Ajay U. Pandya, Mukesh P. Chaudhari, Vinay S. Sharma, Archana George, Gopal N. Shiyal, Pranav S Shrivastav
Developing innovative methods for synthesizing unique 2,3'‐biindole derivatives is crucial for the progression of drug and material discovery. The use of transition‐metal‐catalyzed coupling improves the efficiency and structural diversity in the synthesis of biindoles. Among these methods, heterogeneous catalysis, particularly using Fe3O4 nanocatalyst supported by microcrystalline cellulose (MCC), is promising for green chemistry applications. In the present work, sixteen 2,3'‐biindole derivatives (4a‐p) were prepared using Fe3O4@MCC nano catalyst which demonstrated enhanced performance, cost‐effectiveness, and reusability. The magnetic properties of the catalyst enable easy separation, simplifying purification processes and enhancing overall reaction efficiency to 78‐93%. This method aligns with sustainable chemical practices and offers practical benefits for various industrial applications. This environmentally friendly method boasts several advantages and demonstrates excellent green chemistry metrics, including process mass intensity, environmental impact factor, atom economy, and reaction mass efficiency, atom economy, carbon efficiency, chemical yield and optimum efficiency.
{"title":"Application of Fe3O4@MCC Nanoparticles as a Heterogeneous Catalyst for Sustainable Multicomponent Synthesis of 2,3'‐Biindoles","authors":"Ajay U. Pandya, Mukesh P. Chaudhari, Vinay S. Sharma, Archana George, Gopal N. Shiyal, Pranav S Shrivastav","doi":"10.1002/cctc.202401308","DOIUrl":"https://doi.org/10.1002/cctc.202401308","url":null,"abstract":"Developing innovative methods for synthesizing unique 2,3'‐biindole derivatives is crucial for the progression of drug and material discovery. The use of transition‐metal‐catalyzed coupling improves the efficiency and structural diversity in the synthesis of biindoles. Among these methods, heterogeneous catalysis, particularly using Fe3O4 nanocatalyst supported by microcrystalline cellulose (MCC), is promising for green chemistry applications. In the present work, sixteen 2,3'‐biindole derivatives (4a‐p) were prepared using Fe3O4@MCC nano catalyst which demonstrated enhanced performance, cost‐effectiveness, and reusability. The magnetic properties of the catalyst enable easy separation, simplifying purification processes and enhancing overall reaction efficiency to 78‐93%. This method aligns with sustainable chemical practices and offers practical benefits for various industrial applications. This environmentally friendly method boasts several advantages and demonstrates excellent green chemistry metrics, including process mass intensity, environmental impact factor, atom economy, and reaction mass efficiency, atom economy, carbon efficiency, chemical yield and optimum efficiency.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"38 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jianglong Guo, Qizheng An, Xu Zhang, Yuhao Zhang, Jingjing Jiang, Jing Zhang, Baojie Li, Xupeng Qin, Wei Wang, Qinghua Liu
Due to isolated active sites of single‐atom catalysts (SACs), the catalytic kinetics of SACs are often unsatisfactory in those catalytic reaction processes involving multiple intermediates and reaction pathways, such as the oxygen reduction reaction (ORR). To address this bottleneck and enhance the ORR performance of SACs, we developed a boron‐doped Fe‒Cu dual‐atom catalyst (Fe‒Cu‒B/NC). This catalyst is designed to modulate the oxygen adsorption model and adjust the adsorption strength of oxygen intermediates at the metal sites. In situ synchrotron infrared spectroscopy demonstrated that the Fe‒Cu‒B/NC catalyst facilitates the adsorption of oxygen intermediates on the Fe‒Cu dual sites through a bridge adsorption model, which is more favorable for O–O bond cleavage. Meanwhile, in situ electrochemical impedance spectroscopy revealed that the transformation of the adsorption model can accelerate the kinetics of intermediate species, further enhancing the catalytic efficiency. As a result, Fe‒Cu‒B/NC exhibits good ORR activity and strong durability, retaining 90% of its initial current density after 10 hours of the ORR process in alkaline media.
