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Abstract
Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R1R2N-O•. The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R1 and R2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R1R2N═O+) or reduced to anions (R1R2N-O-), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C-O bonds, allowing for the thermal generation of C radicals through reversible C-O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.
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Affiliation(s)
- Dirk Leifert
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
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Adura C, Aliaga C, Silva F, Vera C, Pino E, Celis F, Aracena A, Tirapegui C. A simple method to estimate the mean number of lipophilic molecules on nanoparticle surfaces by fluorescence measurements. NANOTECHNOLOGY 2021; 32:315711. [PMID: 33906171 DOI: 10.1088/1361-6528/abfc0c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
Measurements of fluorescence intensity of the hydrophobic pyridinium salt (DTPSH) remaining in the organic phase after partition experiments in the DCM/H2O system allowed an approximate method to be developed to estimate the mean number of molecules (N = 942) on the surface of 22.8 nm gold nanoparticles and the separation (1.89 nm) between these organic molecules. This protocol is based on the ability that the organic molecules possess to coat the surface of the nanoparticle, which can migrate from the organic to the aqueous phase as a result of the driving force of the strong binding of sulfur to gold. To validate our estimation, we used a projection of the results obtained by Wales and Ulker to solve the Thomson problem, a mathematicians' challenge, used as a model to calculate the mean distance (1.82 nm) separating particles on the surface, in excellent agreement with the results obtained by our method. The quality of results, the simplicity of calculations, the low fluorescence detection limit, and the inexpensive materials, recommend this procedure for rapid estimates of the mean number of molecules on the surface of nanoparticles.
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Affiliation(s)
- Carolina Adura
- High-Throughput and Spectroscopy Resource Center, The Rockefeller University, 1230 York Avenue, New York, NY 10065, United States of America
| | - Carolina Aliaga
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O'Higgins 3363, Santiago, Chile
- Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Chile
| | - Francisco Silva
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O'Higgins 3363, Santiago, Chile
| | - Cristian Vera
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O'Higgins 3363, Santiago, Chile
| | - Eduardo Pino
- Facultad de Química y Biología, Universidad de Santiago de Chile, Av. Bernardo O'Higgins 3363, Santiago, Chile
| | - Freddy Celis
- Laboratorio de Procesos Fotónicos y Electroquímicos, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Subida Leopoldo Carvallo 270, Valparaíso, Chile
| | - Andrés Aracena
- Universidad de las Américas, Instituto de Ciencias Naturales, Manuel Montt 948, Santiago, Chile
| | - Cristian Tirapegui
- Instituto de Ciencias Químicas Aplicadas, Facultad de Ingeniería, Universidad Autónoma de Chile, El Llano Subercaseaux 2801, San Miguel, Santiago, Chile
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Akari AS, Hodgson GK, Golian KP, Impellizzeri S. Photochemical Insights on Intramolecular Dye‐Sensitized Free‐Radical Processes with a Quinoline Antenna. ChemistrySelect 2021. [DOI: 10.1002/slct.202100027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Aviya S. Akari
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Gregory K. Hodgson
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Karol P. Golian
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
| | - Stefania Impellizzeri
- Laboratory for Nanomaterials and Molecular Plasmonics Department of Chemistry and Biology Ryerson University 350 Victoria St. Toronto ON M5B 2K3 Canada
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Golian KP, Akari AS, Hodgson GK, Impellizzeri S. Fluorescence activation, patterning and enhancement with photogenerated radicals, a prefluorescent probe and silver nanostructures. RSC Adv 2021. [DOI: 10.1039/d0ra09565f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
We designed a switchable fluorophore activated by UVA light and a radical initiator, for optical lithography with concomitant metal-enhanced fluorescence by silver nanoparticles.
