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Keywords = concerted catalysis

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21 pages, 3295 KiB  
Review
Design of Multicatalytic Systems Through Self-Assembly
by Antony E. Fernandes and Alain M. Jonas
Catalysts 2025, 15(3), 265; https://doi.org/10.3390/catal15030265 - 11 Mar 2025
Viewed by 971
Abstract
The development of self-assembled multicatalytic systems has emerged as a promising strategy for mimicking enzymatic catalysis in synthetic systems. This approach leverages the use of non-covalent interactions, such as hydrophobic interactions, hydrogen bonding, metal–ligand coordination, and aromatic stacking, to organize multiple catalytic centers [...] Read more.
The development of self-assembled multicatalytic systems has emerged as a promising strategy for mimicking enzymatic catalysis in synthetic systems. This approach leverages the use of non-covalent interactions, such as hydrophobic interactions, hydrogen bonding, metal–ligand coordination, and aromatic stacking, to organize multiple catalytic centers within a defined, cooperative framework, allowing for enhanced reactivity, selectivity and efficiency, akin to the behavior of natural enzymes. The versatility of this approach enables the modular design, preparation, screening and optimization of systems capable of concerted catalysis and dynamic adaptation, making them suitable for a wide range of reactions, including asymmetric synthesis. The potential of these systems to emulate the precision and functionality of natural enzymes opens new avenues for the development of artificial multicatalytic systems with tailored and adaptable functions. Full article
(This article belongs to the Special Issue New Insights into Synergistic Dual Catalysis)
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22 pages, 3703 KiB  
Article
Theoretical Study on the Metabolic Mechanism of Heptachlor in Human Cytochrome P450 Enzymes
by Xuerui Zhao, Hao Zhang, Xiaoli Shen, Qingchuan Zheng and Song Wang
Int. J. Mol. Sci. 2025, 26(5), 2021; https://doi.org/10.3390/ijms26052021 - 26 Feb 2025
Viewed by 676
Abstract
Heptachlor (HEP) is an insecticide metabolized by cytochrome P450 (CYP) enzymes in the human liver, resulting in the formation of heptachlor epoxide (HEPX). HEPX can persist in the human body for a long duration. Therefore, it can be extremely harmful. A comprehensive understanding [...] Read more.
Heptachlor (HEP) is an insecticide metabolized by cytochrome P450 (CYP) enzymes in the human liver, resulting in the formation of heptachlor epoxide (HEPX). HEPX can persist in the human body for a long duration. Therefore, it can be extremely harmful. A comprehensive understanding of HEP’s metabolic fate may provide a theoretical basis for mitigating associated hazards. However, the specific human CYP isoforms that metabolize HEP, and their metabolic mechanisms, remain unclear. In this study, eight human CYP isoforms were used as catalytic enzymes to investigate the metabolic mechanism of HEP using molecular docking, molecular dynamics simulations, and quantum mechanical calculations. These results indicate that HEP primarily binds to CYP enzymes through hydrophobic interactions, and that the binding positions of HEP are determined by the composition and shape of the hydrophobic pockets near the active site. Based on the reaction distance, CYP2A6, CYP3A4, and CYP3A5 were the only three enzymes that could metabolize HEP. The epoxidation of HEP catalyzed by the doublet state of compound I was effectively concerted, and the rate-determining step was the electrophilic attack of the oxygen atom on HEP. The energy barriers of the rate-determining step vary significantly among different enzymes. A comparison of these energy barriers suggested that CYP3A5 is the most likely enzyme for HEP catalysis in humans. Full article
(This article belongs to the Special Issue Molecular Modeling: Latest Advances and Applications)
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13 pages, 2517 KiB  
Article
The Adaptative Modulation of the Phosphinito–Phosphinous Acid Ligand: Computational Illustration Through Palladium-Catalyzed Alcohol Oxidation
by Romain Membrat, Tété Etonam Kondo, Alexis Agostini, Alexandre Vasseur, Paola Nava, Laurent Giordano, Alexandre Martinez, Didier Nuel and Stéphane Humbel
Molecules 2024, 29(21), 4999; https://doi.org/10.3390/molecules29214999 - 22 Oct 2024
Viewed by 1546
Abstract
The phosphinito–phosphinous acid ligand (PAP) is a singular bidentate-like self-assembled ligand exhibiting dissymmetric but interchangeable electronic properties. This unusual structure has been used for the generation of active palladium hydride through alcohol oxidation. In this paper, we report the first theoretical highlight of [...] Read more.
