1
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Torlopov MA, Martakov IS, Mikhaylov VI, Cherednichenko KA, Sitnikov PА. Synthesis and properties of thiol-modified CNC via surface tosylation. Carbohydr Polym 2023; 319:121169. [PMID: 37567709 DOI: 10.1016/j.carbpol.2023.121169] [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: 04/11/2023] [Revised: 06/08/2023] [Accepted: 06/29/2023] [Indexed: 08/13/2023]
Abstract
SH-containing polymers and nanoparticles are a significant direction in the creation of novel materials. The aim of this work is the synthesis of cellulose nanocrystals (CNC) with a surface modified by tosyl functions (CNC-Ts) and their further modification into SH-containing nanocrystals (CNC-SH). CNC-Ts were synthesized in an aqueous-organic emulsion from never-dried particles, while maintaining the size and supramolecular structure of CNC; the content of Ts-functions is up to 2.5 mmol·g-1. Structure of the derivatives was analyzed by TEM, XRD, CP/MAS 13C NMR and FTIR spectroscopies. Nucleophilic substitution and hydrolysis of the obtained thioisouronium salts leads to the production of CNC-SH. To quantify SH-groups we used elemental analysis, potentiometric titration and Folin-Ciocalteu and Ellman's reagents. It is shown that SH-groups on the surface are partially oxidized and are involved in a dense network of hydrogen bonds. Rheological properties of CNC-SH hydrosols are close to those of CNC, addition of H2O2 at acidic pH leads to an increase in viscosity of the system; H2O2 added at neutral pH causes opposite effect - viscosity decreases. CNC-SH have a high capacity for sorption of Cr(VI) in acidic environments and exhibit photoreductive properties under UV irradiation.
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Affiliation(s)
- Mikhail A Torlopov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation
| | - Ilia S Martakov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation.
| | - Vasily I Mikhaylov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation
| | | | - Petr А Sitnikov
- Institute of Chemistry of Federal Research Centre "Komi Science Centre, the Ural Branch, Russian Academy of Sciences", 167982, 48 Pervomayskaya st., Syktyvkar, Russian Federation
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2
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Zhu L, Song D, Liu YH, Chen MD, Zhang XR, You MY, Zhan JL. Iron-catalyzed regioselective synthesis of ( E)-vinyl sulfones mediated by unprotected hydroxylamines. Org Biomol Chem 2022; 20:9127-9131. [DOI: 10.1039/d2ob01922a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An Fe-catalyzed unprotected hydroxylamine mediated Heck-type coupling between sulfinic acids and alkenes furnished structurally important (E)-vinyl sulfones with moderate to good yields, high atom-economy and regioselectivity.
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Affiliation(s)
- Lin Zhu
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
| | - Dian Song
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
| | - Yi-Han Liu
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
| | - Meng-Di Chen
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
| | - Xin-Ru Zhang
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
| | - Meng-Yan You
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
| | - Jun-Long Zhan
- College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang, Henan 455000, P. R. China
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3
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Computational studies of acidities of some hydroxycoumarins. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.113008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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4
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Belinskaia DA, Terpilovskii MA, Batalova AA, Goncharov NV. Effect of Cys34 Oxidation State of Albumin on Its Interaction with Paraoxon according to Molecular Modeling Data. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2020. [DOI: 10.1134/s1068162019060086] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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5
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Zheng Z, Trofymchuk OS, Kurogi T, Varela E, Mindiola DJ, Walsh PJ. Selenenate Anions (PhSeO
−
) as Organocatalyst: Synthesis of
trans
‐Stilbenes and a PPV Derivative. Adv Synth Catal 2019. [DOI: 10.1002/adsc.201901201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Zhipeng Zheng
- Department of Chemistry, Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation University of Pennsylvania Philadelphia PA 19104-6323 United States
| | - Oleksandra S. Trofymchuk
- Department of Chemistry, Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation University of Pennsylvania Philadelphia PA 19104-6323 United States
- Núcleo Científico Multidisciplinario-DI University of Talca 747 Talca Chile
| | - Takashi Kurogi
- Department of Chemistry, Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation University of Pennsylvania Philadelphia PA 19104-6323 United States
| | - Elena Varela
- Department of Chemistry, Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation University of Pennsylvania Philadelphia PA 19104-6323 United States
| | - Daniel J. Mindiola
- Department of Chemistry, Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation University of Pennsylvania Philadelphia PA 19104-6323 United States
| | - Patrick J. Walsh
- Department of Chemistry, Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation University of Pennsylvania Philadelphia PA 19104-6323 United States
