Inverse detection and heteronuclear editing in 1H-15N correlation and 1H-1H double-quantum NMR spectroscopy in the...

Area of Science:

• Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
• Advanced spectroscopic techniques for molecular structure determination.

Background:

• Heteronuclear correlation spectra and 1H experiments benefit from inverse detection (1H detection) under fast magic angle spinning (MAS).
• Recoupled polarization transfer (REPT) is a method for polarization transfer in NMR.

Purpose of the Study:

• To present a heteronuclear 1H-15N single-quantum correlation (HSQC) experiment using REPT with symmetrical design for easy frequency dimension interchange.
• To demonstrate the utility of inverse 1H-15N REPT-HSQC as a filter for 1H signals in solid-state MAS experiments.
• To showcase the combination of this filter with a 1H-1H DQ experiment for 15N-edited 2D spectra.

Main Methods:

• Implementation of a heteronuclear 1H-15N single-quantum correlation (HSQC) experiment utilizing recoupled polarization transfer (REPT).
• Inverse detection scheme with indirect observation of the 15N dimension and direct detection on 1H.
• Application of the inverse 1H-15N REPT-HSQC scheme as a heteronuclear filter prior to a 1H-1H DQ experiment.

Main Results:

• Experimental sensitivity enhancement by factors of 5-10 compared to conventional 15N detection in HSQC experiments.
• Successful integration of the REPT-HSQC filter with a 1H-1H DQ experiment to produce 2D 15N-edited 1H-1H DQ MAS spectra.
• Demonstration of specific selection or suppression of 1H resonances in solid-state MAS experiments.

Conclusions:

• Inverse detection via REPT significantly enhances sensitivity in solid-state NMR heteronuclear correlation experiments.
• The developed REPT-HSQC scheme serves as an effective heteronuclear filter, enabling selective manipulation of 1H signals.
• This approach improves spectral resolution and facilitates the unraveling of complex information in 1H spectra of solid samples.