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Scharf MJ, Tsuji N, Lindner MM, Leutzsch M, Lõkov M, Parman E, Leito I, List B. Highly Acidic Electron-Rich Brønsted Acids Accelerate Asymmetric Pictet-Spengler Reactions by Virtue of Stabilizing Cation-π Interactions. J Am Chem Soc 2024. [PMID: 39361889 DOI: 10.1021/jacs.4c09421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2024]
Abstract
Electron-rich heteroaromatic imidodiphosphorimidates (IDPis) catalyze the asymmetric Pictet-Spengler reaction of N-carbamoyl-β-arylethylamines with high stereochemical precision. This particular class of catalysts furthermore provides a vital rate enhancement compared to related Brønsted acids. Here we present experimental studies on the underlying reaction kinetics that shed light on the specific origins of rate acceleration. Analysis of Hammett plots, kinetic isotope effects, reaction orders, Eyring plots, and isotopic scrambling experiments, allowed us to gather insights into the molecular interactions between the chiral Brønsted acid and catalytically formed intermediates. Based on rigorously determined pKa values as well as the experimental evidence, we propose that attractive intermolecular forces offered by electron-rich π-surfaces of the chiral counteranion enthalpically stabilize cationic intermediates and transition states by way of cation-π interactions. This view is furthermore supported by in-depth density functional theory calculations. Our deepened understanding of the reaction mechanism allowed us to develop a method for accessing 1-aryltetrahydroisoquinolines from aromatic dimethyl acetals, a substrate class that was thus far inaccessible via catalytic asymmetric Pictet-Spengler reactions.
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Affiliation(s)
- Manuel J Scharf
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Nobuya Tsuji
- Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo 001-0021, Japan
| | - Monika M Lindner
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Markus Leutzsch
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
| | - Märt Lõkov
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Elisabeth Parman
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Tartu 50411, Estonia
| | - Benjamin List
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr 45470, Germany
- Institute for Chemical Reaction Design and Discovery, Hokkaido University, Sapporo 001-0021, Japan
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2
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Shen Y, Zhang Y, Zhang C, Li H, Hu C, Yu Z, Zheng K, Su Z. Elucidating Mechanism and Selectivity in Pyridine Functionalization Through Silylium Catalysis. Chemistry 2024; 30:e202402078. [PMID: 38976314 DOI: 10.1002/chem.202402078] [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: 05/28/2024] [Revised: 07/05/2024] [Accepted: 07/08/2024] [Indexed: 07/09/2024]
Abstract
The functionalization of aromatic N-heterocycles through silylium activation demonstrates exceptional selectivity and efficiency. Density functional theory (DFT) calculations unveil the detailed silylium catalysis mechanism and elucidate the origins of selectivity in this reaction. The phosphoramidimidate sulfonamide (PADI) precatalyst orchestrates of the catalytic cycle via three elementary steps. The Brønsted acidity of precatalyst significantly influences both the formation of silylium-based Lewis acid active species and the silylium activation of pyridine. Unlike disulfonimide (DSI)-type precatalysts, both Tf2NH and PADI precatalysts with strong acidities can easily promote the generation of activated silylium pyridine species. A semi-enclosed 'rigid' electronegative cavity in PADI-type anions constructs a well-defined recognition site, facilitating engagement with the positively charged silylium pyridine species. Due to the high electrophilicity and less steric demand at the C4-position of the pyridine substrate, the product with C4-regioselectivity was predominantly generated.
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Affiliation(s)
- Yanling Shen
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Yan Zhang
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Cefei Zhang
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Haoze Li
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Changwei Hu
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Zhipeng Yu
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Ke Zheng
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
| | - Zhishan Su
- Key Laboratory of Green Chemistry & Technology, Ministry of Education College of Chemistry, Sichuan University, Chengdu, 610064, P. R. China
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3
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Gillhuber S, Holloway JO, Mundsinger K, Kammerer JA, Harmer JR, Frisch H, Barner-Kowollik C, Roesky PW. Visible light photoflow synthesis of a Cu(ii) single-chain polymer nanoparticle catalyst. Chem Sci 2024:d4sc03079f. [PMID: 39246378 PMCID: PMC11376198 DOI: 10.1039/d4sc03079f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2024] [Accepted: 08/14/2024] [Indexed: 09/10/2024] Open
Abstract
We herein pioneer the visible light (λ max = 410 nm) mediated flow synthesis of catalytically active single-chain nanoparticles (SCNPs). Our design approach is based on a copolymer of poly(ethylene glycol) methyl ether methacrylate and a photocleavable 2-((((2-nitrobenzyl)oxy)carbonyl)amino)ethyl methacrylate monomer which can liberate amine groups upon visible light irradiation, allowing for single-chain collapse via the complexation of Cu(ii) ions. We initially demonstrate the successful applicability of our design approach for the batch photochemical synthesis of Cu(ii) SCNPs and transfer the concept to photoflow conditions, enabling, for the first time, the continuous production of functional SCNPs. Critically, we explore their ability to function as a photocatalyst for the cleavage of carbon-carbon single and double bonds on the examples of xanthene-9-carboxylic acid and oleic acid, demonstrating the advantageous effect SCNPs can provide over analogous small molecule catalysts.
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Affiliation(s)
- Sebastian Gillhuber
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT) Engesserstraße 15 76131 Karlsruhe Germany
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
| | - Joshua O Holloway
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
| | - Kai Mundsinger
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
| | - Jochen A Kammerer
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
| | - Jeffrey R Harmer
- Centre for Advanced Imaging, The University of Queensland (UQ) Building 57 Research Road 4072 Brisbane QLD Australia
| | - Hendrik Frisch
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
| | - Christopher Barner-Kowollik
- School of Chemistry and Physics, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Centre for Materials Science, Queensland University of Technology (QUT) 2 George Street 4000 Brisbane QLD Australia
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
| | - Peter W Roesky
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT) Engesserstraße 15 76131 Karlsruhe Germany
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT) Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
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4
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Pikma ML, Tshepelevitsh S, Selberg S, Kaljurand I, Leito I, Kütt A. p KaH values and θH angles of phosphanes to predict their electronic and steric parameters. Dalton Trans 2024; 53:14226-14236. [PMID: 39129417 DOI: 10.1039/d4dt01430h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
Phosphanes play an important role in various applications, serving as a class of organic bases with basicities spanning more than 30 orders of magnitude. Accessing comprehensive basicity data for phosphanes has been challenging due to scattered information across multiple sources and notable gaps in the existing data. In this report, we present basicities (pKaH values) of a diverse set of phosphanes, both newly measured or calculated and collected from the literature. We demonstrate that pKaH values can serve as an alternative to Tolman electronic parameters (TEP values) in evaluating the electronic properties of phosphanes. Additionally, we suggest parameters for assessing the steric properties of phosphanes without the need for preparation or calculation of metal-ligand complexes.
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Affiliation(s)
- Marta-Lisette Pikma
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.
| | - Sofja Tshepelevitsh
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.
| | - Sigrid Selberg
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.
| | - Ivari Kaljurand
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.
| | - Agnes Kütt
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia.
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Díaz-Ruiz M, Nieto-Rodríguez M, Maseras F. Revealing the Mechanistic Features of an Electrosynthetic Catalytic Reaction and the Role of Redox Mediators through DFT Calculations and Microkinetic Modeling. Chemphyschem 2024; 25:e202400402. [PMID: 38739104 DOI: 10.1002/cphc.202400402] [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: 04/09/2024] [Revised: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 05/14/2024]
Abstract
Organic electrosynthesis is an emerging field that provides original selectivity while adding features of atom economy, sustainability, and selectivity. Electrosynthesis is often enhanced by redox mediators or electroauxiliaries. The mechanistic understanding of organic electrosynthesis is however often limited by the low lifetime of intermediates and its difficult detection. In this work, we report a computational analysis of the mechanism of an appealing reaction previously reported by Mei and co-workers which is catalyzed by copper and employs iodide as redox mediator. Our scheme combines DFT calculations with microkinetic modeling and covers both the reaction in solution and the electrodic steps. A detailed mechanistic scheme is obtained which reproduces well experimental data and opens perspectives for the general treatment of these processes.