{"title":"Altering Oxygen Adsorption Model on B‐Doped Fe‐Cu Dual‐Atom Catalysts for Efficient Oxygen Reduction","authors":"Jianglong Guo, Qizheng An, Xu Zhang, Yuhao Zhang, Jingjing Jiang, Jing Zhang, Baojie Li, Xupeng Qin, Wei Wang, Qinghua Liu","doi":"10.1002/cctc.202401272","DOIUrl":"https://doi.org/10.1002/cctc.202401272","url":null,"abstract":"Due to isolated active sites of single‐atom catalysts (SACs), the catalytic kinetics of SACs are often unsatisfactory in those catalytic reaction processes involving multiple intermediates and reaction pathways, such as the oxygen reduction reaction (ORR). To address this bottleneck and enhance the ORR performance of SACs, we developed a boron‐doped Fe‒Cu dual‐atom catalyst (Fe‒Cu‒B/NC). This catalyst is designed to modulate the oxygen adsorption model and adjust the adsorption strength of oxygen intermediates at the metal sites. In situ synchrotron infrared spectroscopy demonstrated that the Fe‒Cu‒B/NC catalyst facilitates the adsorption of oxygen intermediates on the Fe‒Cu dual sites through a bridge adsorption model, which is more favorable for O–O bond cleavage. Meanwhile, in situ electrochemical impedance spectroscopy revealed that the transformation of the adsorption model can accelerate the kinetics of intermediate species, further enhancing the catalytic efficiency. As a result, Fe‒Cu‒B/NC exhibits good ORR activity and strong durability, retaining 90% of its initial current density after 10 hours of the ORR process in alkaline media.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"36 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208739","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ji Feng, Ningbo Wan, Xiaohua Ju, Lin Liu, Liguang Bai, Xiaodong Zhao, Teng He
Hydrogen production from decomposition of ammonia is one of the promising methods to solve the problem of hydrogen storage and transportation. Currently, ruthenium‐based catalysts are widely recognized as highly active catalysts for ammonia decomposition reaction. Here, Ru nanoparticles (NPs) on yttrium oxide derived from yttrium carbonate precursor (c‐Y2O3) was successfully prepared by impregnation method. A hydrogen production rate up to 31.5 mmol gcat−1 min−1 can be obtained over the 5% Ru/c‐Y2O3 catalyst at 450 °C with a weight hour space velocity (WHSV) of 30000 mL gcat−1 h−1, and the activity is stable during a test period of 120 hours. Characterization results reveal that high metal dispersion of Ru NPs, strong metal‐support interaction, high concentration of oxygen vacancies and suitable basicity of Ru/c‐Y2O3 catalyst all have a strong influence on the catalytic performance in ammonia decomposition. NH3 temperature‐programmed surface reaction (NH3‐TPSR) results indicate that a strong NH3 adsorption activation and binding desorption of nitrogen ability on the surface of Ru/c‐Y2O3 catalysts are also beneficial for the high activity. These results provide a reference for the design of efficient Ru‐based ammonia decomposition catalysts for hydrogen production by tuning the precursor of Y2O3 support.
{"title":"Efficient Ru/Y2O3 Catalyst Derived from Ru Nanoparticles on Yttrium Carbonate for Production of Hydrogen from Ammonia Decomposition","authors":"Ji Feng, Ningbo Wan, Xiaohua Ju, Lin Liu, Liguang Bai, Xiaodong Zhao, Teng He","doi":"10.1002/cctc.202401314","DOIUrl":"https://doi.org/10.1002/cctc.202401314","url":null,"abstract":"Hydrogen production from decomposition of ammonia is one of the promising methods to solve the problem of hydrogen storage and transportation. Currently, ruthenium‐based catalysts are widely recognized as highly active catalysts for ammonia decomposition reaction. Here, Ru nanoparticles (NPs) on yttrium oxide derived from yttrium carbonate precursor (c‐Y2O3) was successfully prepared by impregnation method. A hydrogen production rate up to 31.5 mmol gcat−1 min−1 can be obtained over the 5% Ru/c‐Y2O3 catalyst at 450 °C with a weight hour space velocity (WHSV) of 30000 mL gcat−1 h−1, and the activity is stable during a test period of 120 hours. Characterization results reveal that high metal dispersion of Ru NPs, strong metal‐support interaction, high concentration of oxygen vacancies and suitable basicity of Ru/c‐Y2O3 catalyst all have a strong influence on the catalytic performance in ammonia decomposition. NH3 temperature‐programmed surface reaction (NH3‐TPSR) results indicate that a strong NH3 adsorption activation and binding desorption of nitrogen ability on the surface of Ru/c‐Y2O3 catalysts are also beneficial for the high activity. These results provide a reference for the design of efficient Ru‐based ammonia decomposition catalysts for hydrogen production by tuning the precursor of Y2O3 support.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"17 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208741","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Axially chiral Indoline‐based scaffolds are virtually universal in biological and pharmaceutical compounds. Here we demonstrate an atroposelective Rh‐catalyzed 1,6‐enynes with steric hindered N‐alkynyl indoles, which enables simultaneous construction of both axial and central chirality, containing a quaternary carbon center, in one step. Notable features of these reactions include excellent chemo‐, regio‐, diastereo‐ and enantioselectivity, 100% atom‐economy, easily available Segphos ligand, and mild conditions.
