1
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Pliego JR. Hybrid Cluster-Continuum Method for Single-Ion Solvation Free Energy in Acetonitrile Solvent. J Phys Chem A 2024; 128:6440-6449. [PMID: 39052560 PMCID: PMC11317976 DOI: 10.1021/acs.jpca.4c03593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2024] [Revised: 07/08/2024] [Accepted: 07/16/2024] [Indexed: 07/27/2024]
Abstract
A new hybrid discrete-continuum approach named the cluster-continuum static approximation (CCSA) has been proposed for acetonitrile solvent. The continuum part uses the conductor-like polarizable continuum model for electrostatic and a surface area-dependent term for nonelectrostatic solvation. The CCSA includes only one explicit acetonitrile solvent molecule and a damping function, which makes the CCSA method reduce to pure continuum solvation in the case of weaker potential of mean force for solute-solvent interaction. The performance of the model was tested for 22 anions and 22 cations, including challenge species that cannot be adequately described by pure continuum solvation. A comparison was done with the widely used solvent model density (SMD) model. For anions, the CCSA reduces to pure continuum solvation and the method has the same performance as the SMD model, with a standard deviation of the mean signed error (SD-MSE) of 2.7 kcal mol-1 for both models. However, the CCSA method for cations considerably outperforms the SMD model, with an SD-MSE of 3.3 kcal mol-1 for the former and 8.4 kcal mol-1 for the latter. The method can be automated, and the present study suggests that continuum solvation models could be parameterized taking into account the explicit solvation as proposed in this work.
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Affiliation(s)
- Josefredo R. Pliego
- Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, São João del-Rei, Minas Gerais 36301-160, Brazil
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2
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Shen GB, Gao SH, Jia YW, Zhu XQ, Qian BC. Establishing the Thermodynamic Cards of Dipine Models' Oxidative Metabolism on 21 Potential Elementary Steps. Molecules 2024; 29:3706. [PMID: 39125109 PMCID: PMC11313972 DOI: 10.3390/molecules29153706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2024] [Revised: 07/26/2024] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
Dipines are a type of important antihypertensive drug as L-calcium channel blockers, whose core skeleton is the 1,4-dihydropyridine structure. Since the dihydropyridine ring is a key structural factor for biological activity, the thermodynamics of the aromatization dihydropyridine ring is a significant feature parameter for understanding the mechanism and pathways of dipine metabolism in vivo. Herein, 4-substituted-phenyl-2,6-dimethyl-3,5-diethyl-formate-1,4-dihydropyridines are refined as the structurally closest dipine models to investigate the thermodynamic potential of dipine oxidative metabolism. In this work, the thermodynamic cards of dipine models' aromatization on 21 potential elementary steps in acetonitrile have been established. Based on the thermodynamic cards, the thermodynamic properties of dipine models and related intermediates acting as electrons, hydrides, hydrogen atoms, protons, and two hydrogen ions (atoms) donors are discussed. Moreover, the thermodynamic cards are applied to evaluate the redox properties, and judge or reveal the possible oxidative mechanism of dipine models.
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Affiliation(s)
- Guang-Bin Shen
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
| | - Shun-Hang Gao
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
| | - Yan-Wei Jia
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Bao-Chen Qian
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
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3
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Lorenzo Ocampo MV, Murray LJ. Ligand Noninnocence in β-Diketiminate and β-Diketimine Copper Complexes. Inorg Chem 2024. [PMID: 39094038 DOI: 10.1021/acs.inorgchem.4c01613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
Metal-ligand cooperative systems have a long precedent in catalysis, with the classification depending on the site of substrate bond cleavage and formation and on redox state changes. Recently, our group reported the participation of a β-diketiminate ligand in chemical bonding to heterocumulenes such as CO2 and CS2 by tricopper complexes, leading to cooperative catalysis. Herein, we report the reactivity of these copper clusters, [Cu3EL]- (E = S, Se; L = tris(β-diketiminate) cyclophane ligand), toward other electrophiles, viz. alkyl halides and Brønsted acids. We identified a family of ligand-functionalized complexes, Cu3EL (R) (R = primary alkyls), and a series of disubstituted products, Cu3EL (R)2, through single-crystal X-ray diffraction, mass spectrometry, and infrared and UV-visible spectroscopy. As part of mechanistic studies on these alkylation reactions, we evaluated the acid-base reactivity of these complexes and the influence of the backbone substitution on the reduction potential. Implications of these findings for ligand noninnocence and the relevance of the metal core as a cofactor for the ligand's reactivity are discussed.
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Affiliation(s)
- M Victoria Lorenzo Ocampo
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Leslie J Murray
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
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4
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Sujansky SJ, Hoteling GA, Bandar JS. A strategy for the controllable generation of organic superbases from benchtop-stable salts. Chem Sci 2024; 15:10018-10026. [PMID: 38966380 PMCID: PMC11220602 DOI: 10.1039/d4sc02524e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2024] [Accepted: 05/07/2024] [Indexed: 07/06/2024] Open
Abstract
Organic superbases are a distinct class of strong base that enable numerous modern reaction applications. Despite their great synthetic potential, widespread use and study of superbases are limited by their air sensitivity and difficult preparation. To address this, we report air-stable carboxylate salts of BTPP and P2-t-Bu phosphazene superbases that, when added to solution with an epoxide, spontaneously generate freebase. These systems function as effective precatalysts and stoichiometric prereagents for superbase-promoted addition, substitution and polymerization reactions. In addition to improving the synthesis, shelf stability, handling and recycling of phosphazenes, this approach enables precise regulation of the rate of base generation in situ. The activation strategy effectively mimics manual slow addition techniques, allowing for control over a reaction's rate or induction period and improvement of reactions that require strong base but are also sensitive to its presence, such as Pd-catalyzed coupling reactions.
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Affiliation(s)
- Stephen J Sujansky
- Department of Chemistry, Colorado State University Fort Collins Colorado 80523 USA
| | - Garrett A Hoteling
- Department of Chemistry, Colorado State University Fort Collins Colorado 80523 USA
| | - Jeffrey S Bandar
- Department of Chemistry, Colorado State University Fort Collins Colorado 80523 USA
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5
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Marron DP, Galvin CM, Dressel JM, Waymouth RM. Cobaltocene-Mediated Catalytic Hydride Transfer: Strategies for Electrocatalytic Hydrogenation. J Am Chem Soc 2024; 146:17075-17083. [PMID: 38864712 DOI: 10.1021/jacs.4c02177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2024]
Abstract
The selective electrocatalytic hydrogenation of organics with transition metal hydrides is a promising strategy for electrosynthesis and energy storage. We report the electrocatalytic hydrogenation of acetone with a cyclopentadienone-iridium complex in a tandem electrocatalytic cycle with a cobaltocene mediator. The reductive protonation of cobaltocenium with mild acids generates (C5H5)CoI(C5H6) (CpCoI(CpH)), which functions as an electrocatalytic hydride mediator to deliver a hydride to cationic Ir(III) without generating hydrogen. Electrocatalytic hydride transfer by CpCoI(CpH) to a cationic Ir species leads to the efficient (Faradaic efficiency > 90%) electrohydrogenation of acetone, a valuable hydrogenation target as a liquid organic hydrogen carrier (LOHC). Hydride-transfer mediation presents a powerful strategy to generate metal hydrides that are inaccessible by stepwise electron/proton transfer.
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Affiliation(s)
- Daniel P Marron
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
| | - Conor M Galvin
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
| | - Julia M Dressel
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
| | - Robert M Waymouth
- Department of Chemistry, Stanford University, Stanford, California 94306, United States
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6
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Haselbach W, Nolden O, Blaise N, Förster T, Gindorf M, Kippes M, Rademacher MP, Jantz M, van Wilderen LJGW, Bredenbeck J, Wachtveitl J, Gilch P. The slow photo-induced CO 2 release of N-phthaloylglycine. Chem Sci 2024; 15:9719-9732. [PMID: 38939141 PMCID: PMC11206210 DOI: 10.1039/d4sc01604a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 05/09/2024] [Indexed: 06/29/2024] Open
Abstract
Carboxylic acids and carboxylates may release CO2 upon oxidation. The oxidation can be conducted electrochemically as in the Kolbe synthesis or by a suitable oxidant. In N-phthaloylglycine (PG), the photo-excited phthalimide chromophore acts as an oxidant. Here, the photo-kinetics of PG dissolved in acetonitrile is traced by steady-state as well as time-resolved UV/vis and IR spectroscopy. The experiments provide clear evidence that, contrary to earlier claims, the photo-induced CO2 release is slow, i.e. it occurs on the microsecond time range. The triplet state of PG is, therefore, the photo-reactive one.
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Affiliation(s)
- Wiebke Haselbach
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Oliver Nolden
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Nadine Blaise
- Institut für Physikalische und Theoretische Chemie, Goethe Universität Frankfurt Max-von-Laue-Str. 7 60438 Frankfurt/Main Germany
| | - Tom Förster
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Mick Gindorf
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Mathieu Kippes
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Michelle P Rademacher
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Matthias Jantz
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
| | - Luuk J G W van Wilderen
- Institut für Biophysik, Goethe Universität Frankfurt Max-von-Laue-Str. 1 60438 Frankfurt/Main Germany
| | - Jens Bredenbeck
- Institut für Biophysik, Goethe Universität Frankfurt Max-von-Laue-Str. 1 60438 Frankfurt/Main Germany
| | - Josef Wachtveitl
- Institut für Physikalische und Theoretische Chemie, Goethe Universität Frankfurt Max-von-Laue-Str. 7 60438 Frankfurt/Main Germany
| | - Peter Gilch
- Institut für Physikalische Chemie, HHU Düsseldorf Universitätsstr. 1 40225 Düsseldorf Germany
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7
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Ferrara I, Chesnokov GA, Dittmann S, Blacque O, Sievers S, Gademann K. Formal Single Atom Editing of the Glycosylated Natural Product Fidaxomicin Improves Acid Stability and Retains Antibiotic Activity. JACS AU 2024; 4:2267-2280. [PMID: 38938792 PMCID: PMC11200244 DOI: 10.1021/jacsau.4c00206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 04/15/2024] [Accepted: 05/06/2024] [Indexed: 06/29/2024]
Abstract
Fidaxomicin (Fdx) constitutes a glycosylated natural product with excellent antibacterial activity against various Gram-positive bacteria but is approved only for Clostridioides difficile infections. Poor water solubility and acid lability preclude its use for other infections. Herein, we describe our strategy to overcome the acid lability by introducing acid-stable S-linked glycosides. We describe the direct, diastereoselective modification of unprotected Fdx without the need to avoid air or moisture. Using our newly established approach, Fdx was converted to the single atom exchanged analogue S-Fdx, in which the acid labile O-glycosidic bond to the noviose sugar was replaced by the acid stable S-glycosidic bond. Studies of the antibacterial activity of a structurally diverse set of thioglycoside derivatives revealed high potency of acyl derivatives of S-Fdx against Clostridioides difficile (MIC range: 0.12-4 μg/mL) and excellent potency against Clostridium perfringens (MIC range: 0.06-0.5 μg/mL).