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Affiliation(s)
- Marina Díaz-Ruiz
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Avgda. Països, Catalans 16, 43007, Tarragona, Spain
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel⋅lí Domingo s/n, Tarragona, 43007, Spain
| | - Marc Nieto-Rodríguez
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Avgda. Països, Catalans 16, 43007, Tarragona, Spain
- Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel⋅lí Domingo s/n, Tarragona, 43007, Spain
| | - Feliu Maseras
- Institute of Chemical Research of Catalonia (ICIQ-CERCA), The Barcelona Institute of Science and Technology, Avgda. Països, Catalans 16, 43007, Tarragona, Spain
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6
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Obisesan SV, Parvin M, Tao M, Ramos E, Saunders AC, Farnum BH, Goldsmith CR. Installing Quinol Proton/Electron Mediators onto Non-Heme Iron Complexes Enables Them to Electrocatalytically Reduce O 2 to H 2O at High Rates and Low Overpotentials. Inorg Chem 2024; 63:14126-14141. [PMID: 39008564 DOI: 10.1021/acs.inorgchem.4c01977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/17/2024]
Abstract
We prepare iron(II) and iron(III) complexes with polydentate ligands that contain quinols, which can act as electron proton transfer mediators. Although the iron(II) complex with N-(2,5-dihydroxybenzyl)-N,N',N'-tris(2-pyridinylmethyl)-1,2-ethanediamine (H2qp1) is inactive as an electrocatalyst, iron complexes with N,N'-bis(2,5-dihydroxybenzyl)-N,N'-bis(2-pyridinylmethyl)-1,2-ethanediamine (H4qp2) and N-(2,5-dihydroxybenzyl)-N,N'-bis(2-pyridinylmethyl)-1,2-ethanediamine (H2qp3) were found to be much more active and more selective for water production than a previously reported cobalt-H2qp1 electrocatalyst while operating at low overpotentials. The catalysts with H2qp3 can enter the catalytic cycle as either Fe(II) or Fe(III) species; entering the cycle through Fe(III) lowers the effective overpotential. On the basis of their TOF0 values, the successful iron-quinol complexes are better electrocatalysts for oxygen reduction than previously reported iron-porphyrin compounds, with the Fe(III)-H2qp3 arguably being the best homogeneous electrocatalyst for this reaction. With iron, the quinol-for-phenol substitution shifts the product selectivity from H2O2 to water with little impact on the overpotential, but unlike cobalt, this substitution also greatly improves the activity, as assessed by TOFmax, by hastening the protonation and oxygen binding steps. The addition of a second quinol further enhances the activity and selectivity for water but modestly increases the effective overpotential.
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Affiliation(s)
- Segun V Obisesan
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Maksuda Parvin
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Matthew Tao
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Eric Ramos
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Alexander C Saunders
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Byron H Farnum
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
| | - Christian R Goldsmith
- Department of Chemistry and Biochemistry, Auburn University, Auburn, Alabama 36849, United States
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7
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Lee Y, Moon D, Cho J. Controlling Redox Potential of a Manganese(III)-Bis(hydroxo) Complex through Protonation and the Hydrogen-Atom Transfer Reactivity. J Am Chem Soc 2024; 146:15796-15805. [PMID: 38829358 DOI: 10.1021/jacs.4c01927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2024]
Abstract
A series of mononuclear manganese(III)-hydroxo and -aqua complexes, [MnIII(TBDAP)(OH)2]+ (1), [MnIII(TBDAP)(OH)(OH2)]2+ (2) and [MnIII(TBDAP)(OH2)2]3+ (3), were prepared from a manganese(II) precursor and confirmed using various methods including X-ray crystallography. Thermodynamic analysis showed that protonation from hydroxo to aqua species resulted in increased redox potentials (E1/2) in the order of 1 (-0.15 V) < 2 (0.56 V) < 3 (1.11 V), while pKa values exhibited a reverse trend in the order of 3 (3.87) < 2 (11.84). Employing the Bordwell Equation, the O-H bond dissociation free energies (BDFE) of [MnII(TBDAP)(OH)(OH2)]+ and [MnII(TBDAP)(OH2)2]2+, related to the driving force of 1 and 2 in hydrogen atom transfer (HAT), were determined as 75.3 and 77.3 kcal mol-1, respectively. It was found that the thermodynamic driving force of 2 in HAT becomes greater than that of 1 as the redox potential of 2 increases through protonation from 1 to 2. Kinetic studies on electrophilic reactions using a variety of substrates revealed that 1 is only weakly reactive with O-H bonds, whereas 2 can activate aliphatic C-H bonds in addition to O-H bonds. The reaction rates increased by 1.4 × 104-fold for the O-H bonds by 2 over 1, which was explained by the difference in BDFE and the tunneling effect. Furthermore, 3, possessing the highest redox potential value, was found to undergo an aromatic C-H bond activation reaction under mild conditions. These results provide valuable insights into enhancing electrophilic reactivity by modulating the redox potential of manganese(III)-hydroxo and -aqua complexes through protonation.
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Affiliation(s)
- Yuri Lee
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Dohyun Moon
- Beamline Department, Pohang Accelerator Laboratory, Pohang 37673, Republic of Korea
| | - Jaeheung Cho
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
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Mahato M, Maiti A, Ahamed S, Rajbanshi M, Lama S, Das SK. Acid-base equilibrium in non-aqueous medium: colorimetric visualization, estimation of acidity constants and construction of molecular logic gates. RSC Adv 2024; 14:3480-3488. [PMID: 38259994 PMCID: PMC10801445 DOI: 10.1039/d3ra04696f] [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: 07/13/2023] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
A reversible acid-base probe, (N1E, N4E)-N1, N4-bis((Z)-3-(4-(dimethylamino)phenyl)allylidene)benzene-1,4-diamine (MM1), is introduced for the colorimetric visualization of acid-base equilibria in non-aqueous media. MM1 displays reversible acidochromic behavior, showing exciting colorimetric change varying from weak to strong acid. Also, we have fabricated a colorimetric paper strip-based test kit to visualize acid-base equilibria. A dipstick experiment has been demonstrated to visualize the acid-base equilibria in the gaseous state. This acid-base probe has also been employed to estimate the pKa values of several acidic compounds in a non-aqueous medium using overlapping indicator methods. Based on reversible acidochromic UV-visible absorption spectral and colorimetric behavior, we have constructed a reconfigurable dual input and dual output combinational logic circuit and set-reset memorized device employing acid and base as chemically encoded inputs and corresponding optical outputs. The current report evokes a new protocol for developing various reversible acidochromic probes and its implication for constructing opto-chemical molecular logic gates and estimating the acid dissociation constants of various acidic compounds in non-aqueous media.
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Affiliation(s)
- Manas Mahato
- Department of Chemistry, University of North Bengal Darjeeling West Bengal 734013 India
| | - Arpita Maiti
- Department of Chemistry, University of North Bengal Darjeeling West Bengal 734013 India
| | - Sabbir Ahamed
- Department of Chemistry, University of North Bengal Darjeeling West Bengal 734013 India
| | - Madan Rajbanshi
- Department of Chemistry, University of North Bengal Darjeeling West Bengal 734013 India
| | - Shubham Lama
- Department of Chemistry, University of North Bengal Darjeeling West Bengal 734013 India
| | - Sudhir Kumar Das
- Department of Chemistry, University of North Bengal Darjeeling West Bengal 734013 India
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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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10
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Pereira RW, Ramabhadran RO. Accurate Computation of Aqueous p Kas of Biologically Relevant Organic Acids: Overcoming the Challenges Posed by Multiple Conformers, Tautomeric Equilibria, and Disparate Functional Groups with the Fully Black-Box p K-Yay Method. J Phys Chem A 2023; 127:9121-9138. [PMID: 37862610 DOI: 10.1021/acs.jpca.3c02977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2023]
Abstract
The use of static electronic structure calculations to compute solution-phase pKas offers a great advantage in that a macroscopic bulk property could be computed via microscopic computations involving very few molecules. There are various sources of errors in the quantum chemical calculations though. Overcoming these errors to accurately compute pKas of a plethora of acids is an active area of research in physical chemistry pursued by both computational as well as experimental chemists. We recently developed the pK-Yay method in our attempt to accurately compute aqueous pKas of strong and weak acids. The method is fully black-box, computationally inexpensive, and is very easy for even a nonexpert to use. However, the method was thus far tested on very few molecules (only 16 in all). Herein, in order to assess the future applicability of pK-Yay, we study the effect of multiple conformers, the presence of tautomers under equilibrium, and the impact of a wide variety of functional groups (derivatives of acetic acid with substituents at various positions, dicarboxylic acids, aromatic carboxylic acids, amines and amides, phenols and thiols, and fluorine bearing organic acids). Starting with more than 1000 conformers and tautomers, this study establishes that overall errors of ∼ 1.0 pKa units are routinely obtained for a majority of the molecules. Larger errors are noted in cases where multiple charges, intramolecular hydrogen bonding, and several ionizable functional groups are simultaneously present. An important conclusion to emerge from this work is that, the computed pKas are insensitive (difference <0.5) to whether we consider multiple conformers/tautomers or only choose the most stable conformer/tautomer. Further, pK-Yay captures the stereoelectronic effects arising due to differing axial vs equatorial pattern, and is useful to predict the dominant acid-base equilibrium in a system featuring several equilibria. Overall, pK-Yay may be employed in several chemical applications featuring organic molecules and biomonomers.
