An Air-Stable, Neutral Phenothiazinyl Radical with Substantial Radical Stabilization Energy
| Autor: | Deborah Hartmann, Lutz Greb, Lukas M. Sigmund, Fabian Ebner, Nils Gönnheimer, Jonas Spengler, Christoph Jöst |
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| Rok vydání: | 2019 |
| Předmět: |
radical stabilization energy
Radical 010402 general chemistry Photochemistry 01 natural sciences Redox Catalysis law.invention chemistry.chemical_compound law redox chemistry Phenothiazine Redox Chemistry | Hot Paper Electron paramagnetic resonance Full Paper 010405 organic chemistry Ligand Organic Chemistry Cationic polymerization General Chemistry Full Papers radicals Bond-dissociation energy 0104 chemical sciences chemistry Reagent aminyl radicals phenothiazines |
| Zdroj: | Chemistry (Weinheim an Der Bergstrasse, Germany) |
| ISSN: | 1521-3765 |
| Popis: | The vital effect of radical states on the pharmacological activity of phenothiazine‐based drugs has long been speculated. Whereas cationic radicals of N‐substituted phenothiazines show high stability, the respective neutral radicals of N‐unsubstituted phenothiazines have never been isolated. Herein, the 1,9‐diamino‐3,7‐di‐tert‐butyl‐N 1,N 9‐bis(2,6‐diisopropylphenyl)‐10H‐phenothiazin‐10‐yl radical (SQH2 .) is described as the first air‐stable, neutral phenothiazinyl free radical. The crystalline dark‐blue species is characterized by means of EPR and UV/Vis/near‐IR spectroscopy, as well as cyclic voltammetry, spectro‐electrochemical analysis, single‐crystal XRD, and computational studies. The SQH2 . radical stands out from other aminyl radicals by an impressive radical stabilization energy and its parent amine has one of the weakest N−H bond dissociation energies ever determined. In addition to serving as open‐shell reference in medicinal chemistry, its tridentate binding pocket or hydrogen‐bond‐donor ability might enable manifold uses as a redox‐active ligand or proton‐coupled electron‐transfer reagent. Out in the open: An air‐stable phenothiazinyl radical was synthesized and characterized by means of experiments, spectroscopy, and computational investigations. The crystalline dark‐blue compound shows addressable redox activity and represents the first N‐unsubstituted phenothiazine‐based aminyl radical. |
| Databáze: | OpenAIRE |
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