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Affiliation(s)
- Isabella Ferrara
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Gleb A. Chesnokov
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Silvia Dittmann
- Department
for Microbial Physiology and Molecular Biology, Institute of Microbiology,
Center for Functional Genomics of Microbes, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489 Greifswald, Germany
| | - Olivier Blacque
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Susanne Sievers
- Department
for Microbial Physiology and Molecular Biology, Institute of Microbiology,
Center for Functional Genomics of Microbes, University of Greifswald, Felix-Hausdorff-Strasse 8, 17489 Greifswald, Germany
| | - Karl Gademann
- Department
of Chemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zürich, Switzerland
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8
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Kayne M, Murphy PS, Kwon YM, Lee Y, Jackson TA, Wang D. Generation, Characterization and Reactivity of a High-Valent Mononuclear Cobalt(IV)-Diazide Complex. Chemistry 2024; 30:e202401218. [PMID: 38644346 DOI: 10.1002/chem.202401218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 04/20/2024] [Indexed: 04/23/2024]
Abstract
High-valent Fe(IV)=O intermediates of metalloenzymes have inspired numerous efforts to generate synthetic analogs to mimic and understand their substrate oxidation reactivities. However, high-valent M(IV) complexes of late transition metals are rare. We have recently reported a novel Co(IV)-dinitrate complex (1-NO3) that activates sp3 C-H bonds up to 87 kcal/mol. In this work, we have shown that the nitrate ligands in 1-NO3 can be replaced by azide, a more basic coordinating base, resulting in the formation of a more potent Co(IV)-diazide species (1-N3) that reacts with substrates (hydrocarbons and phenols) at faster rate constants and activates stronger C-H bonds than the parent complex 1-NO3. We have characterized 1-N3 employing a combination of spectroscopic and computational approaches. Our results clearly show that the coordination of azide leads to the modulation of the Co(IV) electronic structure and the Co(IV/III) redox potential. Together with the higher basicity of azide, these thermodynamic parameters contribute to the higher driving forces of 1-N3 than 1-NO3 for C-H bond activation. Our discoveries are thus insightful for designing more reactive bio-inspired high-valent late transition metal complexes for activating inert aliphatic hydrocarbons.
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Affiliation(s)
- Michael Kayne
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
| | - Patrick S Murphy
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Yubin M Kwon
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
| | - Yuri Lee
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Timothy A Jackson
- Department of Chemistry and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas, 66045, United States
| | - Dong Wang
- Department of Chemistry and Biochemistry, Center for Biomolecular Structure and Dynamics, University of Montana, Missoula, Montana, 59812, United States
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9
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Schulte T, Wang Z, Li CC, Hamad A, Waldbach F, Pampel J, Petzold R, Leutzsch M, Bahns F, Ritter T. Ruthenium Phenoxo Complexes: An Isolobal Ligand to Cp with Improved Properties. J Am Chem Soc 2024; 146:15825-15832. [PMID: 38819390 PMCID: PMC11177254 DOI: 10.1021/jacs.4c02088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 05/15/2024] [Accepted: 05/20/2024] [Indexed: 06/01/2024]
Abstract
Catalytic π-arene activation is based on catalysts that allow for arene exchange. To date, cyclopentadiene (Cp)-derived catalysts are the most commonly used in π-arene activation despite their low arene exchange rates. Herein, we report the synthesis, analysis, and catalytic application of Ru(II) complexes supported by phenoxo ligands, which are isolobal alternatives to Cp. The phenoxo complexes exhibit arene exchange rates significantly faster than those of the corresponding Cp complexes. The rate can be further increased through the choice of appropriate counterions. The mechanism of the arene exchange process is elucidated by kinetic and computational analyses. We demonstrate the utility of the new catalysts through an SNAr reaction between fluorobenzene and alcohols, including secondary alcohols that could not be used previously in related reactions. Moreover, the catalytic thermal decarboxylation of phenylacetic acids is presented.
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Affiliation(s)
- Tim Schulte
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
- Institute
of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Zikuan Wang
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Chen-Chen Li
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Aboubakr Hamad
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
- Institute
of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Felix Waldbach
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Julius Pampel
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Roland Petzold
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Markus Leutzsch
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
| | - Fritz Bahns
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
- Institute
of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
| | - Tobias Ritter
- Max-Planck-Institut
für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr 45470, Germany
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10
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Norouziyanlakvan S, Berro P, Rao GK, Gabidullin B, Richeson D. Electrocatalytic Reduction of CO 2 and H 2O with Zn(II) Complexes Through Metal-Ligand Cooperation. Chemistry 2024; 30:e202303147. [PMID: 38224468 DOI: 10.1002/chem.202303147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/27/2023] [Accepted: 01/15/2024] [Indexed: 01/16/2024]
Abstract
Air and water-stable zinc (II) complexes of neutral pincer bis(diphenylphosphino)-2,6-di(amino)pyridine ("PN3P") ligands are reported. These compounds, [Zn(κ2-2,6-{Ph2PNR}2(NC5H3))Br2] (R=Me, 1; R=H, 2), were shown to be capable of electrocatalytic reduction of CO2 at -2.3 V vs. Fc+/0 to selectively yield CO in mixed water/acetonitrile solutions. These complexes also electrocatalytically generate H2 from water in acetonitrile solutions, at the same potential, with Faradaic efficiencies of up to 90 %. DFT computations support a proposed mechanism involving the first reduction of 1 or 2 occurring at the PN3P ligand. Furthermore, computational analysis suggested a mechanism involving metal-ligand cooperation of a Lewis acidic Zn(II) and a basic ligand.
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Affiliation(s)
- Somayeh Norouziyanlakvan
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, Canada
| | - Patrick Berro
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, Canada
| | - Gyandshwar Kumar Rao
- Faculty of Science Engineering And Technology, Amity University, Haryana, India, 122413
| | - Bulat Gabidullin
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, Canada
| | - Darrin Richeson
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, Canada
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11
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Sonea A, Crudo NR, Warren JJ. Understanding the Interplay of the Brønsted Acidity of Catalyst Ancillary Groups and the Solution Components in Iron-porphyrin-Mediated Carbon Dioxide Reduction. J Am Chem Soc 2024; 146:3721-3731. [PMID: 38307036 DOI: 10.1021/jacs.3c10127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2024]
Abstract
The rapid and efficient conversion of carbon dioxide (CO2) to carbon monoxide (CO) is an ongoing challenge. Catalysts based on iron-porphyrin cores have emerged as excellent electrochemical mediators of the two proton + two electron reduction of CO2 to CO, and many of the design features that promote function are known. Of those design features, the incorporation of Brønsted acids in the second coordination sphere of the iron ion has a significant impact on catalyst turnover kinetics. The Brønsted acids are often in the form of hydroxyphenyl groups. Herein, we explore how the acidity of an ancillary 2-hydroxyphenyl group affects the performance of CO2 reduction electrocatalysts. A series of meso-5,10,15,20-tetraaryl porphyrins were prepared where only the functional group at the 5-meso position has an ionizable proton. A series of cyclic voltammetry (CV) experiments reveal that the complex with -OMe positioned para to the ionizable -OH shows the largest CO2 reduction rate constants in acetonitrile solvent. This is the least acidic -OH of the compounds surveyed. The turnover frequency of the -OMe derivative can be further improved with the addition of 4-trifluoromethylphenol to the solution. In contrast, the iron-porphyrin complex with -CF3 positioned opposite the ionizable -OH shows the smallest CO2 reduction rate constants, and its turnover frequency is less enhanced with the addition of phenols to the reaction solutions. The origin of this effect is rationalized based on kinetic isotope effect experiments and density functional calculations. We conclude that catalysts with weaker internal acids coupled with stronger external acid additives provide superior CO2 reduction kinetics.
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Affiliation(s)
- Ana Sonea
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Nicholas R Crudo
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada
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12
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Galvin CM, Marron DP, Dressel JM, Waymouth RM. Coordination-Induced Bond Weakening and Electrocatalytic Proton-Coupled Electron Transfer of a Ruthenium Verdazyl Complex. Inorg Chem 2024; 63:954-960. [PMID: 38153690 DOI: 10.1021/acs.inorgchem.3c02775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Coordination of the leucoverdazyl ligand 2,4-diisopropyl-6-(pyridin-2-yl)-1,4-dihydro-1,2,4,5-tetrazin-3(2H)-one VdH to Ru significantly weakens the ligand's N-H bond. Electrochemical measurements show that the metalated leucoverdazyl Ru(VdH)(acetylacetonate)2 RuVdH has a lower pKa (-5 units), BDFE (-7 kcal/mol), and hydricity (-22 kcal/mol) than the free ligand. DFT calculations suggest that the increased acidity is in part attributable to stabilization of the conjugate base Vd-. When free, Vd- distorts to avoid an 8πe- antiaromatic state, but it remains planar when bound to Ru. Proton-coupled electron transfer (PCET) behavior is observed for both the free and metalated leucoverdazyls. PCET equilibrium between the Vd radical and TEMPOH affords a VdH BDFE that is in good agreement with that obtained from electrochemical methods. RuVd exhibits electrocatalytic PCET donor behavior. Under acidic conditions, it reduces the persistent trityl radical ·CAr3 (Ar = p-tert-butylphenyl) to the corresponding triarylmethane HCAr3 via net 1e-/1H+ transfer from RuVdH.