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Affiliation(s)
- Karol P. Golian
- Laboratory for Nanomaterials and Molecular Plasmonics
- Department of Chemistry and Biology
- Ryerson University
- Toronto
- Canada
| | - Aviya S. Akari
- Laboratory for Nanomaterials and Molecular Plasmonics
- Department of Chemistry and Biology
- Ryerson University
- Toronto
- Canada
| | - Gregory K. Hodgson
- Laboratory for Nanomaterials and Molecular Plasmonics
- Department of Chemistry and Biology
- Ryerson University
- Toronto
- Canada
| | - Stefania Impellizzeri
- Laboratory for Nanomaterials and Molecular Plasmonics
- Department of Chemistry and Biology
- Ryerson University
- Toronto
- Canada
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Beejapur HA, Zhang Q, Hu K, Zhu L, Wang J, Ye Z. TEMPO in Chemical Transformations: From Homogeneous to Heterogeneous. ACS Catal 2019. [DOI: 10.1021/acscatal.8b05001] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Hazi Ahmad Beejapur
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang Province Key Laboratory of Biofuel, Biodiesel Laboratory of China Petroleum and Chemical Industry Federation, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Qi Zhang
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang Province Key Laboratory of Biofuel, Biodiesel Laboratory of China Petroleum and Chemical Industry Federation, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Kecheng Hu
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang Province Key Laboratory of Biofuel, Biodiesel Laboratory of China Petroleum and Chemical Industry Federation, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Li Zhu
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang Province Key Laboratory of Biofuel, Biodiesel Laboratory of China Petroleum and Chemical Industry Federation, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Jianli Wang
- State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology, Zhejiang Province Key Laboratory of Biofuel, Biodiesel Laboratory of China Petroleum and Chemical Industry Federation, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310014, P. R. China
| | - Zhibin Ye
- Department of Chemical and Materials Engineering, Concordia University, Montreal, Quebec H3G 1M8, Canada
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Aliaga C, Celis F, Lühr S, Oñate R. TEMPO-Attached Pre-fluorescent Probes Based on Pyridinium Fluorophores. J Fluoresc 2015; 25:979-83. [PMID: 25972068 DOI: 10.1007/s10895-015-1579-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/04/2015] [Indexed: 10/23/2022]
Abstract
The photophysical behavior of three pyridinium-derived fluorophores, the N-aryl-2,4,6-triphenylpyridinium, the N-aryl-5,6-dihydro-2,4-diphenylbenzo[h]quinolinium and the N-aryl-5,6,8,9-tetrahydro-7-phenyldibenzo[c,h]acridinium perchlorates, was investigated. Comparison of their fluorescence quantum yields led to the preparation of a novel, more sensitive pyridinium-based, TEMPO-attached prefluorescent probe for H-abstraction processes, the N-{4-[4-(N-oxyl-2,2,6,6-tetramethylpiperidinyl)carbonylamino]phenyl}-5,6,8,9-tetrahydro-7-phenyldibenzo[c,h]-acridinium perchlorate.
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Affiliation(s)
- Carolina Aliaga
- Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, de Chile,
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Affiliation(s)
- Vanderlei G. Machado
- Departamento
de Química, Universidade Federal de Santa Catarina, UFSC, Florianópolis, SC 88040-900, Brazil
| | - Rafaela I. Stock
- Departamento
de Química, Universidade Federal de Santa Catarina, UFSC, Florianópolis, SC 88040-900, Brazil
| | - Christian Reichardt
- Fachbereich
Chemie, Philipps-Universität, Hans-Meerwein-Strasse, 35032 Marburg, Germany
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Braslau R, Rivera F, Lilie E, Cottman M. Urushiol Detection using a Profluorescent Nitroxide. J Org Chem 2012; 78:238-45. [DOI: 10.1021/jo301135m] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Rebecca Braslau
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
| | - Frank Rivera
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
| | - Erin Lilie
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
| | - MariEllen Cottman
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California, 95064
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Tebben L, Studer A. Nitroxides: applications in synthesis and in polymer chemistry. Angew Chem Int Ed Engl 2011; 50:5034-68. [PMID: 21538729 DOI: 10.1002/anie.201002547] [Citation(s) in RCA: 505] [Impact Index Per Article: 38.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Indexed: 01/23/2023]
Abstract
This Review describes the application of nitroxides to synthesis and polymer chemistry. The synthesis and physical properties of nitroxides are discussed first. The largest section focuses on their application as stoichiometric and catalytic oxidants in organic synthesis. The oxidation of alcohols and carbanions, as well as oxidative C-C bond-forming reactions are presented along with other typical oxidative transformations. A section is also dedicated to the extensive use of nitroxides as trapping reagents for C-centered radicals in radical chemistry. Alkoxyamines derived from nitroxides are shown to be highly useful precursors of C-centered radicals in synthesis and also in polymer chemistry. The last section discusses the basics of nitroxide-mediated radical polymerization (NMP) and also highlights new developments in the synthesis of complex polymer architectures.
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Affiliation(s)
- Ludger Tebben
- Organisch-Chemisches Institut, Westfälische Wilhelms-Universität, Corrensstrasse 40, 48149 Münster, Germany
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