The phosphinito–phosphinous acid ligand (PAP) is a singular bidentate-like self-assembled ligand exhibiting dissymmetric but interchangeable electronic properties. This unusual structure has been used for the generation of active palladium hydride through alcohol oxidation. In this paper, we report the first theoretical highlight of the adaptative modulation ability of this ligand within a direct H-abstraction path for Pd and Pt catalyzed alcohol oxidation. A reaction forces study revealed rearrangements in the ligand self-assembling system triggered by a simple proton shift to promote the metal hydride generation via concerted six-center mechanism. We unveil here the peculiar behavior of the phosphinito–phosphinous acid ligand in this catalysis. Full article
(This article belongs to the Special Issue Fundamental Concepts and Recent Developments in Chemical Bonding)
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27 pages, 2435 KiB  
Article
Phosphorus Chemistry at the Roots of Bioenergetics: Ligand Permutation as the Molecular Basis of the Mechanism of ATP Synthesis/Hydrolysis by FOF1-ATP Synthase
by Sunil Nath
Molecules 2023, 28(22), 7486; https://doi.org/10.3390/molecules28227486 - 8 Nov 2023
Cited by 12 | Viewed by 2167
Abstract
The integration of phosphorus chemistry with the mechanism of ATP synthesis/hydrolysis requires dynamical information during ATP turnover and catalysis. Oxygen exchange reactions occurring at β-catalytic sites of the FOF1-ATP synthase/F1-ATPase imprint a unique record of molecular events [...] Read more.
The integration of phosphorus chemistry with the mechanism of ATP synthesis/hydrolysis requires dynamical information during ATP turnover and catalysis. Oxygen exchange reactions occurring at β-catalytic sites of the FOF1-ATP synthase/F1-ATPase imprint a unique record of molecular events during the catalytic cycle of ATP synthesis/hydrolysis. They have been shown to provide valuable time-resolved information on enzyme catalysis during ATP synthesis and ATP hydrolysis. The present work conducts new experiments on oxygen exchange catalyzed by submitochondrial particles designed to (i) measure the relative rates of Pi–ATP, Pi–HOH, and ATP–HOH isotope exchanges; (ii) probe the effect of ADP removal on the extent of inhibition of the exchanges, and (iii) test their uncoupler sensitivity/resistance. The objectives have been realized based on new experiments on submitochondrial particles, which show that both the Pi–HOH and ATP–HOH exchanges occur at a considerably higher rate relative to the Pi–ATP exchange, an observation that cannot be explained by previous mechanisms. A unifying explanation of the kinetic data that rationalizes these observations is given. The experimental results in (ii) show that ADP removal does not inhibit the intermediate Pi–HOH exchange when ATP and submitochondrial particles are incubated, and that the nucleotide requirement of the intermediate Pi–HOH exchange is adequately met by ATP, but not by ADP. These results contradicts the central postulate in Boyer’s binding change mechanism of reversible catalysis at a F1 catalytic site with Keq~1 that predicts an absolute requirement of ADP for the occurrence of the Pi–HOH exchange. The prominent intermediate Pi–HOH exchange occurring under hydrolytic conditions is shown to be best explained by Nath’s torsional mechanism of energy transduction and ATP synthesis/hydrolysis, which postulates an essentially irreversible cleavage of ATP by mitochondria/particles, independent from a reversible formation of ATP from ADP and Pi. The explanation within the torsional mechanism is also shown to rationalize the relative insensitivity of the intermediate Pi–HOH exchange to uncouplers observed in the experiments in (iii) compared to the Pi–ATP and ATP–HOH exchanges. This is shown to lead to new concepts and perspectives based on ligand displacement/substitution and ligand permutation for the elucidation of the oxygen exchange reactions within the framework of fundamental phosphorus chemistry. Fast mechanisms that realize the rotation/twist, tilt, permutation and switch of ligands, as well as inversion at the γ-phosphorus synchronously and simultaneously and in a concerted manner, have been proposed, and their stereochemical consequences have been analyzed. These considerations take us beyond the binding change mechanism of ATP synthesis/hydrolysis in bioenergetics. Full article
(This article belongs to the Special Issue Organophosphorus Chemistry: A New Perspective, 2nd Edition)
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9 pages, 1916 KiB  
Article
Photocatalytic CO2 Reduction Coupled with Alcohol Oxidation over Porous Carbon Nitride
by Chuntian Qiu, Shan Wang, Jiandong Zuo and Bing Zhang
Catalysts 2022, 12(6), 672; https://doi.org/10.3390/catal12060672 - 20 Jun 2022
Cited by 21 | Viewed by 3126
Abstract
The photocatalytic transformation of CO2 to valuable man-made feedstocks is a promising method for balancing the carbon cycle; however, it is often hampered by the consumption of extra hole scavengers. Here, a synergistic redox system using photogenerated electron-hole pairs was constructed by [...] Read more.
