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Ahlquist, Mårten S. G.ORCID iD iconorcid.org/0000-0002-1553-4027
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Publications (10 of 62) Show all publications
Samuelsen, S., Santilli, C., Ahlquist, M. S. G. & Madsen, R. (2019). Development and mechanistic investigation of the manganese(iii) salen-catalyzed dehydrogenation of alcohols. Chemical Science, 10(4), 1150-1157
Open this publication in new window or tab >>Development and mechanistic investigation of the manganese(iii) salen-catalyzed dehydrogenation of alcohols
2019 (English)In: Chemical Science, ISSN 2041-6520, E-ISSN 2041-6539, Vol. 10, no 4, p. 1150-1157Article in journal (Refereed) Published
Abstract [en]

The first example of a manganese(III) catalyst for the acceptorless dehydrogenation of alcohols is presented. N,N'-Bis(salicylidene)-1,2-cyclohexanediaminomanganese(III) chloride (2) has been shown to catalyze the direct synthesis of imines from a variety of alcohols and amines with the liberation of hydrogen gas. The mechanism has been investigated experimentally with labelled substrates and theoretically with DFT calculations. The results indicate a metal-ligand bifunctional pathway in which both imine groups in the salen ligand are first reduced to form a manganese(III) amido complex as the catalytically active species. Dehydrogenation of the alcohol then takes place by a stepwise outer-sphere hydrogen transfer generating a manganese(III) salan hydride from which hydrogen gas is released.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-244112 (URN)10.1039/c8sc03969k (DOI)000457342200020 ()2-s2.0-85060677462 (Scopus ID)
Note

QC 20190219

Available from: 2019-02-19 Created: 2019-02-19 Last updated: 2019-02-19Bibliographically approved
Wang, Y., Zhan, S. & Ahlquist, M. S. G. (2019). Nucleophilic Attack by OH2 or OH-: A Detailed Investigation on pH Dependent Performance of a Ru Catalyst. Organometallics, 38(6), 1264-1268
Open this publication in new window or tab >>Nucleophilic Attack by OH2 or OH-: A Detailed Investigation on pH Dependent Performance of a Ru Catalyst
2019 (English)In: Organometallics, ISSN 0276-7333, E-ISSN 1520-6041, Vol. 38, no 6, p. 1264-1268Article in journal (Refereed) Published
Abstract [en]

The considerable rate enhancements along with the increase in pH values may be due to the direct involvement of hydroxide anion in attacking electrophilic [Ru-V(tda)(py)(2)O](+) (1; tda = [2,2':6',2 ''-terpyridine]-6,6 ''-dicarboxylate, py = pyridine). The enhanced reaction rate is well in agreement with the descending activation barriers in our calculation. The addition of four extra water molecules in the geometry optimization plays a key role in stabilizing hydroxide anion as well as building a reasonable hydrogen-bonding network, and three of these molecules are required to stabilize the OH as an anion instead of a radical.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-249813 (URN)10.1021/acs.organomet.8b00544 (DOI)000462944200013 ()2-s2.0-85054136598 (Scopus ID)
Note

QC 20190423

Available from: 2019-04-23 Created: 2019-04-23 Last updated: 2019-04-29Bibliographically approved
Zhang, P., Sheng, X., Chen, X., Fang, Z., Jiang, J., Wang, M., . . . Sun, L. (2019). Paired Electrocatalytic Oxygenation and Hydrogenation of Organic Substrates with Water as the Oxygen and Hydrogen Source. Angewandte Chemie International Edition, 58(27), 9155-9159
Open this publication in new window or tab >>Paired Electrocatalytic Oxygenation and Hydrogenation of Organic Substrates with Water as the Oxygen and Hydrogen Source
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2019 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, no 27, p. 9155-9159Article in journal (Refereed) Published
Abstract [en]

