Electrochemical behavior of the molybdotungstate heteropoly complex with neodymium, K10H3[Nd(SiMo7W4O39)(2)]center dot xH(2)O in aqueous solution

The electrochemical behavior of the title compound (denoted Nd(SiMo7W4)(2)(13-)) in aqueous solution has been studied using cyclic voltammetry, sampled d.c. voltammetry, differential pulse voltammetry and bulk electrolysis with coulometry, The stable pH range of Nd(SiMo7W4)(2)(13-) is determined with UV-visible spectra. In the potential range between 0.70 and -0.45 V vs. SCE, the anion in pH 3.8 aqueous solution undergoes one-, one-, two- and two-electron steps of four redox processes attributed to electron addition and removal from the molybdate-oxo framework. The adsorption of the anion on the dropping mercury electrode and a self-inhibition influence of the adsorbed anions on the redox process of those anions dissolved in solution are found. The unusual dependence of the formal potentials on pH is explained with the competition of the protonation and ion-pair formation due to the high negative charge of Nd(SiMo7W4)(2)(13-) and its reduced forms. The electrocatalytic effects of the anion on the bromate are investigated.

Isothermal crystallization studies on neodymium oxide filled nylon 6

Melt mixing of nylon 8 with neodymium oxide particles was carried out with a single-screw extruder. The crystal behaviors of plain nylon 6 and the neodymium oxide filled nylon 6 mixture were studied by means of isothermal crystallization kinetic analysis. Isothermal crystallization thermograms obtained by differential scanning calorimetry (DSC) were analyzed based on the Avrami equation. The neodymium oxide particles acted as a nucleating agent in the mixture. The overall rate of di-isothermal crystallization of the neodymium oxide filled nylon 6 mixture is higher than that of plain nylon 6. The mechanism and modes of plain nylon 6 were the same as those of neodymium oxide filled PA6 mixture.

Influence of intraperitoneal injection of rare earth compounds on the activities of antioxidant enzymes and the level of lipid peroxidation in mice livers

Following intraperitoneal injection of lanthanum and terbium chloride and their complexes of diethyltriaminopentagacetic acid (DTPA) to adult mice with a dose of 0.28 mmol/kg body weight/day for three days. The activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and the content of lipid end product, malonaldehyde (MDA) in the mice livers have been assayed respectively. The results show that the activity of SOD was increased and the content of MDA was reduced for LaCl3 treated mice and the two targets were not changed for TbCl3, but the activity of GSH-Px was reduced markedly for both LaCl3 and TbCl3 while the above three targets were not changed for La-DTPA and Tb-DTPA complexes.

The reactivity of lanthanide alkyl compounds with phenylacetylene: Synthesis and structure of [(Bu(t)Cp)(2)LnC CPh](2) (Ln=Nd, Gd)

[(Bu(t)Cp)(2)LnCH(3)](2) (Ln = Nd, Gd) react with PhC=CH to form the dimeric alkynide-bridged complexes [(Bu(t)Cp)(2)LnC=CPh](2) [Ln = Nd (I), Gd (II)]. Both compounds crystallized from toluene in the monoclinic space group C2/c. The two complexes are homologous, composed of asymmetric metal-alkynide bridges with Nd-C, Gd-C (alkynide) bond lengths of 2.602(4), 2.641(5) (I) and 2.532(6), 2.601(7) Angstrom (II), respectively. The average Nd-C (ring) and Gd-C (ring) distances are 2.746(13) and 2.703(19)Angstrom.

Study on Phenol Compounds Using Multiple Regression and Neural Network Methods

In this paper, the molecular connectivity indices and the electronic charge parameters of forty-eight phenol compounds nave been calculated. and applied for studying the relationship between partition coefficients and structure of phenol compounds. The results demonstrate that the properties of compounds can be described better with selective parameters, and the results obtained by neural network are superior to that by multiplle regression.

Preparation, structure and some physical properties of scheelite-related AgLnMo(2)O(8) compounds

We present the synthesis of the AgLnMo(2)O(8) oxides with Ln = La-Nd, Sm, Gd, Tb and Y. These compounds represent a scheelite-related structure type characterized by MoO42- tetrahedrons. The IR spectra show three transmittance bands in the region of 1000-400 cm(-1), which correspond respectively to the nu(1), nu(2), and nu(3) modes of the tetrahedral MoO42- groups. All of AgLnMo(2)O(8) are insulator materials at room temperature. The temperature dependence of the magnetic susceptibilities of AgLnMo(2)O(8) (Ln = Ce-Nd, Sm, Gd, Tb) show Curie-Weiss Law behaviors with two anomalies occurring at low temperature, whereas AgLaMo2O8 and AgYMo2O8 both exhibit diamagnetic properties as expected. The magnetic moments at room temperature fit very well with those corresponding to rare earth sesquioxides. This suggests that rare earth ions exist in +3 oxidation state in all AgLnMo(2)O(8) compounds.

STRUCTURE-PROPERTY RELATIONSHIP BETWEEN HALF-WAVE POTENTIALS OF ORGANIC-COMPOUNDS AND THEIR TOPOLOGY

A significant correlation was found between half-wave potentials of organic compounds and their topological indices, A(x1), A(x2), and A(x3). The simplicity of calculation of the index from the connectivity in the molecular skeleton, together with the significant correlation, indicates its practical value. Good results have been obtained by using them to predict the half-wave potentials of some organic compounds.