{"title":"Asymmetric Rh‐Catalyzed [2+2+2] Cycloaddition: Synthesis of N‐Alkenylindoles with both Axial and Central Chirality","authors":"Zhenghu Xu, Xuan Zhang, Teng Qi, Tung Chen-Ho","doi":"10.1002/cctc.202401143","DOIUrl":"https://doi.org/10.1002/cctc.202401143","url":null,"abstract":"Axially chiral Indoline‐based scaffolds are virtually universal in biological and pharmaceutical compounds. Here we demonstrate an atroposelective Rh‐catalyzed 1,6‐enynes with steric hindered N‐alkynyl indoles, which enables simultaneous construction of both axial and central chirality, containing a quaternary carbon center, in one step. Notable features of these reactions include excellent chemo‐, regio‐, diastereo‐ and enantioselectivity, 100% atom‐economy, easily available Segphos ligand, and mild conditions.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"58 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Vasilis Tseliou, Marcelo F. Masman, Tanja Knaus, Francesco G. Mutti
Amine dehydrogenases (AmDHs) are NAD(P)H‐dependent oxidoreductases that catalyze the reductive amination between carbonyl compounds and ammonia as the amine donor yielding valuable amines, typically with excellent enantioselectivity. While nature has provided enzymes with inherent AmDH activities, protein engineering techniques allowed researchers to expand the toolbox of available AmDHs, extend their substrate scope, improve their catalytic activities and stability under synthetically relevant conditions and even enable new reactivity concepts. The biocatalytic synthesis of amines using AmDHs has matured to a point where hundreds of aldehydes or ketones, of varying steric demands and bearing diverse functional groups, can be efficiently transformed. This review offers an overview of the available AmDHs and their substrate spectrum, covering from structural and evolutionary analyses to diverse methods employing these enzymes. Depending on the catalytic activities of other enzymes as reaction partners, AmDHs were applied in kinetic resolution (KR) and deracemization processes, cascade reactions for the amination of alcohols and alkenes or for the synthesis of amines and amino alcohols featuring multiple stereogenic centers. Moreover, the synthetic potential of AmDHs in novel pathways, such as the synthesis of secondary amines or alcohols, presents exciting opportunities for expanding their catalytic repertoire.
{"title":"Current Status of Amine Dehydrogenases: From Active Site Architecture to Diverse Applications Across a Broad Substrate Spectrum","authors":"Vasilis Tseliou, Marcelo F. Masman, Tanja Knaus, Francesco G. Mutti","doi":"10.1002/cctc.202400469","DOIUrl":"https://doi.org/10.1002/cctc.202400469","url":null,"abstract":"Amine dehydrogenases (AmDHs) are NAD(P)H‐dependent oxidoreductases that catalyze the reductive amination between carbonyl compounds and ammonia as the amine donor yielding valuable amines, typically with excellent enantioselectivity. While nature has provided enzymes with inherent AmDH activities, protein engineering techniques allowed researchers to expand the toolbox of available AmDHs, extend their substrate scope, improve their catalytic activities and stability under synthetically relevant conditions and even enable new reactivity concepts. The biocatalytic synthesis of amines using AmDHs has matured to a point where hundreds of aldehydes or ketones, of varying steric demands and bearing diverse functional groups, can be efficiently transformed. This review offers an overview of the available AmDHs and their substrate spectrum, covering from structural and evolutionary analyses to diverse methods employing these enzymes. Depending on the catalytic activities of other enzymes as reaction partners, AmDHs were applied in kinetic resolution (KR) and deracemization processes, cascade reactions for the amination of alcohols and alkenes or for the synthesis of amines and amino alcohols featuring multiple stereogenic centers. Moreover, the synthetic potential of AmDHs in novel pathways, such as the synthesis of secondary amines or alcohols, presents exciting opportunities for expanding their catalytic repertoire.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"23 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wenzhi Zhang, Pinhua Yu, Yakang Zhang, Yuanxi Sheng, Chun Fu, Haitao Li, Jiao Geng, Weihua Han, Xingbang Hu
In this work, a green and efficient method was developed to catalyze the nitration of benzene to nitrobenzene in NO2‐O2 system by using acidic ion exchange resin as catalyst under mild (0 °C and atmospheric pressure) and solvent‐free conditions. Based on experimental screening, commercial acid ion exchange resin Amberlite FPC3500 was identified as the optimal catalyst. Under the optimized reaction conditions, 99.9% conversion of benzene was obtained with 99.1% selectivity of nitrobenzene. Furthermore, the catalyst can be easily reused. The results demonstrate a greener route for the production of nitrobenzene.
