Synthesis of Two Schiff Base Transition Metal Complexes Bearing Morpholine Side Chains and Kinetics of PNPP Catalytic Hydrolysis in Brij35 Micelle

Two Schiff base transitional metal complexes bearing morpholine side chains were synthesized and characterized, and were used as a simulative hydrolase in the catalytic hydrolysis of p‐nitrophenyl picolinate (PNPP) in this article. A mechanism of PNPP catalytic hydrolysis in the Brij35 micellar solution was proposed and supported by the results of the spectral analysis and the kinetic calculation. The kinetic model of PNPP catalytic hydrolysis was studied. The some kinetic and the thermodynamic constants on the catalytic reaction were calculated. The results of the study show that the metallomicelle made up of the Schiff base transitional metal complexes and Brij35 micelle revealed a good catalytic activity in PNPP catalytic hydrolysis; the rate of the PNPP catalytic hydrolysis is increased following the increase of the pH values in the buffer solution and affected by the polarization action of metal ion of complex.     

IN SITU OBSERVATION OF MELTING AND CRYSTALLIZATION BEHAVIORS OF POLY(ε-CAPROLACTONE) ULTRA-THIN FILMS BY AFM TECHNIQUE

The melting and crystallization behaviors of poly(ε-caprolactone) (PCL) ultra-thin films with thickness from 15 nm to 8 nm were studied by AFM technique equipped with a hot-stage in real-time. It was found that melting can erase the spherulitic structure for polymer film with high thickness. However, annealing above the melting point can not completely erase the tree-like structure for the thinner polymer film. Generally, the structure formation of thin polymer films of PCL is controlled not only by melting and crystallization but also by dewetting during thermal annealing procedures, and dewetting predominates in the structure formation of ultra-thin films. However, the presence of tree-like morphology at 75 °C may be due to the strong interaction between PCL and mica surface, which may stick the PCL chains onto the mica surface during thermal annealing process. Moreover, the growth of the dendrites was investigated and it was found that crystallization is followed from a dewetted sample, and the branches did not grow with the stems. The crystallization of polymer in the ultra-thin films is a diffusion-controlled process. Both melting and crystallization behaviors of PCL in thin films are influenced by film thickness.     

Synthesis, Structure and Properties of a Novel Cobalt(Ⅱ) Bromide Complex Supported by Phosphine Ligands

<正>The C-Br bond of 2-bromothiophene was successfully cleavaged by tetrakis(trimethylphosphine)cobalt(0). Penta-coordinate cobalt(II) bromide complex 1 (α-C_4H_3S)CoBr(PMe_3)_3 as C-Br bond activation product was obtained. The molecular and crystal structures of complex 1 were determined by single-crystal X-ray diffraction. Complex 1 belongs to the orthorhombic crystal system, space group Pnma with a = 20.428(4) , b =11.036(2) , c = 9.201(2), V = 2074.3(7)~3, Z = 4, D_c = 1.442 g/cm~3, μ = 0.401 mm~(-1), F(000) = 924 and T = 273 K. Complex 1 was also characterized by elemental analysis, IR, UV-Vis, photoluminescence (PL) spectroscopy and TGA.     

Synthesis and characterization of side chain cholesteric liquid crystalline elastomers derived from chiral bisolefinic crosslinking units

In this work we prepared a nematic monomer (4′‐allyloxybiphenyl 4′‐ethoxybenzoate, M₁ ), a chiral crosslinking agent (isosorbide 4‐allyloxybenzoyl bisate, M₂ ) and a series of new side chain cholesteric liquid crystalline elastomers derived from M₁ and M₂ . The chemical structures of the monomers and polymers were confirmed by FTIR and ¹H NMR spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy and X‐ray diffraction. The effect of the content of the crosslinking unit on phase behaviour of the elastomers is discussed. Polymer P₁ showed a nematic phase, P₂ –P₇ showed a cholesteric phase; P₆ formed a blue Grandjean texture over a broad temperature range 145–209.6°C, with no changed on the cooling. Polymers P₄ –P₇ , with more than 6?mol?% of chiral crosslinking agent, gave rise to selective reflection. Elastomers containing less than 15?mol?% of the crosslinking units displayed elasticity, reversible phase transition with wide mesophase temperature ranges, and high thermal stability. Experimental results demonstrated that, with increasing content of crosslinking agent, the glass transition temperatures first fell and then increased; the isotropization temperatures and mesophase temperature ranges decreased.     