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Affiliation(s)
- Roshni W Pereira
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Andhra Pradesh 517507, India
- Centre for Atomic Molecular Optical Sciences and Technology (CAMOST), Tirupati, Andhra Pradesh 517507, India
| | - Raghunath O Ramabhadran
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Tirupati, Andhra Pradesh 517507, India
- Centre for Atomic Molecular Optical Sciences and Technology (CAMOST), Tirupati, Andhra Pradesh 517507, India
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11
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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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12
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Rodrigues PF, Moscovici BK, Hoehne JL, Campos MSDQ, Morandim-Giannetti ADA, Bersanetti PA, Nosé W. Spectrophotometric Analysis of Different Polymethyl Methacrylate Filters and their Importance in the Implantation of Corneal Rings. Curr Eye Res 2023; 48:731-735. [PMID: 37092541 DOI: 10.1080/02713683.2023.2202365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 03/15/2023] [Accepted: 04/09/2023] [Indexed: 04/25/2023]
Abstract
PURPOSE This study evaluated the luminous behavior applied to materials used in intraocular surgeries. METHODS Discs of the different products were delivered in 19.00 mm × 3.00 mm. Each sample was fixed on support keeping it perpendicular to the spectrophotometer beam. Later, their analyses were carried out in the air/PMMA ratio. The graphs of individual profiles of the measurements along the length were constructed according to each of the filters from the spectrophotometric analysis. In addition, descriptive statistics of transmittance and absorbance for each wavelength presented were correlated for each filter. RESULTS It is possible to observe that the minimum absorption measure was found in the Red Filter, especially in the blue and green light spectrum. CONCLUSION Using filters in PMMA materials appears to improve visual quality in corneal implants, especially the red filter, due to greater absorbance of light leading to fewer light scattering phenomena through corneal rings. However, further studies comparing the effects of different filters on Intracorneal rings should be carried out to elucidate this field of study.
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Affiliation(s)
- Pablo Felipe Rodrigues
- Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Bernardo Kaplan Moscovici
- Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Juliana Lopes Hoehne
- Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Mauro Silveira de Queiroz Campos
- Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| | | | | | - Walton Nosé
- Department of Ophthalmology and Visual Sciences, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
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13
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Bai SF, Ma JW, Guo YN, Du XM, Wang YL, Li QL, Lü S. Aminophosphine-substituted Fe/E (E = S, Se) carbonyls related to [FeFe]-hydrogenases: Synthesis, protonation, and electrocatalytic proton reduction. J Mol Struct 2023. [DOI: 10.1016/j.molstruc.2023.135287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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14
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Malik R, Chandra A, Das B, Chandra A. Temperature Dependence of Non-Condon Effects in Two-Dimensional Vibrational Spectroscopy of Water. J Phys Chem B 2023; 127:2488-2498. [PMID: 36893383 DOI: 10.1021/acs.jpcb.2c06794] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Non-Condon effects in vibrational spectroscopy refers to the dependence of a molecule's vibrational transition dipole and polarizability on the coordinates of the surrounding environment. Earlier studies have shown that such effects can be pronounced for hydrogen-bonded systems like liquid water. Here, we present a theoretical study of two-dimensional vibrational spectroscopy under the non-Condon and Condon approximations at varying temperatures. We have performed calculations of both two-dimensional infrared and two-dimensional vibrational Raman spectra to gain insights into the temperature dependence of non-Condon effects in nonlinear vibrational spectroscopy. The two-dimensional spectra are calculated for the OH vibration of interest in the isotopic dilution limit where the coupling between the oscillators is ignored. Generally, both the infrared and Raman line shapes undergo red shifts with decrease in temperature due to strengthening of hydrogen bonds and decrease in the fraction of OH modes with weaker or no hydrogen bonds. The infrared line shape is further red-shifted under the non-Condon effects at a given temperature, while the Raman line shape does not show any such red shift due to non-Condon effects. The spectral dynamics becomes slower on decrease of temperature due to slower hydrogen bond relaxation and, for a given temperature, the spectral diffusion occurs at a faster rate upon inclusion of non-Condon effects. The time scales of spectral diffusion extracted from different metrics agree well with each other and also with experiments. The changes in the spectrum due to non-Condon effects are found to be more significant at lower temperatures.
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Affiliation(s)
- Ravi Malik
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Abhilash Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Banshi Das
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Amalendu Chandra
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
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15
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Billion A, Schorpp M, Feser R, Schmitt M, Eisele L, Scherer H, Sonoda T, Kawa H, Butschke B, Krossing I. The perfluoroadamantoxy aluminate as an ideal weakly coordinating anion? - synthesis and first applications. Dalton Trans 2023; 52:4355-4370. [PMID: 36924178 DOI: 10.1039/d3dt00199g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Weakly coordinating anions (WCAs) facilitate the stabilization and isolation of highly reactive and almost "naked" cations. Alkoxyaluminate-based WCAs such as [Al(OC(CF3)3)4]- ([pf]-) are widely used due to their synthetic accessibility and their high stability. However, small cations are still able to coordinate the oxygen atoms of the [pf]- anion or even to abstract an alkoxy ligand. The novel WCA [Al(OC10F15)4]- ([pfAd]-; OC10F15 = perfluoro-1-adamantoxy) is characterized by a very rigid core framework, thus indicating a higher stability towards fluoride-ion abstraction (DFT calculations) and providing hope to generate less disordered crystal structures. The [pfAd]- anion was generated by the reaction of the highly acidic alcohol perfluoro-1-adamantanol C10F15OH with LiAlH4 in o-DFB. Li[pfAd] could not be synthesized free of impurities (and still contains unreacted alcohol). Yet, starting from contaminated Li[pfAd], the very useful pure salts Ag[pfAd], [Ph3C][pfAd] and [H(OEt2)2][pfAd] could be synthesized. The salts were characterized by NMR spectroscopy, single-crystal X-ray diffraction and IR spectroscopy. Additionally, [NO][pfAd] could be synthesized containing alcohol impurities but nonetheless enabled the synthesis of the salt P9+[pfAd]-. The synthesis of Tl[pfAd] in a mixture of H2O/acetone/o-DFB demonstrated the water stability of the [pfAd]- anion.
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Affiliation(s)
- Andreas Billion
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Marcel Schorpp
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Rebecca Feser
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Manuel Schmitt
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Lea Eisele
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Harald Scherer
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Takaaki Sonoda
- Institute for Materials Chemistry and Engineering, Kyushu University, 6-1 Kasuga koen, Kasuga-shi, Fukuoka, 816-8580, Japan
| | - Hajimu Kawa
- Exfluor Research Corporation, 2350 Double Creek Drive, Round Rock, Texas 78664, USA
| | - Burkhard Butschke
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
| | - Ingo Krossing
- Institut für Anorganische und Analytische Chemie and Freiburger Materialforschungszentrum FMF, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, 79104 Freiburg, Germany.
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16
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Tang HM, Fan WY. Transition Metal Pyrithione Complexes (Ni, Mn, Fe, and Co) as Electrocatalysts for Proton Reduction of Acetic Acid. ACS OMEGA 2023; 8:7234-7241. [PMID: 36844539 PMCID: PMC9948554 DOI: 10.1021/acsomega.3c00412] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 01/26/2023] [Indexed: 06/01/2023]
Abstract
A series of mononuclear first-row transition metal pyrithione M(pyr) n complexes (M = Ni(II), Mn(II), n = 2; M = Co(III), Fe(III), n = 3) have been prepared from the reaction of the corresponding metal salt with the sodium salt of pyrithione. Using cyclic voltammetry, the complexes have been shown to behave as proton reduction electrocatalysts albeit with varying efficiencies in the presence of acetic acid as the proton source in acetonitrile. The nickel complex displays the optimal overall catalytic performance with an overpotential of 0.44 V. An ECEC mechanism is suggested for the nickel-catalyzed system based on the experimental data and supported by density functional theory calculations.
