Angewandte Chemie最新文献

Open metal sites are crucial in catalysis. We have used a “loose coordination strategy” (LCS) to preorganize open metal sites in gold cluster catalysts. A gold nanocluster with composition of [Au₂₆(3,4-Me₂-Ph-form)₉(ⁱPr₂-imy)₃(Me₂S)](BF₄)₂ (ⁱPr₂-imy=1,3-Diisopropylimidazolium tetrafluoroborate, 3,4-Me₂-Ph-form=N,N′-Di(3,4-dimethyl-phenyl)formamidine) (Au₂₆) has been obtained by one pot synthesis, i.e. the direct reduction of Me₂SAuCl in the presence of N-heterocyclic carbenes and amidinate ligands. ESI-TOF-MS reveals that the Me₂S ligand is detached from the cluster to form open sites. The accessibility of the exposed Au atoms has been confirmed quantitatively by luminescent titration with 2-naphthalenethiol. Surprisingly, Au₂₆ has 15 valence electrons, and the presence of an unpaired electron is confirmed by superconducting quantum interference device (SQUID) and electron paramagnetic resonance (EPR). This open-shelled Au₂₆ not only shows unexpected high stability but also exhibits excellent catalytic performance toward the selective oxidation of benzyl alcohol to benzaldehyde, achieving a remarkable turnover number up to 100670.

Despite the increasing interest in radical-based fluoroalkylation techniques, the organofluorine compounds bearing the partially fluorinated hexafluoroisopropyl group remain extremely scarce due to the lack of appropriate reagents. Herein we report an unprecedented photoelectrocatalytic method for the C−H hexafluoroisopropylation of indoles and tryptophan peptides, utilizing the readily available hexafluoro-2-propanol (HFIP) as the fluoroalkylation reagent. In this process, HFIP is converted into hexafluoroisopropyl radicals, enabling fluoroalkylation reactions. This study broadens the potential applications of molecular photoelectrocatalysis, highlighting its capacity to enable transformations that are difficult to accomplish through traditional electrochemical or photochemical approaches.

Efficient catalytic water splitting demands advanced catalysts to improve the slow kinetics of the oxygen evolution reaction (OER). Earth-abundant transition metal oxides show promising OER activity in alkaline media. However, most experimental information available is either from post-mortem studies or in situ space-averaged X-ray techniques in the micrometer range. Therefore, the composition of the active centers under operando conditions is still under debate. In this work, we combine nanoscopic and spectroscopic measurements on the hydroxylation of molecular beam epitaxy (MBE)-prepared Ni and NiFe oxides nanoislands with operando local investigations of Ni and NiFe hydroxide electrocatalysts under OER conditions to reveal the nature of the active centers in 2D OER catalysts. Our results reveal that Fe doping increases the active surface area by island fragmentation, and boosts the intrinsic activity by creating optimized active centers consisting of both Ni and Fe atoms. In addition, our findings show that operando characterization at the nanoscale is crucial to reveal the dynamic nature of the interface of 2D catalysts under reaction conditions.

RNA modifications, such as N6-methylation of adenosine (m⁶A), serve as key regulators of cellular behaviors, and are highly dynamic; however, tools for dynamic monitoring of RNA modifications in live cells are lacking. Here, we develop a genetically encoded live-cell RNA methylation sensor that can dynamically monitor RNA m⁶A level at single-cell resolution. The sensor senses RNA m⁶A in cells via affinity-induced cytoplasmic retention using a nuclear location sequence-fused m⁶A reader. It allows for simultaneously measure RNA m⁶A dynamics and viral invasion at single-cell level. Based on the single-cell analytical tool, we found that SARS-CoV-2 infection enhances host-cell RNA m⁶A level, and high-level RNA m⁶A modification in host cells, in turn, facilitates viral infection. Particularly, Omicron, a variant of SARS-CoV-2, that features as high infection capacity, however, exhibits a reduced facilitation of m⁶A modification in host cells. In addition, the sensor can estimate viral inhibition via measuring cellular m⁶A level, that was explored for screening potential antiviral drugs. The methylation sensor can serve for elucidating the interplay between pathogens and host-cell epigenetics at single-cell level.