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6
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Kosińska M, Zapała L, Zapała W, Woźnicka E. Response of the DFT study to the calculations of selected microdissociation constants of anthranilic acid and its derivatives. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.06.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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7
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Correlation between molecular acidity (pKa) and vibrational spectroscopy. J Mol Model 2019; 25:48. [DOI: 10.1007/s00894-019-3928-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 01/03/2019] [Indexed: 12/17/2022]
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8
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Sulfinate-Organocatalyzed (3+2) Annulation Reaction of Propargyl or Allenyl Sulfones with Activated Imines. European J Org Chem 2018. [DOI: 10.1002/ejoc.201800749] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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9
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Cao X, Rong C, Zhong A, Lu T, Liu S. Molecular acidity: An accurate description with information-theoretic approach in density functional reactivity theory. J Comput Chem 2017; 39:117-129. [PMID: 29076175 DOI: 10.1002/jcc.25090] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 09/14/2017] [Accepted: 10/06/2017] [Indexed: 11/10/2022]
Abstract
Molecular acidity is one of the important physiochemical properties of a molecular system, yet its accurate calculation and prediction are still an unresolved problem in the literature. In this work, we propose to make use of the quantities from the information-theoretic (IT) approach in density functional reactivity theory and provide an accurate description of molecular acidity from a completely new perspective. To illustrate our point, five different categories of acidic series, singly and doubly substituted benzoic acids, singly substituted benzenesulfinic acids, benzeneseleninic acids, phenols, and alkyl carboxylic acids, have been thoroughly examined. We show that using IT quantities such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy, information gain, Onicescu information energy, and relative Rényi entropy, one is able to simultaneously predict experimental pKa values of these different categories of compounds. Because of the universality of the quantities employed in this work, which are all density dependent, our approach should be general and be applicable to other systems as well. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Xiaofang Cao
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research, (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan, 410081, People's Republic of China
| | - Chunying Rong
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research, (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan, 410081, People's Republic of China
| | - Aiguo Zhong
- School of Pharmaceutical and Chemical Engineering, Taizhou University, 1139 Shifu Road, Linhai, Zhejiang, 318000, People's Republic of China
| | - Tian Lu
- Beijing Kein Research Center for Natural Sciences, Beijing, 100022, People's Republic of China
| | - Shubin Liu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research, (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, Hunan, 410081, People's Republic of China.,Research Computing Center, University of North Carolina, Chapel Hill, North Carolina, 27599-3420
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10
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Investigation of the acid-base and electromigration properties of 5‐azacytosine derivatives using capillary electrophoresis and density functional theory calculations. J Chromatogr A 2017; 1479:185-193. [DOI: 10.1016/j.chroma.2016.11.058] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/25/2016] [Accepted: 11/28/2016] [Indexed: 11/20/2022]
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11
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Zhang Y, Chen H, Liu X, Zhang Y, Fang Y, Qin Z. Effective and Reversible Switching of Emulsions by an Acid/Base-Mediated Redox Reaction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:13728-13735. [PMID: 27958741 DOI: 10.1021/acs.langmuir.6b03645] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
To develop a fast, effective, and reversible strategy for phase separation and re-emulsification of the surfactant-based emulsions, a strategy for using acid/base-mediated redox reactions was established to switch the emulsions formed from a redox-responsive anionic surfactant of potassium dodecyl seleninate (C12SeO2K). Upon acidification, C12SeO2K was reduced by KI to give didodecyl diselenide (C12Se)2, a state of almost no surface or interfacial activity; upon basification, (C12Se)2 was oxidized by I2 to give C12SeO2K again. The fractional conversion of C12SeO2K in the reversible switching processes was close to 100%. Consequently, an unusually large change in interfacial tension (ΔIFT) as high as ∼27.1 mN m-1 was obtained at a wider concentration range starting from the critical micelle concentration of C12SeO2K; the highest IFT at the oil-water interface was obtained after an almost complete switch-off, giving an oil-aqueous solution interface very similar to that without any emulsifiers, which leads to the effective and fast phase separation of the C12SeO2K-based switchable emulsions.