{"title":"Nitration of benzene to nitrobenzene using NO2 as nitro source under mild and solvent‐free conditions","authors":"Wenzhi Zhang, Pinhua Yu, Yakang Zhang, Yuanxi Sheng, Chun Fu, Haitao Li, Jiao Geng, Weihua Han, Xingbang Hu","doi":"10.1002/cctc.202401176","DOIUrl":"https://doi.org/10.1002/cctc.202401176","url":null,"abstract":"In this work, a green and efficient method was developed to catalyze the nitration of benzene to nitrobenzene in NO2‐O2 system by using acidic ion exchange resin as catalyst under mild (0 °C and atmospheric pressure) and solvent‐free conditions. Based on experimental screening, commercial acid ion exchange resin Amberlite FPC3500 was identified as the optimal catalyst. Under the optimized reaction conditions, 99.9% conversion of benzene was obtained with 99.1% selectivity of nitrobenzene. Furthermore, the catalyst can be easily reused. The results demonstrate a greener route for the production of nitrobenzene.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"103 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zeolites, renowned for their abundant crystalline structures and moderate acidities, have garnered significant attention in industrial chemical processes. Among them, the diffusion behaviors of various hydrocarbons within zeolite play a pivotal role due to their profound impact on product selectivity and separation efficiency. While acid sites are essential in determining the catalytic performance of zeolites, their effect on intra‐crystalline diffusivities has often been neglected in catalyst design. Herein, we employ a homemade time‐resolved in‐situ Fourier Transform Infrared (TR in‐situ FT‐IR) spectroscopy to investigate the intricate interplay between Brønsted acid sites and various probe molecules. Our study reveals that an augmentation in the density of Brønsted acid sites within H‐ZSM‐5 zeolites remarkably enhances the diffusivity of 1‐butene, in stark contrast to the behavior observed for iso‐butane. This contrasting effect in diffusivity is attributed to the distinct nature of interactions between alkenes and alkanes with Brønsted acid sites. Specifically, the π‐H interactions between alkenes and acid sites act as a driving force, propelling the alkene molecules forward through the zeolite pores. These findings offer valuable insights into designing tailored zeolites with specific acid site properties, controlling the transport behaviors of various probe molecules, and promising new avenues for catalysis and separation.
{"title":"Unraveling Molecular Diffusion Behaviors on the Acidic Sites of H‐ZSM‐5 Zeolite using Time‐Resolved in‐situ FT‐IR Technique","authors":"Yangdong Wang, Xiaoliang Liu, Yu Wang, Jiawei Teng, Zaiku Xie","doi":"10.1002/cctc.202401144","DOIUrl":"https://doi.org/10.1002/cctc.202401144","url":null,"abstract":"Zeolites, renowned for their abundant crystalline structures and moderate acidities, have garnered significant attention in industrial chemical processes. Among them, the diffusion behaviors of various hydrocarbons within zeolite play a pivotal role due to their profound impact on product selectivity and separation efficiency. While acid sites are essential in determining the catalytic performance of zeolites, their effect on intra‐crystalline diffusivities has often been neglected in catalyst design. Herein, we employ a homemade time‐resolved in‐situ Fourier Transform Infrared (TR in‐situ FT‐IR) spectroscopy to investigate the intricate interplay between Brønsted acid sites and various probe molecules. Our study reveals that an augmentation in the density of Brønsted acid sites within H‐ZSM‐5 zeolites remarkably enhances the diffusivity of 1‐butene, in stark contrast to the behavior observed for iso‐butane. This contrasting effect in diffusivity is attributed to the distinct nature of interactions between alkenes and alkanes with Brønsted acid sites. Specifically, the π‐H interactions between alkenes and acid sites act as a driving force, propelling the alkene molecules forward through the zeolite pores. These findings offer valuable insights into designing tailored zeolites with specific acid site properties, controlling the transport behaviors of various probe molecules, and promising new avenues for catalysis and separation.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"176 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Planar chirality, as one of the most important manifestations of chirality, is frequently employed to constrain three‐dimensional chiral configurations. Recent advancements in the study of planar chirality by chemists have opened up innovative possibilities for designing new catalysts, developing novel drugs, and creating new optical materials. However, the flexible ansa chains present a challenge during the synthesis process of these unique planar‐chiral macrocycles, hindering chemists from achieving high enantioselectivity. In this mini review, we primarily introduce the catalytic asymmetric synthesis methods that have been reported for late‐stage functionalization of planar macrocycles to generate planar chirality. Additionally, we present several recent examples of catalytic enantioselective synthesis of mechanically planar‐chiral rotaxanes through late‐stage functionalization methods. The sources of stereoselectivity are also discussed in this mini review. We aim to inform more researchers about this field and attract chemists to engage in this important and scientifically significant area of research.
