Novel imprinted soluble microgels with hydrolytic catalytic activity

The synthesis and kinetic characterisation of soluble imprinted acrylamide based microgels incorporating arginine and tyrosine derivatives as additional functional monomers is reported.     

Size-modulated catalytic activity of enzyme-nanoparticle conjugates: a combined kinetic and theoretical study

A series of experiments were performed to systematically analyze the effect of nanoparticle (NP) size on the catalytic behavior of enzyme-NP conjugates, and a shielding model based on diffusion-collision theory was developed to explain the correlation between the size effects and the kinetic responses.     

Structure and catalytic activity of metallocomplexes immobilized on carriers

Mono-, bi-, and trinuclear Ru complexes with various ligands immobilized on the surface of silica gels modified with -aminopropyl, formamide, sulfide, cyano, or mercapto groups, catalyze hydrodehalogenation ofp-bromotoluene by the transfer of hydrogen from NaBH4 in 2-propanol both in an Ar atmosphere and in air. The structures of the heterogenized metallocomplex catalysts prepared (the nature of the ligand environment, the oxidation number of the central atom) were studied by IR and XP spectroscopy. The immobilized binuclear Ru^II,III tetraacetate, which retains the structure of the original complex, exhibits higher catalytic activity in the hydrogenolysis ofp-bromotoluene than heterogenized mononuclear systems.For Part 5, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 70–74, January, 1995.     

Study of catalytic activity of some solid supports for gas chromatography

Conclusions For chemically unmodified Chromosorb W, Inerton, and domestic Tsvetochrom I the characteristics of the catalytic activity, estimated by the degree of-pinene isomerization, are close and substantially lower than for the other investigated samples of diatomite supports for gas chromatography. The effect of the type of treatment and of the temperature on the catalytic activity of a solid support were studied.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 698–700, March, 1978.     

Structure and catalytic activity of a manganese(III) tetraphenylporpholactone

A manganese(III) complex of tetraphenylporpholactone, Mn(TPPL)Cl, was synthesized and characterized, including by single-crystal X-ray diffraction; the catalytic activity of this complex for olefin epoxidation reactions is compared with that of manganese(III) tetraphenylporphyrin chloride, Mn(TPP)Cl.     

Structure formation and catalytic activity of DNA dissolved in organic solvents

Equal-opportunity dissolver: By attaching polyethylene glycol at its 5' end, DNA (PEG-DNA) can be solubilized in various organic solvents and was shown to form G-quadruplexes by CD spectroscopy. A complex containing iron(III) protoporphyrin?IX (hemin) and G-quadruplex-forming PEG-DNA catalyzed an oxidative reaction in methanol (see scheme).     

Flavin–cyclodextrin conjugates: effect of the structure on the catalytic activity in enantioselective sulfoxidations

A series of flavin–cyclodextrin conjugates has been prepared and tested in the enantioselective oxidations of prochiral aromatic and aliphatic sulfides with hydrogen peroxide. The newly prepared conjugates contain isoalloxazinium or alloxazinium moieties attached to the primary rim of α- and β-cyclodextrins at the C-6 positions. In addition, flavinium units were attached to the secondary rim of the β-cyclodextrin macrocycle. The relationship between the structural features and the catalytic performance of the conjugates, including those recently reported by us, was analyzed. The rate and enantioselectivity of the sulfoxidations catalyzed by flavin–cyclodextrin conjugates are influenced mainly by the size of the cyclodextrin cavity, the type of flavin unit (alloxazine or isoalloxazine), and by the relative orientation of the flavin and cyclodextrin moieties.     