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17
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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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18
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Loke WLJ, Guo W, Sohail M, Bengali AA, Fan WY. Manganese Tricarbonyl Diimine Bromide Complexes as Electrocatalysts for Proton Reduction. Inorg Chem 2022; 61:20699-20708. [DOI: 10.1021/acs.inorgchem.2c03675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Wen Liang James Loke
- Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore
| | - Wenzhuo Guo
- Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore
| | - Muhammad Sohail
- Department of Chemistry, Texas A&M University at Qatar, Doha23874, Qatar
| | - Ashfaq A. Bengali
- Department of Chemistry, Texas A&M University at Qatar, Doha23874, Qatar
| | - Wai Yip Fan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3,117543, Singapore
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19
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Tanabe Y, Nishibayashi Y. Recent advances in catalytic nitrogen fixation using transition metal–dinitrogen complexes under mild reaction conditions. Coord Chem Rev 2022. [DOI: 10.1016/j.ccr.2022.214783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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20
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Ayare PJ, Watson N, Helton MR, Warner MJ, Dilbeck T, Hanson K, Vannucci AK. Molecular Z-Scheme for Solar Fuel Production via Dual Photocatalytic Cycles. J Am Chem Soc 2022; 144:21568-21575. [DOI: 10.1021/jacs.2c08462] [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]
Affiliation(s)
- Pooja J. Ayare
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina29208, United States
| | - Noelle Watson
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida32306, United States
| | - Maizie R. Helton
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina29208, United States
| | - Matthew J. Warner
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina29208, United States
| | - Tristan Dilbeck
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida32306, United States
| | - Kenneth Hanson
- Department of Chemistry & Biochemistry, Florida State University, Tallahassee, Florida32306, United States
| | - Aaron K. Vannucci
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina29208, United States
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21
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Busch M, Ahlberg E, Laasonen K. Universal Trends between Acid Dissociation Constants in Protic and Aprotic Solvents. Chemistry 2022; 28:e202201667. [PMID: 35791810 DOI: 10.1002/chem.202201667] [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: 05/30/2022] [Indexed: 01/07/2023]
Abstract
pKa values in non-aqueous solvents are of critical importance in many areas of chemistry. Our knowledge is, despite their relevance, still limited to the most fundamental properties and few pKa values in the most common solvents. Taking advantage of a recently introduced computationally efficient procedure we computed the pKa values of 182 compounds in 21 solvents. This data set is used to establish for the first time universal trends between all solvents. Our computations indicate, that the total charge of the molecule and the charge of the acidic group combined with the Kamlet-Taft solvatochromic parameters are sufficient to predict pKa values with at least semi- quantitative accuracy. We find, that neutral acids such as alcohols are strongly affected by the solvent properties. This is contrasted by cationic acids like ammonium ions whose pKa is often almost completely independent from the choice of solvent.
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Affiliation(s)
- Michael Busch
- Institute of theoretical chemistry, Ulm University, Albert-Einstein Allee 11, 89069, Ulm, Germany
- Department of chemistry and material science, School of chemical engineering, Aalto University, Kemistintie 1, 02150, Espoo, Finland
| | - Elisabet Ahlberg
- Department of Chemistry and Molecular Biology, University of Gothenburg, Kemigården 4, 41296, Gothenburg, Sweden
| | - Kari Laasonen
- Department of chemistry and material science, School of chemical engineering, Aalto University, Kemistintie 1, 02150, Espoo, Finland
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22
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Riuttamäki S, Laczkó G, Madarász Á, Földes T, Pápai I, Bannykh A, Pihko PM. Carboxylate Catalyzed Isomerization of β,γ-Unsaturated N-Acetylcysteamine Thioesters. Chemistry 2022; 28:e202201030. [PMID: 35604200 PMCID: PMC9541288 DOI: 10.1002/chem.202201030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Indexed: 11/11/2022]
Abstract
We demonstrate herein the capacity of simple carboxylate salts - tetrametylammonium and tetramethylguanidinium pivalate - to act as catalysts in the isomerization of β,γ-unsaturated thioesters to α,β-unsaturated thioesters. The carboxylate catalysts gave reaction rates comparable to those obtained with DBU, but with fewer side reactions. The reaction exhibits a normal secondary kinetic isotope effect (k1H /k1D =1.065±0.026) with a β,γ-deuterated substrate. Computational analysis of the mechanism provides a similar value (k1H /k1D =1.05) with a mechanism where γ-reprotonation of the enolate intermediate is rate determining.
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Affiliation(s)
- Saara Riuttamäki
- Department of ChemistryUniversity of JyväskyläP.O. Box 3540014JyväskyläFinland
| | - Gergely Laczkó
- Institute of Organic ChemistryResearch Centre for Natural SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Ádám Madarász
- Institute of Organic ChemistryResearch Centre for Natural SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Tamás Földes
- Institute of Organic ChemistryResearch Centre for Natural SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Imre Pápai
- Institute of Organic ChemistryResearch Centre for Natural SciencesMagyar tudósok körútja 21117BudapestHungary
| | - Anton Bannykh
- Department of ChemistryUniversity of JyväskyläP.O. Box 3540014JyväskyläFinland
| | - Petri M. Pihko
- Department of ChemistryUniversity of JyväskyläP.O. Box 3540014JyväskyläFinland
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23
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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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24
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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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25
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Busch M, Ahlberg E, Ahlberg E, Laasonen K. How to Predict the p K a of Any Compound in Any Solvent. ACS OMEGA 2022; 7:17369-17383. [PMID: 35647457 PMCID: PMC9134414 DOI: 10.1021/acsomega.2c01393] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/27/2022] [Indexed: 06/15/2023]
Abstract
Acid-base properties of molecules in nonaqueous solvents are of critical importance for almost all areas of chemistry. Despite this very high relevance, our knowledge is still mostly limited to the pK a of rather few compounds in the most common solvents, and a simple yet truly general computational procedure to predict pK a's of any compound in any solvent is still missing. In this contribution, we describe such a procedure. Our method requires only the experimental pK a of a reference compound in water and a few standard quantum-chemical calculations. This method is tested through computing the proton solvation energy in 39 solvents and by comparing the pK a of 142 simple compounds in 12 solvents. Our computations indicate that the method to compute the proton solvation energy is robust with respect to the detailed computational setup and the construction of the solvation model. The unscaled pK a's computed using an implicit solvation model on the other hand differ significantly from the experimental data. These differences are partly associated with the poor quality of the experimental data and the well-known shortcomings of implicit solvation models. General linear scaling relationships to correct this error are suggested for protic and aprotic media. Using these relationships, the deviations between experiment and computations drop to a level comparable to that observed in water, which highlights the efficiency of our method.
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Affiliation(s)
- Michael Busch
- Department
of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland
| | - Ernst Ahlberg
- Universal
Prediction AB, 42677 Gothenburg, Sweden
- Department
of Pharmaceutical Biosciences, Uppsala University, Husargatan 3, 75124 Uppsala, Sweden
| | - Elisabet Ahlberg
- Department
of Chemistry and Molecular Biology, University
of Gothenburg, Kemigården 4, 41296 Gothenburg, Sweden
| | - Kari Laasonen
- Department
of Chemistry and Material Science, School of Chemical Engineering, Aalto University, Kemistintie 1, 02150 Espoo, Finland
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26
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Khabazbashi S, Engelhardt J, Möckel C, Weiss J, Kruve A. Estimation of the concentrations of hydroxylated polychlorinated biphenyls in human serum using ionization efficiency prediction for electrospray. Anal Bioanal Chem 2022; 414:7451-7460. [PMID: 35507099 PMCID: PMC9482908 DOI: 10.1007/s00216-022-04096-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/11/2022] [Accepted: 04/22/2022] [Indexed: 11/29/2022]
Abstract
Hydroxylated PCBs are an important class of metabolites of the widely distributed environmental contaminants polychlorinated biphenyls (PCBs). However, the absence of authentic standards is often a limitation when subject to detection, identification, and quantification. Recently, new strategies to quantify compounds detected with non-targeted LC/ESI/HRMS based on predicted ionization efficiency values have emerged. Here, we evaluate the impact of chemical space coverage and sample matrix on the accuracy of ionization efficiency-based quantification. We show that extending the chemical space of interest is crucial in improving the performance of quantification. Therefore, we extend the ionization efficiency-based quantification approach to hydroxylated PCBs in serum samples with a retraining approach that involves 14 OH-PCBs and validate it with an additional four OH-PCBs. The predicted and measured ionization efficiency values of the OH-PCBs agreed within the mean error of 2.1 × and enabled quantification with the mean error of 4.4 × or better. We observed that the error mostly arose from the ionization efficiency predictions and the impact of matrix effects was of less importance, varying from 37 to 165%. The results show that there is potential for predictive machine learning models for quantification even in very complex matrices such as serum. Further, retraining the already developed models provides a timely and cost-effective solution for extending the chemical space of the application area.
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Affiliation(s)
- Sara Khabazbashi
- Department of Materials and Environmental Science, Stockholm University, Svante Arrhenius väg 16, 106 91, Stockholm, Sweden
| | - Josefin Engelhardt
- Department of Environmental Science, Stockholm University, Svante Arrhenius väg 8, 106 91, Stockholm, Sweden
| | - Claudia Möckel
- Department of Materials and Environmental Science, Stockholm University, Svante Arrhenius väg 16, 106 91, Stockholm, Sweden
| | - Jana Weiss
- Department of Environmental Science, Stockholm University, Svante Arrhenius väg 8, 106 91, Stockholm, Sweden
| | - Anneli Kruve
- Department of Materials and Environmental Science, Stockholm University, Svante Arrhenius väg 16, 106 91, Stockholm, Sweden. .,Department of Environmental Science, Stockholm University, Svante Arrhenius väg 8, 106 91, Stockholm, Sweden.