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Affiliation(s)
- Conor M Galvin
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Daniel P Marron
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Julia M Dressel
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Robert M Waymouth
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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13
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Dutton KG, Jones TJ, Emge TJ, Lipke MC. Cage Match: Comparing the Anion Binding Ability of Isostructural Versus Isofunctional Pairs of Metal-Organic Nanocages. Chemistry 2024; 30:e202303013. [PMID: 37907394 DOI: 10.1002/chem.202303013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/25/2023] [Accepted: 10/31/2023] [Indexed: 11/02/2023]
Abstract
Affinities of six anions (mesylate, acetate, trifluoroacetate, p-toluenecarboxylate, p-toluenesulfonate, and perfluorooctanoate) for three related Pt2+ -linked porphyrin nanocages were measured to probe the influence of different noncovalent recognition motifs (e. g., hydrogen bonding, electrostatics, π bonding) on anion binding. Two new hosts of M6 L3 12+ (1b) and M4 L2 8+ (2) composition (M=(en)Pt2+ , L=(3-py)4 porphyrin) were prepared in a one-pot synthesis and allowed comparison of hosts that differ in structure while maintaining similar N-H hydrogen-bond donor ability. Comparisons of isostructural hosts that differ in hydrogen-bonding ability were made between 1b and a related M6 L3 12+ nanoprism (1a, M=(tmeda)Pt2+ ) that lacks N-H groups. Considerable variation in association constants (K1 =1.6×103 M-1 to 1.3×108 M-1 ) and binding mode (exo vs. endo) were found for different host-guest combinations. Strongest binding was seen between p-toluenecarboxylate and 1b, but surprisingly, association of this guest with 1a was only slightly weaker despite the absence of NH⋅⋅⋅O interactions. The high affinity between p-toluenecarboxylate and 1a could be turned off by protonation, and this behavior was used to toggle between the binding of this guest and the environmental pollutant perfluorooctanoate, which otherwise has a lower affinity for the host.
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Affiliation(s)
- Kaitlyn G Dutton
- Department of Chemistry and Chemical Biology, Rutgers University - New Brunswick, 123 Bevier Road Piscataway, NJ, 08854, USA
| | - Taro J Jones
- Department of Chemistry and Chemical Biology, Rutgers University - New Brunswick, 123 Bevier Road Piscataway, NJ, 08854, USA
| | - Thomas J Emge
- Department of Chemistry and Chemical Biology, Rutgers University - New Brunswick, 123 Bevier Road Piscataway, NJ, 08854, USA
| | - Mark C Lipke
- Department of Chemistry and Chemical Biology, Rutgers University - New Brunswick, 123 Bevier Road Piscataway, NJ, 08854, USA
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14
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La Penna G, Machetti F. Probing Reactivity with External Forces: The Case of Nitroacetamides in Water. Molecules 2023; 29:9. [PMID: 38202592 PMCID: PMC10780269 DOI: 10.3390/molecules29010009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 12/11/2023] [Accepted: 12/15/2023] [Indexed: 01/12/2024] Open
Abstract
Many computational methods have been applied to interpret and predict changes in reactivity by slight modifications of a given molecular scaffold. We describe a novel and simple method based on approximate density-functional theory of valence electrons that can be applied within a large high-performance computational infrastructure to probe such changes using a statistical sample of molecular configurations, including the solvent. All the used computational tools are fully open-source. Following our previous application, we are able to explain the high acidity of C-H bond at α position in nitro compounds when the amide linkage an ammonium group is inserted into the α substituent.
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Affiliation(s)
- Giovanni La Penna
- Istituto di Chimica dei Composti Organometallici (ICCOM), Consiglio Nazionale delle Ricerche (CNR), via Madonna Del Piano 10, I-50019 Firenze, Italy;
- Section of Roma-Tor Vergata, Istituto Nazionale di Fisica Nucleare (INFN), via della Ricerca Scientifica 1, I-00133 Roma, Italy
| | - Fabrizio Machetti
- Istituto di Chimica dei Composti Organometallici (ICCOM), Consiglio Nazionale delle Ricerche (CNR), c/o Dipartimento di Chimica “Ugo Schiff”, via Della Lastruccia 13, I-50019 Firenze, Italy
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15
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Kütt A. Step-by-Step Replacement of Cyano Groups by Tricyanovinyls-The Influence on the Acidity. Molecules 2023; 28:8157. [PMID: 38138645 PMCID: PMC10745934 DOI: 10.3390/molecules28248157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Revised: 12/14/2023] [Accepted: 12/16/2023] [Indexed: 12/24/2023] Open
Abstract
Acid-base properties are the simplest expression of compounds' coordinating ability. In the present work, we studied in silico how the gas-phase Brønsted acidity (GA) of several polycyano-substituted compounds change when cyano (CN) groups are replaced by 1,2,2-tricyanovinyl (TCNV) groups in (iso)cyanic acid, dicyanoamine, cyanoform, and hydrogen tetracyanoborate. Different tautomers and conformers/isomers are included in this study. Gas-phase acidity values are compared with the acidities of various acids, including percyanated protonated monocarba-closo-dodecaborate (carborane acid) and dodecaborate, as well as hydrogen cyanide and 1,2,2-tricyanoethene. An estimation of acetonitrile (MeCN), dimethylsufoxide (DMSO), and 1,2-dichloroethane (DCE) acidities is presented using the COSMO-RS method and correlation analysis. The strongest acid with four TCNV groups shows remarkable acidic properties.
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Affiliation(s)
- Agnes Kütt
- Institute of Chemistry, University of Tartu, Ravila 14A, 50411 Tartu, Estonia
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16
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Moon HW, Wang F, Bhattacharyya K, Planas O, Leutzsch M, Nöthling N, Auer AA, Cornella J. Mechanistic Studies on the Bismuth-Catalyzed Transfer Hydrogenation of Azoarenes. Angew Chem Int Ed Engl 2023; 62:e202313578. [PMID: 37769154 DOI: 10.1002/anie.202313578] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 09/28/2023] [Accepted: 09/28/2023] [Indexed: 09/30/2023]
Abstract
Organobismuth-catalyzed transfer hydrogenation has recently been disclosed as an example of low-valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide mechanistic insights into a Bi-catalyzed transfer hydrogenation of azoarenes using p-trifluoromethylphenol (4) and pinacolborane (5) as hydrogen sources. A kinetic analysis elucidated the rate orders in all components in the catalytic reaction and determined that 1 a (2,6-bis[N-(tert-butyl)iminomethyl]phenylbismuth) is the resting state. In the transfer hydrogenation of azobenzene using 1 a and 4, an equilibrium between 1 a and 1 a ⋅ [OAr]2 (Ar=p-CF3 -C6 H4 ) is observed, and its thermodynamic parameters are established through variable-temperature NMR studies. Additionally, pKa -gated reactivity is observed, validating the proton-coupled nature of the transformation. The ensuing 1 a ⋅ [OAr]2 is crystallographically characterized, and shown to be rapidly reduced to 1 a in the presence of 5. DFT calculations indicate a rate-limiting transition state in which the initial N-H bond is formed via concerted proton transfer upon nucleophilic addition of 1 a to a hydrogen-bonded adduct of azobenzene and 4. These studies guided the discovery of a second-generation Bi catalyst, the rate-limiting transition state of which is lower in energy, leading to catalytic transfer hydrogenation at lower catalyst loadings and at cryogenic temperature.
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Affiliation(s)
- Hye Won Moon
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Feng Wang
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Kalishankar Bhattacharyya
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Oriol Planas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Nils Nöthling
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Alexander A Auer
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Josep Cornella
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
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17
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Zhang HT, Xie F, Guo YH, Xiao Y, Zhang MT. Selective Four-Electron Reduction of Oxygen by a Nonheme Heterobimetallic CuFe Complex. Angew Chem Int Ed Engl 2023; 62:e202310775. [PMID: 37837365 DOI: 10.1002/anie.202310775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/16/2023]
Abstract
We report herein the first nonheme CuFe oxygen reduction catalyst ([CuII (bpbp)(μ-OAc)2 FeIII ]2+ , CuFe-OAc), which serves as a functional model of cytochrome c oxidase and can catalyze oxygen reduction to water with a turnover frequency of 2.4×103 s-1 and selectivity of 96.0 % in the presence of Et3 NH+ . This performance significantly outcompetes its homobimetallic analogues (2.7 s-1 of CuCu-OAc with %H2 O2 selectivity of 98.9 %, and inactive of FeFe-OAc) under the same conditions. Structure-activity relationship studies, in combination with density functional theory calculation, show that the CuFe center efficiently mediates O-O bond cleavage via a CuII (μ-η1 : η2 -O2 )FeIII peroxo intermediate in which the peroxo ligand possesses distinctive coordinating and electronic character. Our work sheds light on the nature of Cu/Fe heterobimetallic cooperation in oxygen reduction catalysis and demonstrates the potential of this synergistic effect in the design of nonheme oxygen reduction catalysts.
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Affiliation(s)
- Hong-Tao Zhang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Fei Xie
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yu-Hua Guo
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Yao Xiao
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
| | - Ming-Tian Zhang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing, 100084, China
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18
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Trowbridge L, Averkiev B, Sues PE. Electrocatalytic Hydrogen Evolution using a Nickel-based Calixpyrrole Complex: Controlling the Secondary Coordination Sphere on an Electrode Surface. Chemistry 2023; 29:e202301920. [PMID: 37665793 PMCID: PMC10842979 DOI: 10.1002/chem.202301920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 08/31/2023] [Accepted: 09/04/2023] [Indexed: 09/06/2023]
Abstract
Incorporating design elements from homogeneous catalysts to construct well defined active sites on electrode surfaces is a promising approach for developing next generation electrocatalysts for energy conversion reactions. Furthermore, if functionalities that control the electrode microenvironment could be integrated into these active sites it would be particularly appealing. In this context, a square planar nickel calixpyrrole complex, Ni(DPMDA) (DPMDA=2,2'-((diphenylmethylene)bis(1H-pyrrole-5,2-diyl))bis(methaneylylidene))bis(azaneylylidene))dianiline) with pendant amine groups is reported that forms a heterogeneous hydrogen evolution catalyst using anilinium tetrafluoroborate as the proton source. The supported Ni(DPMDA) catalyst was surprisingly stable and displayed fast reaction kinetics with turnover frequencies (TOF) up to 25,900 s-1 or 366,000 s-1 cm-2 . Kinetic isotope effect (KIE) studies revealed a KIE of 5.7, and this data, combined with Tafel slope analysis, suggested that a proton-coupled electron transfer (PCET) process involving the pendant amine groups was rate-limiting. While evidence of an outer-sphere reduction of the Ni(DPMDA) catalyst was observed, it is hypothesized that the control over the secondary coordination sphere provided by the pendant amines facilitated such high TOFs and enabled the PCET mechanism. The results reported herein provide insight into heterogeneous catalyst design and approaches for controlling the secondary coordination sphere on electrode surfaces.