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Affiliation(s)
- Yuandi Zhang
- School of Chemical & Materials Engineering, Key Laboratory of Food Colloids and Biotechnology Ministry of Education, Jiangnan University , Wuxi 214122, PR China
| | - Hui Chen
- School of Chemical & Materials Engineering, Key Laboratory of Food Colloids and Biotechnology Ministry of Education, Jiangnan University , Wuxi 214122, PR China
| | - Xuefeng Liu
- School of Chemical & Materials Engineering, Key Laboratory of Food Colloids and Biotechnology Ministry of Education, Jiangnan University , Wuxi 214122, PR China
| | - Yongmin Zhang
- School of Chemical & Materials Engineering, Key Laboratory of Food Colloids and Biotechnology Ministry of Education, Jiangnan University , Wuxi 214122, PR China
| | - Yun Fang
- School of Chemical & Materials Engineering, Key Laboratory of Food Colloids and Biotechnology Ministry of Education, Jiangnan University , Wuxi 214122, PR China
| | - Zhirong Qin
- Zhejiang Zanyu Technology Co. Ltd. , Hangzhou 310009, PR China
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12
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Xue XS, Wang Y, Yang C, Ji P, Cheng JP. Toward Prediction of the Chemistry in Ionic Liquids: An Accurate Computation of Absolute pKa Values of Benzoic Acids and Benzenethiols. J Org Chem 2015; 80:8997-9006. [DOI: 10.1021/acs.joc.5b00693] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiao-Song Xue
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071, China
| | - Ya Wang
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071, China
| | - Chen Yang
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071, China
| | - Pengju Ji
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jin-Pei Cheng
- State
Key Laboratory of Elemento-organic Chemistry, Collaborative Innovation
Center of Chemical Science and Engineering (Tianjin), College of Chemistry, Nankai University, Tianjin 300071, China
- Center
of Basic Molecular Science, Department of Chemistry, Tsinghua University, Beijing 100084, China
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13
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Abstract
Computational prediction of condensed phase acidity is a topic of much interest in the field today. We introduce the methods available for predicting gas phase acidity and pKas in aqueous and non-aqueous solvents including high-level electronic structure methods, empirical linear free energy relationships (LFERs), implicit solvent methods, explicit solvent statistical free energy methods, and hybrid implicit–explicit approaches. The focus of this paper is on implicit solvent methods, and we review recent developments including new electronic structure methods, cluster-continuum schemes for calculating ionic solvation free energies, as well as address issues relating to the choice of proton solvation free energy to use with implicit solvation models, and whether thermodynamic cycles are necessary for the computation of pKas. A comparison of the scope and accuracy of implicit solvent methods with ab initio molecular dynamics free energy methods is also presented. The present status of the theory and future directions are outlined.
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14
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Selective trapping of SNO-BSA and GSNO by benzenesulfinic acid sodium salt: mechanistic study of thiosulphonate formation and feasibility as a protein S-nitrosothiol detection strategy. Tetrahedron Lett 2013; 54. [PMID: 24187391 DOI: 10.1016/j.tetlet.2013.08.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The conversion of S-nitrosothiols to thiosulphonates by reaction with the sodium salt of benzenesulfinic acid (PhSO2Na) has been examined in detail with the exemplary substrates S-nitrosoglutathione (GSNO) and S-nitrosylated bovine serum albumin (SNO-BSA). The reaction stoichiometry (2:1, PhSO2Na:RSNO) and the rate law (first order in both PhSO2Na and RSNO) have been determined under mild acidic conditions (pH 4.0). The products have been identified as the corresponding thiosulphonates (GSSO2Ph and BSA-SSO2Ph) along with PhSO2NHOH obtained in a 1:1 ratio. GSH, GSSG, and BSA were unreactive to PhSO2Na.
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15
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Theoretical calculation of pKa values of the Nortryptiline and Amitryptiline drugs in aqueous and non-aqueous solvents. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.06.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Fifen JJ, Nsangou M, Dhaouadi Z, Motapon O, Jaidane NE. Structures of protonated methanol clusters and temperature effects. J Chem Phys 2013; 138:184301. [DOI: 10.1063/1.4802480] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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17
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Fifen JJ, Nsangou M, Dhaouadi Z, Motapon O, Jaidane NE. Solvation Energies of the Proton in Methanol. J Chem Theory Comput 2013; 9:1173-81. [PMID: 26588760 DOI: 10.1021/ct300669v] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
pKa's, proton affinities, and proton dissociation free energies characterize numerous properties of drugs and the antioxidant activity of some chemical compounds. Even with a higher computational level of theory, the uncertainty in the proton solvation free energy limits the accuracy of these parameters. We investigated the thermochemistry of the solvation of the proton in methanol within the cluster-continuum model. The scheme used involves up to nine explicit methanol molecules, using the IEF-PCM and the strategy based on thermodynamic cycles. All computations were performed at B3LYP/6-31++G(dp) and M062X/6-31++G(dp) levels of theory. It comes out from our calculations that the functional M062X is better than B3LYP, on the evaluation of gas phase clustering energies of protonated methanol clusters, per methanol stabilization of neutral methanol clusters and solvation energies of the proton in methanol. The solvation free energy and enthalpy of the proton in methanol were obtained after converging the partial solvation free energy of the proton in methanol and the clustering free energy of protonated methanol clusters, as the cluster size increases. Finally, the recommended values for the solvation free energy and enthalpy of the proton in methanol are -257 and -252 kcal/mol, respectively.
