Carboxy ester hydrolysis promoted by a zinc(II) 2-[bis(2-aminoethyl)amino]ethanol complex: A new model for indirect activation on the serine nucleophile by zinc(II) in zinc enzymes

J. Xia; Y. Xu; S. A. Li; W. Y. Sun; K. B. Yu; W. X. Tang

doi:10.1021/ic000642n

Carboxy ester hydrolysis promoted by a zinc(II) 2-[bis(2-aminoethyl)amino]ethanol complex: A new model for indirect activation on the serine nucleophile by zinc(II) in zinc enzymes

J. Xia, Y. Xu, S. A. Li, W. Y. Sun, K. B. Yu, W. X. Tang^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

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Abstract

A complexation study on the new Zn(II) complexes of asymmetric tripodal ligand 2-[bis(2-aminoethyl)amino]ethanol (L) has revealed that the alcoholic OH group of complex ZnL exhibits remarkable acidity with a very low pK_a value of 7.7 at 25 °C. Both the monomeric complex [ZnH_-0.25L(H₂O)](ClO₄)_1.75 (I) and the dimeric alkoxide-coordinating complex [Zn₂(H_-1L)₂](ClO₄)₂ (II) were synthesized, and their structures were determined by X-ray diffraction. The Zn(II)-bound alkoxide, as the reactive nucleopile toward the hydrolysis of esters, has shown a second-order rate constant of 0.13 ± 0.01 M^-1 s^-1 in 10% (v/v) CH₃CN at 25 °C in 4-nitrophenyl acetate (NA) hydrolysis, which is almost the same as the corresponding value for the very reactive alcohol-pendent [12]aneN₃-Zn complex. Present work shows for the first time that Zn(II) complexes of the asymmetric tripodal polyamine bearing an ethoxyl pod can also serve as good models of Zn(II)-containing enzymes.

Original language	English
Pages (from-to)	2394-2401
Number of pages	8
Journal	Inorganic Chemistry
Volume	40
Issue number	10
DOIs	https://doi.org/10.1021/ic000642n
Publication status	Published - 7 May 2001
Externally published	Yes

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title = "Carboxy ester hydrolysis promoted by a zinc(II) 2-[bis(2-aminoethyl)amino]ethanol complex: A new model for indirect activation on the serine nucleophile by zinc(II) in zinc enzymes",

abstract = "A complexation study on the new Zn(II) complexes of asymmetric tripodal ligand 2-[bis(2-aminoethyl)amino]ethanol (L) has revealed that the alcoholic OH group of complex ZnL exhibits remarkable acidity with a very low pKa value of 7.7 at 25 °C. Both the monomeric complex [ZnH-0.25L(H2O)](ClO4)1.75 (I) and the dimeric alkoxide-coordinating complex [Zn2(H-1L)2](ClO4)2 (II) were synthesized, and their structures were determined by X-ray diffraction. The Zn(II)-bound alkoxide, as the reactive nucleopile toward the hydrolysis of esters, has shown a second-order rate constant of 0.13 ± 0.01 M-1 s-1 in 10% (v/v) CH3CN at 25 °C in 4-nitrophenyl acetate (NA) hydrolysis, which is almost the same as the corresponding value for the very reactive alcohol-pendent [12]aneN3-Zn complex. Present work shows for the first time that Zn(II) complexes of the asymmetric tripodal polyamine bearing an ethoxyl pod can also serve as good models of Zn(II)-containing enzymes.",

author = "J. Xia and Y. Xu and Li, {S. A.} and Sun, {W. Y.} and Yu, {K. B.} and Tang, {W. X.}",

year = "2001",

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doi = "10.1021/ic000642n",

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T2 - A new model for indirect activation on the serine nucleophile by zinc(II) in zinc enzymes

AU - Xia, J.

AU - Xu, Y.

AU - Li, S. A.

AU - Sun, W. Y.

AU - Yu, K. B.

AU - Tang, W. X.

PY - 2001/5/7

Y1 - 2001/5/7

N2 - A complexation study on the new Zn(II) complexes of asymmetric tripodal ligand 2-[bis(2-aminoethyl)amino]ethanol (L) has revealed that the alcoholic OH group of complex ZnL exhibits remarkable acidity with a very low pKa value of 7.7 at 25 °C. Both the monomeric complex [ZnH-0.25L(H2O)](ClO4)1.75 (I) and the dimeric alkoxide-coordinating complex [Zn2(H-1L)2](ClO4)2 (II) were synthesized, and their structures were determined by X-ray diffraction. The Zn(II)-bound alkoxide, as the reactive nucleopile toward the hydrolysis of esters, has shown a second-order rate constant of 0.13 ± 0.01 M-1 s-1 in 10% (v/v) CH3CN at 25 °C in 4-nitrophenyl acetate (NA) hydrolysis, which is almost the same as the corresponding value for the very reactive alcohol-pendent [12]aneN3-Zn complex. Present work shows for the first time that Zn(II) complexes of the asymmetric tripodal polyamine bearing an ethoxyl pod can also serve as good models of Zn(II)-containing enzymes.

AB - A complexation study on the new Zn(II) complexes of asymmetric tripodal ligand 2-[bis(2-aminoethyl)amino]ethanol (L) has revealed that the alcoholic OH group of complex ZnL exhibits remarkable acidity with a very low pKa value of 7.7 at 25 °C. Both the monomeric complex [ZnH-0.25L(H2O)](ClO4)1.75 (I) and the dimeric alkoxide-coordinating complex [Zn2(H-1L)2](ClO4)2 (II) were synthesized, and their structures were determined by X-ray diffraction. The Zn(II)-bound alkoxide, as the reactive nucleopile toward the hydrolysis of esters, has shown a second-order rate constant of 0.13 ± 0.01 M-1 s-1 in 10% (v/v) CH3CN at 25 °C in 4-nitrophenyl acetate (NA) hydrolysis, which is almost the same as the corresponding value for the very reactive alcohol-pendent [12]aneN3-Zn complex. Present work shows for the first time that Zn(II) complexes of the asymmetric tripodal polyamine bearing an ethoxyl pod can also serve as good models of Zn(II)-containing enzymes.

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Carboxy ester hydrolysis promoted by a zinc(II) 2-[bis(2-aminoethyl)amino]ethanol complex: A new model for indirect activation on the serine nucleophile by zinc(II) in zinc enzymes

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