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27
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Steuer L, Kaifer E, Himmel HJ. Redox‐Active Dendrimer‐Like Oligoguanidines and Their Use in a Proton‐Coupled Electron Transfer Reaction. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Lena Steuer
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Elisabeth Kaifer
- Ruprecht Karls Universitat Heidelberg Fakultat fur Chemie und Geowissenschaften Chemistry GERMANY
| | - Hans-Jörg Himmel
- Ruprecht-Karls-Universität Heidelberg Institut für Anorganische Chemie Im Neuenheimer Feld 270 69120 Heidelberg GERMANY
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28
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Shen GB, Qian BC, Zhang GS, Luo GZ, Fu YH, Zhu XQ. Thermodynamics regulated organic hydride/acid pairs as novel organic hydrogen reductants. Org Chem Front 2022. [DOI: 10.1039/d2qo01605b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Organic hydride/acid pairs could realize transformation of N-substituted organic hydrides from hydride reductants to thermodynamics regulated hydrogen reductants on conveniently choosing suitable organic hydrides and acids with various acidities.
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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
| | - Gao-Shuai Zhang
- 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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29
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Kheirjou S, Rüütel A, Darnell A, Haljasorg T, Leito I. Macrocyclic versus open-chain carbazole receptors for carboxylate binding. Org Biomol Chem 2022; 20:2121-2130. [DOI: 10.1039/d1ob02398e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Anion recognition properties of six synthetic acyclic and macrocyclic carbazole-based receptors have been studied by 1H-NMR as well as with COSMO-RS calculations towards acetate, benzoate, lactate, sorbate and formate. The...
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30
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Axelsson M, Marchiori CFN, Huang P, Araujo CM, Tian H. Small Organic Molecule Based on Benzothiadiazole for Electrocatalytic Hydrogen Production. J Am Chem Soc 2021; 143:21229-21233. [PMID: 34855386 PMCID: PMC8704194 DOI: 10.1021/jacs.1c10600] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
A small organic molecule
2,1,3-benzothiadiazole-4, 7-dicarbonitrile
(BTDN) is assessed for electrocatalytic hydrogen evolution on glassy
carbon electrode and shows a hydrogen production Faradaic efficiency
of 82% in the presence of salicylic acid. The key catalytic intermediates
of reduced species BTDN–• and protonated
intermediates are characterized or hypothesized by using various spectroscopic
methods and density functional theory (DFT)-based calculations. With
the experimental and theoretical results, a catalytic mechanism of
BTDN for electrocatalytic H2 evolution is proposed.
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Affiliation(s)
- Martin Axelsson
- Department of Chemistry-Ångström Laboratory, Uppsala University, Uppsala SE 751 20, Sweden
| | - Cleber F N Marchiori
- Department of Engineering and Physics, Karlstad University, Karlstad 65188, Sweden
| | - Ping Huang
- Department of Chemistry-Ångström Laboratory, Uppsala University, Uppsala SE 751 20, Sweden
| | - C Moyses Araujo
- Department of Engineering and Physics, Karlstad University, Karlstad 65188, Sweden.,Department of Physics and Astronomy, Ångström Laboratory, Uppsala University, Uppsala 751 20, Sweden
| | - Haining Tian
- Department of Chemistry-Ångström Laboratory, Uppsala University, Uppsala SE 751 20, Sweden
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31
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Stratakes BM, Wells KA, Kurtz DA, Castellano FN, Miller AJM. Photochemical H 2 Evolution from Bis(diphosphine)nickel Hydrides Enables Low-Overpotential Electrocatalysis. J Am Chem Soc 2021; 143:21388-21401. [PMID: 34878278 DOI: 10.1021/jacs.1c10628] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Molecules capable of both harvesting light and forming new chemical bonds hold promise for applications in the generation of solar fuels, but such first-row transition metal photoelectrocatalysts are lacking. Here we report nickel photoelectrocatalysts for H2 evolution, leveraging visible-light-driven photochemical H2 evolution from bis(diphosphine)nickel hydride complexes. A suite of experimental and theoretical analyses, including time-resolved spectroscopy and continuous irradiation quantum yield measurements, led to a proposed mechanism of H2 evolution involving a short-lived singlet excited state that undergoes homolysis of the Ni-H bond. Thermodynamic analyses provide a basis for understanding and predicting the observed photoelectrocatalytic H2 evolution by a 3d transition metal based catalyst. Of particular note is the dramatic change in the electrochemical overpotential: in the dark, the nickel complexes require strong acids and therefore high overpotentials for electrocatalysis; but under illumination, the use of weaker acids at the same applied potential results in a more than 500 mV improvement in electrochemical overpotential. New insight into first-row transition metal hydride photochemistry thus enables photoelectrocatalytic H2 evolution without electrochemical overpotential (at the thermodynamic potential or 0 mV overpotential). This catalyst system does not require sacrificial chemical reductants or light-harvesting semiconductor materials and produces H2 at rates similar to molecular catalysts attached to silicon.
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Affiliation(s)
- Bethany M Stratakes
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Kaylee A Wells
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Daniel A Kurtz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Felix N Castellano
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, United States
| | - Alexander J M Miller
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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32
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Agarwal RG, Coste SC, Groff BD, Heuer AM, Noh H, Parada GA, Wise CF, Nichols EM, Warren JJ, Mayer JM. Free Energies of Proton-Coupled Electron Transfer Reagents and Their Applications. Chem Rev 2021; 122:1-49. [PMID: 34928136 DOI: 10.1021/acs.chemrev.1c00521] [Citation(s) in RCA: 145] [Impact Index Per Article: 48.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We present an update and revision to our 2010 review on the topic of proton-coupled electron transfer (PCET) reagent thermochemistry. Over the past decade, the data and thermochemical formalisms presented in that review have been of value to multiple fields. Concurrently, there have been advances in the thermochemical cycles and experimental methods used to measure these values. This Review (i) summarizes those advancements, (ii) corrects systematic errors in our prior review that shifted many of the absolute values in the tabulated data, (iii) provides updated tables of thermochemical values, and (iv) discusses new conclusions and opportunities from the assembled data and associated techniques. We advocate for updated thermochemical cycles that provide greater clarity and reduce experimental barriers to the calculation and measurement of Gibbs free energies for the conversion of X to XHn in PCET reactions. In particular, we demonstrate the utility and generality of reporting potentials of hydrogenation, E°(V vs H2), in almost any solvent and how these values are connected to more widely reported bond dissociation free energies (BDFEs). The tabulated data demonstrate that E°(V vs H2) and BDFEs are generally insensitive to the nature of the solvent and, in some cases, even to the phase (gas versus solution). This Review also presents introductions to several emerging fields in PCET thermochemistry to give readers windows into the diversity of research being performed. Some of the next frontiers in this rapidly growing field are coordination-induced bond weakening, PCET in novel solvent environments, and reactions at material interfaces.
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Affiliation(s)
- Rishi G Agarwal
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Scott C Coste
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Benjamin D Groff
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Abigail M Heuer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Hyunho Noh
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Giovanny A Parada
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States.,Department of Chemistry, The College of New Jersey, Ewing, New Jersey 08628, United States
| | - Catherine F Wise
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
| | - Eva M Nichols
- Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
| | - Jeffrey J Warren
- Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - James M Mayer
- Department of Chemistry, Yale University, New Haven, Connecticut 06520, United States
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33
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Tang HM, Fan WY. Dithiolato-Bridged Nickel(II) Salicylcysteamine Complexes as Robust Proton Reduction Electrocatalysts: Cyclic Voltammetry and Computational Studies. Inorg Chem 2021; 60:17933-17941. [PMID: 34739253 DOI: 10.1021/acs.inorgchem.1c02524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A series of Schiff-base nickel(II) complexes were prepared from the reaction of nickel(II) acetate with N-salicylcysteamine [HO-C6H4-CH═N(CH2)2SH] ligands. These complexes were analyzed to be dimeric nickel complexes containing two bridging thiolato ligands. Using cyclic voltammetry, they were found to be efficient homogeneous proton reduction electrocatalysts when acetic acid was used as the proton source in acetonitrile. Catalysis was triggered upon electrochemical reduction of the nickel complex. In particular, rate constants (kobs) in the range of 104 s-1 at moderate overpotentials of 0.5-0.6 V were achieved when chloro- or bromo-containing nickel complexes were used. Combined with the experimental data, density functional theory calculations lent support to an ECEC mechanism, with the first electrochemical reduction step contributing significantly to the rate-determining step.
