Simultaneous Identification of Neutral and Anionic Species in Complex Mixtures without Separation

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.

Direct Chiral 19F NMR Analysis of Fluorine-Containing Analytes and Its Application to Simultaneous Chiral Analysis

We have demonstrated the efficient chiral analysis of fluorine-containing compounds by ¹⁹F NMR spectroscopy. The highly sensitive fluorine nucleus allowed chiral analysis of complex mixtures and even asymmetric reaction mixtures of multisubstrates. A single ¹⁹F NMR experiment was sufficient to determine the enantiomeric excesses and yields of the five products simultaneously.

1 H NMR Chemosensing of Potassium Ions Enabled by Guest-Induced Selectivity Switch of a Gold Nanoparticle/Crown Ether Nanoreceptor

A sensing protocol to detect potassium ions in water by ¹ H NMR spectroscopy is described. The method exploits the K⁺ -modulated affinity of 18-crown-6 functionalized gold nanoparticles towards organic ions, combined with NOE magnetization transfer. Binding of K⁺ to the crown ether moieties switches the nanoreceptor preference (and its ability to transfer magnetization) from organic cations (tyramine) to organic anions (phloretate). In this way, a ratiometric NMR signal is produced with a detection limit of 0.6 mM. Detection can be performed in 20 min with standard instruments and with little interference from other alkali and alkaline earth metal ions present in the sample.

Sensor Technologies Empowered by Materials and Molecular Innovations

Functional synthetic designer materials can impact many advanced technologies, and the chemical sensor area is intimately reliant on these new chemical innovations. The transduction of chemical and biological signals is necessary for low cost omnipresent chemical sensing and will be realized by chemical designs of new transduction materials. We are poised for many new innovations to empower new generations of sensor technologies. Materials innovations promise to expand the capabilities of present hardware, drive down the cost, and ensure broad implementation of these methods.