Base-free oxidative homocoupling of arylboronic esters

Base-free oxidative homocoupling reaction of arylboronic esters has been found to proceed using a catalytic amount of a palladium-1,3-bis(diphenylphosphino)propane (DPPP) complex under an oxygen atmosphere, affording a variety of biaryls in modest to excellent yields. Even arylboronic esters bearing a base-sensitive functional group are applicable to the reaction.     

有机金属络合物用于高分子富氧膜的研究进展

本文介绍了能够可逆吸附分子氧的有机金属络合物用于高分子富氧膜的研究进展，以及以双重吸附理论进行的膜的促进输送机理。     

2,8,9-三氧杂-5-氮杂-1-硼杂双环[3,3,3]十一碳烷的合成

本文报导了具有N→B配位键的2,8,9-三氧杂-5-氮杂-1-硼杂双环[3,3,3]十一碳烷的合成及性质。化合物(1)的制备已有报导,而化合物(2),(3)则为新的化合物。我们研究了它们的成环条件,制备的最佳条件及化学稳定性。     

Characterization and Crystal Structure of a New Holmium(Ⅲ) Complex with the Macrocyclic Ligand Derived from 2,6-Dfformyl-4-methylphenol and Diethylenetriamine

The title compound (13,27-dimethyl-3,6,9,17,20,23-hexaazatricyclo-[23.3.1.111,15]-triaconta- 1 (29),2,9,11,13,15(30), 16,23,25,27-decaene-29,30-diol-N3,N6,N9,O29,O30)-bis(nitrato-O,O')-holmium(Ⅲ) nitrate hydrate has been prepared and characterized by elemental analysis, infrared spectra, and electrospray mass spectra. Its crystal and molecular structures were determined by X-ray diffraction methods. The crystal crystallizes in the monoclinic system, space group C2/c with a = 23.737(12), b = 14.237(7), c = 19.801(10) (A), β = 91.36(1)°, Mr = 831.57, V = 6690(6) (A)3, Z = 8,Dc = 1.651 g/cma, F(000) = 3344, R = 0.0482 and wR = 0.0923. The holmium ion is located in one of the compartments of the macrocyclic ligand and presents a distorted tricapped trigonal prismatic coordination geometry. The macrocycle is coordinated with two oxygen and three nitrogen atoms.Two nitrates are chelated in the opposite positions of the macrocycle, and the third one is ionic.     

STUDIES OF ELECTRON SPIN RESONANCE ON BILIRUBIN FREE RADICALS

The nature of ESR signals derived from bilirubin-Ⅸα has been studied by focusing onthe samples treated with free radical generating and inhibiting systems, i.e. X-XOD, Fe/EDTA, SOD, mannitol/ascorbate, CO, KCN, etc. In all the cases, the stable signals comprisethose originated from semiquinone radical (g = 2.0012) and superoxide free radical (g_∥=2.041, g_⊥= 2.0040). The superoxide is shown binding with certain metal ions chelated bybilirubin. The free radical scavengers are able to destroy these radicals. The kinetic curveof the regeneration of bilirubin radicals has been determined and the reaction follows azero order mechanism. It is likely that both the physiological and toxic actions of bilirubinare related to the characters of its free radicals. Bilirubin is discussed as "active oxygensink" in mammalians.     

Simulation of aerated lagoon using artificial neural networks and multivariate regression techniques

The aim of this study was to develop an empirical model that provides accurate predictions of the biochemical oxygen demand of the output stream from the aerated lagoon at International Paper of Brazil, one of the major pulp and paper plants in Brazil. Predictive models were calculated from functional link neural networks (FLNNs), multiple linear regression, principal components regression, and partial least-squares regression (PLSR). Improvement in FLNN modeling capability was observed when the data were preprocessed using the PLSR technique. PLSR also proved to be a powerful linear regression technique for this problem, which presents operational data limitations.     

Solvothermal Synthesis, Crystal Structure and Electrochemical Property of Complex [Co(p-MBA)2(2,2''-bipy)(H2O)]·(H2O)

One novel complex [Co(p-MBA)2(2,2'-bipy)(H2O)]·(H2O) has been synthesized by the reaction of p-methylbenzoic acid with 2,2'-bipyridine in the solvent mixture of water and methanol. It crystallizes in triclinic, space group P-1 with a=0.70479(14), b=1.1211(2), c=1.6718(3) nm, α=103.806(3), β=90.795(3), γ=104.207(3)°, V=1.2399(4) nm3, Mr=512.41, Dc=1.373 g/cm3, Z=2, F(000)=532, μ=0.733 mm-1, R=0.0432 and wR=0.0957. The crystal structural analysis shows that the cobalt atom is coordinated with three oxygen atoms from two p-methylbenzoic acids and one water molecule and two nitrogen atoms from one 2,2'-bipyridine,forming a distorted square-pyramidal coordination geometry. The cyclic voltammetry behavior of the complex is also reported.     

Oxidation of thiol compounds by molecular oxygen in aqueous solutions

Side self-oxidation of thiols was studied. It was found that these reactions in neutral and alkaline solutions are induced by impurities of variable-valence metals. The ability of transition metals to catalyze oxidation of thiols changes in the order Cu > Mn > Fe > Ni Co. The plot of the self-oxidation rate vs. pH passes through a maximum whose position on the pH scale depends on both the nature of metal and the structure of the thiol oxidized. For thiols having different structures, the kinetic orders in reactions catalyzed by copper ions differently vary with pH, which is apparently associated with the formation of complexes possessing different catalytic activity.     

Synthesis and Crystal Structure of Complex [Pb(qina)2(DMSO)]·H2O

A novel complex [Pb(qina)2(DMSO)]·H2O was synthesized, of which qina- is the quinaldic acid radical and DMSO the dimethyl sulfoxide. Elemental analysis, IR spectra, and X-ray single-crystal diffraction were carried out to determine the composition and crystal structure. This complex belongs to monoclinic system, space group P121/n1, with a = 7.1553(17), b = 17.543(2), c = 17.306(2)(A),β = 91.671(4)°, C22H20N2O6PbS, Mr = 647.65, Z = 4, V= 2171.5(6)(A)3, Dc= 1.981g/cm3,μ = 7.908 mm-1, F(000) = 1248, -9≤h≤6, -23≤k≤ 19, -22≤l≤22, R= 0.0221 and wR =0.0488. Weak coordinate bond is formed between oxygen atom in DMSO and Pb(Ⅱ ). There are also weak interactions, such as π-π interaction, hydrogen bonds and so on, among the complex molecules.