The photocatalytic transformation of CO2 to valuable man-made feedstocks is a promising method for balancing the carbon cycle; however, it is often hampered by the consumption of extra hole scavengers. Here, a synergistic redox system using photogenerated electron-hole pairs was constructed by employing a porous carbon nitride with many cyanide groups as a metal-free photocatalyst. Selective CO2 reduction to CO using photogenerated electrons was achieved under mild conditions; simultaneously, various alcohols were effectively oxidized to value-added aldehydes using holes. The results showed that thermal calcination process using ammonium sulfate as porogen contributes to the construction of a porous structure. As-obtained cyanide groups can facilitate charge carrier separation and promote moderate CO2 adsorption. Electron-donating groups in alcohols could enhance the activity via a faster hydrogen-donating process. This concerted photocatalytic system that synergistically utilizes electron-hole pairs upon light excitation contributes to the construction of cost-effective and multifunctional photocatalytic systems for selective CO2 reduction and artificial photosynthesis. Full article
(This article belongs to the Special Issue Advanced Catalysts for Achieving Hydrogen Economy from Liquids)
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50 pages, 17858 KiB  
Review
Macroporosity Control by Phase Separation in Sol-Gel Derived Monoliths and Microspheres
by Ana C. Marques and Mário Vale
Materials 2021, 14(15), 4247; https://doi.org/10.3390/ma14154247 - 29 Jul 2021
Cited by 15 | Viewed by 5696
Abstract
Macroporous and hierarchically macro/mesoporous materials (mostly monoliths and microspheres) have attracted much attention for a variety of applications, such as supporting or enabling materials in chromatography, energy storage and conversion, catalysis, biomedical devices, drug delivery systems, and environmental remediation. A well-succeeded method to [...] Read more.
Macroporous and hierarchically macro/mesoporous materials (mostly monoliths and microspheres) have attracted much attention for a variety of applications, such as supporting or enabling materials in chromatography, energy storage and conversion, catalysis, biomedical devices, drug delivery systems, and environmental remediation. A well-succeeded method to obtain these tailored porous materials relies on the sol-gel technique, combined with phase separation by spinodal decomposition, and involves as well emulsification as a soft template, in the case of the synthesis of porous microspheres. Significant advancements have been witnessed, in terms of synthesis methodologies optimized either for the use of alkoxides or metal–salts and material design, including the grafting or immobilization of a specific species (or nanoparticles) to enable the most recent trends in technological applications, such as photocatalysis. In this context, the evolution, in terms of material composition and synthesis strategies, is discussed in a concerted fashion in this review, with the goal of inspiring new improvements and breakthroughs in the framework of porous materials. Full article
(This article belongs to the Special Issue Porous Support Materials)
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35 pages, 9699 KiB  
Review
Organocatalysis and Beyond: Activating Reactions with Two Catalytic Species
by Arianna Sinibaldi, Valeria Nori, Andrea Baschieri, Francesco Fini, Antonio Arcadi and Armando Carlone
Catalysts 2019, 9(11), 928; https://doi.org/10.3390/catal9110928 - 6 Nov 2019
Cited by 35 | Viewed by 9217
Abstract
Since the beginning of the millennium, organocatalysis has been gaining a predominant role in asymmetric synthesis and it is, nowadays, a foundation of catalysis. Synergistic catalysis, combining two or more different catalytic cycles acting in concert, exploits the vast knowledge acquired in organocatalysis [...] Read more.
