Electrochemical studies on vitamin B-12 and its derivatives

The electrochemical studies on vitamin B-12 and its derivatives were reviewed in this paper. The importance of electrochemical studies for explaining the mechanism of B-12 coenzyme in body was discussed. The latest results of electrochemical studies on vitamin B-12 and its derivatives was reviewed. A prospect for the electrochemical studies in vitamin B-12 and its derivatives was suggested.

Lutetium: A special lanthanide prefers dimer in fullerene cages

Endohedral dilutetium fullerenes, Lu-2@C-2n(2n = 76 similar to 112), have been extracted from the soot prepared by are-burning method for the first time and different from other lanthanide encapsulated fullerenes, there is no signal corresponding to Lu@C-82 even in mass spectrum of the high-temperature, high-pressure extract.

Study on ferrocene derivatives diffusion dynamics in polymer electrolyte by solid-state voltammetry

The diffusion rates of seven ferrocene derivatives have been estimated in polyelectrolyte PEG . LiClO4 by using non-steady-state chronoamperometry. The D-app of ferrocene derivatives increases with temperature, and the dependency of D-app on temperature obeys the Arrhenius equation. The D-app of ferrocene derivatives decreases with increasing size of electroactive species. The Delta D-app values of D-T>Tm and D-T T-m in the polyelectrolyte. On the other hand, the diffusion behaviour of ferrocene derivatives is qualitatively analyzed by using cyclic voltammetry. Copyright (C) 1996 Elsevier Science Ltd

Ansa-metallocene derivatives .2. Syntheses and structures of tetramethyldisiloxandiyl bis(1-indenyl and tetrahydroindenyl) zirconium dichlorides

The ansa-zirconocene derivative tetramethyldisiloxandiyl bis(1-indenyl) zirconium dichloride (1) has been prepared by the reaction of the dilithium salt of 1,3-bis(l-indenyl) tetramethyldisiloxane with ZrCl4 . 2THF, After catalytic hydrogenation, the corresponding tetrahydroindenyl complex (2) has been formed. Both 1 and 2 have been shown by H-1 NMR spectra to be the mixture of the cis(meso) and trans(rac) isomers, The pure trans isomers 1(l), 2(l) and cis isomer 2(c) were obtained by recrystallization, The crystal structures of 1(l) and 2(c) were determined by X-ray diffraction. Both crystals of 1(l) and 2(c) are monoclinics, belonging to space groups P2(1)/n(1(l)) and P2(1)/c(2(c)). In the unit cell of 2(c), one of the six-membered rings of the tetrahydroindenyl Ligands has two different conformations which have the same probabilities.

Convenient preparation and properties of C-60(OH)(x)

In this paper, we introduce a very convenient method to produce water soluble C-60 derivatives- fullerols by the reaction of C-60 with potassium in toluene solution, FT-IR, H-1 NMR and FABMS proved the multi-hydroxyl and C-60 cage structures of the products, The properties of unstability to light, heat, basicity of aqueous solution and the solubility in some common polar solvents were also described.

STUDY ON ELECTROCATALYTIC OXIDATION OF NADH BY FERROCENE DERIVATIVES AND DETERMINATION OF CATALYTIC RATE-CONSTANT AT MICRODISK ELECTRODE

The electrocatalytic oxidation of NADH by ferrocene derivatives and the influence of complexation with beta-cyclodextrin (beta-CD) were investigated at a microdisk electrode in a buffer solution. The cyclic voltammetric behavior of the ferrocene derivatives on the microdisk electrode was used to determine the electron-transfer rate constant from NADH to the ferricinium species. The heterogeneous rate constants and the diffusion coefficient of ferrocene derivatives were determined with the microdisk electrode. The effect of temperature and pH on the electrocatalytic oxidation of NADH were assessed.