{"title":"Enantioselective Construction of Planar‐Chiral Molecules by Catalytic Asymmetric Late‐Stage Functionalizations","authors":"Yu-Hang Zhao, Deng Zhu, Zhi-Min Chen","doi":"10.1002/cctc.202401312","DOIUrl":"https://doi.org/10.1002/cctc.202401312","url":null,"abstract":"Planar chirality, as one of the most important manifestations of chirality, is frequently employed to constrain three‐dimensional chiral configurations. Recent advancements in the study of planar chirality by chemists have opened up innovative possibilities for designing new catalysts, developing novel drugs, and creating new optical materials. However, the flexible ansa chains present a challenge during the synthesis process of these unique planar‐chiral macrocycles, hindering chemists from achieving high enantioselectivity. In this mini review, we primarily introduce the catalytic asymmetric synthesis methods that have been reported for late‐stage functionalization of planar macrocycles to generate planar chirality. Additionally, we present several recent examples of catalytic enantioselective synthesis of mechanically planar‐chiral rotaxanes through late‐stage functionalization methods. The sources of stereoselectivity are also discussed in this mini review. We aim to inform more researchers about this field and attract chemists to engage in this important and scientifically significant area of research.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"21 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Javier Suarez, Sergio Ojeda Santillán, Rafael Vazquez-Duhalt, Olivia A. Graeve
We describe the design and catalytic activity of enzymatic nanoreactors based on copper oxide nanoparticles surface‐functionalized with laccase (CuO‐Lac) from Coriolopsis gallica. Transmission electron micrographs show complete laccase coverage on the nanoparticle surfaces. In addition, the catalytic rate (kcat) of the immobilized laccase is two‐fold higher at an optimized pH, when compared with free laccase, while the affinity constant (KM) is not significantly affected. Importantly, the total turnover number (TNN) of the CuO‐Lac nanoreactors reaches 358 ± 9 × 106 mol ABTS/mol laccase, which is four times higher than the TTN obtained for the free enzyme (88 ± 3 × 106). Thus, our nanoreactors exhibit a significant improvement in laccase catalytic performance. Inductively coupled plasma mass spectrometry was used to confirm the loss of copper ions from free laccase during the catalytic cycle, suggesting that the CuO nanoparticles act as a copper ion source that prevents enzyme inactivation. This work contributes to an improved understanding of the CuO‐laccase interface and confirms that CuO nanoparticles serve as copper sources for laccase during catalysis.