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Affiliation(s)
- Jean Jules Fifen
- University of Ngaoundere, Faculty of Science, P.O. Box 454, Ngaoundere, Cameroon.,Fundamental Physics Lab, Graduate Training Unit in Physics and Engineering Sciences, Faculty of Science, University of Douala, P.O. Box 24157, Douala, Cameroon
| | - Mama Nsangou
- University of Ngaoundere, Faculty of Science, P.O. Box 454, Ngaoundere, Cameroon.,University of Maroua, P.O. Box 46, Maroua, Cameroon
| | - Zoubeida Dhaouadi
- Laboratoire de Spectroscopie Atomique et Moléculaire, Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire 1060, Tunis, Tunisia
| | - Ousmanou Motapon
- Fundamental Physics Lab, Graduate Training Unit in Physics and Engineering Sciences, Faculty of Science, University of Douala, P.O. Box 24157, Douala, Cameroon
| | - Nejm-Eddine Jaidane
- Laboratoire de Spectroscopie Atomique et Moléculaire, Faculté des Sciences de Tunis, Université de Tunis El Manar, Campus Universitaire 1060, Tunis, Tunisia
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18
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Keith JA, Carter EA. Quantum Chemical Benchmarking, Validation, and Prediction of Acidity Constants for Substituted Pyridinium Ions and Pyridinyl Radicals. J Chem Theory Comput 2012; 8:3187-206. [PMID: 26605730 DOI: 10.1021/ct300295g] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sensibly modeling (photo)electrocatalytic reactions involving proton and electron transfer with computational quantum chemistry requires accurate descriptions of protonated, deprotonated, and radical species in solution. Procedures to do this are generally nontrivial, especially in cases that involve radical anions that are unstable in the gas phase. Recently, pyridinium and the corresponding reduced neutral radical have been postulated as key catalysts in the reduction of CO2 to methanol. To assess practical methodologies to describe the acid/base chemistry of these species, we employed density functional theory (DFT) in tandem with implicit solvation models to calculate acidity constants for 22 substituted pyridinium cations and their corresponding pyridinyl radicals in water solvent. We first benchmarked our calculations against experimental pyridinium deprotonation energies in both gas and aqueous phases. DFT with hybrid exchange-correlation functionals provide chemical accuracy for gas-phase data and allow absolute prediction of experimental pKas with unsigned errors under 1 pKa unit. The accuracy of this economical pKa calculation approach was further verified by benchmarking against highly accurate (but very expensive) CCSD(T)-F12 calculations. We compare the relative importance and sensitivity of these energies to selection of solvation model, solvation energy definitions, implicit solvation cavity definition, basis sets, electron densities, model geometries, and mixed implicit/explicit models. After determining the most accurate model to reproduce experimentally-known pKas from first principles, we apply the same approach to predict pKas for radical pyridinyl species that have been proposed relevant under electrochemical conditions. This work provides considerable insight into the pitfalls using continuum solvation models, particularly when used for radical species.