The use of water as an oxygen and hydrogen source for the paired oxygenation and hydrogenation of organic substrates to produce valuable chemicals is of utmost importance as a means of establishing green chemical syntheses. Inspired by the active Ni3+ intermediates involved in electro-catalytic water oxidation by nickel-based materials, we prepared NiBx as a catalyst and used water as the oxygen source for the oxygenation of various organic compounds. NiBx was further employed as both an anode and a cathode in a paired electrosynthesis cell for the respective oxygenation and hydrogenation of organic compounds, with water as both the oxygen and hydrogen source. Conversion efficiency and selectivity of >= 99% were observed during the oxygenation of 5-hydroxy-methylfurfural to 2,5-furandicarboxylic acid and the simultaneous hydrogenation of p-nitrophenol to p-aminophenol. This paired electrosynthesis cell has also been coupled to a solar cell as a stand-alone reactor in response to sunlight.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2019
Keywords
electrochemistry, green chemical synthesis, hydrogenation, oxygenation, water
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-255764 (URN)10.1002/anie.201903936 (DOI)000476691200033 ()31025774 (PubMedID)2-s2.0-85066906976 (Scopus ID)
Note

QC 20190816

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Zhan, S., De Gracia Triviño, J. A. & Ahlquist, M. S. G. (2019). The Carboxylate Ligand as an Oxide Relay in Catalytic Water Oxidation. Journal of the American Chemical Society, 141(26), 10247-10252
Open this publication in new window or tab >>The Carboxylate Ligand as an Oxide Relay in Catalytic Water Oxidation
2019 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 26, p. 10247-10252Article in journal (Refereed) Published
Abstract [en]

Carboxylate groups have diverse functionalities in ligands of transition metal catalysts. Here we present a conceptually different function of the carboxylates: the oxide relay. It functions by providing an intramolecular nucleophilic oxygen close to the oxo group to facilitate O-O bond formation and at a later stage a remote electrophilic center to facilitate OH- nucleophilic attack. Empirical valence bond-molecular dynamics (EVB-MD) models were generated for key bond forming steps, diffusion coefficients and binding free energies from potential of mean force estimations were calculated from molecular dynamics (MD) simulations, activation free energies of chemical steps were calculated using density functional theory (DFT). The catalyst studied is the extremely active Ru(tda)(py)(2) water oxidation catalyst. The combination of simulation methods allowed for estimation of the turnover frequencies, which were within 1 order of magnitude from the experimental results at different pH values. From the calculated reaction rates we find that at low pH the OH- anion nucleophilic attack is the rate limiting step, which changes at high pH to the O-O bond formation step. Both steps are extremely rapid, and key to the efficiency is the oxide relay functionality of a pendant carboxylate group. We cannot exclude all alternative mechanisms and suggest isotope experiments using O-18-labeled water to support or invalidate the oxide relay mechanism. The functionality was discovered for a ruthenium catalyst, but since there is nothing in the mechanism restricting it to this metal, the oxide relay functionality could open new ways to design the next-generation water oxidation catalysts with improved activity.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-255384 (URN)10.1021/jacs.9b02585 (DOI)000474669700018 ()31190538 (PubMedID)2-s2.0-85068382861 (Scopus ID)
Note

QC 20190730

Available from: 2019-07-30 Created: 2019-07-30 Last updated: 2019-10-04Bibliographically approved
Ahlquist, M. S. G. & Marcos-Escartin, R. (2018). Bicarbonate hydrogenation by iron: Effects of solvent and ligand on the mechanism. Paper presented at 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA. Abstract of Papers of the American Chemical Society, 255
Open this publication in new window or tab >>Bicarbonate hydrogenation by iron: Effects of solvent and ligand on the mechanism
2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-232278 (URN)000435539900119 ()
Conference
255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA
Note

QC 20180718

Available from: 2018-07-18 Created: 2018-07-18 Last updated: 2018-07-18Bibliographically approved
Zhan, S. & Ahlquist, M. S. G. (2018). Dynamics and Reactions of Molecular Ru Catalysts at Carbon Nanotube-Water Interfaces. Journal of the American Chemical Society, 140(24), 7498-7503
Open this publication in new window or tab >>Dynamics and Reactions of Molecular Ru Catalysts at Carbon Nanotube-Water Interfaces
2018 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 24, p. 7498-7503Article in journal (Refereed) Published
Abstract [en]

