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

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.