Since the beginning of the millennium, organocatalysis has been gaining a predominant role in asymmetric synthesis and it is, nowadays, a foundation of catalysis. Synergistic catalysis, combining two or more different catalytic cycles acting in concert, exploits the vast knowledge acquired in organocatalysis and other fields to perform reactions that would be otherwise impossible. Merging organocatalysis with photo-, metallo- and organocatalysis itself, researchers have ingeniously devised a range of activations. This feature review, focusing on selected synergistic catalytic approaches, aims to provide a flavor of the creativity and innovation in the area, showing ground-breaking examples of organocatalysts, such as proline derivatives, hydrogen bond-mediated, Cinchona alkaloids or phosphoric acids catalysts, which work cooperatively with different catalytic partners. Full article
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10 pages, 8417 KiB  
Communication
Concerted Catalysis by Nanocellulose and Proline in Organocatalytic Michael Additions
by Naliharifetra Jessica Ranaivoarimanana, Kyohei Kanomata and Takuya Kitaoka
Molecules 2019, 24(7), 1231; https://doi.org/10.3390/molecules24071231 - 29 Mar 2019
Cited by 16 | Viewed by 4275
Abstract
Cellulose nanofibers (CNFs) have recently attracted much attention as catalysts in various reactions. Organocatalysts have emerged as sustainable alternatives to metal-based catalysts in green organic synthesis, with concerted systems containing CNFs that are expected to provide next-generation catalysis. Herein, for the first time, [...] Read more.
Cellulose nanofibers (CNFs) have recently attracted much attention as catalysts in various reactions. Organocatalysts have emerged as sustainable alternatives to metal-based catalysts in green organic synthesis, with concerted systems containing CNFs that are expected to provide next-generation catalysis. Herein, for the first time, we report that a representative organocatalyst comprising an unexpected combination of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-oxidized CNFs and proline shows significantly enhanced catalytic activity in an asymmetric Michael addition. Full article
(This article belongs to the Special Issue Emerging Trends in Nanocelluloses)
14 pages, 2713 KiB  
Review
The Fe Protein: An Unsung Hero of Nitrogenase
by Andrew J. Jasniewski, Nathaniel S. Sickerman, Yilin Hu and Markus W. Ribbe
Inorganics 2018, 6(1), 25; https://doi.org/10.3390/inorganics6010025 - 3 Feb 2018
Cited by 34 | Viewed by 9260
Abstract
Although the nitrogen-fixing enzyme nitrogenase critically requires both a reductase component (Fe protein) and a catalytic component, considerably more work has focused on the latter species. Properties of the catalytic component, which contains two highly complex metallocofactors and catalyzes the reduction of N [...] Read more.
Although the nitrogen-fixing enzyme nitrogenase critically requires both a reductase component (Fe protein) and a catalytic component, considerably more work has focused on the latter species. Properties of the catalytic component, which contains two highly complex metallocofactors and catalyzes the reduction of N2 into ammonia, understandably making it the “star” of nitrogenase. However, as its obligate redox partner, the Fe protein is a workhorse with multiple supporting roles in both cofactor maturation and catalysis. In particular, the nitrogenase Fe protein utilizes nucleotide binding and hydrolysis in concert with electron transfer to accomplish several tasks of critical importance. Aside from the ATP-coupled transfer of electrons to the catalytic component during substrate reduction, the Fe protein also functions in a maturase and insertase capacity to facilitate the biosynthesis of the two-catalytic component metallocofactors: fusion of the [Fe8S7] P-cluster and insertion of Mo and homocitrate to form the matured [(homocitrate)MoFe7S9C] M-cluster. These and key structural-functional relationships of the indispensable Fe protein and its complex with the catalytic component will be covered in this review. Full article
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11 pages, 1172 KiB  
Short Note
Acetic Acid-Catalyzed Formation of N-Phenylphthalimide from Phthalanilic Acid: A Computational Study of the Mechanism
by Ohgi Takahashi, Ryota Kirikoshi and Noriyoshi Manabe
Int. J. Mol. Sci. 2015, 16(6), 12174-12184; https://doi.org/10.3390/ijms160612174 - 28 May 2015
Cited by 5 | Viewed by 8094
Abstract
In glacial acetic acid, phthalanilic acid and its monosubstituents are known to be converted to the corresponding phthalimides in relatively good yields. In this study, we computationally investigated the experimentally proposed two-step (addition-elimination or cyclization-dehydration) mechanism at the second-order Møller-Plesset perturbation (MP2) level [...] Read more.