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Affiliation(s)
- Logan Trowbridge
- Department of Chemistry, Kansas State University, 1212 Mid-Campus Drive North, Manhattan, Kansas, 66503, USA
| | - Boris Averkiev
- Department of Chemistry, Kansas State University, 1212 Mid-Campus Drive North, Manhattan, Kansas, 66503, USA
| | - Peter E Sues
- Department of Chemistry, Kansas State University, 1212 Mid-Campus Drive North, Manhattan, Kansas, 66503, USA
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19
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Nguyen BX, Sonea A, Warren JJ. Further Understanding the Roles of Solvent, Brønsted Acids, and Hydrogen Bonding in Iron Porphyrin-Mediated Carbon Dioxide Reduction. Inorg Chem 2023; 62:17602-17611. [PMID: 37847220 DOI: 10.1021/acs.inorgchem.3c01855] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Improving our understanding of how molecules and materials mediate the electrochemical reduction of carbon dioxide (CO2) to upgraded products is of great interest as a means to address climate change. A leading class of molecules that can facilitate the electrochemical conversion of CO2 to carbon monoxide (CO) is iron porphyrins. These molecules can have high rate constants for CO2-to-CO conversion; they are robust, and they rely on abundant and inexpensive synthetic building blocks. Important foundational work has been conducted using chloroiron 5,10,15,20-tetraphenylporphyrin (FeTPPCl) in N,N-dimethylformamide (DMF) solvent. A related and recent report points out that the corresponding perchlorate complex, FeTPPClO4, can have superior function due to its solubility in other organic solvents. However, the importance of hydrogen bonding and solvent effects was not discussed. Herein, we present a detailed kinetic study of the triflate (CF3SO3-) complex of FeTPP in DMF and in MeCN using a range of phenol Brønsted acid additives. We also detected the formation of Fe(III)TPP-phenolate complexes using cyclic voltammetry experiments. Importantly, our new analysis of apparent rate constants with different added phenols allows for a modification to the established mechanistic model for CO2-to-CO conversion. Critically, our improved model accounts for hydrogen bonding and solvent effects by using simple hydrogen bond acidity and basicity descriptors. We use this augmented model to rationalize function in other reported porphyrin systems and to make predictions about operational conditions that can enhance the CO2 reduction chemistry.
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Affiliation(s)
- Bach Xuan Nguyen
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby V5A 1S6, British Columbia, Canada
| | - Ana Sonea
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby V5A 1S6, British Columbia, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby V5A 1S6, British Columbia, Canada
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20
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Laze L, Quevedo-Flores B, Bosque I, Gonzalez-Gomez JC. Alkanes in Minisci-Type Reaction under Photocatalytic Conditions with Hydrogen Evolution. Org Lett 2023. [PMID: 37819209 DOI: 10.1021/acs.orglett.3c02619] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
We report herein a protocol for the selective activation of C(sp3)-H bonds based on the interplay of two readily available organic catalysts and their successful implementation in cross-coupling azaarenes with alkanes. This Minisci-like reaction is promoted by visible light at room temperature and is free from chemical oxidants, metals, and chlorinated solvents. A wide range of substrates are compatible, including some bioactive molecules. Mechanistic studies support a dual catalytic cycle with H2 evolution.
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Affiliation(s)
- Loris Laze
- Instituto de Síntesis Orgánica (ISO) and Departamento de Química Orgánica, Universidad de Alicante, 03080 Alacant, Spain
| | - Beatriz Quevedo-Flores
- Instituto de Síntesis Orgánica (ISO) and Departamento de Química Orgánica, Universidad de Alicante, 03080 Alacant, Spain
| | - Irene Bosque
- Instituto de Síntesis Orgánica (ISO) and Departamento de Química Orgánica, Universidad de Alicante, 03080 Alacant, Spain
| | - Jose C Gonzalez-Gomez
- Instituto de Síntesis Orgánica (ISO) and Departamento de Química Orgánica, Universidad de Alicante, 03080 Alacant, Spain
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21
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Shen GB, Qian BC, Luo GZ, Fu YH, Zhu XQ. Thermodynamic Evaluations of Amines as Hydrides or Two Hydrogen Ions Reductants and Imines as Protons or Two Hydrogen Ions Acceptors, as Well as Their Application in Hydrogenation Reactions. ACS OMEGA 2023; 8:31984-31997. [PMID: 37692224 PMCID: PMC10483529 DOI: 10.1021/acsomega.3c03804] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/10/2023] [Indexed: 09/12/2023]
Abstract
Since the hydrogenation of imines (X) and the dehydrogenation of amines (XH2) generally involve the two hydrogen ions (H- + H+) transfer, the thermodynamic abilities of various amines releasing hydrides or two hydrogen ions as well as various imines accepting protons or two hydrogen ions are important and characteristic physical parameters. In this work, the pKa values of 84 protonated imines (XH+) in acetonitrile were predicted. Combining Gibbs free energy changes of amines releasing hydrides in acetonitrile from our previous work with the pKa(XH+) values, the Gibbs free energy changes of amines releasing two hydrogen ions and imines accepting two hydrogen ions were derived using Hess's law by constructing thermochemical cycles, and the thermodynamic evaluations of amines as hydrides or two hydrogen ions reductants and imines as protons or two hydrogen ions acceptors are well compared and discussed. Eventually, the practical application of thermodynamic data for amines and imines on hydrogenation feasibility, mechanism, and possible elementary steps was shown and discussed in this paper from the point of thermodynamics.
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Affiliation(s)
- Guang-Bin Shen
- School
of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Bao-Chen Qian
- School
of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Guang-Ze Luo
- School
of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Yan-Hua Fu
- College
of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan 455000, China
| | - Xiao-Qing Zhu
- The
State Key Laboratory of Elemento-Organic Chemistry, Department of
Chemistry, Nankai University, Tianjin 300071, China
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22
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Dale HA, Hodges GR, Lloyd-Jones GC. Kinetics and Mechanism of Azole n-π*-Catalyzed Amine Acylation. J Am Chem Soc 2023; 145:18126-18140. [PMID: 37526380 PMCID: PMC10436283 DOI: 10.1021/jacs.3c06258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Indexed: 08/02/2023]
Abstract
Azole anions are highly competent in the activation of weak acyl donors, but, unlike neutral (aprotic) Lewis bases, are not yet widely applied as acylation catalysts. Using a combination of in situ and stopped-flow 1H/19F NMR spectroscopy, kinetics, isotopic labeling, 1H DOSY, and electronic structure calculations, we have investigated azole-catalyzed aminolysis of p-fluorophenyl acetate. The global kinetics have been elucidated under four sets of conditions, and the key elementary steps underpinning catalysis deconvoluted using a range of intermediates and transition state probes. While all evidence points to an overarching mechanism involving n-π* catalysis via N-acylated azole intermediates, a diverse array of kinetic regimes emerges from this framework. Even seemingly minor changes to the solvent, auxiliary base, or azole catalyst can elicit profound changes in the temporal evolution, thermal sensitivity, and progressive inhibition of catalysis. These observations can only be rationalized by taking a holistic view of the mechanism and a set of limiting regimes for the kinetics. Overall, the analysis of 18 azole catalysts spanning nearly 10 orders of magnitude in acidity highlights the pitfall of pursuing ever more nucleophilic catalysts without regard for catalyst speciation.
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Affiliation(s)
- Harvey
J. A. Dale
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
| | - George R. Hodges
- Jealott’s
Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42 6EY, U.K.
| | - Guy C. Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
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23
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Skavenborg ML, Møller MS, Mossin S, Waite TD, McKenzie CJ. Sulfonamido-Pincer Complexes of Cu(II) and the Electrocatalysis of O 2 Reduction. Inorg Chem 2023; 62:12741-12749. [PMID: 37535840 DOI: 10.1021/acs.inorgchem.3c01262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
Heteroleptic copper complexes of an asymmetrical pincer ligand containing a central anionic sulfonamide donor (pyridine-2-yl-sulfonyl)(quinolin-8-yl)-amide (psq), which contains a central anionic sulfonamido donor have been prepared. Meridional κ3-N,N″,N‴ binding with the co-ligands acetate, chloride, or acetonitrile (MeCN), trans to the central sulfonamido N-donor, is revealed by the X-ray crystal structures of [Cu(OAc)(psq)(H2O)], [CuCl(psq)]2, and [Cu(psq)(MeCN)](PF6). Either overall distorted square pyramidal or octahedral geometries of the copper atom are satisfied by coordinated water in the case of the acetate complex or interactions with periphery sulfonamido oxygen atoms on adjacent molecules in the dimeric chloride and 1D polymeric acetonitrile complexes. The cyclic voltammogram (CV) of [Cu(OAc)(psq)(H2O)] shows a quasi-reversible CuII/CuI reduction at -0.930 V (vs Fc+/Fc0, MeCN), and an irreversible CuII/CuI reduction for [Cu(psq)(MeCN)](PF6) is seen at -0.838 V. This signal is split into two quasi-reversible redox processes on the addition of 2,2,2-trifluoroethanol (TFE). This suggests that TFE pushes a solution equilibrium toward a dimeric acetate complex analogous to [CuCl(psq)]2, which shows two quasi-reversible waves at -0.666 V and -0.904 V vs Fc+/Fc0 consistent with its dimeric solid-state structure. A comparison of the CVs of [Cu(OAc)(psq)(H2O)] under either a N2 or an O2 atmosphere revealed that this complex catalyzes turnover electro-reduction of O2 to H2O2 and H2O. The rate of reaction increases on addition of a weak organic acid, and a coulombic efficiency of 48% for H2O2 was determined by iodometric titration. We propose that a CuI complex formed on electroreduction binds O2 to yield an intermediate superoxide complex. On electron and proton transfer to this species, a bifurcated route back to the O2-activating CuI complex is feasible with either release of H2O2 or O-O cleavage resulting in the liberation of H2O. The CuI complex is regenerated by subsequent reduction and protonation to close the cycle.
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Affiliation(s)
- Mathias L Skavenborg
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
- Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Mads Sondrup Møller
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
| | - Susanne Mossin
- Department of Chemistry, Technical University of Denmark, Kemitorvet, Building 207, 2800 Kgs Lyngby, Denmark
| | - T David Waite
- Water Research Centre, School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052, Australia
| | - Christine J McKenzie
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, 5230 Odense M, Denmark
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24
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Xue J, Zhang YS, Huan Z, Yang JD, Cheng JP. Deoxygenation of Phosphine Oxides by P III/P V═O Redox Catalysis via Successive Isodesmic Reactions. J Am Chem Soc 2023. [PMID: 37410888 DOI: 10.1021/jacs.3c05270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
Deoxygenation of phosphine oxides is of great significance to synthesis of phosphorus ligands and relevant catalysts, as well as to the sustainability of phosphorus chemistry. However, the thermodynamic inertness of P═O bonds poses a severe challenge to their reduction. Previous approaches in this regard rely primarily on a type of P═O bond activation with either Lewis/Brønsted acids or stoichiometric halogenating reagents under harsh conditions. Here, we wish to report a novel catalytic strategy for facile and efficient deoxygenation of phosphine oxides via successive isodesmic reactions, whose thermodynamic driving force for breaking the strong P═O bond was compensated by a synchronous formation of another P═O bond. The reaction was enabled by PIII/P═O redox sequences with the cyclic organophosphorus catalyst and terminal reductant PhSiH3. This catalytic reaction avoids the use of the stoichiometric activator as in other cases and features a broad substrate scope, excellent reactivities, and mild reaction conditions. Preliminary thermodynamic and mechanistic investigations disclosed a dual synergistic role of the catalyst.
