Rigid Orthogonal Bis-TEMPO Biradicals with Improved Solubility for Dynamic Nuclear Polarization

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• 作者：Eric L. Dane ; Bj枚rn Corzilius ; Egon Rizzato ; Pierre Stocker ; Thorsten Maly ; Albert A. Smith ; Robert G. Griffin ; Olivier Ouari ; Paul Tordo ; Timothy M. Swager
• 刊名：The Journal of Organic Chemistry
• 出版年：2012
• 出版时间：February 17, 2012
• 年：2012
• 卷：77
• 期：4
• 页码：1789-1797
• 全文大小：400K
• 年卷期：v.77,no.4(February 17, 2012)
• ISSN：1520-6904

文摘

The synthesis and characterization of oxidized bis-thioketal-trispiro dinitroxide biradicals that orient the nitroxides in a rigid, approximately orthogonal geometry are reported. The biradicals show better performance as polarizing agents in dynamic nuclear polarization (DNP) NMR experiments as compared to biradicals lacking the constrained geometry. In addition, the biradicals display improved solubility in aqueous media due to the presence of polar sulfoxides. The results suggest that the orientation of the radicals is not dramatically affected by the oxidation state of the sulfur atoms in the biradical, and we conclude that a biradical polarizing agent containing a mixture of oxidation states can be used for improved solubility without a loss in performance.