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Your search keyword '"Zeng, Xiancheng"' showing total 29 results
Start Over Author "Zeng, Xiancheng" Publisher elsevier bv
29 results on '"Zeng, Xiancheng"'

5. Metallomicellar catalysis: accelerated hydrolysis of BNPP by copper(II), zinc(II), and nickel(II) complexes of long alkanol–imidazole in CTAB micellar solution

Author

Yu Xiaoqi, Bao Jin-ku, Du Juan, Jiang Fubin, and Zeng Xiancheng

Subjects
Inorganic chemistry, chemistry.chemical_element, Substrate (chemistry), Zinc, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, Biomaterials, Hydrophobic effect, chemistry.chemical_compound, Hydrolysis, Nickel, Colloid and Surface Chemistry, chemistry, Imidazole, Ternary complex
Abstract

Two alkanol–imidazole ligands have been synthesized. Metal (Cu(II), Zn(II), Ni(II)) complexes of these ligands have been investigated as catalysts for the hydrolysis of bis(p-nitrophenyl) phosphate (BNPP) in the buffered CTAB co-micellar solution at 30 °C and various pH values, respectively. The ternary complex kinetic model for metallomicellar catalysis was employed to analyze the results, to obtain the kinetic and thermodynamic parameters. The effect of the structure of the ligands and the microenvironment of the reaction on the hydrolytic reaction of BNPP has been discussed in detail. The results indicate that the hydrophobic interaction between the substrate and the metallomicellar catalyst and the micellar microenvironment are important factors.

Published
2004

6. Enhanced Hydrolysis of Carboxylic Acid Esters Catalyzed by Metallomicelles Made of Cu(II) and Zn(II) Complexes

Author

Jiang Bingying, Zeng Xiancheng, Kou Xingming, Du Juan, and Xiang Qingxiang

Subjects
chemistry.chemical_classification, Ligand, Carboxylic acid, Inorganic chemistry, Medicinal chemistry, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, Biomaterials, Hydrolysis, Colloid and Surface Chemistry, chemistry, Nucleophile, Alkoxy group, Ternary complex, Alkyl
Abstract

Rate enhancement for hydrolysis of p-nitrophenyl picolinate (PNPP) and p-nitrophenyl acetate (PNPA) at 25°C in the pH range 6.5–8.5 have been measured kinetically in the presence of Cu(II) and Zn(II) complexes of substituted long alkyl pyridine ligand (L) under buffered co-micellar conditions with cationic surfactant CTAB. The results indicate that the activated ligand hydroxyl group can act as effective nucleophilic species in the reactions, and the complexes, especially that with Zn(II), effectively catalyze the hydrolysis of PNPP, which can be explained by the higher nucleophilicity of alkoxyl anion in Zn(II) complex than that in Cu(II) complex. A ternary complex kinetic model involving metal ion, ligand, and substrate and a bimolecular micellar reaction model have been proposed for the catalytic hydrolysis of PNPP and PNPA, respectively. Relative kinetic and thermodynamic parameters have been obtained, and the results confirmed the reasonability of such kinetic models.

Published
2002

7. Metallomicellar Catalysis: Catalytic Cleavage of p-Nitrophenyl Picolinate by Cu2+ Complex of 4-Chloride-2,6-bis(N-hydroxyethylaminomethyl)-benzophenol in Micellar Solution

Author

Xie Jia-qing, Jiang Bingying, Zeng Xiancheng, and Xiang Yan

Subjects
Reaction mechanism, Inorganic chemistry, Ether, Medicinal chemistry, Micelle, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, Biomaterials, chemistry.chemical_compound, Nitrophenol, Colloid and Surface Chemistry, Reaction rate constant, chemistry, Hydroxide, Ternary complex
Abstract

The hydrolysis of p -nitrophenyl picolinate (PNPP) catalyzed by the Cu(II) complex of 4-chloride-2,6-bis( N -hydroxyethylaminomethyl)-benzophenol was investigated kinetically by observing the rates of release of p -nitrophenol in the presence of three surfactants, which are hexadecyltrimethylammonium bromide, n -lauroylsarcosine sodium, and polyoxyethylene(23) lauryl ether, at different pH and 25°C. The scheme for the reaction involving a ternary complex comprising ligand, metal ion, and substrate in a micelle was established, and the relative kinetic and thermodynamic parameters were determined, including first-order rate constant ( k N ), association constant ( K s ) for ternary complex, and p K a for the hydroxide ion of the ternary complex. The reaction mechanism was discussed.

