A new gradient-controlled method for improving the spectral width of ultrafast 2D NMR experiments

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Analytical Chemistry
• Spectroscopy

Background:

• Ultrafast 2D NMR enables single-scan 2D spectrum acquisition.
• Current limitations include restricted spectral width and resolution in the ultrafast dimension due to gradient amplitude and filter bandwidth constraints.
• Existing methods using selective pulses to shift resonances have drawbacks.

Purpose of the Study:

• To develop a novel strategy for increasing the accessible spectral width in the ultrafast dimension of 2D NMR experiments.
• To overcome the resolution limitations associated with current ultrafast 2D NMR techniques.
• To provide a method applicable to various ultrafast 2D NMR experiments, especially heteronuclear ones.

Main Methods:

• A new gradient-controlled folding method is proposed.
• This method utilizes suitably chosen gradients placed on each side of the mixing period.
• It avoids the use of selective pulses, mitigating their associated drawbacks.

Main Results:

• The proposed method achieves "folded-like" spectra along the ultrafast dimension.
• It successfully increases the spectral width without compromising spectral resolution.
• Demonstrated efficiency and robustness across different compounds and pulse sequences (DQF-COSY, TOCSY, HSQC).

Conclusions:

• The gradient-controlled folding method effectively expands spectral width in ultrafast 2D NMR.
• This approach offers a robust alternative to selective pulse methods.
• It shows significant promise for improving heteronuclear 2D NMR applications.