title: Remarkable reactivity of alkoxide/acetato-bridged binuclear copper(II) complex as artificial carboxylesterase.
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 pKa1of 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. 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.
authors.affiliation: School of Chemistry and Environmental Engineering, Sichuan University of Science and Engineering, Zigong, 643000, China.|Laboratory of Biomimetic Catalysis, Key Laboratory of Green Catalysis of Sichuan Institute of High Education, Zigong, 643000, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Xu
authors.affiliation: School of Chemistry and Environmental Engineering, Sichuan University of Science and Engineering, Zigong, 643000, China. jwdxb@163.com.|Laboratory of Biomimetic Catalysis, Key Laboratory of Green Catalysis of Sichuan Institute of High Education, Zigong, 643000, China. jwdxb@163.com.
authors.forename: Weidong
authors.initials: W
authors.lastname: Jiang
authors.affiliation: School of Chemistry and Environmental Engineering, Sichuan University of Science and Engineering, Zigong, 643000, China.|Laboratory of Biomimetic Catalysis, Key Laboratory of Green Catalysis of Sichuan Institute of High Education, Zigong, 643000, China.
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Liu
authors.affiliation: School of Chemistry and Environmental Engineering, Sichuan University of Science and Engineering, Zigong, 643000, China.|Laboratory of Biomimetic Catalysis, Key Laboratory of Green Catalysis of Sichuan Institute of High Education, Zigong, 643000, China.
authors.forename: Fuan
authors.initials: F
authors.lastname: Liu
authors.affiliation: School of Chemistry and Environmental Engineering, Sichuan University of Science and Engineering, Zigong, 643000, China.|Laboratory of Biomimetic Catalysis, Key Laboratory of Green Catalysis of Sichuan Institute of High Education, Zigong, 643000, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xiang
mesh_terms: D000085:Acetates / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010848:Picolinic Acids / Q000737:chemistry*
chemical_list: C514685:4-nitrophenyl picolinate; D000085:Acetates; D009942:Organometallic Compounds; D010087:Oxides; D010848:Picolinic Acids; D003300:Copper
keywords: Artificial enzyme; Bimetallic cooperation; Comparable kinetics; Hydrolysis