Toward understanding the activity of cobalt carbonic anhydrase: A comparative study of zinc- and cobalt-cyclen

Ma, Renhu; Schuette, George F.; Broadbelt, Linda J.

doi:10.1016/j.apcata.2014.12.022

Cited by 13 publications

(9 citation statements)

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“…Lipscomb and Lindskog mechanisms have been reported for bicarbonate ion formation from OH – .CO 2 complex during enzyme catalyzed CO 2 hydration. − In Lipscomb mechanism, proton transfer takes place for bicarbonate ion formation while in Lindskog mechanism, OH – ·CO 2 complex rotates to change the metal–oxygen (M-O) coordination for bicarbonate formation. − Transition state for Lipscomb mechanism is represented as TS2 while transition state for Lindskog mechanism is represented as TS2′ in our study. Proton moved away from O atom of IM2 complex to attain the transition state TS2 following the Lipscomb mechanism.…”

Section: Resultsmentioning

confidence: 74%

Computational Insights into Biomimetic CO₂ Hydration Activities of (Poly)borate Ions

Verma

Deshpande

2017

J. Phys. Chem. C

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Borate-based compounds have been observed to be CO 2 capture agents in natural and synthetic setups. Carbon capture in such systems has been proposed to take place via hydration of CO 2 resulting in bicarbonate ion formation. Several experimental studies have reported borate-based catalysts for CO 2 hydration reaction, and the mechanism of the reaction has been proposed to follow the enzymatic carbonic anhydrase action. In view of the absence of detailed physical insights into the mechanistic aspects of borate-catalyzed CO 2 hydration, computational investigations were carried out in this study under the density functional theory framework to explain the mechanism of the reaction over borate-based systems. Three borate-based systems, namely, borate ions, triborate ions, and tetraborate ions, were tested as the catalysts for the aqueous phase carbon capture reaction. Free energy landscapes provided the details of the elementary steps of the reaction, concluding the mechanism of the reaction to be indeed biomimetic consisting of parallel and bent CO 2 complexation, intramolecular proton transfer, bicarbonate ion complex formation and displacement of bicarbonate ion by water molecule to form (poly)borate−water complexes. All three ions were found to be active for catalyzing the reaction. NMR and FTIR spectra of all the intermediates proposed during the biomimetic mechanism were computed and compared against the experimentally reported spectra. The comparative analyses proved the identities of the intermediates, thus further confirming the mechanism of the reaction.

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Section: Resultsmentioning

confidence: 74%

Computational Insights into Biomimetic CO₂ Hydration Activities of (Poly)borate Ions

Verma

Deshpande

2017

J. Phys. Chem. C

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“…103,110,112 Cobalt cyclen also had a higher pK a than zinc cyclen leading to a higher intrinsic rate constant. 110 In industrial applications such as CO 2 absorption, cyclen showed good reaction rates at pH > 9 and/or under low bicarbonate concentrations of <5 M making them ideal for use in CO 2 separation processes. 1,5,9-triazacyclododecane zinc complex (Zn−tri), as shown in Figure 4b, having a pK a similar to that of CA, is another synthetic catalyst studied widely for its catalytic hydration activity for CO 2 .…”

Section: Catalyzed Hydration Of Comentioning

confidence: 99%

“…1,4,7,10-tetraazacyclododecane chelate of zinc(II) perchlorate (referred as zinc cyclen, Figure a) is an organometallic catalyst that has been well studied for CO 2 hydration. − Even though it has a lower kinetic rate than CA, zinc cyclen has been shown to retain its activity at temperatures of ∼75 °C and maintain its structure at temperatures of ∼100 °C . Computational studies have aided the understanding of the reaction mechanism of zinc cyclen .…”

Section: Catalyzed Hydration Of Co2mentioning

confidence: 99%

Biomimetic Catalysis of CO₂ Hydration: A Materials Perspective

Verma

Bhaduri

Kumar

et al. 2021

Ind. Eng. Chem. Res.