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Affiliation(s)
- Hui Min Tang
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Wai Yip Fan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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34
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Tran T, Nguyen A, Torres D, Pham MT, Petit AS. Computational Investigation of the Formation of Substituted Isoindole N-Oxides through the Photo-oxidative Cyclization of 2'-Alkynylacetophenone Oximes. J Org Chem 2021; 86:15020-15032. [PMID: 34668707 DOI: 10.1021/acs.joc.1c01715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Our recently published joint experiment-theory study of the photo-oxidative intramolecular cyclization of 2'-alkynylacetophenone oximes, performed in collaboration with the de Lijser group, presented the first reported formation of isoindole N-oxides. That study focused on determining a mechanistic explanation for the unexpected chemistry observed when three 2'-alkynylacetophenone oximes were photo-oxidized with 9,10-dicyanoanthracene (DCA), specifically the derivatives with a phenyl, isopropyl, or n-butyl substituent at the alkynyl group. Here, we use density functional theory to develop a broader understanding of the scope of this chemistry. In particular, we demonstrate that substituents on the alkynyl group and on the central benzene ring can significantly modulate the thermodynamic driving force for oxime radical cation generation when DCA is used as the photosensitizer. In contrast, substituents are shown to have a small impact on the chemical reactivity of the radical cation intermediates. In particular, 5-exo radical cation cyclization, which ultimately results in an isoindole N-oxide product, is always kinetically and sometimes also thermodynamically preferred over 6-endo radical cation cyclization, which would produce an isoquinoline N-oxide product. Overall, this study provides mechanistic insights into the diversity of isoindole N-oxides that can be produced through the photo-oxidative cyclization of 2'-alkynylacetophenone oximes.
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Affiliation(s)
- Thao Tran
- Department of Chemistry and Biochemistry, California State University - Fullerton, Fullerton, California 92834-6866, United States
| | - Anh Nguyen
- Department of Chemistry and Biochemistry, California State University - Fullerton, Fullerton, California 92834-6866, United States
| | - Danielle Torres
- Department of Chemistry and Biochemistry, California State University - Fullerton, Fullerton, California 92834-6866, United States
| | - My Tien Pham
- Department of Chemistry and Biochemistry, California State University - Fullerton, Fullerton, California 92834-6866, United States
| | - Andrew S Petit
- Department of Chemistry and Biochemistry, California State University - Fullerton, Fullerton, California 92834-6866, United States
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35
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Oakley K, Sterling K, Shearer J, Kim E. Controlled Protonation of [2Fe-2S] Leading to MitoNEET Analogues and Concurrent Cluster Modification. Inorg Chem 2021; 60:16074-16078. [PMID: 34672568 DOI: 10.1021/acs.inorgchem.1c02622] [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: 11/29/2022]
Abstract
MitoNEET, a key regulatory protein in mitochondrial energy metabolism, exhibits a uniquely ligated [2Fe-2S] cluster with one histidine and three cysteines. This unique cluster has been postulated to sense the redox environment and release Fe-S cofactors under acidic pH. Reported herein is a synthetic system that shows how [2Fe-2S] clusters react with protons and rearrange their coordination geometry. The low-temperature stable, site-differentiated clusters [Fe2S2(SPh)3(CF3COO)]2- and [Fe2S2(SPh)3(py)]- have been prepared via controlled protonation below -35 °C and characterized by NMR, UV-vis, and X-ray absorption spectroscopy. Both complexes exhibit anodically shifted redox potentials compared to [Fe2S2(SPh)4]2- and convert to [Fe4S4(SPh)4]2- upon warming to room temperature. The current study provides insight into how mitoNEET releases its [2Fe-2S] in response to highly tuned acidic conditions, the chemistry of which may have further implications in Fe-S biogenesis.
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Affiliation(s)
- Kady Oakley
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Kevin Sterling
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Eunsuk Kim
- Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States
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36
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Norouziyanlakvan S, Rao GK, Ovens J, Gabidullin B, Richeson D. Electrocatalytic H 2 Generation from Water Relying on Cooperative Ligand Electron Transfer in "PN 3 P" Pincer-Supported Ni II Complexes. Chemistry 2021; 27:13518-13522. [PMID: 34415632 DOI: 10.1002/chem.202102031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Indexed: 11/07/2022]
Abstract
Water is the most sustainable source for H2 production, and the efficient electrocatalytic production of H2 from mixed water/acetonitrile solutions by using two new air-stable nickel(II) pincer complexes, [Ni(κ3 -2,6-{Ph2 PNR}2 (NC5 H3 )Br2 ] (R=H I, Me II) is reported. Hydrogen generation from H2 O/CH3 CN solutions is initiated at -2 V against Fc+/0 , and bulk electrocatalysis studies showed that the catalyst functions with an excellent Faradaic efficiency and a turnover frequency of 160 s-1 . A DFT computational investigation of the reduction behavior of I and II revealed a correlation of H2 formation with charge donation from electrons originating in a reduced ligand-localized orbital. As a result, these catalysts are proposed to proceed by a novel mechanism involving electron/proton transfer between a Ni0I species bonded to an anionic PN3 P ligand ("L- /Ni0I ") and a NiI -hydride ("Ni-H"). Furthermore, these catalysts are able to reduce phenol and acetic acid, more active proton sources, at lower potentials that correlate with the substrate pKa .
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Affiliation(s)
- Somayeh Norouziyanlakvan
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, ON K1 N 6 N5
| | - Gyandshwar Kumar Rao
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, ON K1 N 6 N5
| | - Jeffrey Ovens
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, ON K1 N 6 N5
| | - Bulat Gabidullin
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, ON K1 N 6 N5
| | - Darrin Richeson
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie, Ottawa, ON K1 N 6 N5
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37
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Rahman Z, Das SK. Ionic Liquids based Acid‐base Indicators for Aqueous to the Non‐Aqueous Medium: An Overview. ChemistrySelect 2021. [DOI: 10.1002/slct.202102273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ziaur Rahman
- Department of Chemistry University of North Bengal West Bengal India- 734013
| | - Sudhir Kumar Das
- Department of Chemistry University of North Bengal West Bengal India- 734013
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38
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Kretsch J, Kreyenschmidt A, Schillmöller T, Lõkov M, Herbst‐Irmer R, Leito I, Stalke D. Bis(4-benzhydryl-benzoxazol-2-yl)methane - from a Bulky NacNac Alternative to a Trianion in Alkali Metal Complexes. Chemistry 2021; 27:9858-9865. [PMID: 34036637 PMCID: PMC8361911 DOI: 10.1002/chem.202100616] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Indexed: 11/25/2022]
Abstract
A novel sterically demanding bis(4-benzhydryl-benzoxazol-2-yl)methane ligand 6 (4-BzhH2 BoxCH2 ) was gained in a straightforward six-step synthesis. Starting from this ligand monomeric [M(4-BzhH2 BoxCH)] (M=Na (7), K (81 )) and dimeric [{M(4-BzhH2 BoxCH)}2 ] (M=K (82 ), Rb (9), Cs (10)) alkali metal complexes were synthesised by deprotonation. Abstraction of the potassium ion of 8 by reaction with 18-crown-6 resulted in the solvent separated ion pair [{(THF)2 K@(18-crown-6)}{bis(4-benzhydryl-benzoxazol-2-yl)methanide}] (11), including the energetically favoured monoanionic (E,E)-(4-BzhH2 BoxCH) ligand. Further reaction of 4-BzhH2 BoxCH2 with three equivalents KH and two equivalents 18-crown-6 yielded polymeric [{(THF)2 K@(18-crown-6)}{K@(18-crown-6)K(4-Bzh BoxCH)}]n (n→∞) (12) containing a trianionic ligand. The neutral ligand and herein reported alkali complexes were characterised by single X-ray analyses identifying the latter as a promising precursor for low-valent main group complexes.
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Affiliation(s)
- Johannes Kretsch
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstraße 437077GöttingenGermany
| | | | - Timo Schillmöller
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstraße 437077GöttingenGermany
| | - Märt Lõkov
- Institute of ChemistryUniversity of TartuRavila 14a50411TartuEstonia
| | - Regine Herbst‐Irmer
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstraße 437077GöttingenGermany
| | - Ivo Leito
- Institute of ChemistryUniversity of TartuRavila 14a50411TartuEstonia
| | - Dietmar Stalke
- Institut für Anorganische ChemieGeorg-August-Universität GöttingenTammannstraße 437077GöttingenGermany
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39
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Yang C, Farmer LA, Pratt DA, Maldonado S, Stephenson CRJ. Mechanism of Electrochemical Generation and Decomposition of Phthalimide- N-oxyl. J Am Chem Soc 2021; 143:10324-10332. [PMID: 34213314 DOI: 10.1021/jacs.1c04181] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Phthalimide N-oxyl (PINO) is a potent hydrogen atom transfer (HAT) catalyst that can be generated electrochemically from N-hydroxyphthalimide (NHPI). However, catalyst decomposition has limited its application. This paper details mechanistic studies of the generation and decomposition of PINO under electrochemical conditions. Voltammetric data, observations from bulk electrolysis, and computational studies suggest two primary aspects. First, base-promoted formation of PINO from NHPI occurs via multiple-site concerted proton-electron transfer (MS-CPET). Second, PINO decomposition occurs by at least two second-order paths, one of which is greatly enhanced by base. Optimal catalytic efficiency in PINO-catalyzed oxidations occurs in the presence of bases whose corresponding conjugate acids have pKa's in the range of ∼11-15, which strikes a balance between promoting PINO formation and minimizing its decay.