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Affiliation(s)
- Jing Xue
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yu-Shan Zhang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Zhen Huan
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Dong Yang
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Pei Cheng
- Center of Basic Molecular Science (CBMS), Department of Chemistry, Tsinghua University, Beijing 100084, China
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
- Haihe Laboratory of Sustainable Chemical Transformations, Tianjin 300192, China
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25
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Dalligos D, Pilling MJ, Dimitrakis G, Ball LT. Coaxial Dielectric Spectroscopy as an In-Line Process Analytical Technique for Reaction Monitoring. Org Process Res Dev 2023; 27:1094-1103. [PMID: 37342802 PMCID: PMC10278184 DOI: 10.1021/acs.oprd.3c00081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Indexed: 06/23/2023]
Abstract
The suitability of broadband dielectric spectroscopy (DS) as a tool for in-line (in situ) reaction monitoring is demonstrated. Using the esterification of 4-nitrophenol as a test-case, we show that multivariate analysis of time-resolved DS data-collected across a wide frequency range with a coaxial dip-probe-allows reaction progress to be measured with both high precision and high accuracy. In addition to the workflows for data collection and analysis, we also establish a convenient method for rapidly assessing the applicability of DS to previously untested reactions or processes. We envisage that, given its orthogonality to other spectroscopic methods, its low cost, and its ease of implementation, DS will be a valuable addition to the process chemist's analytical toolbox.
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Affiliation(s)
- Desiree
M. Dalligos
- Department
of Chemical and Environmental Engineering, University of Nottingham, Coates Building, Nottingham NG7 2RD, U.K.
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
| | - Michael J. Pilling
- Chemical
Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield SK10 2NA, U.K.
| | - Georgios Dimitrakis
- Department
of Chemical and Environmental Engineering, University of Nottingham, Coates Building, Nottingham NG7 2RD, U.K.
| | - Liam T. Ball
- School
of Chemistry, University of Nottingham, Nottingham NG7 2RD, U.K.
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26
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Beamer AW, Buss JA. Synthesis, Structural Characterization, and CO 2 Reactivity of a Constitutionally Analogous Series of Tricopper Mono-, Di-, and Trihydrides. J Am Chem Soc 2023. [PMID: 37276588 DOI: 10.1021/jacs.3c04170] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The formation of hydrides at heterogeneous copper surfaces results in dramatic structural and reactivity changes, yet the morphologies of these materials and their respective roles in catalysis are not well understood. Of particular interest is the reactivity of heterogeneous copper hydrides with carbon dioxide (CO2), an early mechanistic branching point in the CO2 reduction reaction. Herein, we report the synthesis, characterization, and reactivity of tricopper compounds supported by a facially biased, chelating tris(carbene) ligand scaffold. This sterically bulky environment affords access to an isolable series of tricopper hydrides: [LCu3H]2+ (4), [LCu3H2]+ (3), and LCu3H3 (6). Single-crystal X-ray diffraction and solution NMR spectroscopy studies reveal both geometric flexibility within the Cu3 core and fluxionality of hydride ligands across the Cu3 cluster, providing both atomically precise experimental analogues of static surface species and emulating dynamic ligand behavior proposed for surfaces. Electronic structure calculations serve as a predictor of hydricity, which was likewise benchmarked experimentally via both protonolysis and hydride abstraction reactions. Increased hydride number (and commensurately lower cluster charge) results in more hydridic complexes, with a thermodynamic hydricity range spanning >30 kcal/mol. These thermochemical studies serve as an accurate predictor of CO2 reactivity. Together, this Cu3Hx series exhibits the structure/reactivity relationships proposed for catalytically active copper surfaces, validating the application of carefully designed molecular clusters toward elucidating mechanisms in surface science.
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Affiliation(s)
- Andrew W Beamer
- Willard Henry Dow Laboratory, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Joshua A Buss
- Willard Henry Dow Laboratory, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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27
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VanderWeide A, Prokopchuk DE. Cyclopentadienyl ring activation in organometallic chemistry and catalysis. Nat Rev Chem 2023:10.1038/s41570-023-00501-1. [PMID: 37258685 DOI: 10.1038/s41570-023-00501-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2023] [Indexed: 06/02/2023]
Abstract
The cyclopentadienyl (Cp) ligand is a cornerstone of modern organometallic chemistry. Since the discovery of ferrocene, the Cp ligand and its various derivatives have become foundational motifs in catalysis, medicine and materials science. Although largely considered an ancillary ligand for altering the stereoelectronic properties of transition metal centres, there is mounting evidence that the core Cp ring structure also serves as a reservoir for reactive protons (H+), hydrides (H-) or radical hydrogen (H•) atoms. This Review chronicles the field of Cp ring activation, highlighting the pivotal role that Cp ligands can have in electrocatalytic H2 production, N2 reduction, hydride transfer reactions and proton-coupled electron transfer.
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28
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Arslan E, Haslak ZP, Monard G, Dogan I, Aviyente V. Quantum Mechanical Prediction of Dissociation Constants for Thiazol-2-imine Derivatives. J Chem Inf Model 2023; 63:2992-3004. [PMID: 37126823 PMCID: PMC10207282 DOI: 10.1021/acs.jcim.2c01468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Indexed: 05/03/2023]
Abstract
As weak acids or bases, in solution, drug molecules are in either their ionized or nonionized states. A high degree of ionization is essential for good water solubility of a drug molecule and is required for drug-receptor interactions, whereas the nonionized form improves a drug's lipophilicity, allowing the ligand to cross the cell membrane. The penetration of a drug ligand through cell membranes is mainly governed by the pKa of the drug molecule and the membrane environment. In this study, with the aim of predicting the acetonitrile pKa's (pKa(MeCN)) of eight drug-like thiazol-2-imine derivatives, we propose a very accurate and computationally affordable protocol by using several quantum mechanical approaches. Benchmark studies were conducted on a set of training molecules, which were selected from the literature with known pKa(water) and pKa(MeCN). Highly well-correlated pKa values were obtained when the calculations were performed with the isodesmic method at the M062X/6-31G** level of theory in conjunction with SMD solvation model for nitrogen-containing heterocycles. Finally, experimentally unknown pKa(MeCN) values of eight thiazol-2-imine structures, which were previously synthesized by some of us, are proposed.
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Affiliation(s)
- Evrim Arslan
- Department
of Chemistry, Bogazici University, Bebek, 34342 Istanbul, Turkey
| | - Zeynep Pinar Haslak
- Department
of Chemistry, Bogazici University, Bebek, 34342 Istanbul, Turkey
- Université
de Reims Champagne-Ardenne, 51687 Reims, France
| | - Gérald Monard
- Université
de Lorraine, CNRS, LPCT, F-54000 Nancy, France
| | - Ilknur Dogan
- Department
of Chemistry, Bogazici University, Bebek, 34342 Istanbul, Turkey
| | - Viktorya Aviyente
- Department
of Chemistry, Bogazici University, Bebek, 34342 Istanbul, Turkey
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29
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Rodrigues ACB, Lopes SMM, Cunha C, Braz J, Pinho E Melo TMVD, Seixas de Melo JS, Pineiro M. The role of solvents and concentrations in the properties of oxime bearing A 2B corroles. Phys Chem Chem Phys 2023; 25:10263-10277. [PMID: 36919842 DOI: 10.1039/d2cp05941j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Abstract
A comprehensive study on the electronic spectral, photophysical and acid-base properties of phenyl- and methyl-oxime corrole derivatives and of triphenylcorrole (model corrole) has been performed, aiming to shed light on the existing species in the ground and excited states. Solvents and corrole concentration are found to govern the properties of the studied compounds and are determinants of their applicability in in vivo studies. In THF, the neutral corrole has two tautomeric forms (T1 and T2). In DMSO, the deprotonated form shows a characteristic long-wavelength Q band slightly shifted to blue when compared with the T1 tautomer and a higher fluorescence quantum yield. In ACN, with the increase of the corrole concentration formation of an aggregate due to homoconjugation (with dimer characteristics) is observed, and pioneeringly reported using UV-Vis and fluorescence studies and confirmed by carrying out titrations with TFA. The effect of the oxime group on the pK values of a corrole is found to influence the formation of a homoconjugate, namely by precluding its formation (at higher concentrations) when compared with the model corrole. TDDFT electronic quantum calculations support the experimental observations, namely the existence of tautomers and deprotonated species, with their respective electronic spectral features, further allowed proposing a structure for the homoconjugate complex in ACN. The characteristics of the oxime-corroles, namely a pK of ∼ 5, absorption and emission at ca. 650 nm and solvent dependent properties, make them good candidates for their use in biological systems either as probes, sensors, or as new sensitizers for photodynamic therapy.
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Affiliation(s)
- Ana Clara B Rodrigues
- University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
| | - Susana M M Lopes
- University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
| | - Carla Cunha
- University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
| | - João Braz
- University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
| | | | - J Sérgio Seixas de Melo
- University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
| | - Marta Pineiro
- University of Coimbra, CQC-IMS, Department of Chemistry, Rua Larga, 3004-535 Coimbra, Portugal.
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30
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Sarwa A, Białońska A, Garbicz M, Szyszko B. Plenates: Anion-Dependent Self-Assembly of the Pyrrole Cage Encapsulating Silver(I) Clusters. Chemistry 2023; 29:e202203850. [PMID: 36594926 DOI: 10.1002/chem.202203850] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/02/2023] [Accepted: 01/03/2023] [Indexed: 01/04/2023]
Abstract
The self-assembly of 2,5-diformylpyrrole, tris(2-aminoethyl)amine, and silver(I) yielded, depending on the size and basicity of the anion, new cascade complexes or plenates, that is, cryptates incorporating Agn n+ clusters. The nature of the product was counterion-dependent, and its formation was either driven by cascade anion binding or by argentophilic interactions stabilizing the cluster within the cavity. The reaction of plenates with tetrabutylammonium halides resulted in the protonation-coupled replacement of the Ag3 3+ with anion(s), yielding cascade cryptates.