Published
2002

8. Metallomicellar Catalysis Cleavage of p-Nitrophenyl Picolinate Catalyzed by Binuclear Metal Complexes Coordinating Tripeptide in CTAB Micellar Solution

Author

Cheng Siqing, Zeng Xiancheng, Xie Jia-qing, Li Yantuan, and Xiang Yan

Subjects
Ligand, Inorganic chemistry, Homogeneous catalysis, Tripeptide, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, Biomaterials, Metal, Hydrolysis, chemistry.chemical_compound, Colloid and Surface Chemistry, chemistry, visual_art, Polymer chemistry, visual_art.visual_art_medium, Bifunctional, Ternary complex
Abstract

The catalytic hydrolysis of p-nitrophenyl picolinate (PNPP) by Cu(II) and Zn(II) complexes coordinating tripeptide were studied kinetically by observing the rates of release of p-nitrophenol in the buffered micellar solution at 25 degrees C and different pH values. The experimental results indicate that 1 : 2 ligand : metal ion complexes in CTAB micellar solution are the active species in the reaction, and the complexes, especially that with Cu(II), efficiently catalyze the hydrolysis of PNPP. As a result, a kinetic model of binuclear metal complex catalysis involving a ternary complex in CTAB micellar solution is proposed to analyze the kinetic behavior of catalysis, and thus, relative kinetic and thermodynamic parameters are obtained. The results predict that the catalytic reaction by metallomicelle with binuclear complex involves a bifunctional mechanism. Copyright 2001 Academic Press.

Published
2001

9. Metallomicellar Catalysis Hydrolysis of p-Nitrophenyl Picolinate Catalyzed by Copper(II), Nickel(II), and Zinc(II) Complexes of Long Alkyl Pyridine Ligands in Micellar Solution

Author

Meng Xiangguang, Cheng Siqing, Yu Xiaoqi, and Zeng Xiancheng

Subjects
chemistry.chemical_classification, Chemistry, Inorganic chemistry, chemistry.chemical_element, Zinc, Micelle, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Catalysis, Biomaterials, Metal, Nickel, Hydrolysis, Colloid and Surface Chemistry, visual_art, Polymer chemistry, visual_art.visual_art_medium, Ternary complex, Alkyl
Abstract

The ternary complex kinetic model for metallomicellar catalysis has been proposed in this paper. The catalytic effects of bivalent metal ion (Cu(2+), Zn(2+), and Ni(2+)) complexes of long alkyl pyridine ligands upon the hydrolysis of p-nitrophenyl picolinate (PNPP) have been studied kinetically in aqueous buffer of pH ranging from 5.0 to 8.5 at 30 degrees C. The effect of pH on the reactivity is discussed. The results indicate that the metallomicelles formed by pyridine ligands promote the hydrolysis of PNPP, and the order is Cu(II) system>Ni(II) system>Zn(II) system. A stereochemical modification of the complex in the CTAB micelle is suggested as a likely explanation for the observed phenomena. Copyright 2000 Academic Press.

Published
2000

16. Mechanical Anisotropy of Ankyrin Repeats

Author

Lee, Whasil, primary, Zeng, Xiancheng, additional, Rotolo, Kristina, additional, Yang, Ming, additional, Schofield, Christopher J., additional, Bennett, Vann, additional, Yang, Weitao, additional, and Marszalek, Piotr E., additional

Published
2012
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25. Metallomicellar catalysis

Author

Jiang, Fubin, primary, Jiang, Bingying, additional, Cao, Yangshu, additional, Meng, Xiangguang, additional, Yu, Xiaoqi, additional, and Zeng, Xiancheng, additional

Published
2005
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