MC8 Peptide-Mediated Her-2 Receptor Targeting Based on PEI-β-CyD as Gene Delivery Vector

A novel vector with high gene delivery efficiency and special cell targeting ability was developed using a good strategy that utilized low molecular weight polyethylenimine (PEI; molecular weight, 600 KDa [PEI600]) cross-linked to β-cyclodextrin (β-CyD) via a facile synthetic route. Human epidermal growth factor receptor 2 (Her-2) are highly expressed in a variety of human cancer cells and are potential targets for cancer therapy. MC8 peptides, which have been proven to combine especially with Her-2 on cell membranes were coupled to PEI-β-CyD using N-succinimidyl-3-(2-pyridyldithio) propionate as a linker. The ratios of PEI600, β-CyD, and peptide were calculated based on proton integral values obtained from the ¹H-NMR spectra of the resulting products. Electron microscope observations showed that MC8-PEI-β-CyD can efficiently condense plasmid DNA (pDNA) into nanoparticles of about 200 nm, and MTT assays suggested the decreased toxicity of the polymer. Experiments on gene delivery efficiency in vitro showed that MC8-PEI-β-CyD/pDNA polyplexes had significantly greater transgene activities than PEI-β-CyD/pDNA in the Skov3 and A549 cells, which positively expressed Her-2, whereas, no such effect was observed in the MCF-7 cells, which negatively expressed Her-2. Our current research indicated that the synthesized nonviral vector shows improved gene delivery efficiency and targeting specificity in Her-2 positive cells.     

Glucose Oxidase/Cellulose–Carbon Nanotube Composite Paper as a Biocompatible Bioelectrode for Biofuel Cells

Biofuel cells are devices for generating electrical energy directly from chemical energy of renewable biomass using biocatalysts such as enzymes. Efficient electrical communication between redox enzymes and electrodes is essential for enzymatic biofuel cells. Carbon nanotubes (CNTs) have been recognized as ideal electrode materials because of their high electrical conductivity, large surface area, and inertness. Electrodes consisting entirely of CNTs, which are known as CNT paper, have high surface areas but are typically weak in mechanical strength. In this study, cellulose (CL)–CNT composite paper was fabricated as electrodes for enzymatic biofuel cells. This composite electrode was prepared by vacuum filtration of CNTs followed by reconstitution of cellulose dissolved in ionic liquid, 1-ethyl-3-methylimidazolium acetate. Glucose oxidase (GOx), which is a redox enzyme capable of oxidizing glucose as a renewable fuel using oxygen, was immobilized on the CL–CNT composite paper. Cyclic voltammograms revealed that the GOx/CL–CNT paper electrode showed a pair of well-defined peaks, which agreed well with that of FAD/FADH_2, the redox center of GOx. This result clearly shows that the direct electron transfer (DET) between the GOx and the composite electrode was achieved. However, this DET was dependent on the type of CNTs. It was also found that the GOx immobilized on the composite electrode retained catalytic activity for the oxidation of glucose.     

Metal-based anticancer agents: targeting androgen-dependent and androgen-independent prostate and COX-positive pancreatic cancer cells by phenanthrenequinone semicarbazone and its metal complexes

A planar, polycyclic and aromatic hydrocarbon ligand, namely 9,10-phenanthrenequinone semicarbazone, and its transition metal complexes have been synthesized and structurally characterized. The in vitro antiproliferative activity of these compounds against five human cancer cell lines revealed that they were effective against androgen receptor-positive/negative prostate cancer cells as well as COX-positive pancreatic BxPC-3 cancer cell line. The driving force behind such antiproliferative activity seems to be the up-regulated COX expression in these cells, which was amenable for targeting through metal complexation. These structural motifs can, therefore, serve as a starting point for developing novel cytotoxic agents against the growing number of prostate and pancreatic cancers.     

Synthesis and Stereochemistry of Some new Derivatives of 1,2-O-Cyclohexylidene-α-D-Xylofuranuronic Acid

Abstract

1,2-O-Cyclohexylidene-α-d-xylofuranuronic acid (2) has been converted into its 3-O-acetyl derivative and consecutively to the corresponding acid chloride and ethyl ester. Direct reaction of 2 with ethanol in the presence of p-to-luene sulphonic acid gave the ethyl ester. Reaction of 2 with phosphorus pentachloride in dry ether gave the acid chloride of 1,2-O-cyclohexylidene-3-O-dichlorophosphoryl–α-d-xylofuranuronic acid. Conformational data have been obtained from ¹H and ¹³C NMR measurements.     

Studies on the Synthesis and Antiproliferative Activities of 13‐cis‐Retinoyl Sugar Derivatives

New retinoyl sugar derivatives of 13‐cis‐retinoic acid were synthesized in three ways in this paper in order to enhance pharmacal effects, especially antiproliferative activities of 13‐cis‐retinoic acid. Their structures were confirmed by IR, ¹H‐NMR, ¹³C‐NMR, and MS spectra and their antiproliferative activities were determined in vitro using human cancer lines. Results showed that some compounds possessed potential antitumor activities.     

The catalytic activity of Zn(II) and Mn(II) organometallic complexes

Zn(II) and Mn(II) organometallic complexes I and II were first used to catalyze the cyanosilylation reaction, and good catalytic results (24–99 %) were achieved. The catalytic activity of the complexes was determined by ¹H NMR.