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Affiliation(s)
- Cheng Yang
- Willard Henry Dow Laboratory, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
| | - Luke A Farmer
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontairo K1N 6N5, Canada
| | - Derek A Pratt
- Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontairo K1N 6N5, Canada
| | - Stephen Maldonado
- Willard Henry Dow Laboratory, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States.,Program in Applied Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Corey R J Stephenson
- Willard Henry Dow Laboratory, Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109, United States
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40
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Hashimoto Y, Hosokawa S, Liang F, Suzuki Y, Dai N, Tana G, Eda K, Kakiuchi T, Okazoe T, Harada H, Tsuda A. Photo-on-Demand Base-Catalyzed Phosgenation Reactions with Chloroform: Synthesis of Arylcarbonate and Halocarbonate Esters. J Org Chem 2021; 86:9811-9819. [PMID: 34182754 DOI: 10.1021/acs.joc.1c01210] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Carbonate esters are utilized as solvents and reagents for C1 building blocks in organic synthesis. This study reports a novel photo-on-demand in situ synthesis of carbonate esters with CHCl3 solutions containing a mixture of an aromatic or haloalkyl alcohol having relatively high acidity, and an organic base. We found that the acid-base interaction of the alcohol and base in the CHCl3 solution plays a key role in enabling the photochemical reaction. This reaction allows practical syntheses of diphenyl carbonate derivatives, haloalkyl carbonates, and polycarbonates, which are important chemicals and materials in industry.
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Affiliation(s)
- Yuka Hashimoto
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Sasuga Hosokawa
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Fengying Liang
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Yuto Suzuki
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Namin Dai
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Gegen Tana
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Kazuo Eda
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Toshifumi Kakiuchi
- Innovative Technology Laboratories, AGC Inc., Suehiro 1-1 Tsurumi-ku, Yokohama City, Kanagawa 230-0045, Japan
| | - Takashi Okazoe
- Materials Integration Laboratories, AGC Inc., Suehiro 1-1 Tsurumi-ku, Yokohama City, Kanagawa 230-0045, Japan
| | - Hidefumi Harada
- Tokyo Research Laboratory, Mitsubishi Gas Chemical Company, Inc., Nijyuku 6-1-1 Katsushika-ku, Tokyo 125-8601, Japan
| | - Akihiko Tsuda
- Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
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41
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Abstract
![]()
Practical, efficient,
and general methods for the diversification
of N-heterocycles have been a recurrent goal in chemical
synthesis due to the ubiquitous influence of these motifs within bioactive
frameworks. Here, we describe a direct, catalytic, and selective functionalization
of azines via silylium activation. Our catalyst design enables mild
conditions and a remarkable functional group tolerance in a one-pot
setup.
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Affiliation(s)
- Carla Obradors
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr, 45470, Germany
| | - Benjamin List
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, Mülheim an der Ruhr, 45470, Germany
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42
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Ermondi G, Vallaro M, Saame J, Toom L, Leito I, Ruiz R, Caron G. Rifampicin as an example of beyond-rule-of-5 compound: Ionization beyond water and lipophilicity beyond octanol/water. Eur J Pharm Sci 2021; 161:105802. [PMID: 33716188 DOI: 10.1016/j.ejps.2021.105802] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 03/04/2021] [Accepted: 03/06/2021] [Indexed: 10/21/2022]
Abstract
Ionization and lipophilicity in early drug discovery are commonly characterized in water and octanol/water, respectively and thus do not consider the non-polar features of the biomembrane core. This is particularly limiting for bRo5 compounds which may adapt their properties (e.g. ionization and lipophilicity) to the environment. In this paper we used experimental methods to characterize rifampicin for its ionization properties in various water/cosolvent mixtures and in pure MeCN and its lipophilicity in octanol/water and toluene/water systems. Moreover, we also measured log k'80 PLRP-S, a chromatographic index of lipophilicity in non-polar media. Results show that the existence domain of neutral rifampicin is limited compared to the zwitterion, but the lipophilic cationic species is extremely relevant in non-polar environments.
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Affiliation(s)
- Giuseppe Ermondi
- Molecular Biotechnology and Health Sciences Dept., Università degli Studi di Torino, via Quarello 15, Torino 10135, Italy
| | - Maura Vallaro
- Molecular Biotechnology and Health Sciences Dept., Università degli Studi di Torino, via Quarello 15, Torino 10135, Italy
| | - Jaan Saame
- University of Tartu, Institute of Chemistry, Ravila 14a, Tartu 50411, Estonia
| | - Lauri Toom
- University of Tartu, Institute of Chemistry, Ravila 14a, Tartu 50411, Estonia
| | - Ivo Leito
- University of Tartu, Institute of Chemistry, Ravila 14a, Tartu 50411, Estonia
| | - Rebeca Ruiz
- Pion Inc., Forest Row Business Park, Forest Row RH18 5DW, UK
| | - Giulia Caron
- Molecular Biotechnology and Health Sciences Dept., Università degli Studi di Torino, via Quarello 15, Torino 10135, Italy.
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43
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Kütt A, Tshepelevitsh S, Saame J, Lõkov M, Kaljurand I, Selberg S, Leito I. Strengths of Acids in Acetonitrile. European J Org Chem 2021. [DOI: 10.1002/ejoc.202001649] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Agnes Kütt
- University of Tartu Institute of Chemistry Ravila 14a 50411 Tartu Estonia
| | | | - Jaan Saame
- University of Tartu Institute of Chemistry Ravila 14a 50411 Tartu Estonia
| | - Märt Lõkov
- University of Tartu Institute of Chemistry Ravila 14a 50411 Tartu Estonia
| | - Ivari Kaljurand
- University of Tartu Institute of Chemistry Ravila 14a 50411 Tartu Estonia
| | - Sigrid Selberg
- University of Tartu Institute of Chemistry Ravila 14a 50411 Tartu Estonia
| | - Ivo Leito
- University of Tartu Institute of Chemistry Ravila 14a 50411 Tartu Estonia
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44
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Tyburski R, Liu T, Glover SD, Hammarström L. Proton-Coupled Electron Transfer Guidelines, Fair and Square. J Am Chem Soc 2021; 143:560-576. [PMID: 33405896 PMCID: PMC7880575 DOI: 10.1021/jacs.0c09106] [Citation(s) in RCA: 211] [Impact Index Per Article: 70.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Indexed: 12/23/2022]
Abstract
Proton-coupled electron transfer (PCET) reactions are fundamental to energy transformation reactions in natural and artificial systems and are increasingly recognized in areas such as catalysis and synthetic chemistry. The interdependence of proton and electron transfer brings a mechanistic richness of reactivity, including various sequential and concerted mechanisms. Delineating between different PCET mechanisms and understanding why a particular mechanism dominates are crucial for the design and optimization of reactions that use PCET. This Perspective provides practical guidelines for how to discern between sequential and concerted mechanisms based on interpretations of thermodynamic data with temperature-, pressure-, and isotope-dependent kinetics. We present new PCET-zone diagrams that show how a mechanism can switch or even be eliminated by varying the thermodynamic (ΔGPT° and ΔGET°) and coupling strengths for a PCET system. We discuss the appropriateness of asynchronous concerted PCET to rationalize observations in organic reactions, and the distinction between hydrogen atom transfer and other concerted PCET reactions. Contemporary issues and future prospects in PCET research are discussed.
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Affiliation(s)
- Robin Tyburski
- Ångström
Laboratory, Department of Chemistry, Uppsala
University, Box 523, SE75120 Uppsala, Sweden
| | - Tianfei Liu
- Department
of Chemistry, University of North Carolina
at Chapel Hill, Chapel
Hill, North Carolina 27599-3290, United States
| | - Starla D. Glover
- Ångström
Laboratory, Department of Chemistry, Uppsala
University, Box 523, SE75120 Uppsala, Sweden
| | - Leif Hammarström
- Ångström
Laboratory, Department of Chemistry, Uppsala
University, Box 523, SE75120 Uppsala, Sweden
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45
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Kim WS, Espinoza Castro VM, Abiad A, Ko M, Council A, Nguyen A, Marsalla L, Lee V, Tran T, Petit AS, de Lijser HJP. Mechanistic Investigation of the Formation of Isoindole N-Oxides in the Electron Transfer-Mediated Oxidative Cyclization of 2'-Alkynylacetophenone Oximes. J Org Chem 2021; 86:693-708. [PMID: 33337137 DOI: 10.1021/acs.joc.0c02318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
This paper describes a joint experiment-theory investigation of the formation and cyclization of 2'-alkynylacetophenone oxime radical cations using photoinduced electron transfer (PET) with DCA as the photosensitizer. Using a combination of experimental 1H and 13C nuclear magnetic resonance (NMR) spectra, high-resolution mass spectrometry, and calculated NMR chemical shifts, we identified the products to be isoindole N-oxides. The reaction was found to be stereoselective; only one of the two possible stereoisomers is formed under these conditions. A detailed computational investigation of the cyclization reaction mechanism suggests facile C-N bond formation in the radical cation leading to a 5-exo intermediate. Back-electron transfer from the DCA radical anion followed by barrierless intramolecular proton transfer leads to the final product. We argue that the final proton transfer step in the mechanism is responsible for the stereoselectivity observed in experiment. As a whole, this work provides new insights into the formation of complex heterocycles through oxime and oxime ether radical cation intermediates produced via PET. Moreover, it represents the first reported formation of isoindole N-oxides.
