Heteronuclear-filtered 1H homonuclear multi-quantum correlation experiment at 100 kHz magic-angle spinning

Abstract

Remarkable advances in fast magic-angle spinning (MAS) techniques significantly improve the resolution of 1H solid-state nuclear magnetic resonance (NMR) spectra. Here, we introduce a heteronuclear-filtered 1H homonuclear multi-quantum (MQ) correlation strategy available at a MAS rate of 100 kHz by combining 1H{X} heteronuclear-filtered methods and 1H homonuclear MQ correlation experiments. The proposed strategy was applied to selectively extract 1H signals of aluminum lactate (Al-Lac) in a mixture of Al-Lac and zinc lactate (Zn-Lac) using 27Al-filtered methods (i.e., 1H{27Al} heteronuclear multiple quantum correlation (HMQC) or 1H{27Al} symmetry-based resonance-echo saturation-pulse double-resonance (S-RESPDOR)). We demonstrate that incorporating these 27Al-filtered methods into two-dimensional (2D) 1H–1H double-quantum (DQ)/single-quantum (SQ), triple-quantum (TQ)/SQ, and even three-dimensional (3D) 27Al/1H(DQ)/1H(SQ) experiments can facilitate the acquisition of spectra without signal overlap and targeted characterization of the 1H species surrounding 27Al sites. The proposed strategy is considered to efficiently extract key structural information from complex spin systems.

Keywords

• Solid-state NMR spectroscopy
• Proton
• Heteronuclear filter
• Homonuclear correlation
• Multi-quantum
• Ultra-fast magic angle spinning