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Affiliation(s)
- Aleksandra Sarwa
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383, Wrocław, Poland
| | - Agata Białońska
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383, Wrocław, Poland
| | - Mateusz Garbicz
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383, Wrocław, Poland
| | - Bartosz Szyszko
- Department of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383, Wrocław, Poland
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31
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Abstract
Homogeneous electrocatalysis has been well studied over the past several decades for the conversion of small molecules to useful products for green energy applications or as chemical feedstocks. However, in order for these catalyst systems to be used in industrial applications, their activity and stability must be improved. In naturally occurring enzymes, redox equivalents (electrons, often in a concerted manner with protons) are delivered to enzyme active sites by small molecules known as redox mediators (RMs). Inspired by this, co-electrocatalytic systems with homogeneous catalysts and RMs have been developed for the conversion of alcohols, nitrogen, unsaturated organic substrates, oxygen, and carbon dioxide. In these systems, the RMs have been shown to both increase the activity of the catalyst and shift selectivity to more desired products by altering catalytic cycles and/or avoiding high-energy intermediates. However, the area is currently underdeveloped and requires additional fundamental advancements in order to become a more general strategy. Here, we summarize the recent examples of homogeneous co-electrocatalysis and discuss possible future directions for the field.
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Affiliation(s)
- Amelia G Reid
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
| | - Charles W Machan
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
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32
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Huang T, Jiang H, Douglin JC, Chen Y, Yin S, Zhang J, Deng X, Wu H, Yin Y, Dekel DR, Guiver MD, Jiang Z. Single Solution-Phase Synthesis of Charged Covalent Organic Framework Nanosheets with High Volume Yield. Angew Chem Int Ed Engl 2023; 62:e202209306. [PMID: 36395246 DOI: 10.1002/anie.202209306] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 09/22/2022] [Accepted: 11/17/2022] [Indexed: 11/19/2022]
Abstract
Covalent organic framework nanosheets (COF-NSs) are emerging building blocks for functional materials, and their scalable fabrication is highly desirable. Current synthetic methods suffer from low volume yields resulting from confined on-surface/at-interface growth space and complex multiple-phase synthesis systems. Herein, we report the synthesis of charged COF-NSs in open space using a single-phase organic solution system, achieving magnitudes higher volume yields of up to 18.7 mg mL-1 . Charge-induced electrostatic repulsion forces enable in-plane anisotropic secondary growth from initial discrete and disordered polymers into large and crystalline COF-NSs. The charged COF-NS colloidal suspensions are cast into thin and compact proton exchange membranes (PEMs) with lamellar morphology and oriented crystallinity, displaying outstanding proton conductivity, negligible dimensional swelling, and good H2 /O2 fuel cell performance.
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Affiliation(s)
- Tong Huang
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.,State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, Tianjin, 300072, China.,State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, Nanjing, 210009, China
| | - Haifei Jiang
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China.,State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, Tianjin, 300072, China
| | - John C Douglin
- The Wolfson Department of Chemical Engineering, Technion, Israel Institute of Technology, Haifa, 3200003, Israel
| | - Yu Chen
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Shuoyao Yin
- State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, Tianjin, 300072, China
| | - Junfeng Zhang
- State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, Tianjin, 300072, China.,National Industry-Education Platform of Energy Storage, Tianjin University, Tianjin, 300072, China
| | - Xiaojuan Deng
- Analysis and Testing Center, Tianjin University, Tianjin, 300072, China
| | - Hong Wu
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
| | - Yan Yin
- State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, Tianjin, 300072, China.,National Industry-Education Platform of Energy Storage, Tianjin University, Tianjin, 300072, China
| | - Dario R Dekel
- The Wolfson Department of Chemical Engineering, Technion, Israel Institute of Technology, Haifa, 3200003, Israel.,The Nancy & Stephen Grand Technion Energy Program (GTEP), Technion, Israel Institute of Technology, Haifa, 3200003, Israel
| | - Michael D Guiver
- State Key Laboratory of Engines, School of Mechanical Engineering, Tianjin University, Tianjin, 300072, China.,National Industry-Education Platform of Energy Storage, Tianjin University, Tianjin, 300072, China
| | - Zhongyi Jiang
- Key Laboratory for Green Chemical Technology of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072, China
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33
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Thiele M, Rose T, Lõkov M, Stadtfeld S, Tshepelevitsh S, Parman E, Opara K, Wölper C, Leito I, Grimme S, Niemeyer J. Multifunctional Organocatalysts - Singly-Linked and Macrocyclic Bisphosphoric Acids for Asymmetric Phase-Transfer and Brønsted-Acid Catalysis. Chemistry 2023; 29:e202202953. [PMID: 36161384 PMCID: PMC10099347 DOI: 10.1002/chem.202202953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Indexed: 01/12/2023]
Abstract
The linking of phosphoric acids via covalent or mechanical bonds has proven to be a successful strategy for the design of novel organocatalysts. Here, we present the first systematic investigation of singly-linked and macrocyclic bisphosphoric acids, including their synthesis and their application in phase-transfer and Brønsted acid catalysis. We found that the novel bisphosphoric acids show dramatically increased enantioselectivities in comparison to their monophosphoric acid analogues. However, the nature, length and number of linkers has a profound influence on the enantioselectivities. In the asymmetric dearomative fluorination via phase-transfer catalysis, bisphosphoric acids with a single, rigid bisalkyne-linker give the best results with moderate to good enantiomeric excesses. In contrast, bisphosphoric acids with flexible linkers give excellent enantioselectivities in the transfer-hydrogenation of quinolines via cooperative Brønsted acid catalysis. In the latter case, sufficiently long linkers are needed for high stereoselectivities, as found experimentally and supported by DFT calculations.
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Affiliation(s)
- Maike Thiele
- Faculty of Chemistry (Organic Chemistry) and, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141, Essen, Germany
| | - Thomas Rose
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstrasse 4, 53115, Bonn, Germany
| | - Märt Lõkov
- University of Tartu, Institute of Chemistry, 14a Ravila str, 50411, Tartu, Estonia
| | - Sophia Stadtfeld
- Faculty of Chemistry (Organic Chemistry) and, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141, Essen, Germany
| | - Sofja Tshepelevitsh
- University of Tartu, Institute of Chemistry, 14a Ravila str, 50411, Tartu, Estonia
| | - Elisabeth Parman
- University of Tartu, Institute of Chemistry, 14a Ravila str, 50411, Tartu, Estonia
| | - Karina Opara
- Faculty of Chemistry (Organic Chemistry) and, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141, Essen, Germany
| | - Christoph Wölper
- Faculty of Chemistry, Inorganic Chemistry, University of Duisburg-Essen, 45141, Essen, Germany
| | - Ivo Leito
- University of Tartu, Institute of Chemistry, 14a Ravila str, 50411, Tartu, Estonia
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Rheinische Friedrich-Wilhelms-Universität Bonn, Beringstrasse 4, 53115, Bonn, Germany
| | - Jochen Niemeyer
- Faculty of Chemistry (Organic Chemistry) and, Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, 45141, Essen, Germany
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34
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Zhao X, Yang JD, Cheng JP. Revisiting the Electrochemistry of TEMPOH Analogues in Acetonitrile. J Org Chem 2023; 88:540-547. [PMID: 36573883 DOI: 10.1021/acs.joc.2c02537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Hydroxylamines, represented by 1-hydroxy-2,2,6,6-tetramethylpiperidine (TEMPOH), are widely involved as active species in various chemical and electrochemical oxidations. The electrochemical behavior of TEMPOH is crucial to understanding the mechanisms of TEMPO-mediated redox sequences. However, compared to abundant studies on TEMPOH electrochemistry in aqueous solutions, the sole value of its oxidation potential Eox(TEMPOH) in organic solutions was reported to be 0.7 V (vs Fc in acetonitrile), seemingly conflicting with experimentally observed facile oxidation of TEMPOH. Herein, the electrochemistry of TEMPOH derivatives in acetonitrile was revisited, featuring much smaller oxidation potentials (about 0 V) than literature ones. Acid/base effects and kinetic studies lent credibility to these new values. Such a 0.7 V energy discrepancy impelled us to review the thermodynamic properties and oxidation mechanisms of TEMPOH deduced from the old value.
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Affiliation(s)
- Xiao Zhao
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Dong Yang
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Pei Cheng
- Center of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China.,State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
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35
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Boyd EA, Peters JC. Sm(II)-Mediated Proton-Coupled Electron Transfer: Quantifying Very Weak N-H and O-H Homolytic Bond Strengths and Factors Controlling Them. J Am Chem Soc 2022; 144:21337-21346. [PMID: 36346706 PMCID: PMC10281198 DOI: 10.1021/jacs.2c09580] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Coordination of alcohols to the single-electron reductant samarium diiodide (SmI2) results in substantial O-H bond weakening, affording potent proton-coupled electron transfer (PCET) reagents. However, poorly defined speciation of SmI2 in tetrahydrofuran (THF)/alcohol mixtures limits reliable thermodynamic analyses of such systems. Rigorous determination of bond dissociation free energy (BDFE) values in such Sm systems, important to evaluating their reactivity profiles, motivates studies of model Sm systems where contributing factors can be teased apart. Here, a bulky and strongly chelating macrocyclic ligand ((tBu2ArOH)2Me2cyclam) maintains solubility, eliminates dimerization pathways, and facilitates clean electrochemical behavior in a well-defined functional model for the PCET reactivity of SmII with coordinating proton sources. Direct measurement of thermodynamic parameters enables reliable experimental estimation of the BDFEs in 2-pyrrolidone and MeOH complexes of ((tBu2ArO)2Me2cyclam)SmII, thereby revealing exceptionally weak N-H and O-H BDFEs of 27.2 and <24.1 kcal mol-1, respectively. Expanded thermochemical cycles reveal that this bond weakening stems from the very strongly reducing SmII center and the formation of strong SmIII-alkoxide (and -pyrrolidonate) interactions in the PCET products. We provide a detailed analysis comparing these BDFE values with those that have been put forward for SmI2 in THF in the presence of related proton donors. We suggest that BDFE values for the latter systems may in fact be appreciably higher than the system described herein. Finally, protonation and electrochemical reduction steps necessary for the regeneration of the PCET donors from SmIII-alkoxides are demonstrated, pointing to future strategies aimed at achieving (electro)catalytic turnover using SmII-based PCET reagents.