{"title":"Enhanced Catalytic Stability of Laccase Immobilized on Copper Oxide Nanoparticles","authors":"F. Javier Suarez, Sergio Ojeda Santillán, Rafael Vazquez-Duhalt, Olivia A. Graeve","doi":"10.1002/cctc.202401232","DOIUrl":"https://doi.org/10.1002/cctc.202401232","url":null,"abstract":"We describe the design and catalytic activity of enzymatic nanoreactors based on copper oxide nanoparticles surface‐functionalized with laccase (CuO‐Lac) from Coriolopsis gallica. Transmission electron micrographs show complete laccase coverage on the nanoparticle surfaces. In addition, the catalytic rate (kcat) of the immobilized laccase is two‐fold higher at an optimized pH, when compared with free laccase, while the affinity constant (KM) is not significantly affected. Importantly, the total turnover number (TNN) of the CuO‐Lac nanoreactors reaches 358 ± 9 × 106 mol ABTS/mol laccase, which is four times higher than the TTN obtained for the free enzyme (88 ± 3 × 106). Thus, our nanoreactors exhibit a significant improvement in laccase catalytic performance. Inductively coupled plasma mass spectrometry was used to confirm the loss of copper ions from free laccase during the catalytic cycle, suggesting that the CuO nanoparticles act as a copper ion source that prevents enzyme inactivation. This work contributes to an improved understanding of the CuO‐laccase interface and confirms that CuO nanoparticles serve as copper sources for laccase during catalysis.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"38 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
2,2,6,6'‐Tetramethylpiperidine‐N‐oxyl (TEMPO) is a highly efficient oxidation catalyst, valued for its environmentally benign nature, particularly in comparison to transition‐metal catalysts. Despite their merits, TEMPO‐based catalysts are not notably cost‐effective. Immobilization of TEMPO onto supports offers a promising strategy to overcome this limitation. In this work, we present the synthesis and application of immobilized TEMPO catalysts 2–5, prepared via a straightforward condensation reaction, for the aerobic oxidation of alcohols. These catalysts demonstrate remarkable activity for alcohol oxidations under continuous‐flow conditions, employing nitric acid as the co‐catalyst. Notably, catalyst 2 immobilized by COOH silica gel exhibits outstanding performance for the oxidation of benzyl alcohol by oxygen gas, achieving a turnover frequency (TOF) of 15 h−1 and a turnover number (TON) exceeding 300. Catalyst 2 further demonstrates broad substrate scope, effectively oxidizing primary, secondary, and benzylic alcohols. Post‐reaction analysis of spent catalyst 2 reveals that deactivation primarily stems from nitrosation of the N‐O bond. Interestingly, the amide moiety remains intact despite the harsh acidic reaction conditions.
2,2,6,6'-Tetramethylpiperidine-N-oxyl (TEMPO) 是一种高效氧化催化剂，因其对环境无害而备受推崇，尤其是与过渡金属催化剂相比。基于 TEMPO 的催化剂尽管有其优点，但成本效益并不显著。将 TEMPO 固定在载体上为克服这一局限性提供了一种很有前景的策略。在这项工作中，我们介绍了通过直接缩合反应制备的固定化 TEMPO 催化剂 2-5 的合成和应用，用于醇类的有氧氧化。这些催化剂采用硝酸作为助催化剂，在连续流条件下进行醇氧化时表现出了卓越的活性。值得注意的是，由 COOH 硅胶固定的催化剂 2 在氧气氧化苯甲醇时表现出卓越的性能，其周转频率（TOF）达到 15 h-1，周转次数（TON）超过 300。催化剂 2 还具有广泛的底物范围，可有效氧化伯醇、仲醇和苄醇。对废催化剂 2 的反应后分析表明，失活主要源于 N-O 键的亚硝基化。有趣的是，尽管催化剂 2 在苛刻的酸性反应条件下，其酰胺分子仍然完好无损。
{"title":"TEMPO‐Catalyzed Continuous‐flow Aerobic Oxidations of Alcohols on Silica","authors":"Kai Takizawa, Takuma Ishihara, Shinki Tani, Yusuke Hamada, Koichiro Masuda, Shun-ya Onozawa, Kazuhiko Sato, Shū Kobayashi","doi":"10.1002/cctc.202401152","DOIUrl":"https://doi.org/10.1002/cctc.202401152","url":null,"abstract":"2,2,6,6'‐Tetramethylpiperidine‐N‐oxyl (TEMPO) is a highly efficient oxidation catalyst, valued for its environmentally benign nature, particularly in comparison to transition‐metal catalysts. Despite their merits, TEMPO‐based catalysts are not notably cost‐effective. Immobilization of TEMPO onto supports offers a promising strategy to overcome this limitation. In this work, we present the synthesis and application of immobilized TEMPO catalysts 2–5, prepared via a straightforward condensation reaction, for the aerobic oxidation of alcohols. These catalysts demonstrate remarkable activity for alcohol oxidations under continuous‐flow conditions, employing nitric acid as the co‐catalyst. Notably, catalyst 2 immobilized by COOH silica gel exhibits outstanding performance for the oxidation of benzyl alcohol by oxygen gas, achieving a turnover frequency (TOF) of 15 h−1 and a turnover number (TON) exceeding 300. Catalyst 2 further demonstrates broad substrate scope, effectively oxidizing primary, secondary, and benzylic alcohols. Post‐reaction analysis of spent catalyst 2 reveals that deactivation primarily stems from nitrosation of the N‐O bond. Interestingly, the amide moiety remains intact despite the harsh acidic reaction conditions.","PeriodicalId":141,"journal":{"name":"ChemCatChem","volume":"7 1","pages":""},"PeriodicalIF":4.5,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142208750","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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