We report a novel rare spin correlation experiment termed ADEQUATE with composite refocusing (CR), which is the ¹H-detected version of 2D INADEQUATE CR. ADEQUATE CR begins with a polarization transfer from protons to the attached carbon, followed by ¹³C–¹³C double-quantum (DQ) preparation. Unlike the ADEQUATE class of experiments, ¹³C DQ coherence is converted after evolution to single-quantum single transitions (SQ-STs) by CR. ¹³C SQ-ST is then transferred back to the coupled protons by a coherence order selective reconversion. The present sequence produces partial transition selectivity in the ¹H dimension as does ¹H Indirect detected ¹³C Low-Abundance Single-transition correlation Spectroscopy (HICLASS), thereby mitigating the reduction in sensitivity enhancement because of the presence of homonuclear proton couplings. However, unlike HICLASS (which is an experiment that involves SQ-TS evolution), no homonuclear zero quantum mixing is required on the ¹³C channel in the present experiment. Experimental results are demonstrated on a variety of samples, establishing the efficiency of the proposed method. Copyright © 2014 John Wiley & Sons, Ltd.

Overhauser–DNP-enhanced homonuclear 2D ¹⁹F correlation spectroscopy with diagonal suppression is presented for small molecules in the solution state at moderate fields. Multi-frequency, multi-radical studies demonstrate that these relatively low-field experiments may be operated with sensitivity rivalling that of standard 200–1000 MHz NMR spectroscopy. Structural information is accessible without a sensitivity penalty, and diagonal suppressed 2D NMR correlations emerge despite the general lack of multiplet resolution in the 1D ODNP spectra. This powerful general approach avoids the rather stiff excitation, detection, and other special requirements of high-field ¹⁹F NMR spectroscopy.

Overhauser–DNP-enhanced homonuclear 2D ¹⁹F correlation spectroscopy with diagonal suppression is presented for small molecules in the solution state at moderate fields. Multi-frequency, multi-radical studies demonstrate that these relatively low-field experiments may be operated with sensitivity rivalling that of standard 200–1000 MHz NMR spectroscopy. Structural information is accessible without a sensitivity penalty, and diagonal suppressed 2D NMR correlations emerge despite the general lack of multiplet resolution in the 1D ODNP spectra. This powerful general approach avoids the rather stiff excitation, detection, and other special requirements of high-field ¹⁹F NMR spectroscopy.