Chemistry - A European Journal最新文献

The development of efficient strategies for constructing cyclic organosilicon frameworks is considered of great importance because of their structural diversity and synthetic utility. Herein, we report a SmI₂/Sm-mediated silacyclization of unsaturated organic compounds with readily available dichlorosilanes and -disilanes, enabling convenient access to 4-7-membered silacyclic compounds. Mechanistic investigations indicate that the reaction involves silyl radical intermediates and proceeds via a reductive radical-polar crossover (RRPCO) pathway. The present findings showcase the broad potential of Sm reagents in Si─C bond formation, providing a versatile strategy for constructing diverse silicon-containing frameworks.

The discovery of fluorescence receptors that selectively bind small molecules with high affinity in aqueous media is critical for the development of new sensing and bioimaging assays. We herein report a new fluorescence receptor-dye chemosensor based on the monofunctionalization of p-sulfonatocalix[4]arene (SC4) receptor with pyrene (SC4-4Py). The SC4-4Py conjugate was found to retain the exceptional binding properties of SC4, allowing the high-affinity recognition of neurotransmitters, amino acids, and biogenic amines in aqueous solution and their optical detection. The SC4-4Py chemosensor operates through a photoinduced electron transfer (PET) mechanism triggered by conformational changes in the calixarene structure upon binding, allowing single-wavelength fluorescence detection of target analytes and its expansion into a dual-wavelength ratiometric indicator displacement assay (IDA) that relies on competitive PET between the pyrene and non-covalently bound lucigenin dye.

To address the issues of capacity decay and poor rate performance of Bi₂S₃ anode materials, which are caused by their intrinsically low conductivity and significant volume expansion during cycling, this study adopts a redox self-assembly strategy. Under mild hydrothermal conditions, oxygen-containing functional groups on the surface of graphene oxide (GO) induce the directed growth of Bi₂S₃ along the [001] crystallographic direction, successfully constructing a Bi₂S₃/GO composite anode with strong interfacial coupling. This structure effectively suppresses the agglomeration of Bi₂S₃ nanorods, forms a 3D conductive network, alleviates volume strain, and avoids structural damage caused by traditional high-temperature sulfidation processes. Electrochemical tests show that the 1.0-Bi₂S₃/GO composite retains a capacity of 300 mAh·g^-1 after 100 cycles at a current density of 100 mA·g^-1. At a high rate of 5000 mA·g^-1, it still exhibits a reversible capacity of 198.62 mAh·g^-1, and after current recovery, the capacity rapidly increases to 439 mAh·g^-1, with a capacity retention rate exceeding 70%. The lithium-ion diffusion coefficient reaches 8.7×10^{-1 2} cm²·s^-1, which is 2.8 times higher than that of the pure phase. Mechanistic analysis reveals that the characteristic peak (τ = 0.3 s) in the distribution relaxation time (DRT) relaxation spectrum corresponds to the pseudocapacitive behavior on the GO surface, with a contribution rate of 58% at a scan rate of 2 mV·s^-1, significantly optimizing the ion storage dynamics at the interface. Additionally, the built-in electric field at the interface facilitates charge transfer, effectively shortening the relaxation time. The synergistic π-π stacking buffering network further enhances structural stability and reaction reversibility. This study, through the "directed growth-pseudocapacitance regulation-relaxation matching" triple mechanism, provides new insights for the design of high-performance sulfide-based anodes.

This work reports the preparation and computational investigation of a bis-dichlorosilyl functionalized C₄-cumulene (2), which was synthesized by employing Amidinato-chlorosilylene, L(Cl)Si: (L = PhC(N^tBu)₂). Compound 2 was characterized by single-crystal X-ray diffraction, mass spectrometry, and NMR spectroscopy. The stability, distribution of spin densities, and the nature of Si-C bonds of 2 were studied by employing natural bond orbital (NBO) analysis, atoms in molecules (AIM), and energy decomposition analysis-natural orbital for chemical valence (EDA-NOCV). The EDA-NOCV analysis showed that compound 2 possesses electron-sharing covalent sigma and dative covalent sigma bonds (Si↔C and C→Si) between the Ph₂C₄ fragment in the anionic doublet state and silyl-amidine groups in the cationic doublet state. This may be due to the electron-deficient nature of olefin and electron-rich N-donating functional groups on silicon atoms. Compound 2 displays unprecedented chemical bonding in this class of compounds as predicted by EDA-NOCV calculations. We have also compared the bonding situation of compound 2 with a previously reported compound 3.

The gregatins constitute a distinctive family of fungal metabolites exhibiting notable phytotoxic and antimicrobial activities, which have attracted sustained interest from the synthetic community since their discovery. Despite their deceptively simple molecular architectures, the structural elucidation and asymmetric synthesis of gregatins have long remained challenging. Among them, gregatin A serves as the prototypical member and a proposed biosynthetic precursor to several dimeric congeners, including penicilfuranone A, asperones A and B, and citrifurans A and D. Over the past decades, remarkable progress has been achieved in the total and asymmetric synthesis of these compounds, reflecting the continuous evolution of synthetic strategies toward greater efficiency, selectivity, and biomimetic relevance. This review summarizes the methodological innovations and strategic advances that have shaped the total synthesis of gregatin A and its structurally related dimers, highlighting the broader conceptual evolution of asymmetric synthesis in complex natural product chemistry.

