Key Laboratory of Green Catalysis of Sichuan Institute of High Education

Zigong, China

Key Laboratory of Green Catalysis of Sichuan Institute of High Education

Zigong, China
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Xu B.,University of Sichuan | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Jiang W.,University of Sichuan | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | And 6 more authors.
Journal of Biological Inorganic Chemistry | Year: 2017

Abstract: Bromo-containing binuclear Schiff base copper(II) complex, Cu2L(OAc), with an alkoxo/acetato-bridged moiety was employed as a model of carboxylesterases to promote the hydrolytic cleavage of p-nitrophenyl picolinate (PNPP). Furthermore, the reactivity of a mononuclear complex (CuHL) was evaluated for comparing it with that of binuclear one. The results reveal that the as-prepared binuclear Cu2L(OAc) efficiently accelerated the hydrolysis of PNPP, giving rise to excess four orders of magnitude rate enhancement in contrast to the un-catalyzed reaction. Cu2L(OAc) represented an enzyme-like bell-shaped pH-responsive kinetic behavior. Moreover, the binuclear one is more reactive than its mononuclear analogue (CuHL) by two orders of magnitude. The total efficiency of Cu2L(OAc) is about 61-fold than that of its mononuclear analogue, CuHL. In addition, a contrast experiment reveals that binuclear Cu2L(OAc) displayed good activity in the hydrolysis of PNPP as well another active ester, i.e., S-2-benzothiazolyl 2-amino-alpha-(methoxyimino)-4-thiazolethiolacetate (AE-active ester). Noteworthyly, it was found that mononuclear one inspired more obvious rate enhancement in the hydrolysis of AE-active ester relative to PNPP hydrolysis. The estimated pKa1 of bound water on the binuclear Cu2L(OAc) using second derivative method (SDM) is relatively smaller than that for CuHL by a gap of about 0.8 pK unit, which facilitates the hydrolysis of PNPP. Graphical Abstract: Four orders of magnitude rate enhancement was observed for the catalytic hydrolysis of p-nitrophenyl picolinate (PNPP) by one μ-alkoxide/acetato-bridged binuclear copper(II) complex under physiological conditions. Substrate specificity of the resulting binuclear complexes was observed for the hydrolysis of PNPP and AE-active ester.[Figure not available: see fulltext.] © 2017 SBIC


Jiang W.,University of Sichuan | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Xu B.,University of Sichuan | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | And 5 more authors.
Colloid and Polymer Science | Year: 2014

One new hydroxyl-functionalized imidazole derivative (L) was synthesized and characterized. Further, the related mononuclear zinc(II) and cobalt(II) complexes were prepared and used as mimic hydrolases to catalyze the hydrolytic cleavage of p-nitrophenyl picolinate (PNPP) in buffered aqueous solution and a micellar solution of cetyltrimethylammonium bromide (CTAB). Observations show that for all of catalytic systems, the hydrolysis of PNPP was pH-dependent in the pH range of 7.00-8.20. Besides, hydrolysis rates of PNPP displayed a constant increase with the increasing concentration of substrate. In the case of CoL-containing system, moreover, much greater acceleration for PNPP hydrolysis was observed in comparison with the ZnL-containing system. However, micellar effect of CTAB micelle aggregates on the PNPP hydrolysis was not obvious only showing 1.0∼1.3 folds rate difference in contrast to buffered aqueous solution. © 2014 Springer-Verlag.


Ren Y.,China West Normal University | Fan G.,China West Normal University | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Liu F.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education
RSC Advances | Year: 2014

Magnetic palladium/reduced graphene oxide nanocomposites (Pd/rGO-Fe 3O4) were prepared by depositing Pd nanoparticles on an rGO-Fe3O4 magnetic support. The as-prepared nanocomposites were investigated as catalysts for the hydrodechlorination of 4-chlorophenol in the aqueous phase. The complete conversion of 4-chlorophenol (with a concentration as high as 2.5 g L-1) to phenol was obtained in a reaction time of 40 min at room temperature and balloon hydrogen pressure without any additives. The excellent catalytic activity of the Pd/rGO-Fe 3O4 can be attributed to the small particle size of Pd, and an electron-deficient state of Pd in the catalyst as a result of the strong interaction between the active sites and the oxygen of the oxygen-containing groups on the rGO-Fe3O4 support. © 2014 the Partner Organisations.