Organofluorines, particularly those containing trifluoromethyl (CF₃) groups, play a critical role in medicinal chemistry. While trifluoromethylation of alkenes provides a powerful synthetic route to construct CF₃-containing compounds with broad structural and functional diversity, achieving enantioselective control in these reactions remains a formidable challenge. In this study, we engineered a nonheme iron enzyme, quercetin 2,3-dioxygenase from Bacillus subtilis (BsQueD), for the enantioselective trifluoromethylazidation of alkenes. Through directed evolution, the final variant BsQueD-CF₃ exhibited excellent enantioselectivity, with an enantiomeric ratio (e.r.) of up to 98 : 2. Preliminary mechanistic studies suggest the involvement of radical intermediates. This work expands biocatalytic organofluorine chemistry by reprogramming metalloenzymes for innovative trifluoromethylation reactions.

Photodynamic therapy (PDT) has emerged as a promising targeted treatment for cancer. However, current PDT is limited by low tissue penetration, insufficient phototoxicity (toxicity with light irradiation), and undesirable cytotoxicity (toxicity without light irradiation). Here, we report the discovery of cyanine-carborane salts as potent photosensitizers (PSs) that harness the near-infrared (NIR) absorbing [cyanine⁺] with the inertness of [carborane⁻]. The implementation of [cyanine⁺] [carborane⁻] salts dramatically enhance cancer targeting of the PSs and decrease cytotoxicity. We characterize the cellular uptake of the cyanine-carborane PSs, organelle localization, generation of reactive oxygen species (ROS) with the ability to cogenerate multiple ROS species, suppression of pro-metastatic pathways, and activation of apoptotic pathways. We further demonstrate the ability of optimized PSs to eliminate tumors in vivo using an orthotopic mouse model of breast cancer. These newly developed [cyanine⁺] [carborane⁻] salt PSs introduce a potent therapeutic approach against aggressive breast cancer while decreasing side effects.

The analysis of the microstructure of supramolecular copolymers is difficult because of their dynamic character. Here, benzene-1,3,5-tricarboxamide (BTA) co-assemblies are analysed by ion mobility – mass spectrometry (IM–MS) to reveal the presence of various sequences. For example, the IM–MS mobilogram for hexamers composed of 4 units from a first monomer and 2 units from a second monomer is a broad distribution due to the presence of 9 possible isomeric sequences, which can be sorted out based on calculated collision cross-sections. This approach gives unprecedented information on supramolecular copolymer sequences.

In their Research Article (e202416506), Xiang Chen and co-authors developed a knowledge–data dual-driven framework that incorporates domain expertise into artificial intelligence models, achieving notable accuracy in predicting properties such as melting, boiling, and flash points of battery electrolytes.

Catalyst-free alkyne couplings using bis(pentafluorophenyl)boron enolates are reported by Masatoshi Shibuya, Souta Yuruka and Yoshihiko Yamamoto in their Communication (e202417910). The strongly Lewis acidic boron center activates a carbon–carbon triple bond, enabling C−C bond formation between the boron enolate and the alkyne.

X. Li, S. Yang, M. Liu, X. Yang, Q. Xu, G. Zeng, Z. Jiang, Angew. Chem. Int. Ed. 2023, 62, e202304356

DOI: 10.1002/ange.202304356

Correction 1: In the Supporting Information of this article, Page 15, a wrong version of Figure S11 was inadvertently included. The PXRD patterns depicted for the samples after treatment with boiling water and acid-base treatment were incorrect. The correct version of Figure S11 is shown below.

Correction 2: In the Supporting Information, Page 18, the unit of the y-axis of Figure S14 has a typo. The unit should be “J/J₀(%)”. The correct version of Figure S14 is shown below.

Correction 3: In the Supporting Information, Page 38, the caption of Table S5 has a typo. The table caption should read: “Table S5. Atomistic coordinates for the AA-stacking mode of amide-COF optimized using DFTB+ method. Lattice type: orthorhombic, Space group: PMMM; α= β = 90° γ = 120°, a = 22.428619 Å, b = 22.524134 Å, c = 3.555884 Å.”

The original Supporting Information was replaced with a corrected version of the Supporting Information. The authors apologize for these errors which do not affect the data analysis and conclusions of the original Research Article.