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Rising temperatures and changing weather patterns have made the effect of climate change more evident setting up an alarm for the need of quick action for its mitigation. Carbon capture utilization and storage (CCUS) is an effective step in this direction. One of the key reactions in the heart of aqueous CCUS technologies is the reversible hydration of CO2. The reaction is catalyzed biologically by the enzymes of the carbonic anhydrase family, and for its industrial realization, catalysts including organometallic compounds and metallic nanoparticles have been widely investigated. These catalysts enhance the reaction rates at moderate conditions of temperature, pressure, and pH for suitable applications for CO2 separation and mineralization. However, the use of catalysts is limited by their industrial scale production costs and/or reusability. In this review, we present a materials perspective of different catalysts that have been developed worldwide for CO2 hydration with a specific emphasis on the biomimetic mechanism of the catalytic activity of the catalysts.

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“…Few mimics have approached the impressive turnover frequencies achieved by HCAII. The wide gap between enzymatic and mimic activities has not yet been bridged by the experimental ,, and computational studies ,,− of mimics or enzymes, − and few exhaustive catalyst screening efforts have been carried out for CO 2 hydration.…”

Section: Introductionmentioning

confidence: 99%

When Is Ligand pK_a a Good Descriptor for Catalyst Energetics? In Search of Optimal CO₂ Hydration Catalysts

Kim

Kulik

2018

J. Phys. Chem. A

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We present a detailed study of nearly 70 Zn molecular catalysts for CO hydration from four diverse ligand classes ranging from well-studied carbonic anhydrase mimics (e.g., cyclen) to new structures we obtain by leveraging diverse hits from large organic libraries. Using microkinetic analysis and establishing linear free energy relationships, we confirm that turnover is sensitive to the relative thermodynamic stability of reactive hydroxyl and bound bicarbonate moieties. We observe a wide range of thermodynamic stabilities for these intermediates, showing up to 6 kcal/mol improvement over well-studied cyclen catalysts. We observe a good correlation between the p K of the Zn-OH moiety and the resulting relative stability of hydroxyl moieties over bicarbonate, which may be rationalized by the dominant effect of the difference in higher Zn-OH bond order in comparison to weaker bonding in bicarbonate and water. A direct relationship is identified between isolated organic ligand p K and the p K of a bound water molecule on the catalyst. Thus, organic ligand p K, which is intuitive, easy to compute or tabulate, and much less sensitive to electronic structure method choice than whole-catalyst properties, is a good quantitative descriptor for predicting the effect of through-bond electronic effects on relative CO hydration energetics. We expect this to be applicable to other reactions where is it essential to stabilize turnover-determining hydroxyl species with respect to more weakly bound moieties. Finally, we note exceptions for rigid ligands (e.g., porphyrins) that are observed to preferentially stabilize hydroxyl over bicarbonate without reducing p K values as substantially. We expect the strategy outlined here, to (i) curate diverse ligands from large organic libraries and (ii) identify when ligand-only properties can determine catalyst energetics, to be broadly useful for both experimental and computational catalyst design.

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Toward understanding the activity of cobalt carbonic anhydrase: A comparative study of zinc- and cobalt-cyclen

Cited by 13 publications

References 58 publications

Computational Insights into Biomimetic CO₂ Hydration Activities of (Poly)borate Ions

Computational Insights into Biomimetic CO₂ Hydration Activities of (Poly)borate Ions

Biomimetic Catalysis of CO₂ Hydration: A Materials Perspective

When Is Ligand pK_a a Good Descriptor for Catalyst Energetics? In Search of Optimal CO₂ Hydration Catalysts

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Toward understanding the activity of cobalt carbonic anhydrase: A comparative study of zinc- and cobalt-cyclen

Cited by 13 publications

References 58 publications

Computational Insights into Biomimetic CO2 Hydration Activities of (Poly)borate Ions

Computational Insights into Biomimetic CO2 Hydration Activities of (Poly)borate Ions

Biomimetic Catalysis of CO2 Hydration: A Materials Perspective

When Is Ligand pKa a Good Descriptor for Catalyst Energetics? In Search of Optimal CO2 Hydration Catalysts

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Computational Insights into Biomimetic CO₂ Hydration Activities of (Poly)borate Ions

Computational Insights into Biomimetic CO₂ Hydration Activities of (Poly)borate Ions

Biomimetic Catalysis of CO₂ Hydration: A Materials Perspective

When Is Ligand pK_a a Good Descriptor for Catalyst Energetics? In Search of Optimal CO₂ Hydration Catalysts