STUDIES ON STRUCTURE-CARCINOGENIC ACTIVITY RELATIONSHIP OF N-NITROSO COMPOUNDS

The electronic parameters of 12 N-nitroso compounds have been computated with semiempirical quantum chemical calculation, and the study on the relationships between the structures of these compounds and the carcinogenic activities have been performed by using multivariate regression analysis and neural network with satisfactory results.

RELATIONSHIP BETWEEN CONFORMATION OF TASTE COMPOUNDS AND THEIR ACTIVITIES

The conformation analysis and study on structure-taste relation-ships of 4 taste compounds have been performed, the results reveal that the sweetnees will decrease with the increase of the specific dihedral angle O-1-C-2-C-3-C-4, and the mechanism was intepreted.

SEMICONDUCTOR TO METAL TRANSITION IN LN(2)MO(3)O(9) COMPOUNDS

Ln(2)Mo(3)O(12) and Ce2Mo3O12.25 are reduced by hydrogen yielding Mo4+ oxides of the formula Ln(2)Mo(3)O(9) (Ln = La, Ce, Pr, Nd, Sm, Gd and Dy). The new compound Ce2Mo3O9 has the same structure as other Ln(2)Mo(3)O(9) compounds. All of the products are single phase materials and crystallize in a tetragonal scheelite type structure with Mo2O6 clusters. The IR spectra of the Ln(2)Mo(3)O(9) oxides show two absorption bands. These compounds are black n-type semiconductors, and exhibit Curie-Weiss Law behavior from 100K to 250K. Temperature dependence of the electrical properties of these compounds were measured for the first time, and a semiconductor-metal transition was found at about 250 degrees C.

EXPERT-SYSTEM FOR ELUCIDATION OF STRUCTURES OF ORGANIC-COMPOUNDS

An expert system for the elucidation of the structures of organic compounds-ESESOC-II has been designed. It is composed of three parts: spectroscopic data analysis, structure generator, and evaluation of the candidate structures. The heart of ESESOC is the structure generator, as an integral part, which accepts the specific types of information, e.g. molecular formulae, substructure constraints, and produces an exhaustive and irredundant list of candidate structures. The scheme for the structural generation is given, in which the depth-first search strategy is used to fill the bonding adjacency matrix (BAM) and a new method is introduced to remove the duplicates.

GAS-PHASE ION-MOLECULE REACTIONS OF BUCKMINSTERFULLERENE C-60 WITH SOME SMALL ORGANIC-COMPOUNDS IN MASS-SPECTROMETER

In chemical ionization mass spectrometry (CIMS) gas phase C-60(+) or C-60 can react with fragment ions from three chloromethane and four multichloroethane molecular ions via ion-molecule reactions. A dozen of gas-phase adduct ions of C-60 are observed, and most of them contain chlorine atoms. The results of the comparison and analysis show that the relative intensities of adductions are not directly proportional to the corresponding fragment ions in the MS of reagents,which implies that some fragment ions containing radicals are more reactive with C-60(+) or C-60. This indicates that the alkene-like C-60(+) or C-60 can act as a radical sponge in addition reactions.

CHEMICAL-IONIZATION MASS-SPECTROMETRY OF SOME NITRO-CONTAINING BIFUNCTIONAL AROMATIC-COMPOUNDS - LOCATION OF PROTONATION SITE

It is found that the nitro substituent of some aromatic bifunctional compounds shows unusual reactivity towards protonation. In the chemical ionization mass spectra of nitrobenzoic acids and their esters and amides, and of nitrophenols and their ethers, protonations on the carboxyl, ester, amide, hydroxyl or alkoxyl groups are highly suppressed by that on the nitro group. As a result, fragmentations based on protonation on these groups unexpectedly become negligible. Ortho effects were observed for all the ortho isomers where the initial protonation on the nitro group is followed by an intramolecular proton transfer reaction, which leads to the expected 'normal' fragmentations. Protonation on the nitro substituent is much more favourable in energy than on any of the other substituents. The interaction of the two substituents through the conjugating benzene ring is found to be responsible for this 'unfair' competitive protonation. The electron-attracting nitro group strongly destabilizes the MH+ ions formed through protonation on the other substituent; although the COR (R = OH, OMe, OEt, NH2) groups are also electron-withdrawing, their effects are weaker than that of NO2; thus protonation on the latter group produces more-stable MH+ ions. On the other hand, an electron-releasing group OR (R = H, Me, Et) stabilizes the nitro-protonated species; the stronger the electron-donating effect of this group the more stable the nitro-protonated ions.

TRIS(TERT-BUTYLCYCLOPENTADIENYL)NEODYMIUM-MU-CHLORO-TRIS(TETRAHYDROFURAN)LITHIUM, [ND(ETA(5)-(T)BUCP)3(MU-CL)LI(THF)3]

The title complex, tris[2(eta5)-tert-butylcyclopentadi-enyl]-mu-chloro-1:2kappa2Cl-tris(tetrahydrofuran-1kappaO)lithiumneodymium, [Nd(C9H13)3(mu-Cl)Li(C4H8O)3], consists of the neutral moiety ((t)BuCp)3Nd linked to the cation [Li(thf)3]+ by a mu-Cl bridge

ELECTROCATALYTIC OXIDATION AND AMPEROMETRIC DETERMINATION OF SULFHYDRYL COMPOUNDS AT A COPPER HEXACYANOFERRATE FILM GLASSY-CARBON ELECTRODE IN LIQUID-CHROMATOGRAPHY

Electrocatalytic oxidation of sulfhydryl compounds was effective on a copper hexacyanoferrate (CuHCF) film glassy carbon electrode, at a significantly reduced overpotential (0.55 to 0.65 V) and for a broader pH range (2.0 to 7.0). The electrocatalysis was