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Affiliation(s)
- Emily A Boyd
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
| | - Jonas C Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology (Caltech), Pasadena, California 91125, United States
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36
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Rüütel A, Tshepelevitsh S, Leito I. One Hundred Carboxylate Receptors. J Org Chem 2022; 87:14186-14193. [PMID: 36214741 DOI: 10.1021/acs.joc.2c01725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This work presents a compilation of binding constant (logKass) values in DMSO-d6/H2O (0.5% m/m) for a variety of receptors with 12 carboxylate anions (formate, acetate, lactate, pivalate, sorbate, hexanoate, benzoate, glyphosate, glucuronate, ibuprofen, naproxen, and ketoprofen). A total of 489 logKass values are listed for 100 anion receptor molecules. Most logKass values originate from previously published articles, along with some values for previously unpublished receptor molecules, spanning a workflow of 8 years. The purpose of this study is to serve as a comprehensive information source for selecting suitable receptor candidates to be used in practical carboxylate sensing applications, such as constructing ion-selective electrodes (ISE-s). To support such decision making, all receptors are presented together with lipophilicity (logPo/w) data.
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Affiliation(s)
- Alo Rüütel
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411Tartu, Estonia
| | - Sofja Tshepelevitsh
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411Tartu, Estonia
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411Tartu, Estonia
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37
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Apostle A, Fang S. Dissolve-spin: Desalting oligonucleotides for MALDI MS analysis. JOURNAL OF MASS SPECTROMETRY : JMS 2022; 57:e4893. [PMID: 36415947 DOI: 10.1002/jms.4893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/25/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Desalting oligonucleotides (ONs) for matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) analysis was achieved using a simple dissolve-spin approach. The ON is dissolved in an organic solvent. Insoluble salts are removed by centrifugation. ONs are highly polar molecules and are generally believed insoluble in organic solvents with moderate polarity such as acetonitrile (ACN), 1,4-dioxane, ethyl acetate, and THF. However, we found that in the presence of a suitable proton source such as pyridinium chloride, a quantity of ON that is sufficient for MALDI MS analysis could be dissolved. Because inorganic salts are insoluble in such relatively non-polar solvents, the finding can be utilized for desalting ONs for MALDI MS analysis. Comparisons of MS spectra of intentionally salted ONs that underwent the new desalting procedure with those that did not undergo the procedure provided unambiguous evidence that the desalting method is highly effective.
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Affiliation(s)
- Alexander Apostle
- Department of Chemistry and Health Research Institute, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931, USA
| | - Shiyue Fang
- Department of Chemistry and Health Research Institute, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49931, USA
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38
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Paired electrosynthesis in the CH3CN/CHal4 system: a one-pot procedure for diarylamines and N,N’-diarylbenzidines halogenation. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.141217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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39
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Jia SM, Huang YH, Wang ZL, Fan FX, Fan BH, Sun HX, Wang H, Wang F. Hydroamination of Unactivated Alkenes with Aliphatic Azides. J Am Chem Soc 2022; 144:16316-16324. [PMID: 36047787 DOI: 10.1021/jacs.2c07643] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We report here an efficient and highly diastereoselective intermolecular anti-Markovnikov hydroamination of unactivated alkenes with aliphatic azides in the presence of silane. The system tolerates a wide range of azides and alkenes and operates with alkene as limiting reagent. Mechanistic studies suggest a radical chain pathway that involves aminium radical formation, radical addition to alkenes and HAT from silane to β-aminium alkyl radical. The use of sterically bulky silane is proposed to contribute to the excellent diastereoselectivity for HAT. Computational analysis uncovers the reaction pathway of aliphatic azide activation with silyl radical for aminyl radical formation.
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Affiliation(s)
- Si-Ming Jia
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Yi-Hang Huang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Zhan-Lin Wang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Fang-Xu Fan
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Bo-Han Fan
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Hao-Xiang Sun
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Hao Wang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
| | - Fei Wang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China
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40
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Scharf MJ, List B. A Catalytic Asymmetric Pictet-Spengler Platform as a Biomimetic Diversification Strategy toward Naturally Occurring Alkaloids. J Am Chem Soc 2022; 144:15451-15456. [PMID: 35976162 PMCID: PMC9446894 DOI: 10.1021/jacs.2c06664] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
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Tetrahydroisoquinoline (THIQ) alkaloids constitute a
large and
diverse class of bioactive natural products, with the parent compounds
and related downstream biosynthetic secondary metabolites spanning
thousands of isolated structures. Chemoenzymatic synthetic approaches
toward the relevant THIQs rely on Pictet–Spenglerases such
as norcoclaurine synthase (NCS), the scope of which is strictly limited
to dopamine-related phenolic substrates. To overcome these limitations
in the context of chemical synthesis, we herein report asymmetric
Pictet–Spengler reactions of N-carbamoyl-β-arylethylamines
with diverse aldehydes toward enantioenriched THIQs. The obtained
products proved to be competent intermediates in the synthesis of
THIQ, aporphine, tetrahydroberberine, morphinan, and androcymbine
natural products. Novel catalyst design with regard to the stabilization
of cationic intermediates was crucial to accomplish high reactivity
while simultaneously achieving unprecedented stereoselectivity for
the reaction of biologically relevant substrates.
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Affiliation(s)
- Manuel J Scharf
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470Mülheim an der Ruhr, Germany
| | - Benjamin List
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470Mülheim an der Ruhr, Germany
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41
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Rahman Z, Rajbanshi M, Mahato M, Ghanta S, Kumar Das S. A phthalimide scaffold smart molecule for visualization of acid-base equilibrium and determination of acid dissociation constants in the non-aqueous medium. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.119365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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42
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El-Maiss J, Balakrishnan D, García CP. Universal control of proton concentration using an electrochemically generated acid compatible with miniaturization. NANOSCALE ADVANCES 2022; 4:3233-3242. [PMID: 36132824 PMCID: PMC9419449 DOI: 10.1039/d2na00275b] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/16/2022] [Indexed: 06/16/2023]
Abstract
Controlling locally produced acidity in miniaturized spaces is of high importance to manage simultaneous chemical reactions. Here, we present a platform that hosts miniaturized micro-reactors each one enabling electrochemical control of the acidity in ∼nL volumes. We demonstrated the local control of chemical reactions with the deprotection of strong acid labile groups in a region of 150 μm of diameter of upstanding glass using high proton concentrations (∼10-1 M) and the acidity contrasts between the cell region and the outside. We demonstrated accurate control of the proton concentration in aqueous and organic solvents and the control of chemical reactions in organic electrolytes achieved with a sulfonated tetrafluoroethylene-based membrane, which isolates the acid generating electrodes from the reagents in the solution. The quantitative control of the acidity by faradaic currents was demonstrated by the calibration of carboxyfluorescein adjusted with external titrations and with a tautomer transition occurring at pH 4.2. To the best of our knowledge, this platform shows the best control of acidity in the smallest volume reported so far.
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Affiliation(s)
- Janwa El-Maiss
- Nanomaterials Unit of the Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST) Belvaux L-4422 Luxembourg
| | - Divya Balakrishnan
- Nanomaterials Unit of the Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST) Belvaux L-4422 Luxembourg
| | - César Pascual García
- Nanomaterials Unit of the Materials Research and Technology Department, Luxembourg Institute of Science and Technology (LIST) Belvaux L-4422 Luxembourg
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43
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Sun R, Liu M, Wang P, Qin Y, Schnedermann C, Maher AG, Zheng SL, Liu S, Chen B, Zhang S, Dogutan DK, Lindsey JS, Nocera DG. Syntheses and Properties of Metalated Tetradehydrocorrins. Inorg Chem 2022; 61:12308-12317. [PMID: 35892197 DOI: 10.1021/acs.inorgchem.2c01642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The monoanionic tetrapyrrolic macrocycle B,C-tetradehydrocorrin (TDC) resides chemically between corroles and corrins. This chemical space remains largely unexplored due to a lack of reliable synthetic strategies. We now report the preparation and characterization of Co(II)- and Ni(II)-metalated TDC derivatives ([Co-TDC]+ and [Ni-TDC]+, respectively) with a combination of crystallographic, electrochemical, computational, and spectroscopic techniques. [Ni-TDC]+ was found to undergo primarily ligand-centered electrochemical reduction, leading to hydrogenation of the macrocycle under cathodic electrolysis in the presence of acid. Transient absorption (TA) spectroscopy reveals that [Ni-TDC]+ and the two-electron-reduced [Ni-TDC]- possess long-lived excited states, whereas the excited state of singly reduced [Ni-TDC] exhibits picosecond dynamics. The Co(I) compound [Co-TDC] is air stable, highlighting the notable property of the TDC ligand to stabilize low-valent metal centers in contradistinction to other tetrapyrroles such as corroles, which typically stabilize metals in higher oxidation states.
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Affiliation(s)
- Rui Sun
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Mengran Liu
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Pengzhi Wang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Yangzhong Qin
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Christoph Schnedermann
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Andrew G Maher
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Shao-Liang Zheng
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Sijia Liu
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Boyang Chen
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Shaofei Zhang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Dilek K Dogutan
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
| | - Jonathan S Lindsey
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Daniel G Nocera
- Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
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44
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Fokin I, Kuessner KT, Siewert I. Electroreduction of Carbonyl Compounds Catalyzed by a Manganese Complex. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Igor Fokin
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
| | - Kai-Thorben Kuessner
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
| | - Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
- Universität Göttingen, International Center for Advanced Energy Studies, Tammannstr. 4, 37077 Göttingen, Germany
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45
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Lin L, Spasyuk DM, Lalancette RA, Prokopchuk DE. Coordination-Induced Weakening of a C(sp 3)-H Bond: Homolytic and Heterolytic Bond Strength of a CH-Ni Agostic Interaction. J Am Chem Soc 2022; 144:12632-12637. [PMID: 35786956 DOI: 10.1021/jacs.2c05667] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The scission of a C(sp3)-H bond to form a new metal-alkyl bond is a fundamental step in coordination chemistry and catalysis. However, the extent of C-H bond weakening when this moiety interacts with a transition metal is poorly understood and quantifying this phenomenon could provide insights into designing more efficient C-H functionalization catalysts. We present a nickel complex with a robust adamantyl reporter ligand that enables the measurement of C-H acidity (pKa) and bond dissociation free energy (BDFE) for a C(sp3)-H agostic interaction, showing a decrease in pKa by dozens of orders of magnitude and BDFE decrease of about 30 kcal/mol upon coordination. X-ray crystallographic data is provided for all molecules, including a distorted square planar NiIII metalloradical and "doubly agostic" NiII(κ2-CH2) complex.