SYNTHESIS AND PHOTOCHROMISM IN SOLUTION OF PHENOXYNAPHTHACENEQUINONE DERIVATIVES

Two new phenoxynaphthacenequinone derivatives, 6-[4-(2-(4-hydroxyphenyl)isopropyl)phenoxy] -5,12-naphthacenequinone (7) and 6-[4-(potassium sulfophenylazo)phenoxy]-5,12-naphthacenequinone (8), were synthesized, and their photochromism in solution was investigated and compared with that of 6-phenoxy-5,12-naphthacenequinone (1). On the basis of the spectral data and the selective irreversible reaction of ammonia with the colored phenoxy-ana-naphthacenequinone, the concentrations of the ana forms at the photostationary state (PSS), achieved by 365 nm UV irradiation, and the molar extinction coefficients of the pure ana forms at 481-482 nm of compounds 1, 7 and 8 in dimethylsulfoxide (DMSO) were found to be 83 mol.% and 1.70x10(4) mol(-1) dm(3) cm(-1), 82 mol.% and 1.62x10(4) mol(-1) dm(3) cm(-1) and 16 mol.% and approximately 1.34x10(4) mol(-1) dm(3) cm(-1) respectively; the absorption spectra of the colored ana forms of 7 and 1 in DMSO were estimated; the rate;constants of photoconversion induced by 365 nm light were obtained. The results show the strong effect of the structure of the phenoxynaphthacenequinones on their photochromism in solution. In addition to DMSO solution, compound 7 exhibited normal photochromism in toluene, benzene, chloroform and a DMSO-ethanol mixed solvent, but not in dimethylformamide (DMF) in which a photoinduced reaction occurred between 7 and DMF or impurities.

INTRAANNULAR AND INTERANNULAR SUBSTITUENT MIGRATION AND INTRAMOLECULAR IPSO SUBSTITUTION OF BIPHENYL DERIVATIVES IN MASS-SPECTROMETRY

Biphenyl derivatives undergo extensive intraannular substituent migrations and subsequent intramolecular ipso substitutions giving rise to a fluorenyl cation and a biphenylene radical cation as common products in mass spectrometry. For biphenyls bearing an alkyl group, interannular substituent migration resulting in a substituted tropylium ion is also observed. Electron-withdrawing groups are found to be much more favourable to these reactions than the electron-donating ones.

SOLUTION PROPERTIES OF POLYANILINE AND ITS DERIVATIVES

Solutions of polyaniline (PAn), poly(ortho-toluidine) (POT) and poly(ortho-anisidine) (PAs) in N-methyl pyrrolidinone (NMP) were examined by viscometric, gel permeation chromatographic (GPC) and theological methods. Strong intermolecular interaction and molecular aggregation are shown.

THERMAL BEHAVIORS OF INTRINSIC POLYANILINE AND ITS DERIVATIVES

Thermal properties of polyaniline (PAn), polytoluidine(POT) and polyanisidine(PAs) were examined by TG and DSC techniques. The weight-uptake of POT at 200-300 degrees C was observed and carefully discussed.

H-1 NMR Titration Studies of Two Novel DTPA Derivatives

Polyaminopolycarboxylate gadolinium (III) complexes have been studied intensively in recent years because of their potential uses as contrast agents for magnetic resonance imaging (MHI)([1]). The research interests are mainly focussed on Gd3+ complexes of DTPA, DOTA and their various derivatives. Four kinds of Gd3+ complexes can be used presently in clinical MRI, which are GD(DTPA)([2]), Gd(DOTA)([3]), Gd(DTPA-BMA)([4]) and Gd(HP-DO3A)([5]). Here report two new DTPA bis (amide) derivatives-diethylenetriaminepentaacetic acid-N, N ''-bis (dimethylamide) (DTPA-BDMA) and -bis (diethylamide) (DTPA-BDEA).

ELECTROCHEMICAL STUDY OF PYRAZOLONE DERIVATIVES AT THE LIQUID/LIQUID INTERFACE

Pyrazolone derivatives, such as antipyrine, aminopyrine, and 4-aminoantipyrine, can transfer across the water/nitrobenzene interface to produce a pair of well-defined symmetric, reversible anodic-cathodic peaks by cyclic voltammetri. The transfer mechanis

BINDING OF CYTOCHROME-C WITH 4-PYRIDYL DERIVATIVES MODIFIED ON THE GOLD ELECTRODE

In this work, the adsorption or binding of cytochrome c with 4-pyridyl derivatives modified on the gold electrode was studied. It was found that the concentrations of electrolyte had much influence on the adsorption of cytochrome c. At lower concentration

ELECTROCHEMICAL MECHANISM FOR FULLERENE FORMATION IN PLASMA ARCS

During the synthesis of fullerenes by dc plasma arcs, it has been found that the anodic graphite rod consistently burns up, while the cathodic graphite rod grows slag at its end. Further investigations revealed that the anodic and cathodic graphite rods p

CYCLIC VOLTAMMETRIC STUDY OF QUININE DERIVATIVES TRANSFER ACROSS THE WATER NITROBENZENE INTERFACE

Quinine derivatives, quinine hydrochloride and 8-hydroxyquinoline, transfer across the water/nitrobenzene interface was studied by cyclic voltammetry. The effect of solution acidity on the transfer behaviour was observed. Transfer mechanism was discussed