Novel Biradicals for Direct Excitation Highfield Dynamic Nuclear Polarization

Novel Biradicals for Direct Excitation Highfield Dynamic Nuclear Polarization Full article

Journal

Journal of Physical Chemistry C
ISSN: 1932-7447

Output data

Year: 2018, Volume: 122, Number: 21, Pages: 11422-11432 Pages count : 11 DOI: 10.1021/acs.jpcc.8b02570

Authors

Bothe Sarah ¹ , Nowag Jens ¹ , Klimavicius Vytautas ¹ , Hoffmann Markus ² , Troitskaya Tatiana I. ³ , Amosov Evgenii V. ³ , Tormyshev Victor M. ^3,4 , Kirilyuk Igor ^3,4 , Taratayko Andrey ^3,4 , Kuzhelev Andrey ^3,4 , Parkhomenko Dmitriy ³ , Bagryanskaya Elena ^3,4 , Gutmann Torsten ¹ , Buntkowsky Gerd ¹

Affiliations

1	(Данные Web of science) Tech Univ Darmstadt, Eduard Zintl Inst Inorgan & Phys Chem, Alarich Weiss Str 8, D-64287 Darmstadt, Germany
2	(Данные Web of science) SUNY Coll Brockport, Dept Chem & Biochem, Brockport, NY 14420 USA
3	(Данные Web of science) NN Vorozhtsov Novosibirsk Inst Organ Chem SB RAS, Pr Lavrentieva 9, Novosibirsk 630090, Russia
4	(Данные Web of science) Novosibirsk State Univ, Pirogova 2, Novosibirsk 630090, Russia

Synthesis of novel trityl-nitroxyl biradicals and their performance as polarization agents in DNP-enhanced solid-state MAS NMR spectroscopy is presented. Signal enhancements in H-1, H-1 -> C-13 CP MAS, and C-13 MAS experiments obtained with these radicals dissolved in 1,1,2,2-tetrachloroethane (TCE) solution are compared with the enhancements obtained from TCE solutions of binitroxyl radicals. The signal enhancements are correlated with the distance between the radical centers of the biradicals, as determined by theoretical structure calculations. Some of the biradical TCE solutions display direct-channel resonances in C-13 MAS experiments as well as indirect channel resonances induced via the proton spin reservoir. Differential scanning calorimetry reveals that only these solutions do not form any solid crystalline phases upon rapid cooling, suggesting that molecular motions needed for polarization transfer from radicals to C-13 via the proton spin reservoir remain active at the experimental low temperatures of nominal 120 K. DNP magnetic field sweep enhancement profiles for selected new biradicals are presented as well. These indicate that the DNP transfer is dominated by the cross-effect mechanism.

Bothe S. , Nowag J. , Klimavicius V. , Hoffmann M. , Troitskaya T.I. , Amosov E.V. , Tormyshev V.M. , Kirilyuk I. , Taratayko A. , Kuzhelev A. , Parkhomenko D. , Bagryanskaya E. , Gutmann T. , Buntkowsky G.
Novel Biradicals for Direct Excitation Highfield Dynamic Nuclear Polarization
Journal of Physical Chemistry C. 2018. V.122. N21. P.11422-11432. DOI: 10.1021/acs.jpcc.8b02570 WOS Scopus РИНЦ

Published online:	May 4, 2018
Published print:	May 31, 2018

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