Toward Nanomolar Multi-Component Analysis by 19F NMR

19F-labeled molecular probes for fingerprint identification and quantitative analysis of malondialdehyde in urine

Aldehydes are crucial cellular intermediates and early diagnostic biomarkers for numerous diseases and injuries. Despite significant advancements in aldehyde detection, accurately distinguishing and quantifying these biomarkers remains challenging due to their similar chemical reactivities. 19F nuclear magnetic resonance (19F NMR) spectroscopy, characterized by a broad spectral range and unique chemical shifts, provides a powerful approach for the simultaneous and quantitative analysis of multiple targets. Here, we rationally designed a class of 19F-labeled molecular probes featuring a hydrazine moiety as the aldehyde recognition site, enabling specific identification and differentiation of aldehydes via easily interpretable changes in 19F chemical shifts. The chemical shift of the probe 19F-AP-1 at δ19F -120.8 ppm shifted to -112.3 ppm after its reaction with malondialdehyde (MDA). This approach allows for the selective "fingerprint" recognition of malondialdehyde (MDA) within complex aldehyde mixtures under the specified 19F NMR conditions (256 scans, 376 MHz transmitter frequency) with the acquisition time of 7 min 39 s, overcoming interferences from background matrices. This work provides a robust method that allows for qualitative and quantitative analyses of MDA directly in human urine samples without requiring pretreatment, highlighting its potential applicability for MDA detection across a range of biological fluids.

Molecules, Up Your Spins!

Nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI) are indispensable tools in science and medicine, offering insights into the functions of biological processes [...].

Bioinspired Fluorine Labeling for 19F NMR-Based Plasma Amine Profiling

Metabolite profiling serves as a powerful tool that advances our understanding of biological systems, disease mechanisms, and environmental interactions. In this study, we present an approach employing 19F-nuclear magnetic resonance (19F NMR) spectroscopy for plasma amine profiling. This method utilizes a highly efficient and reliable fluorine-labeling reagent, 3,5-difluorosalicylaldehyde, which effectively emulates pyridoxal phosphate, facilitating the formation of Schiff base compounds with primary amines. The fluorine labeling allows for distinct resolution of 19F NMR signals from amine mixtures, leading to precise identification and quantification of amine metabolites in human plasma. This advancement offers valuable tools for furthering metabolomics research.

19 F-Labeled Probes for Recognition-Enabled Chromatographic 19 F NMR

The NMR technique is among the most powerful analytical methods for molecular structural elucidation, process monitoring, and mechanistic investigations; however, the direct analysis of complex real-world samples is often hampered by crowded NMR spectra that are difficult to interpret. The combination of fluorine chemistry and supramolecular interactions leads to a unique detection method named recognition-enabled chromatographic (REC) 19 F NMR, where interactions between analytes and 19 F-labeled probes are transduced into chromatogram-like 19 F NMR signals of discrete chemical shifts. In this account, we summarize our endeavor to develop novel 19 F-labeled probes tailored for separation-free multicomponent analysis. The strategies to achieve chiral discrimination, sensitivity enhancement, and automated analyte identification will be covered. The account will also provide a detailed discussion of the underlying principles for the design of molecular probes for REC 19 F NMR where appropriate.

Regioselective Aromatic Perfluoro-tert-butylation Using Perfluoro-tert-butyl Phenyl Sulfone and Arynes

The selective introduction of perfluoro-tert-butyl group (PFtB, the bulkier analogue of CF₃ group) into arenes has long been sought after but remains a formidable task. We herein report the first general synthetic protocol to realize aromatic perfluoro-tert-butylation. The key to the success is the identification of PFtB phenyl sulfone as a new source of PFtB anion, which reacts with arynes in a highly regioselective manner to afford perfluoro-tert-butylated arenes in high yields. The application of the method is demonstrated by the preparation of sensitive ¹⁹F-labeled NMR probes with an extraordinary resolving ability.