Immobilization of molecular catalysts to electrode surfaces can improve the recyclability and electron transfer rates. The drawback is that most experimental techniques and theoretical methods are not applicable. Here we present results from a study of a ruthenium water oxidation catalyst [(RuO)-O-V(bda)L-2] in explicit water at a carbon nanotube water interface, forming the key O-O bond between two 128 atom catalysts, all fully dynamically. Our methodology is based on a recently developed empirical valence bond (EVB) model. We follow the key steps of the reaction including diffusion of the catalysts at the interface, formation of the prereactive dimer, and the bond formation between the two catalysts. On the basis of the calculated parameters, we compute the turnover frequency (TOF) at the experimental loading, in excellent agreement with the experiments. The key O-O bond formation was significantly retarded at the surface, and limiting components were identified that could be improved by catalyst modification.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-232254 (URN)10.1021/jacs.8b00433 (DOI)000436211600026 ()29798669 (PubMedID)2-s2.0-85047638616 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180720

Available from: 2018-07-20 Created: 2018-07-20 Last updated: 2019-04-29Bibliographically approved
Zhan, S., Zou, R. & Ahlquist, M. S. G. (2018). Dynamics with Explicit Solvation Reveals Formation of the Prereactive Dimer as Sole Determining Factor for the Efficiency of Ru(bda)L-2 Catalysts. ACS Catalysis, 8(9), 8642-8648
Open this publication in new window or tab >>Dynamics with Explicit Solvation Reveals Formation of the Prereactive Dimer as Sole Determining Factor for the Efficiency of Ru(bda)L-2 Catalysts
2018 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 9, p. 8642-8648Article in journal (Refereed) Published
Abstract [en]

This report describes all key steps in the O-O bond formation from two separated [Ru-V=O(bda)L-2](+) cations to form the dinuclear [(bda)L2RuIV-O-Ru-IV(bda)L-2](2+) in explicit solvent. The three steps involve the diffusion of the catalysts in the water phase, formation of the prereactive dimer, and the bond formation between the two catalysts. On the basis of the calculated parameters, we compute the rate constant of two catalysts with different L-ligands, isoquinoline and picoline, and the computed values are in excellent agreement with the experimental ones. The interaction of the axial ligands is key to the improved rates of the larger ligand, mainly by facilitating the formation of the prereactive dimer from the solvated monomer. By comparing the binding free energy of hydrophilic Ru-IV-OH and hydrophobic Ru-V=O, the hydrophobic driving force of Ru-V=O in this system has been estimated to 1 kcal mol(-1).

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
Keywords
water oxidation, binding free energy, diffusion rate, O-O bond formation, rate constant, molecular dynamics, empirical valence bond
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-235594 (URN)10.1021/acscatal.8b02519 (DOI)000444364800095 ()2-s2.0-85052393349 (Scopus ID)
Note

QC 20181001

Available from: 2018-10-01 Created: 2018-10-01 Last updated: 2019-04-29Bibliographically approved
Marcos, R., Bertini, F., Rinkevicius, Z., Peruzzini, M., Gonsalvi, L. & Ahlquist, M. S. G. (2018). Mechanistic Studies on NaHCO3 Hydrogenation and HCOOH Dehydrogenation Reactions Catalysed by a Fe-II Linear Tetraphosphine Complex. Chemistry - A European Journal, 24(20), 5366-5372
Open this publication in new window or tab >>Mechanistic Studies on NaHCO3 Hydrogenation and HCOOH Dehydrogenation Reactions Catalysed by a Fe-II Linear Tetraphosphine Complex
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2018 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 20, p. 5366-5372Article in journal (Refereed) Published
Abstract [en]

We present a theoretical extension of the previously published bicarbonate hydrogenation to formate and formic acid dehydrogenation catalysed by Fe-II complexes bearing the linear tetraphosphine ligand tetraphos-1. The hydrogenation reaction was found to proceed at the singlet surface with two competing pathways: A)H-2 association to the Fe-H species followed by deprotonation to give a Fe(H)(2) intermediate, which then reacts with CO2 to give formate. B)CO2 insertion into the Fe-H bond, followed by H-2 association and subsequent deprotonation. B was found to be slightly preferred with an activation energy of 22.8kcalmol(-1), compared to 25.3 for A. Further we have reassigned the Fe-H complex, as a Fe(H)(H-2), which undergoes extremely rapid hydrogen exchange.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
catalysis, CO2 hydrogenation, density functional theory, iron, reaction mechanisms
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-227226 (URN)10.1002/chem.201704927 (DOI)000429703700044 ()29243870 (PubMedID)2-s2.0-85040864758 (Scopus ID)
Note