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Affiliation(s)
- Wan Shin Kim
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Victor M Espinoza Castro
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Amanda Abiad
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Michael Ko
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Ashley Council
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Anh Nguyen
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Laura Marsalla
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Vicky Lee
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Thao Tran
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - Andrew S Petit
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
| | - H J Peter de Lijser
- Department of Chemistry and Biochemistry, California State University, Fullerton, California 92834-6866, United States
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46
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Pramanik P, Sahoo R, Kumar Das S, Halder M. Fabrication of a GUMBOS-based acid-base indicator: smart probe for sensing acids and bases in any solvent. Phys Chem Chem Phys 2020; 22:28045-28054. [PMID: 33367395 DOI: 10.1039/d0cp03157g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
This report outlines the synthesis of an ionic liquid-based pH-responsive indicator to sense acids or bases in non-polar as well as polar solvents. Herein, we have assembled a new ionic liquid (IL) comprised of a group of uniform materials based on organic salts (GUMBOS) by attaching a quaternary phosphonium ionic liquid with a very common acid-base indicator, methyl orange, via simple ion-exchange reaction. This integrated IL-based indicator is highly soluble in less polar solvents and exhibits good sensitivity toward the presence of acids/bases in those media. Furthermore, this indicator has been exploited in determining the dissociation constants of several acids in non-aqueous aprotic solvents by overlapping indicator method and hence this report provides essential information toward the understanding of many fundamental chemical reactions. This report has further scope for the synthesis of novel aqueous suspended nanomaterials, i.e., the nanoparticles derived from GUMBOS (nanoGUMBOS) by a simple flash nano-precipitation method. The nanomaterial has been well characterized by different spectroscopic and microscopic studies. The obtained nanoparticles also exhibit substantial pH-responsive behaviors in aqueous medium and show better susceptibility as compared to the free organic indicator. Thus, this report explores detailed studies on the IL-based indicator in sensing the acidity/basicity of various media.
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Affiliation(s)
- Prabal Pramanik
- Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur-721302, India
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47
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Pereira RW, Ramabhadran RO. pK-Yay: A Black-Box Method Using Density Functional Theory and Implicit Solvation Models to Compute Aqueous p Ka Values of Weak and Strong Acids. J Phys Chem A 2020; 124:9061-9074. [PMID: 32970437 DOI: 10.1021/acs.jpca.0c06298] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The concept of pKa is very important in chemistry and biology. Over the past two decades, electronic structure calculations have made huge strides toward becoming reliable counterparts to experiments in determining solution-phase pKa values. However, invariably, the computation of pKa values involves the use of methods whose error bars are intrinsically larger (definitely >2 kcal/mol with density functionals) than the accuracy desired for the estimation of pKa values (<1 or 1.5 pKa units). This scenario presents an ample scope for innovation in developing systematic error cancellation methods even today. In this work, we have developed the pK-Yay method. It is a user-friendly black-box method used to compute aqueous pKa values of strong and weak acids employing routinely used and computationally inexpensive density functionals and implicit solvation models. It does not require the use of any explicit solvent molecule or modifying any other parameter in an electronic structure program. As part of evaluating the method, a comprehensive test set of 26 weak and strong organic and mineral acids covering 35 pKa units (20 to -15) was assembled. The detailed description of the method, its performance with different functionals (ωB97X-D performed best for organic acids with a mean absolute error (MAE) of 0.8 pKa units, and B2-PLYP performed best for strong acids with an MAE of 1.6 pKa units), the strengths and limitations in the present version, and a future scope to improve the accuracy and reduce its empirical nature are presented herein.
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Affiliation(s)
- Roshni W Pereira
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Tirupati, Andhra Pradesh 517507, India.,Centre for Atomic, Molecular, and Optical Sciences and Technology (CAMOST), Tirupati, Andhra Pradesh 517507, India
| | - Raghunath O Ramabhadran
- Department of Chemistry, Indian Institute of Science Education and Research (IISER), Tirupati, Andhra Pradesh 517507, India.,Centre for Atomic, Molecular, and Optical Sciences and Technology (CAMOST), Tirupati, Andhra Pradesh 517507, India
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48
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Billups JR, Fokakis ZN, Creutz SE. Octahedral Iron Complexes of Pyrazine(diimine) Pincers: Ligand Electronic Effects and Protonation. Inorg Chem 2020; 59:15228-15239. [DOI: 10.1021/acs.inorgchem.0c02211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jaylan R. Billups
- Department of Chemistry, Mississippi State University, Starkville Mississippi 39762, United States
| | - Zoe N. Fokakis
- Department of Chemistry, Mississippi State University, Starkville Mississippi 39762, United States
| | - Sidney E. Creutz
- Department of Chemistry, Mississippi State University, Starkville Mississippi 39762, United States
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49
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Togasaki K, Arai T, Nishimura Y. Effect of Moderate Hydrogen Bonding on Tautomer Formation via Excited-State Intermolecular Proton-Transfer Reactions in an Aromatic Urea Compound with a Steric Base. J Phys Chem A 2020; 124:6617-6628. [PMID: 32786662 DOI: 10.1021/acs.jpca.0c05045] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU), which forms weak hydrogen bonds despite the high basicity caused by its hindered structure, was used to investigate tautomer formation via excited-state intermolecular proton-transfer (ESPT) reactions. The kinetics of the ESPT reactions of anthracen-2-yl-3-phenylurea (2PUA) in the presence of DBU were compared to that observed for the acetate anion (Ac) using time-resolved fluorescence measurement. Based on the association constants in the ground state, the intermolecular hydrogen bond between 2PUA and DBU was less stable than the bond between 2PUA and Ac due to steric hindrance and the geometry of the hydrogen bond. In the fluorescence spectra, 2PUA-DBU displayed prominent tautomeric emission in chloroform (CHCl3), whereas 2PUA-Ac exhibited distinct tautomeric emissions in dimethyl sulfoxide (DMSO). Kinetic analysis revealed that the rate constant of the ESPT reaction of 2PUA-DBU remarkably decreased when the proton-accepting ability of the solvent increased whereas the reaction of 2PUA-Ac was linked to the solvent polarity rather than proton-accepting ability. These results indicated that moderate hydrogen bonds due to steric hindrance were influenced by the type of solvent present, particularly if the solvents exhibited proton-accepting capabilities like DMSO. This, in turn, affected the rate constant of tautomer formation.
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Affiliation(s)
- Kei Togasaki
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Tatsuo Arai
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
| | - Yoshinobu Nishimura
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8571, Japan
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50
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Voronova ED, Golub IE, Pavlov A, Belkova NV, Filippov OA, Epstein LM, Shubina ES. Dichotomous Si-H Bond Activation by Alkoxide and Alcohol in Base-Catalyzed Dehydrocoupling of Silanes. Inorg Chem 2020; 59:12240-12251. [PMID: 32805120 DOI: 10.1021/acs.inorgchem.0c01293] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The activation of silanes in dehydrogenative coupling with alcohols under general base catalysis was studied experimentally (using multinuclear NMR, IR, and UV-visible spectroscopies) and computationally (at DFT M06/6-311++G(d,p) theory level) on the example of Ph4-nSiHn (n = 1-3) interaction with (CF3)2CHOH in the presence of Et3N. The effect of the phenyl groups' number and H- substitution by the electron-withdrawing (CF3)2CHO- group on Si-H bond hydricity (quantified as hydride-donating ability, HDA) and Lewis acidity of silicon atom (characterized by maxima of molecular electrostatic potential) was accessed. Our results show the coordination of Lewis base (Y = Me3N, ROH, OR-) leads to the increased hydricity of pentacoordinate hypervalent Ph4-nSi(Y)Hn complexes and a decrease of the reaction barrier for H2 release. The formation of tertiary complexes [Ph4-nSi(Y)Hn]···HOR is a critical prerequisite for the dehydrocoupling with alkoxides being ideal activators. The latter can be external or internal, generated by in situ HOR deprotonation. The mutual effect of tetrel interaction and dihydrogen bonding in tertiary complexes (RO-)Ph4-nSiHn···HOR leads to dichotomous activation of Si-H bond promoting the proton-hydride transfer and H2 release.
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Affiliation(s)
- Evgenia D Voronova
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia
| | - Igor E Golub
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia
| | - Alexander Pavlov
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia
| | - Natalia V Belkova
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia
| | - Oleg A Filippov
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia.,Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklay Str., Moscow 117997, Russia
| | - Lina M Epstein
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia
| | - Elena S Shubina
- A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28 Vavilova St., 119991 Moscow, Russia
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