title: Host-guest complexes as water-soluble high-performance DNP polarizing agents.
abstract: Dynamic nuclear polarization (DNP) enhances the sensitivity of solid-state NMR (SSNMR) spectroscopy by orders of magnitude and, therefore, opens possibilities for novel applications from biology to materials science. This multitude of opportunities implicates a need for high-performance polarizing agents, which integrate specific physical and chemical features tailored for various applications. Here, we demonstrate that for the biradical bTbK in complex with captisol (CAP), a β-cyclodextrin derivative, host-guest assembling offers a new and easily accessible approach for the development of new polarizing agents. In contrast to bTbK, the CAP-bTbK complex is water-soluble and shows significantly improved DNP performance compared to the commonly used DNP agent TOTAPOL. Furthermore, NMR and EPR data reveal improved electron and nuclear spin relaxation properties for bTbK within the host molecule. The numerous possibilities to functionalize host molecules will permit designing novel radical complexes targeting diverse applications.
authors.affiliation: Institutes of Biophysical Chemistry, ‡Physical and Theoretical Chemistry and §Center for Biomolecular Magnetic Resonance BMRZ, Goethe University Frankfurt , 60438 Frankfurt/M., Germany.
authors.forename: Jiafei
authors.initials: J
authors.lastname: Mao
authors.forename: Dmitry
authors.initials: D
authors.lastname: Akhmetzyanov
authors.forename: Olivier
authors.initials: O
authors.lastname: Ouari
authors.forename: Vasyl
authors.initials: V
authors.lastname: Denysenkov
authors.forename: Björn
authors.initials: B
authors.lastname: Corzilius
authors.forename: Jörn
authors.initials: J
authors.lastname: Plackmeyer
authors.forename: Paul
authors.initials: P
authors.lastname: Tordo
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Prisner
authors.forename: Clemens
authors.initials: C
authors.lastname: Glaubitz