preparation methods (electropolishing and etching) were applied on the Zr foil prior to anodizaton. In addition, the anodization time and NH4F concentration were varied. The structure and morphologies of the nanotubes and their crystallinity were confirmed using scanning electron microscope and x-ray diffractometer, respectively. ZrO2 nanotubes with large diameters and thick walls were formed at lower NH4F concentration and longer anodization time. On the other hand, smaller nanotubes with thinner walls were produced when the NH4F concentration was increased. The synthesized nanotubes were predominantly tetragonal ZrO2 with small amounts of monoclinic ZrO2.

Reactivity of base catalysed hydrolysis of 2-pyridinylmethylene-8-quinolinyl-Schiff base iron(II) iodide complexes: solvent effects

2013 ◽  
Vol 67 (4) ◽  
Author(s):  
Ahmad Mohamad ◽  
Mohamed Adam
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Solvent Effects ◽  
Base Hydrolysis ◽  
Iodide Ions ◽  
Ligand Structure ◽  
Solvation Parameters ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Direct Condensation

AbstractThree ligands of 2-pyridinylmethylene-8-quinolinyl (L1), methyl-2-pyridinylmethylene-8-quinolinyl (L2), and phenyl-2-pyridinylmethylene-8-quinolinyl (L3), Schiff bases were synthesised by direct condensation of 8-aminoquinoline with 2-pyridinecarboxaldehyde, 2-acetylpyridine, or 2-benzoylpyridine. They coordinated to Fe(II) ion in a 1: 2 mole ratio followed by treatment with iodide ions affording complexes with a general formula [Fe(L)2]I2·2H2O, (L = L1, L2, or L3). Spectrophotometric evaluation of the kinetics of base catalysed hydrolysis of these complex cations was carried out with an aqueous solution of NaOH in different ratios of water/methanol binary mixtures. Kinetics of the hydrolysis followed the rate law (k 2[OH−] + k 3[OH−]2)[complex]. Reactivity trends and their rate constants were compared and discussed in terms of ligand structure and solvation parameters. The methanol ratio affects the hydrolysis as a co-solvent which was analysed into initial and transition state components. The increase in the rate constant of the base hydrolysis of Fe(II) complexes, as the ratio of methanol increases, is predominantly caused by the strong effect of the organic co-solvent on the transition states.

scholarly journals Kinetic and e.p.r. studies of cyanide and azide binding to the copper sites of dopamine (3,4-dihydroxyphenethylamine) β-mono-oxygenase

1984 ◽  
Vol 220 (2) ◽  
pp. 447-454 ◽  
Author(s):  
N J Blackburn ◽  
D Collison ◽  
J Sutton ◽  
F E Mabbs
Keyword(s):  
Competitive Inhibition ◽  
Charge Transfer Band ◽  
The Other ◽  
Native Enzyme ◽  
Interacting Species ◽  
Other Hand ◽  
Show Evidence ◽  
Simultaneous Decrease ◽  
Copper Sites ◽  
Kinetics Of

The kinetics of inhibition of dopamine (3,4-dihydroxyphenethylamine) beta-mono-oxygenase by cyanide (CN-) and azide (N3-) ions have been investigated by using steady-state methods. Both anions show complex non-competitive-inhibition patterns with respect to ascorbate, suggestive of anion binding at two different sites on the oxidized enzyme. To further investigate this finding, e.p.r. titrations of CN- and N3- binding to the 63Cu-reconstituted enzyme were carried out. Addition of approx. 2 equiv. of CN- to copper elicits a new signal with g = 2.217, g = 2.025, A = 17.0 mT characteristic of a copper (II)-cyano complex. Simulations show that this signal accounts for half the copper (II) in the enzyme. The remainder of the enzyme-bound copper is expressed by a signal close to, but not identical with, that of native enzyme. Further addition of CN- induces a simultaneous decrease in intensity of both of these signals so that their 1:1 ratio is maintained. Binding of N3-, on the other hand, changes the e.p.r. spectrum to a form different from either that of the native or CN‒ -treated enzyme, and integrates to 100% of the copper in the enzyme (g = 2.252, g = 2.050, A = 16.5 mT). Resolved superhyperfine structure is apparent in the g region. N3- binding is also accompanied by the appearance of a broad charge-transfer band centred at 387 nm. Neither 9 nor 35 GHz e.p.r. spectra show evidence for more than one (non-interacting) species of Cu(II) in native enzyme and N3- derivatives. The binding and reactivity of CN-, on the other hand, argues against independent copper sites in the enzyme.

X-IRRADIATION OF RIBOSE AND DEOXYRIBOSE DERIVATIVES

1962 ◽  
Vol 40 (1) ◽  
pp. 1553-1565
Author(s):  
D. K. Myers
Keyword(s):  
Aqueous Solution ◽  
Nucleic Acids ◽  
The Other ◽  
Free Sugar ◽  
Blood Samples ◽  
Other Hand ◽  
Dilute Aqueous Solution ◽  
X Irradiation ◽  
In Cells

During X-irradiation of ribosides and deoxyribosides in dilute aqueous solution, purine and sugar moieties were destroyed at approximately the same rate. Pyrimidine moieties, on the other hand, were destroyed more rapidly, resulting in a fairly rapid liberation of free sugar during irradiation of pyrimidine ribosides or deoxyribosides. No marked differences in the rates of destruction of ribose and deoxyribose derivatives were observed in these experiments.Similar reactions were observed during irradiation of blood samples. However, acid-soluble ribonucleotides in the blood proved to be much more sensitive than the nucleic acids or proteins to destruction by X-radiation. The significance of these findings is discussed with relation to the damage produced in cells by X-irradiation.

Sign in / Sign up

Export Citation Format

Share Document