Natural isonitriles are promising lead compounds for medicinal chemistry. Their identification is, however, challenging due to the hydrolytic lability of the isonitrile group. Here, we use the azomethine imine (AMI)-isonitrile ligation in a reactivity-based screening protocol for the chemoselective derivatization of natural isonitriles. The herein developed AMI probe rapidly reacts with isonitriles-primary, secondary, tertiary, as well as aromatic-to stable conjugates. A dibromide mass tag enables the detection of low-abundance isonitriles, even in complex biological matrices. The ligation establishes a new stereogenic center, thereby allowing facile distinction between achiral and chiral isonitriles by the formation of racemates or diastereoisomers, respectively. In addition, a unique reactivity of isonitriles bearing an α-COOH group was unraveled. This AMI probe enabled the detection of known bacterially produced isonitriles and the identification of a novel fungal isonitrile.

The Mg─Mg-bonded compound [K(THF)₃]₂[LMg─MgL]₂ (1, L = [(2,6-iPr₂C₆H₃)NC(CH₃)]₂ ^2-) can promote reductive 4,4'-homocoupling of pyridine and derivatives under ambient conditions, yielding the 4,4'-dihydro-4,4'-bipyridinate products 2-6. Interestingly, these species can be viewed as "dimerized" metal-1,4-dihydropyridinates (bis-M-DHPs) and can transfer hydrogen or deuterium (as proton and hydride) to pyridines, imines and alkenes. This may provide a facile access to new H/D-donors, readily obtained from commercially available pyridines and a conveniently synthesized magnesium(I) complex, for controllable H-transfer (HT) to different types of unsaturated molecules. The coupling and HT mechanisms were elucidated by DFT calculations.

Noncovalent halogen bonding, particularly the three-center four-electron (3c-4e^-) [N⋯X⋯N]⁺ motif, represents a critical tool in supramolecular chemistry and materials science. While I⁺-based systems are well-studied, this review focuses on the emerging and highly functional [N⋯Br⋯N]⁺ motif and its application in halogen-bonded organic frameworks (XOFs). The authors comprehensively summarize the synthetic strategies required to overcome the instability of the Br⁺ species, including halogen bond network spatial constraint, cation substitution, ligand exchange, and precise anionic regulation. Structural analysis reveals that the shorter N⋯Br bond length (2.07 Å) and stronger electron-deficient characteristics of the Br⁺-bridge provide unique functional advantages. This structural superiority translates to enhanced performance in applications such as selective alcohol oxidation and highly efficient photocatalytic H₂O₂ production, where XOFs(Br) materials consistently outperform their I-analogues and molecular precursors. Furthermore, it also highlights the potential of XOFs(Br) in biomedical fields, including superior antimicrobial activity and applications in photothermal therapy. This work confirms the significant potential of the [N⋯Br⋯N]⁺ motif to drive future innovation in controllable functional materials, paving the way for the design of stable Br⁺-bridged XOFs for catalysis, precision medicine, and others.

Asymmetric transition metal catalysis represents the most reliable method for the chiral induction in organic scaffolds and to synthesize a wide array of valuable 3D-molecules. However, accessing both enantiomers of the chiral molecules from a catalyst(s) having the same chirality through ingenious stereo-control has remained a highly demanding task. Herein, we disclose the catalytic enantiodivergent synthesis of 3-vinylphthalides from arylcarboxylic acids and cyclopropenes, an efficient surrogate for vinylcarbenes. Through engineering the chiral cyclopentadienylrhodium(III) catalysts, both enantiomers have been achieved with excellent yield and enantioselectivity via regioselective C─H bond functionalization using a weakly coordinating directing group and asymmetric [4+1]-annulation. Experimental and computational investigations revealed the mechanism of the oxidative annulation and enantiodetermining ring-opening isomerization of cyclopropenes, which is governed by the stereoselective cleavage of the C─C bond. The present study opens a new avenue in asymmetric C─H bond functionalization and allows access to both enantiomers of the target molecules without altering the chirality of the ligand.

New series of triazole/pyrazole and tetrazole/triazole/pyrazole ligands were synthesized and coordinated with various transition metals to yield a diverse library of 14 complexes. All compounds were fully characterized by elemental analysis, mass spectrometry, powder X-ray diffractometry, and a range of spectroscopic techniques (¹H NMR, ¹³C NMR, FT-IR, and UV-visible diffuse reflectance). The crystal and molecular structures were elucidated via single-crystal X-ray diffraction, and their supramolecular features were explored through Hirshfeld surface analysis. The ⁵⁷Fe Mössbauer and magnetic SQUID measurements confirmed the high-spin nature of the Fe^II complex 1. In the three human cancer cell lines, most metal complexes are somewhat more cytotoxic than the inactive ligands, with Co(II) complexes 2 and 8 being the most potent in two of the cell lines (with IC₅₀ values in the two-digit micromolar range). Overall, this study highlights how blending tetrazole/triazole/pyrazole ligands with transition metals can lead to coordination compounds with potential in anticancer research, as a proof of concept. These results add valuable insight to the expanding field of metal-based therapeutics and could help guide the development of next-generation, more effective agents.