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Article: Effect of cyclodextrin dimers with bipyridyl and biphenyl linking groups on carboxyl ester hydrolysis catalyzed by zinc complex

TitleEffect of cyclodextrin dimers with bipyridyl and biphenyl linking groups on carboxyl ester hydrolysis catalyzed by zinc complex
Authors
KeywordsCarboxylic Ester
Cyclodextrin Dimer
Hydrolysis
Kinetics
Zinc Complex
Issue Date2009
PublisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/molcata
Citation
Journal Of Molecular Catalysis A: Chemical, 2009, v. 308 n. 1-2, p. 61-67 How to Cite?
AbstractTwo new β-cyclodextrin dimers, biphenyl-4,4′-bis(6-monodeoxy-6-ammoniomethyl-β-cyclodextrin) (Host 1, H1) and 2,2′-bipyridyl-5,5′-bis(6-monodeoxy-6-ammoniomethyl-β-cyclodextrin) (Host 2, H2), were synthesized and further assembled with a zinc complex containing a hydrophobic group to construct two host-guest systems, ZnL(H1) and ZnL(H2) (L = 4-(4′-tert-butylbenzyl)diethylenetriamine), acting as supramolecular metallohydrolase models. In such system, the chemical equilibrium constants were determined by pH potentiometric titration at 298 ± 0.1 K. Two deprotonation constants of the Zn(II)-coordinated water, 8.68 ± 0.03 (pKa1) and 10.50 ± 0.04 (pKa2), were obtained respectively for the ZnL(H1) system whereas only one pKa1 value was obtained for ZnL(H2) (9.38 ± 0.02). The kinetics of p-nitrophenyl acetate (pNA) hydrolysis catalyzed by ZnL(H1) and ZnL(H2) were examined respectively from pH 7.56 to 10.56 at 298 ± 0.1 K. The pH profile of rate constant of pNA hydrolysis catalyzed by ZnL(H1) exhibits an exponential increase with second-order rate constants of 0.98 and 8.41 M-1 s-1 for mono- and di-hydroxyl active species, indicating a potent catalytic activity relative to the reported mononuclear and polynuclear Zn(II) species. However, the pH profile of rate constant of hydrolysis catalyzed by ZnL(H2) only shows a saturated kinetic behavior with the second-order rate constant of 1.26 M-1 s-1, suggesting a kinetic process controlled only by an acid-base equilibrium. All kinetic results are in good agreement with thermodynamic data for hydroxyl activated species in ZnL(H1) and ZnL(H2) systems. © 2009 Elsevier B.V. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/168385
ISSN
2015 Impact Factor: 3.958
2015 SCImago Journal Rankings: 1.072
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorZhou, YHen_US
dc.contributor.authorZhao, Men_US
dc.contributor.authorSun, Hen_US
dc.contributor.authorMao, ZWen_US
dc.contributor.authorJi, LNen_US
dc.date.accessioned2012-10-08T03:18:17Z-
dc.date.available2012-10-08T03:18:17Z-
dc.date.issued2009en_US
dc.identifier.citationJournal Of Molecular Catalysis A: Chemical, 2009, v. 308 n. 1-2, p. 61-67en_US
dc.identifier.issn1381-1169en_US
dc.identifier.urihttp://hdl.handle.net/10722/168385-
dc.description.abstractTwo new β-cyclodextrin dimers, biphenyl-4,4′-bis(6-monodeoxy-6-ammoniomethyl-β-cyclodextrin) (Host 1, H1) and 2,2′-bipyridyl-5,5′-bis(6-monodeoxy-6-ammoniomethyl-β-cyclodextrin) (Host 2, H2), were synthesized and further assembled with a zinc complex containing a hydrophobic group to construct two host-guest systems, ZnL(H1) and ZnL(H2) (L = 4-(4′-tert-butylbenzyl)diethylenetriamine), acting as supramolecular metallohydrolase models. In such system, the chemical equilibrium constants were determined by pH potentiometric titration at 298 ± 0.1 K. Two deprotonation constants of the Zn(II)-coordinated water, 8.68 ± 0.03 (pKa1) and 10.50 ± 0.04 (pKa2), were obtained respectively for the ZnL(H1) system whereas only one pKa1 value was obtained for ZnL(H2) (9.38 ± 0.02). The kinetics of p-nitrophenyl acetate (pNA) hydrolysis catalyzed by ZnL(H1) and ZnL(H2) were examined respectively from pH 7.56 to 10.56 at 298 ± 0.1 K. The pH profile of rate constant of pNA hydrolysis catalyzed by ZnL(H1) exhibits an exponential increase with second-order rate constants of 0.98 and 8.41 M-1 s-1 for mono- and di-hydroxyl active species, indicating a potent catalytic activity relative to the reported mononuclear and polynuclear Zn(II) species. However, the pH profile of rate constant of hydrolysis catalyzed by ZnL(H2) only shows a saturated kinetic behavior with the second-order rate constant of 1.26 M-1 s-1, suggesting a kinetic process controlled only by an acid-base equilibrium. All kinetic results are in good agreement with thermodynamic data for hydroxyl activated species in ZnL(H1) and ZnL(H2) systems. © 2009 Elsevier B.V. All rights reserved.en_US
dc.languageengen_US
dc.publisherElsevier BV. The Journal's web site is located at http://www.elsevier.com/locate/molcataen_US
dc.relation.ispartofJournal of Molecular Catalysis A: Chemicalen_US
dc.subjectCarboxylic Esteren_US
dc.subjectCyclodextrin Dimeren_US
dc.subjectHydrolysisen_US
dc.subjectKineticsen_US
dc.subjectZinc Complexen_US
dc.titleEffect of cyclodextrin dimers with bipyridyl and biphenyl linking groups on carboxyl ester hydrolysis catalyzed by zinc complexen_US
dc.typeArticleen_US
dc.identifier.emailSun, H:hsun@hkucc.hku.hken_US
dc.identifier.authoritySun, H=rp00777en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/j.molcata.2009.03.026en_US
dc.identifier.scopuseid_2-s2.0-67649491444en_US
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-67649491444&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume308en_US
dc.identifier.issue1-2en_US
dc.identifier.spage61en_US
dc.identifier.epage67en_US
dc.identifier.isiWOS:000268359900008-
dc.publisher.placeNetherlandsen_US
dc.identifier.scopusauthoridZhou, YH=13104031900en_US
dc.identifier.scopusauthoridZhao, M=23972068800en_US
dc.identifier.scopusauthoridSun, H=7404827446en_US
dc.identifier.scopusauthoridMao, ZW=23989068600en_US
dc.identifier.scopusauthoridJi, LN=20734334600en_US

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