FIELD: chemistry.
SUBSTANCE: invention relates to a dynamic nuclear polarisation method of a compound which contains one or more carboxyl groups, distinguished by that, the radical of formula (I) 
, where M is one equivalent cation of an alkali metal; and R1, which are identical or different, each represents a C1-C6-alkyl group with a straight or branched chain or a -(CH2)n-X-R2 group, where n equals 1, 2 or 3; X is O; and R2 is a C1-C4alkyl group with a straight or branched chain, which are used a paramagnetic agent in the said dynamic nuclear polarisation process. The invention also relates to new radicals, to their use as paramagnetic agents.
EFFECT: obtaining new radicals of formula (I), which are used as paramagnetic agents in dynamic nuclear polarisation processes.
17 cl, 3 ex
