The development of F-19-labeled NMR probes has become a pivotal tool in analytical chemistry. Recent advancements in probe design enable precise identification of nitrogen-containing analytes, significantly enhancing the analysis of these biologically important analytes in complex mixtures. This short review highlights recent progress with probes based on covalent derivatization and dynamic exchange strategies, which yield distinct F-19 NMR signals for each nitrogen-containing analyte. These strategies facilitate separation-free multicomponent analysis and chiral discrimination. Discussions will cover design principles, scope, limitations, and strategies to enhance the sensitivity and resolving ability. By addressing current challenges, F-19-labeled NMR probes hold the potential to revolutionize the detection of biologically relevant molecules, catalyzing new discoveries in chemical and biochemical research. 1 Introduction 2 F-19-Labeled Probes Based on Covalent Derivatization 2.1 Non-Chiral F-19-Labeled Probes Based on Covalent Derivatization 2.2 Chiral F-19-Labeled Probes Based on Covalent Derivatization 3 F-19-Labeled Probes Based on Dynamic Ligand Exchange 3.1 Non-Chiral F-19-Labeled Probes Based on Dynamic Ligand Exchange 3.2 Chiral F-19-Labeled Probes Based on Dynamic Ligand Exchange 4 Conclusion and Outlook

Four biobased phosphate-containing aryl monomers with methoxy, allyl, and vinyl groups as substituents have been successfully synthesized. Copolymerizing these monomers with thiophenol or mercaptans via the photoclick thiol-ene reaction gives the polymers with refractive indices (n D) of 1.63-1.70 and Abbe numbers (v D) of 12.8-38.5. An investigation of the relationship of the v D values with the substituents on the benzene rings of the monomers indicates that methoxy and vinyl groups can collectively increase the v D values. In comparison with allyl groups, vinyl groups endow the polymers with both higher n D and v D. Moreover, these polymers also display high transmittance, high thermostability, and low haze values in the visible-light region, suggesting that these biobased functional monomers are satisfactory precursors used in the fabrication of optical devices.

The recent developed bottom-up on-surface synthesis offers unprecedent opportunities for the fabrication of two-dimensional (2D) carbon-based networks with atomic precision. Hierarchical coupling approach has been proposed as an efficient strategy for improving the corresponding reaction selectivity and quality of target structures. Herein, we report the synthesis of a nitrogen-doped carbon-based network on Ag(100) utilizing a hierarchical Ullmann coupling strategy. The accurate identification of reaction intermediates and products by scanning tunneling microscopy allows us to unravel the reaction mechanism. The synthetic process of 2D carbon-based networks is kinetics-driven, relying on the competition between dechlorination and C-C coupling. We expect that our discussion on the mechanism of hierarchical coupling may shed light on the rational design and precise synthesis of 2D carbon-based networks on surfaces.

Diphenylprolinol silyl ethers have been successfully identified as efficient chiral amines in the enantioselective allenation reaction of terminal alkynes and 2-alkynals. This reaction provides a diverse set of chiral allenynes with excellent enantioselectivity and decent yields. Furthermore, the current protocol is also compatible for the late-stage modification of some complex bioactive molecules, highlighting its potential in drug discovery.

Panax ginseng C.A.Mey is a famous natural herbal medicine worldwide. Mountain-cultivated ginseng (MCG) and garden-cultivated ginseng (GCG) are two types of Panax ginseng. There is a significant difference in economic benefits between MCG and GCG, which can always lead to problems such as adulteration and substitution of MCG with lower-priced alternatives. We explored the quality marker of ginseng at the intact protein level and established a foundation for the quality control of ginseng. Cellulose nanocrystal assisted sample preparation combined with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) equipped with a high mass detector was performed to analyze intact proteins in ginseng. The results revealed that the ribonuclease-like storage protein is the most abundant protein in MCG and GCG. Meanwhile, the molecular weight of the ribonuclease-like storage protein showed great difference between different ginseng species, which is 26.2 kDa in MCG and 24.2 kDa in GCG. The ribonuclease-like storage protein glycosylation modification difference provides data support for the differentiation between MCG and GCG. This study showed that glycosylated modified ribonuclease-like storage protein can be a crucial quality marker of ginseng, facilitating the rapid distinction between MCG and GCG.

The generation of difluorocarbene from difluoromethane bis(sulfonium ylide) 1 through spin-forbidden excitation under irradiation with 450 nm blue light was reported. The formation of difluorocarbene was confirmed by its reaction with styrene derivatives for the generation of difluorocyclopropanation and insertion into RX-H bonds (X = O, S) for the generation of RXCF2H. The spin-forbidden excitation mechanism for the formation of difluorocarbene from difluoromethane bis(sulfonium ylide) was supported by spectroscopic and kinetic studies as well as computational chemistry. The homolytic cleavage of two S-C bonds in compound 1 under irradiation was confirmed by time-resolved EPR spectroscopic studies of the precursor's free-radical-capturing reaction, as well as the isolation of the dimer of dimethyl (phenylthiol)malonyl radical. Further studies showed that the homolytic cleavage process occurred asynchronously in the solvent cage based on the isotope-labeled scrambling experiments and DFT calculations.

It has been established that N-acetyltransferase (murine NAT1 (mNAT1) and human NAT2 (hNAT2)) mediates insulin sensitivity in type 2 diabetes. Here we show that mNAT1 deficiency leads to a decrease in cellular spermidine-a natural polyamine exhibiting health-protective and anti-ageing effects-but understanding of its mechanism is limited. We identify that mNAT1 and hNAT2 modulate a type of post-translational modification involving acetylated spermidine, which we name acetylhypusination, on receptor-interacting serine/threonine-protein kinase 1 (RIPK1)-a key regulator of inflammation and cell death. Spermidine supplementation decreases RIPK1-mediated cell death and diabetic phenotypes induced by NAT1 deficiency in vivo. Furthermore, insulin resistance and diabetic kidney disease mediated by vascular pathology in NAT1-deficient mice can be blocked by inhibiting RIPK1. Finally, we demonstrate a decrease in spermidine and activation of RIPK1 in the vascular tissues of human patients with diabetes. Our study suggests a role for vascular pathology in diabetes onset and progression and identifies the inhibition of RIPK1 kinase as a potential therapeutic approach for the treatment of type 2 diabetes. Zhang et al. show that the activation of RIPK1 is suppressed by acetylhypusination in a spermidine-dependent manner. Disruption of this axis contributes to RIPK1-mediated vascular pathology to promote insulin resistance and diabetic kidney pathology.