Stable free radicals. X. Nitronyl nitroxide monoradicals and biradicals as possible small molecule spin labels

Abstract The application of thermally and chemically stable nitroxide free radicals to a variety of motional problems in polymeric systems has been investigated. Solvents do not cause significant motion in glassy polymers until the glass transition is lowered to the temperature of measurement. With nonsolvents the results depend on the nature of the sample preparation as well as on the polymer-solvent pair. Molecular motion at the surface of a polymer immersed in a nonsolvent was investigated by means of surface-labeled latex spheres. The application of nitroxides as spin labels to the measurement of translational diffusion coefficients is explored and discussed. Finally, the application of the technique to adsorption and motion of surfactants and polymers onto surfaces is reported.

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Synthesis of stable free radicals: A novel family of oligopyridine based nitronyl-nitroxide biradicals

Tetrahedron Letters ◽

10.1016/0040-4039(94)88026-3 ◽

1994 ◽

Vol 35 (8) ◽

pp. 1211-1214 ◽

Cited By ~ 22

Author(s):

Gilles Ulrich ◽

Raymond Ziessel ◽

Dominique Luneau ◽

Paul Rey

Keyword(s):

Free Radicals ◽

Nitronyl Nitroxide ◽

Stable Free Radicals

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Synthesis and Application of Stable Nitroxide Free Radicals Fused with Carbocycles and Heterocycles

Current Organic Chemistry ◽

10.2174/1385272823666190318163321 ◽

2019 ◽

Vol 23 (4) ◽

pp. 480-501 ◽

Cited By ~ 1

Author(s):

Balázs Bognár ◽

Györgyi Úr ◽

Cecília Sár ◽

Olga H. Hankovszky ◽

Kálmán Hideg ◽

...

Keyword(s):

Free Radicals ◽

Free Radical ◽

Building Blocks ◽

Spin Labels ◽

Spin Probes ◽

Electroactive Materials ◽

The Past ◽

Synthetic Methodologies ◽

Stable Free Radicals ◽

Stable Nitroxide

Stable nitroxide free radicals have traditionally been associated with 2,2,6,6- tetramethylpiperidine-1-oxyl (TEMPO) or its 4-substituted derivatives as relatively inexpensive and readily accessible compounds with limited possibilities for further chemical modification. Over the past two decades, there has been a resurgence of interest in stable free radicals with proper functionalization tuned for various applications. The objective of this review is to present recent results with synthetic methodologies to achieve stable nitroxide free radicals fused with aromatic carbocycles and heterocycles. There are two main approaches for accessing stable nitroxide free radicals fused with arenes, e.g., isoindoline- like nitroxides: further functionalization and oxidation of phthalimide or inventive functionalization of pyrroline nitroxide key compounds. The latter also offers the constructions of versatile heterocyclic scaffolds (furan, pyrrole, thiophene, 1,2-thiazole, selenophene, pyrazole, pyrimidine, pyridine, pyridazine, 1,5-benzothiazepine) that are fused with pyrroline or tetrahydropyridine nitroxide rings. The possible applications of these new stable nitroxide free radicals, such as covalent spin labels and noncovalent spin probes of proteins and nucleic acids, profluorescent probes, building blocks for construction of dual active drugs and electroactive materials, and substances for controlled free radical polymerization, are discussed.

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A Simple Method of Synthesis of 3-Carboxy-2,2,5,5-Tetraethylpyrrolidine-1-oxyl and Preparation of Reduction-Resistant Spin Labels and Probes of Pyrrolidine Series

Molecules ◽

10.3390/molecules26195761 ◽

2021 ◽

Vol 26 (19) ◽

pp. 5761

Author(s):

Sergey A. Dobrynin ◽

Mikhail S. Usatov ◽

Irina F. Zhurko ◽

Denis A. Morozov ◽

Yuliya F. Polienko ◽

...

Keyword(s):

Free Radicals ◽

Magnetic Resonance ◽

Magnetic Resonance Spectroscopy ◽

Biomedical Research ◽

Molecular Probes ◽

Spin Labels ◽

Resonance Spectroscopy ◽

Simple Method ◽

Tissue Homogenates ◽

Stable Free Radicals

Stable free radicals are widely used as molecular probes and labels in various biophysical and biomedical research applications of magnetic resonance spectroscopy and imaging. Among these radicals, sterically shielded nitroxides of pyrrolidine series demonstrate the highest stability in biological systems. Here, we suggest new convenient procedure for preparation of 3-carboxy-2,2,5,5-tetraethylpyrrolidine-1-oxyl, a reduction-resistant analog of widely used carboxy-Proxyl, from cheap commercially available reagents with the yield exceeding the most optimistic literature data. Several new spin labels and probes of 2,2,5,5-tetraethylpyrrolidine-1-oxyl series were prepared and reduction of these radicals in ascorbate solutions, mice blood and tissue homogenates was studied.

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