Bi-Mo-Nb复合氧化物的结构与对丙烯氧化的催化活性

本文用XRD, IR, Raman, SEM和ESR等方法研究了系列氧化物Bi~2Mo~3-3XNb~2xO~12-4X(X=0.00, 0.02, 0.05, 0.10, 0.15, 0.20, 0.25) 的结构和对丙烯氧化的催化活性。结果表明, 在X<0.25范围内, 催化剂基本保持典型的α-Bi~2Mo~3O~12结构, 少量Nb^5+的掺杂, 可取代晶格中的Mo^6+, 产生氧空位,无序分布的氧空位的浓度先随X值的增加而增加, 当X=0.15时达到最大值, 催化剂对丙烯氧化的催化活性与这种氧空位的浓度成正比, 反应遵循Redox机理。     

Synthesis and catalytic applications of soluble polymer-supported BINOL

The synthesis of a soluble polymer containing BINOL residues is described. Titanium-BINOLate and AlLibis(binaphthoxide) catalysts are easily generated from this polymer and applied to the asymmetric reaction of Et₂Zn with benzaldehyde and the asymmetric Michael addition, respectively. The products are obtained in good yields with high enantioselectivities.     

Antioxidant and cytotoxic properties of some new dipeptide-indole conjugates

In this study, 10 new indole-dipeptide conjugates were synthesized, and their anticancer activity was determined against on A2780 (ovarian cancer cell line) and MCF-7 (breast cancer cell line) cells. Among compounds, 5 and 10 showed better activity against A2780 cell lines than the standard drug docatexel at 0.1 and 1 μM concentrations, while only compound 5 showed better activity than docatexel, the MCF-7 cell line at 0.1 and 1 μM concentrations. The antioxidant potencies of the compounds were low in both the DPPH and iron reducing power methods tested when compared to standard antioxidants used in this work.     

Submicron polyethylene particles from catalytic emulsion polymerization

Particles of linear polyethylene (M(n) = (2-3) x 10(3) g x mol(-)(1); M(w)/M(n) = 2-4) obtained by catalytic emulsion polymerization of ethylene possess a nonspherical, lentil-like shape with an average aspect ratio of ca. 10 and diameters from 30 to >300 nm, as determined by TEM and AFM. The particle structure results from a stacking of the lamellae along the one shorter axis of the lentils (i.e., their height, by contrast to the diameter). In addition to these multilamellae particles, remarkably, a considerable number of the particles consist of only a single lamella. The thickness of the lamellae (spacing) as determined by TEM is only 9-11 nm, depending on the polymerization temperature during the synthesis of the dispersions. Crystallization in the dispersions during emulsion polymerization differs dramatically from the usual heterogeneous nucleation of bulk polyethylene samples. Each submicron droplet crystallizes individually, independently from the other droplets, resulting in large supercoolings of around 55 degrees C.     

Phase-transfer catalytic activity of soluble polystyrenes containing crown ether moieties and hydroxyl groups adjacent to the macrorings

Soluble polystyrenes with crown ether structures and hydroxyl groups adjacent to the macrorings were prepared by the reaction of epoxide-containing polystyrenes with monoaza-15-crown-5 or monoaza-18-crown-6. Rate of formation of the polymer-bound alkali cation-crown alkoxide ion pair from the soluble polystyrenes and aqueous NaOH or KOH depended on the loading of crown ether and hydroxyl units and on the size of the macroring. The elimination of HCl from less reactive 2-chloroethylbenzene with aqueous NaOH or KOH in the presence of the soluble polystyrene catalysts under two-phase conditions was limited mainly by the intrinsic reaction rate. The elimination of HBr from more reactive 2-bromoethylbenzene in the presence of the less (11%) ring-substituted polymer catalyst with 18-crown unit was limited by the alkoxide formation rate. © 1994 John Wiley & Sons, Inc.     