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Affiliation(s)
- John A Keith
- Department of Mechanical and Aerospace Engineering, ‡Program in Applied and Computational Mathematics, and the Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544-5263, United States
| | - Emily A Carter
- Department of Mechanical and Aerospace Engineering, ‡Program in Applied and Computational Mathematics, and the Andlinger Center for Energy and the Environment, Princeton University , Princeton, New Jersey 08544-5263, United States
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19
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Bourlès E, Isaac M, Lebrun C, Latour JM, Sénèque O. Oxidation of Zn(Cys)4 zinc finger peptides by O2 and H2O2: products, mechanism and kinetics. Chemistry 2011; 17:13762-72. [PMID: 22052717 DOI: 10.1002/chem.201101913] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Indexed: 11/10/2022]
Abstract
The reactivity of a series of Zn(Cys)(4) zinc finger model peptides towards H(2)O(2) and O(2) has been investigated. The oxidation products were identified by HPLC and ESI-MS analysis. At pH<7.5, the zinc complexes and the free peptides are oxidised to bis-disulfide-containing peptides. Above pH 7.5, the oxidation of the zinc complexes by H(2)O(2) also yields sulfinate- and sulfonate-containing overoxidised peptides. At pH 7.0, monitoring of the reactions between the zinc complexes and H(2)O(2) by HPLC revealed the sequential formation of two disulfides. Several techniques for the determination of the rate constant for the first oxidation step corresponding to the attack of H(2)O(2) by the Zn(Cys)(4) site have been compared. This rate constant can be reliably determined by monitoring the oxidation by HPLC, fluorescence, circular dichroism or absorption spectroscopy in the presence of excess ethyleneglycol bis(2-aminoethyl ether)tetraacetic acid. In contrast, monitoring of the release of zinc with 4-(2-pyridylazo)resorcinol or of the thiol content with 5,5'-dithiobis(2-nitrobenzoate) did not yield reliable values of this rate constant for the case in which the formation of the second disulfide is slower than the formation of the first. The kinetic measurements clearly evidence a protective effect of zinc on the oxidation of the cysteines by both H(2)O(2) and O(2), which points to the fact that zinc binding diminishes the nucleophilicity of the thiolates. In addition, the reaction between the zinc finger and H(2)O(2) is too slow to consider zinc fingers as potential sensors for H(2)O(2) in cells.
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Affiliation(s)
- Emilie Bourlès
- Laboratoire de Chimie et Biologie des Métaux, UMR 5249 CNRS/CEA/Université Joseph Fourier, 17 rue des Martyrs, 38054 Grenoble Cedex 9, France
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20
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Estimating the acidity of singly and multiply substituted benzoic acids via electrostatic potential at the nucleus. Chem Phys Lett 2011. [DOI: 10.1016/j.cplett.2011.07.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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21
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Reyes AM, Hugo M, Trostchansky A, Capece L, Radi R, Trujillo M. Oxidizing substrate specificity of Mycobacterium tuberculosis alkyl hydroperoxide reductase E: kinetics and mechanisms of oxidation and overoxidation. Free Radic Biol Med 2011; 51:464-73. [PMID: 21571062 DOI: 10.1016/j.freeradbiomed.2011.04.023] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Revised: 04/07/2011] [Accepted: 04/12/2011] [Indexed: 11/17/2022]
Abstract
Alkyl hydroperoxide reductase E (AhpE), a novel subgroup of the peroxiredoxin family, comprises Mycobacterium tuberculosis AhpE (MtAhpE) and AhpE-like proteins present in many bacteria and archaea, for which functional characterization is scarce. We previously reported that MtAhpE reacted ~10(3) times faster with peroxynitrite than with hydrogen peroxide, but the molecular reasons for that remained unknown. Herein, we investigated the oxidizing substrate specificity and the oxidative inactivation of the enzyme. In most cases, both peroxidatic thiol oxidation and sulfenic acid overoxidation followed a trend in which those peroxides with the lower leaving-group pK(a) reacted faster than others. These data are in agreement with the accepted mechanisms of thiol oxidation and support that overoxidation occurs through sulfenate anion reaction with the protonated peroxide. However, MtAhpE oxidation and overoxidation by fatty acid-derived hydroperoxides (~10(8) and 10(5) M(-1) s(-1), respectively, at pH 7.4 and 25°C) were much faster than expected according to the Brønsted relationship with leaving-group pK(a). A stoichiometric reduction of the arachidonic acid hydroperoxide 15-HpETE to its corresponding alcohol was confirmed. Interactions of fatty acid hydroperoxides with a hydrophobic groove present on the reduced MtAhpE surface could be the basis of their surprisingly fast reactivity.
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Affiliation(s)
- Aníbal M Reyes
- Departamento de Bioquímica, Universidad de la República, 11800 Montevideo, Uruguay
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22
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Kassim R, Ramseyer C, Enescu M. Oxidation of Zinc–Thiolate Complexes of Biological Interest by Hydrogen Peroxide: A Theoretical Study. Inorg Chem 2011; 50:5407-16. [DOI: 10.1021/ic200267x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rima Kassim
- Centre de Recherche Universitaire de Djibouti (CRUD), University of Djibouti, Avenue Georges Clemenceau, Djibouti
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