Diffusion-ordered NMR spectroscopy (DOSY) serves as a noninvasive spectroscopic method for studying intact mixtures and identifying individual components present in mixtures according to their diffusion behaviors. However, DOSY techniques generally fail to discriminate complex compositions which exhibit crowded or overlapped NMR signals, particularly under adverse magnetic field conditions. Herein, we exploit the spatially selective pure shift-based DOSY strategy to address this challenge by eliminating inhomogeneous line broadenings and extracting pure shift singlets, thereby expediting diffusion analyses on complex mixtures. More importantly, this strategy is further applied to observing and analyzing electro-oxidation processes of blended alcohols, suggesting its potential to monitoring in situ electrochemical reactions. This study demonstrates a meaningful NMR trial for diffusion analysis on complex mixtures under adverse experimental circumstances, and particularly, it provides a proofof-concept technique for electrochemical studies and shows promising prospects for applications in chemistry, biology, energy, etc.

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Diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY) plays a vital role in mixture studies. However, its applications to complex mixture samples are generally limited by spectral congestion along the chemical shift domain caused by extensive J coupling networks and abundant compounds. Herein, we develop the in-phase multidimensional DOSY strategy for complex mixture analyses by simultaneously revealing molecular self-diffusion behaviors and multiplet structures with optimal spectral resolution. As a proof of concept, two pure shift-based three-dimensional (3D) DOSY protocols are proposed to record high-resolution 3D spectroscopic view with separated mixture components and their resolved multiplet coupling structures, thus suitable for analyzing complex mixtures that contain abundant compounds and complicated molecular structures, even under adverse magnetic field conditions. Therefore, this study shows a promising tool for component analyses and multiplet structure studies on practical mixture samples.