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Affiliation(s)
- Lirong Lin
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Denis M Spasyuk
- Canadian Light Source, 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N2V3, Canada
| | - Roger A Lalancette
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
| | - Demyan E Prokopchuk
- Department of Chemistry, Rutgers University-Newark, 73 Warren Street, Newark, New Jersey 07102, United States
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46
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Sülzner N, Haberhauer J, Hättig C, Hellweg A. Prediction of acid pK a values in the solvent acetone based on COSMO-RS. J Comput Chem 2022; 43:1011-1022. [PMID: 35460090 DOI: 10.1002/jcc.26864] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/25/2022] [Accepted: 03/29/2022] [Indexed: 11/08/2022]
Abstract
In this contribution we extent the use of the conductor-like screening model for realistic solvation (COSMO-RS) to the prediction of pKa values in acetone, a commonly used dipolar aprotic solvent. For this, we calculated the Gibbs free energy of dissociation of 120 organic acids (nine acrylic acids, 87 benzoic acids, nine phenols, and 15 benzenesulfonamides) using COSMO-RS at the two levels BP-TZVP and BP-TZVPD-FINE and determined the parameters for a linear free energy relation for the p K a prediction by performing linear fits to experimental values. Our results suggest that the data set dissects into two groups, with the phenols being different from the other three subsets. The acrylic and benzoic acids and the sulfonamides can be treated together and yield an excellent linear correlation ( r 2 > 0.95 ) with an RMSD of only ~0.3. The slope is found to be significantly smaller than the theoretical value ( 1 / RT ln 10 ), only 45% of it, which is in accordance with findings in the literature. The phenols, however, while similarly well correlated in their own subset with an RMSD of 1.7-1.9, exhibit a slope larger than one. We discuss both a higher uncertainty in the reference values as well as physical origins as possible reasons.
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Affiliation(s)
- Niklas Sülzner
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, 44780, Germany
| | - Julia Haberhauer
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, 44780, Germany
| | - Christof Hättig
- Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, Bochum, 44780, Germany
| | - Arnim Hellweg
- Dassault Systèmes Deutschland GmbH, Am Kabellager 11-15, Köln, 51063, Germany
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47
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Akyeva AY, Kansuzyan AV, Vukich KS, Kuhn L, Saverina EA, Minyaev ME, Pechennikov VM, Egorov MP, Alabugin IV, Vorobyev SV, Syroeshkin MA. Remote Stereoelectronic Effects in Pyrrolidone- and Caprolactam-Substituted Phenols: Discrepancies in Antioxidant Properties Evaluated by Electrochemical Oxidation and H-Atom Transfer Reactivity. J Org Chem 2022; 87:5371-5384. [PMID: 35363496 DOI: 10.1021/acs.joc.2c00207] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
New antioxidants are commonly evaluated via two main approaches, i.e., the ability to donate an electron and the ability to intercept free radicals. We compared these approaches by evaluating the properties of 11 compounds containing both antioxidant moieties (mono- and polyphenols) and auxiliary pharmacophores (pyrrolidone and caprolactam). Several common antioxidants, such as butylated hydroxytoluene (BHT), 2,3,5-trimethylphenol (TMP), quercetin, and dihydroquercetin, were added for comparison. The antioxidant properties of these compounds were determined by their rates of reaction with 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and their oxidation potentials from cyclic voltammetry. Although these methods test different chemical properties, their results correlate reasonably well. However, several exceptions exist where the two methods give opposite predictions! One of them is the different behavior of mono- and polyphenols: polyphenols can react with DPPH more than an order of magnitude faster than monophenols of a similar oxidation potential. The second exception stems from the size of a "bystander" lactam ring at the benzylic position. Although the phenols with a seven-membered lactam ring are harder to oxidize, the sterically nonhindered compounds react with DPPH about 2× faster than the analogous five-membered lactams. The limitations of computational methods, especially those based on a single parameter, are also evaluated and discussed.
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Affiliation(s)
- Anna Ya Akyeva
- N.D. Zelinsky Institute of Organic Chemistry, 119991 Moscow Russia
| | | | - Katarina S Vukich
- N.D. Zelinsky Institute of Organic Chemistry, 119991 Moscow Russia.,I.M. Sechenov First Moscow State Medical University, 119991 Moscow, Russia
| | - Leah Kuhn
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | | | | | | | - Mikhail P Egorov
- N.D. Zelinsky Institute of Organic Chemistry, 119991 Moscow Russia
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Stepan V Vorobyev
- Gubkin Russian State University of Oil and Gas, 65 Leninsky Prospect, 119991 Moscow, Russia
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48
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Wootten MM, Le Bailly BAF, Tshepelevitsh S, Leito I, Clayden J. Inducing a pH-dependent conformational response by competitive binding to Zn 2+ of a series of chiral ligands of disparate basicity. Chem Sci 2022; 13:2258-2269. [PMID: 35310487 PMCID: PMC8864710 DOI: 10.1039/d1sc06812a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/09/2022] [Indexed: 12/24/2022] Open
Abstract
Molecules that change shape in response to environmental conditions are central to biological molecular communication devices and their synthetic chemical analogues. Here we report a molecular system in which a series of chiral anionic ligands of differing basicity are selectively protonated according to the pH of the medium. A cationic circular dichroism (CD) reporter complex responds to anion binding by selecting one of two alternative enantiomeric conformations. Exploiting the principle that less basic anions have, in general, weaker electrostatic interactions than more basic anions, a set of three chiral acids with large (>5 unit) pKa differences and differing configurations were sequentially deprotonated in acetonitrile by addition of base, allowing the most basic anion in the mixture at any time to bind to the reporter complex. A characteristic CD output resulted, which changed in sign as the next-most basic anion was revealed by the next deprotonation in the series. Four cycles of switching between three ligand-bound states were achieved with minimal changes in signal magnitude, by alternating addition of base and acid. The pH-dependent conformational response was used to transduce a signal by appending to the binding site a 2-aminoisobutyric acid (Aib) oligomer, whose M or P helical conformation depended on the chirality of the bound ligand, and was reported by a remote 13C-labelled NMR reporter group. The multicomponent system thus converts a pH signal into a programmable conformational response which induces a remote spectroscopic effect. A chemical system comprising a series of chiral acids of differing pKa, a metal, and a conformationally labile chromophore responds to pH with a CD spectrum that reports the absolute stereochemistry of the most basic anion in the mixture.![]()
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Affiliation(s)
- Matthew M Wootten
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | | | | | - Ivo Leito
- Institute of Chemistry, University of Tartu Ravila 14a Tartu 50411 Estonia
| | - Jonathan Clayden
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
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49
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Leesment A, Selberg S, Tammiste M, Vu AH, Nguyen TH, Taylor-King L, Leito I. Quantifying Acidity in Heterogeneous Systems: Biphasic p Ka Values. Anal Chem 2022; 94:4059-4064. [PMID: 35195999 DOI: 10.1021/acs.analchem.1c05510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Acidities of lipophilic compounds, such as various ligands or catalysts, in systems consisting of an aqueous phase at equilibrium with a water-immiscible phase (lipid bilayers, phase transfer catalysis, sensor membranes, to name just few) are typically approximated by the aqueous pKa values. Our research shows that such approximations can lead to seriously biased estimations of the acidities as the bulk of solvated H+ ions reside in the aqueous phase, while the lipophilic species─both neutral acid and anion─predominantly reside in the organic phase. Therefore, the use of aqueous pKa in such situations is not justified. In this work, we provide a more accurate description of the acidities of acids in such systems by applying the biphasic pKa concept. Biphasic pKa values (pKaow values) of 35 acids of various structures and chemical properties were determined in a 1-octanol:water system. We provide detailed descriptions of the UV-vis and NMR measurement methods. The directly obtained (apparent) pKaow values depend on concentration. Concentration-independent values were obtained by extrapolating the apparent values to zero concentration using a Debye-Hückel model.
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Affiliation(s)
- Andre Leesment
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Sigrid Selberg
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Merili Tammiste
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Anh Hai Vu
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.,Department of Chemistry, Biomedical Center (BMC), Uppsala University, 75124 Uppsala, Sweden
| | - Thuong Hoai Nguyen
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.,Université Claude Bernard Lyon 1, B222, Batiment B, Puvis de Monod, 23 rue Marguerite, 69100 Villeurbanne, France
| | - Luke Taylor-King
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia.,Department of Chemistry, University of Liverpool, Crown Street, L69 7ZD Liverpool, United Kingdom
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
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50
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Siewert I. Electrochemical CO 2 Reduction Catalyzed by Binuclear LRe 2(CO) 6Cl 2 and LMn 2(CO) 6Br 2 Complexes with an Internal Proton Source. Acc Chem Res 2022; 55:473-483. [PMID: 35077152 DOI: 10.1021/acs.accounts.1c00609] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The synthesis of certain commodity chemicals, e.g., methanol and acetic acid, relies on CO, which is currently mainly produced by the combustion of carbon or natural gas. Photo- or electrochemical conversion of atmospheric CO2 to CO represents an attractive alternative strategy as this approach is carbon-neutral. Such photo- or electrochemically formed CO can also be used in the Fischer-Tropsch process forming liquid hydrocarbons for energy storage applications. The multiple electroreduction of CO2 is preferably coupled with proton transfer steps as this requires less energy than the single outer-sphere 1e- reduction of CO2.In 1984 and 2011, it was shown that [(Lbpy)Re(CO)3Cl] (1) and [(Lbpy)Mn(CO)3Br] (2), respectively, mediate the electrochemical 2e-/2H+ reduction of CO2 forming CO and water (Lbpy = 2,2'-bipyridine). Since proton management is crucial for catalysis, recently the impact of internal proton sources close to the axial position in such complexes has been investigated. However, binuclear complexes have been used rarely as mediators although it has been shown very early for 1 that electron management is also important: the 2e-/2H+ reduction pathway with 1 exhibits a higher reaction rate than going via the singly reduced species, though the pathway requires a higher overpotential. In this Account, we focus on recent developments of binuclear LMn2(CO)6 and LRe2(CO)6 mediators with an internal phenol group in the electroreduction of CO2. In contrast to mononuclear derivatives, for which the impact of the internal proton source on catalysis is very diverse, we always observed a higher reaction rate and for the Mn complexes also a lower overpotential with the binuclear complexes compared to the mononuclear variants. Spectroscopic, electrochemical, and computational studies on the mono- and binuclear complexes shed light on their reactivity under reductive conditions, elucidated the structure of reduced species, unraveled the kinetics for catalytically productive and unproductive (side) reactions, and allowed us to derive some hypothesis on the CO2 reduction mechanism. Finally, I emphasize that the electrohydrogenation of the polar double bonds by the binuclear complex LMn2(CO)6 with a central phenol unit is not restricted to CO2 but is also applicable to organic compounds with C═O bonds.
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Affiliation(s)
- Inke Siewert
- Universität Göttingen, Institut für Anorganische Chemie, Tammannstr. 4, 37077 Göttingen, Germany
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