Patent ID: 7985594

Claim:
A method comprising steps of: providing a frozen sample in a magnetic field, wherein the sample includes a biradical and an analyte with at least one spin half nucleus; polarizing the at least one spin half nucleus of the analyte by irradiating the frozen sample with radiation having a frequency that excites electron spin transitions in the biradical; optionally melting the frozen sample to produce a molten sample; and detecting nuclear spin transitions in the at least one spin half nucleus of the analyte in the frozen or molten sample, wherein the biradical has the formula (I): wherein Q 1 is a cyclic nitroxide group of the formula: wherein each instance of R 9 is, independently, hydrogen, substituted or unsubstituted hydroxyl; substituted or unsubstituted thiol; substituted or unsubstituted amino; nitro; halo; cyano; azido; substituted or unsubstituted, cyclic or acyclic C 1-6 aliphatic; substituted or unsubstituted, cyclic or acyclic C 1-6 heteroaliphatic; substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl, acyl; C 1-6 alkyl sulfonyl; C 1-6 alkyl sulfinyl; substituted or unsubstituted aryl sulfinyl; or substituted or unsubstituted aryl sulfonyl; R 10 is hydrogen, substituted or unsubstituted, cyclic or acyclic C 1-6 aliphatic; substituted or unsubstituted, cyclic or acyclic C 1-6 heteroaliphatic; substituted or unsubstituted aryl, or substituted or unsubstituted heteroaryl; W is N or ⊕ N—O⊖; Q 2 is the group —X 2 -L 2 -M 2 , where Q 1 and Q 2 may be the same or different; R 1 is hydrogen; a suitable hydroxyl protecting group; substituted or unsubstituted, cyclic or acyclic C 1-6 aliphatic; substituted or unsubstituted, cyclic or acyclic C 1-6 heteroaliphatic; substituted or unsubstituted aryl, substituted or unsubstituted heteroaryl; acyl; C 1-6 alkyl sulfonyl; C 1-6 alkyl sulfinyl; substituted or unsubstituted aryl sulfinyl; or substituted or unsubstituted aryl sulfonyl; X 1 and X 2 are, independently, —O—, —S—, or —N(R 2 )—, wherein R 2 is hydrogen, a suitable amino protecting group; substituted or unsubstituted amino; substituted or unsubstituted hydroxyl; substituted or unsubstituted, cyclic or acyclic C 1-6 aliphatic; substituted or unsubstituted, cyclic or acyclic C 1-6 heteroaliphatic; substituted or unsubstituted aryl; substituted or unsubstituted heteroaryl; acyl; C 1-6 alkyl sulfonyl; C 1-6 alkyl sulfinyl; substituted or unsubstituted aryl sulfinyl; or substituted or unsubstituted aryl sulfonyl; L 1 and L 2 are, independently, a direct bond; substituted or unsubstituted, cyclic or acyclic C 1-6 aliphatic; or substituted or unsubstituted, cyclic or acyclic C 1-6 heteroaliphatic; and M 2 is a substituted or unsubstituted, cyclic or acyclic nitroxide.