In glacial acetic acid, phthalanilic acid and its monosubstituents are known to be converted to the corresponding phthalimides in relatively good yields. In this study, we computationally investigated the experimentally proposed two-step (addition-elimination or cyclization-dehydration) mechanism at the second-order Møller-Plesset perturbation (MP2) level of theory for the unsubstituted phthalanilic acid, with an explicit acetic acid molecule included in the calculations. In the first step, a gem-diol tetrahedral intermediate is formed by the nucleophilic attack of the amide nitrogen. The second step is dehydration of the intermediate to give N-phenylphthalimide. In agreement with experimental findings, the second step has been shown to be rate-determining. Most importantly, both of the steps are catalyzed by an acetic acid molecule, which acts both as proton donor and acceptor. The present findings, along with those from our previous studies, suggest that acetic acid and other carboxylic acids (in their undissociated forms) can catalyze intramolecular nucleophilic attacks by amide nitrogens and breakdown of the resulting tetrahedral intermediates, acting simultaneously as proton donor and acceptor. In other words, double proton transfers involving a carboxylic acid molecule can be part of an extensive bond reorganization process from cyclic hydrogen-bonded complexes. Full article
(This article belongs to the Special Issue Chemical Bond and Bonding 2015)
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12 pages, 1210 KiB  
Article
Glycolic Acid-Catalyzed Deamidation of Asparagine Residues in Degrading PLGA Matrices: A Computational Study
by Noriyoshi Manabe, Ryota Kirikoshi and Ohgi Takahashi
Int. J. Mol. Sci. 2015, 16(4), 7261-7272; https://doi.org/10.3390/ijms16047261 - 31 Mar 2015
Cited by 13 | Viewed by 6934
Abstract
Poly(lactic-co-glycolic acid) (PLGA) is a strong candidate for being a drug carrier in drug delivery systems because of its biocompatibility and biodegradability. However, in degrading PLGA matrices, the encapsulated peptide and protein drugs can undergo various degradation reactions, including deamidation at [...] Read more.
Poly(lactic-co-glycolic acid) (PLGA) is a strong candidate for being a drug carrier in drug delivery systems because of its biocompatibility and biodegradability. However, in degrading PLGA matrices, the encapsulated peptide and protein drugs can undergo various degradation reactions, including deamidation at asparagine (Asn) residues to give a succinimide species, which may affect their potency and/or safety. Here, we show computationally that glycolic acid (GA) in its undissociated form, which can exist in high concentration in degrading PLGA matrices, can catalyze the succinimide formation from Asn residues by acting as a proton-transfer mediator. A two-step mechanism was studied by quantum-chemical calculations using Ace-Asn-Nme (Ace = acetyl, Nme = NHCH3) as a model compound. The first step is cyclization (intramolecular addition) to form a tetrahedral intermediate, and the second step is elimination of ammonia from the intermediate. Both steps involve an extensive bond reorganization mediated by a GA molecule, and the first step was predicted to be rate-determining. The present findings are expected to be useful in the design of more effective and safe PLGA devices. Full article
(This article belongs to the Special Issue Chemical Bond and Bonding 2015)
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14 pages, 1096 KiB  
Article
Acetic Acid Can Catalyze Succinimide Formation from Aspartic Acid Residues by a Concerted Bond Reorganization Mechanism: A Computational Study
by Ohgi Takahashi, Ryota Kirikoshi and Noriyoshi Manabe
Int. J. Mol. Sci. 2015, 16(1), 1613-1626; https://doi.org/10.3390/ijms16011613 - 12 Jan 2015
Cited by 17 | Viewed by 10286
Abstract
Succinimide formation from aspartic acid (Asp) residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe) as a model compound, we propose the possibility that acetic acid (AA), which [...] Read more.
Succinimide formation from aspartic acid (Asp) residues is a concern in the formulation of protein drugs. Based on density functional theory calculations using Ace-Asp-Nme (Ace = acetyl, Nme = NHMe) as a model compound, we propose the possibility that acetic acid (AA), which is often used in protein drug formulation for mildly acidic buffer solutions, catalyzes the succinimide formation from Asp residues by acting as a proton-transfer mediator. The proposed mechanism comprises two steps: cyclization (intramolecular addition) to form a gem-diol tetrahedral intermediate and dehydration of the intermediate. Both steps are catalyzed by an AA molecule, and the first step was predicted to be rate-determining. The cyclization results from a bond formation between the amide nitrogen on the C-terminal side and the side-chain carboxyl carbon, which is part of an extensive bond reorganization (formation and breaking of single bonds and the interchange of single and double bonds) occurring concertedly in a cyclic structure formed by the amide NH bond, the AA molecule and the side-chain C=O group and involving a double proton transfer. The second step also involves an AA-mediated bond reorganization. Carboxylic acids other than AA are also expected to catalyze the succinimide formation by a similar mechanism. Full article
(This article belongs to the Special Issue Chemical Bond and Bonding 2015)
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