Synthesis, spectral and catalytic activity of some manganese(II) bis-benzimidazole diamide complexes

Four Mn(II) complexes bound to a neutral bis-benzimidazole diamide ligand N,N'-bis(2-methyl benzimidazolyl 2,2'-oxy-diethanamide) (GBOA) have been synthesized and characterized. Anionic ligand associated with the complexes varies as Cl- CH3COO-, SCN- and ClO4-. X-ray structure of one of the complexes [Mn(GBOA)2(H2O)2]Cl(2)·4H2O was solved and shows that the Mn(II) ion is hexacoordinate. Two equatorial positions are occupied by benzimidazole imine nitrogen atoms while the other two sites are occupied by amide carbonyl oxygens. The imine nitrogen and carbonyl oxygens are bound to Mn(II) by different arms of the two ligands while axial sites are occupied by two water molecules. Two Cl- anions are outside the coordination sphere and form an extensive 3D H-bonded network. Axially distorted octahedral geometry is confirmed for all the four complexes by low temperature EPR spectroscopy. Distortion parameter D was found to be similar for [Mn(GBOA)2(H2O)2]Cl(2)·4H2O and [Mn(GBOA)2(H2O)2]·(CH3COO)2·H2O. Cyclic voltammograms have been obtained for all the four complexes and E(1/2) values are dependent on the anionic ligand being in the coordination sphere or outside. [Mn(GBOA)2(H2O)2]Cl(2)·4H2O and [Mn(GBOA)2(H2O)2]·(CH3COO)2·H2O carry out the selective oxidation of N-benzyldimethylamine, and 1-methyl-pyrollidine to their respective carbonyl products with catalytic efficiency of 35-50%.     

Synthesis and catalytic activity of some cationic rhodium(I) complexes with substituted quinolines

Summary The synthesis and properties of cationic complexes of the type [Rh(NBD)L₂]ClO₄, [Rh(NBD)L(PPh₃)]ClO₄ and [Rh(CO)L(PPh₃)₂]ClO₄ (L = substituted quinolines) are described. The diolefin complexes catalyse hydrogen transfer from isopropanol to some unsaturated substrates.     

Double-bond isomerization and hydrogenation in polyethylene with soluble nickel catalysts

Polyethylene exhibits an increase in melt viscosity (melt index drop-off) when subjected to extreme thermal treatment. Although stabilizers and antioxidants do not prevent this change it has been possible to stabilize high-density polyethylene by isomerization or hydrogenation of the polymer unsaturation. A soluble nickel octoate–triethylauminum complex was an active catalyst system for these reactions. A triethyl-aluminum/nickel ratio of three appeared optimum for maximum activity. Of particular interest regarding this catalyst system was the fact that the terminal vinyl unsaturation of the polymer had to be isomerized to some internal position before hydrogenation commenced. However, when this catalyst system was impregnated on a predried silica or when butyllithium was substituted for triethylaluminum, both isomerization and hydrogenation occurred simultaneously. The addition of a light olefin such as ethylene to the reaction mixture slowed the overall reaction until most of the ethylene had been hydrogenated. At this point the isomerization–hydrogenation reaction path previously mentioned commenced.     

Dependence of the catalytic activity of organoaluminum compounds and some of their complexes on their composition

The influence of the acidity of organoaluminum compounds and their complexes on the catalytic activity in polymerization of trioxane has been studied. It is found that the catalytic activity of organoaluminum compounds of the type R_nALX_3?n depends on n as well as the nature of R or X. Catalytic activity of the complexes also depends on the type of cocatalyst used. The change of electroconductivity in the course of formation of some initiator complexes has been studied and an attempt has been made to determine the relation between conductivity and polymerization activity.     

Structure and properties of ultra-high modulus polyethylene

The relationship between formation, structure and tensile modulus of ultrahigh modulus polyethylene is explained on the basis of a structural model in which entanglements formed during the deformation process play an important rôle. The results of wide- and small-angle X-ray scattering are interpreted in terms of structural parameters derived from this model.     

Synthesis and catalytic performance of a soluble asymmetric zinc phthalocyanine

The soluble asymmetric phthalocyanine (Pc) (ZnPc-OH) was synthesized and used as a photosensitizer to degrade water pollutants. The catalytic ability of zinc Pc was proved by degrading Rhodamine B. In addition, ZnPc-OH, which has good solubility, can be used in photodynamic therapy.