Jiang W.,Sichuan University of Science & Engineering | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Xu B.,Sichuan University of Science & Engineering | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | And 3 more authors.
Colloid and Polymer Science | Year: 2015

Two alkoxo/hydroxide-bridged dinuclear copper(II) complexes (Cu2L1 and Cu2L2) were prepared for evaluating their activity towards the hydrolysis of p-nitrophenyl picolinate (PNPP). Importantly, this work investigated the effects of varied micelles of four surfactants, e.g., cationic gemini 16-2-16 and 16-6-16, single-chain CTAB (hexadecyltrimethylammonium bromide), and LSS (n-lauroylsarcosine sodium), on the PNPP hydrolysis by the as-prepared copper(II) complexes. The experimental results indicate that at neutral pH both of complexes exhibited much better activity by excess four-order of magnitude rate enhancement. For instant, rate constants of PNPP hydrolysis by Cu2L1 and bromo-containing Cu2L2 are approximate 49,569.6- and 31,123.5-fold than that of PNPP spontaneous hydrolysis. In addition, the hydrolytic reactivity of the bromo-containing Cu2L2 is subordinate to that one without bromine, Cu2L1. Moreover, it is found that the micellar solution of gemini 16-6-16 is proved to be the best medium, and whereas LSS micellar solution is the worst one. Particularly, the pKa values of the Cu(II)-bound H2O are determined by a new methodology which is correlative to second derivatives. © 2015, Springer-Verlag Berlin Heidelberg.


Xu B.,University of Sichuan | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Wang Y.,University of Sichuan | And 7 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2014

One μ-alkoxo/hydroxide-bridged dinuclear copper(II) complex (Cu2L) and a mononuclear analogue (CuL) with symmetric Schiff base compound were employed as carboxylesterase models to promote the hydrolysis of a carboxylic acid ester, p-nitrophenyl picolinate (PNPP). Also the introducing of a Gemini surfactant, bis(hexadecyldimethylammonium)hexane bromide (16-6-16, 2Br-), gave interested observations relative to those controlled trials preformed in buffer and a micellar solution of traditional single-chain surfactant, CTAB (cetyltrimethylammonium bromide). The results indicated that the dinuclear Cu2L efficiently accelerated PNPP hydrolysis with 18,096- and 49,569.6-fold rate enhancement under moderate conditions (pH 7.00, 25°C) in buffer and 16-6-16 micellar solution, respectively. Much greater rate enhancement was observed in 16-6-16 micelles in contrast with CTAB micelles, launching 1.6-2.6 folds difference in hydrolysis rate of PNPP at pH 7.00. Additionally, the Cu2L-induced PNPP hydrolysis showed a bell-shaped rate-pH profile, which is an enzyme-like behaviour. Interestingly, rate-pH curves could provide the direct evidence for the interfacial effects of Gemini 16-6-16 micelles on the deprotonation of coordinated water, indicating about 0.2 unit pKa1 difference of the Cu2L-bound H2O between in micellar phase and bulk phase. Cu2L was found to be approximately 199.3- and 288.7-fold reactive than CuL in buffer and 16-6-16 micellar solution, respectively. Significant activity difference between both complexes probably results from the bimetallic coorperation of the two catalytic copper sites and more open binding site of Cu2L. © 2014 Elsevier B.V.


Jiang W.,University of Sichuan | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Xu B.,University of Sichuan | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | And 5 more authors.
Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry | Year: 2015

Two novel phenoxo-bridged homobinuclear copper(II) complexeswith L-threonine Schiff bases as artificial hydrolases were prepared and screened for catalytic activity in the hydrolysis of p-nitrophenyl picolinate (PNPP), a classic model of carboxylic acid esters. Kinetic analysis testified that the two complexes exhibited good activity with rate acceleration of two orders of magnitude in aqueous solution. In addition, the one copper(II) complex containing 5'-bromo substituent was much more efficient than its bromo-free analogue, showing approximately 1.1̃5.3 times kinetic advantage over a phrange of 7.00-8.20. © Taylor & Francis Group, LLC.


Xu B.,University of Sichuan | Xu B.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | Jiang W.,University of Sichuan | Jiang W.,Key Laboratory of Green Catalysis of Sichuan Institute of High Education | And 3 more authors.
International Journal of Chemical Kinetics | Year: 2015

Two phenoxo-bridged dinuclear copper(II) complexes (Cu2L1 2 , Cu2L2 2 ) with Nsalicylidene glycine Schiff bases were prepared and evaluated their performance for catalyzing the hydrolysis of p-nitrophenyl picolinate (PNPP). The observations reveal that the as-prepared dinuclear copper(II) complexes exhibited better activity by two to three orders of magnitude rate enhancement in comparison with the autohydrolysis rate of PNPP. Chloro-containing Cu2L2 2 aroused approximately three times kinetic advantage over chloro-free Cu2L1 2 at pH 7.0, which is probably contributed to the electron-withdrawing inductive effect of the 5′ -chloride group. Moreover, it was found that the pH-responded kinetic behavior displayed an enzyme-like property for the PNPP hydrolysis by the two complexes. © 2015 Wiley Periodicals Inc.

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