QC 20180521

Available from: 2018-05-21 Created: 2018-05-21 Last updated: 2019-10-08Bibliographically approved
Daniel, Q., Duan, L., Timmer, B. J. J., Chen, H., Luo, X., Ambre, R., . . . Sun, L. (2018). Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst. ACS Catalysis, 8(5), 4375-4382
Open this publication in new window or tab >>Water Oxidation Initiated by In Situ Dimerization of the Molecular Ru(pdc) Catalyst
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2018 (English)In: ACS Catalysis, ISSN 2155-5435, E-ISSN 2155-5435, Vol. 8, no 5, p. 4375-4382Article in journal (Refereed) Published
Abstract [en]

The mononuclear ruthenium complex [Ru(pdc)L-3] (H(2)pdc = 2,6-pyridinedicarboxylic acid, L = N-heterocycles such as 4-picoline) has previously shown promising catalytic efficiency toward water oxidation, both in homogeneous solutions and anchored on electrode surfaces. However, the detailed water oxidation mechanism catalyzed by this type of complex has remained unclear. In order to deepen understanding of this type of catalyst, in the present study, [Ru(pdc)(py)(3)] (py = pyridine) has been synthesized, and the detailed catalytic mechanism has been studied by electrochemistry, UV-vis, NMR, MS, and X-ray crystallography. Interestingly, it was found that once having reached the Ru-IV state, this complex promptly formed a stable ruthenium dimer [Ru-III(pdc)(py)(2)-O-Ru-IV(pdc)(py)(2)](+). Further investigations suggested that the present dimer, after one pyridine ligand exchange with water to form [Ru-III(pdc)(py)(2)-O-Ru-IV(pdc)(py)(H2O)](+), was the true active species to catalyze water oxidation in homogeneous solutions.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2018
Keywords
solar fuels, water oxidation, electrochemistry, ruthenium dimer, mechanism of O-O bond formation
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-231630 (URN)10.1021/acscatal.7b03768 (DOI)000431727300070 ()2-s2.0-85046695744 (Scopus ID)
Note

QC 20180702

Available from: 2018-07-02 Created: 2018-07-02 Last updated: 2018-07-02Bibliographically approved
Zhan, S., Mårtensson, D., Purg, M., Kamerlin, S. C. L. & Ahlquist, M. S. G. (2017). Capturing the Role of Explicit Solvent in the Dimerization of Ru-V(bda) Water Oxidation Catalysts. Angewandte Chemie International Edition, 56(24), 6962-6965
Open this publication in new window or tab >>Capturing the Role of Explicit Solvent in the Dimerization of Ru-V(bda) Water Oxidation Catalysts
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2017 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 56, no 24, p. 6962-6965Article in journal (Refereed) Published
Abstract [en]

A ground-breaking empirical valence bond study for a soluble transition-metal complex is presented. The full reaction of catalyst monomers approaching and reacting in the Ru-V oxidation state were studied. Analysis of the solvation shell in the reactant and along the reaction coordinate revealed that the oxo itself is hydrophobic, which adds a significant driving force to form the dimer. The effect of the solvent on the reaction between the prereactive dimer and the product was small. The solvent seems to lower the barrier for the isoquinoline (isoq) complex while it is increased for pyridines. By comparing the reaction in the gas phase and solution, the proposed p-stacking interaction of the isoq ligands is found to be entirely driven by the water medium.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2017
Keywords
diradical coupling reaction, empirical valence bond, hydrophobic oxo, solvation effect, water oxidation
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-209064 (URN)10.1002/anie.201701488 (DOI)000402523900049 ()28493633 (PubMedID)2-s2.0-85019990678 (Scopus ID)
Funder
Knut and Alice Wallenberg Foundation
Note

QC 20170620

Available from: 2017-06-20 Created: 2017-06-20 Last updated: 2019-04-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-1553-4027

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