A Natural Glycyrrhizic Acid‐Tailored Light‐Responsive Gelator

The construction of stimuli‐responsive materials by using naturally occurring molecules as building blocks has received increasing attention owing to their bioavailability, biocompatibility, and biodegradability. Herein, a symmetrical azobenzene‐functionalized natural glycyrrhizic acid (trans‐ GAG ) was synthesized and could form stable supramolecular gels in DMSO/H₂O and MeOH/H₂O. Owing to trans–cis isomerization, this gel exhibited typical light‐responsive behavior that led to a reversible gel–sol transition accompanied by a variation in morphology and rheology. Additionally, this trans‐ GAG gel displayed a distinct injectable self‐healing property and outstanding biocompatibility. This work provides a simple yet rational strategy to fabricate stimuli‐responsive materials from naturally occurring, eco‐friendly molecules.     

Hierarchical MoS2@TiO2 Heterojunctions for Enhanced Photocatalytic Performance and Electrocatalytic Hydrogen Evolution

Hierarchical MoS₂@TiO₂ heterojunctions were synthesized through a one‐step hydrothermal method by using protonic titanate nanosheets as the precursor. The TiO₂ nanosheets prevent the aggregation of MoS₂ and promote the carrier transfer efficiency, and thus enhance the photocatalytic and electrocatalytic activity of the nanostructured MoS₂. The obtained MoS₂@TiO₂ has significantly enhanced photocatalytic activity in the degradation of rhodamine B (over 5.2 times compared with pure MoS₂) and acetone (over 2.8 times compared with pure MoS₂). MoS₂@TiO₂ is also beneficial for electrocatalytic hydrogen evolution (26 times compared with pure MoS₂, based on the cathodic current density). This work offers a promising way to prevent the self‐aggregation of MoS₂ and provides a new insight for the design of heterojunctions for materials with lattice mismatches.     

1α-羟基去氢表雄酮的合成

本文以1,4-雄烯二酮为起始原料,经羰基保护、溴代、异构化、羰基还原、环氧化、开环及脱保护7步反应以28.3%的总收率合成1α-羟基去氢表雄酮。该方法具有高效经济、技术可行、安全环保等优点,为1α-羟基去氢表雄酮的规模生产及维生素D类药物合成研究奠定理论基础。     

An efficient Fe(III)-catalyzed 1,6-conjugate addition of para-quinone methides with fluorinated silyl enol ethers toward β,β-diaryl α-fluorinated ketones

Reported here is a highly efficient 1,6-conjugate addition of fluorinated silyl enol ethers to para-quinone methides, allowing facile access to a range of β,β-diaryl α-fluorinated ketones with good to high yields. Fe(OTf)₃ was identified as the optimal catalyst, with the loading of 3?mol%. Notably, this represent the first 1,6-conjugate addition with fluorinated silyl enol ethers. The synthetic potential of the resulting adducts is also demonstrated.     

A coumarin based highly selective fluorescent chemosensor for sequential recognition of Cu2+ and PPi

In this study, we have successfully synthesized a new coumarin based fluorescent chemosensor 1, in which tren and quinolone are introduced as receptors for sequential recognition of Cu²⁺ and PPi. The structure of chemosensor 1 was characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. Sensor 1 showed an obvious “on-off” fluorescence quenching response toward Cu²⁺, and the quenching efficiency reached a maximum of 99.6% with the addition of 20 equiv. of Cu²⁺. The 1-Cu²⁺ complex showed an “off-on” fluorescence enhancement response toward PPi over many competitive anions, especially HPO₄^2? and H₂PO₄^?. The detection limit of sensor 1 was 1.9?×?10^?6?M to Cu²⁺ and 5.96?×?10^?8?M to PPi. In addition, sensor 1 showed a 1:1 binding stoichiometry to Cu²⁺ and sensor 1-Cu²⁺ showed a 2: 1 binding stoichiometry to PPi in CH₃CN/HEPES buffer medium (9:1 v/v, pH?=?7.4). The stable pH range of sensor 1 to Cu²⁺ and 1-Cu²⁺ to PPi was from 4 to 8.     

Isolated Platinum Atoms Stabilized by Amorphous Tungstenic Acid: Metal–Support Interaction for Synergistic Oxygen Activation

Oxygen activation plays a crucial role in many important chemical reactions such as oxidation of organic compounds and oxygen reduction. For developing highly active materials for oxygen activation, herein, we report an atomically dispersed Pt on WO₃ nanoplates stabilized by in situ formed amorphous H₂WO₄ out‐layer and the mechanism for activating molecular oxygen. Experimental and theoretical studies demonstrate that the isolated Pt atoms coordinated with oxygen atoms from [WO₆] and water of H₂WO₄, consequently leading to optimized surface electronic configuration and strong metal–support interaction (SMSI). In exemplified reactions of butanone oxidation sensing and oxygen reduction, the atomic Pt/WO₃ hybrid exhibits superior activity than those of Pt nanoclusters/WO₃ and bare WO₃ as well as enhanced long‐term durability. This work will provide insight into the origin of activity and stability for atomically dispersed materials, thus promoting the development of highly efficient and durable single atom‐based catalysts.     

Bandgap‐Tunable Preparation of Smooth and Large Two‐Dimensional Antimonene

As a highly stable band gap semiconductor, antimonene is an intriguing two‐dimensional (2D) material in optoelectronics. However, its short layer distance and strong binding energy make it challenging to prepare high‐quality large 2D antimonene; therefore, its predicted tunable band gap has not been experimentally confirmed. Now, an approach to prepare smooth and large 2D antimonene with uniform layers that uses a pregrinding and subsequent sonication‐assisted liquid‐phase exfoliation process has been established. Mortar pregrinding provides a shear force along the layer surfaces, forming large, thin antimony plates, which can then easily be exfoliated into smooth, large antimonene, avoiding long sonication times and antimonene destruction. The resulting antimonene also enabled verification of the tunable band gap from 0.8 eV to 1.44 eV. Hole extraction and current enhancement by about 30 % occurred when the antimonene was used as a hole transport layer in perovskite solar cells.     

Terminal Hydride Species in [FeFe]‐Hydrogenases Are Vibrationally Coupled to the Active Site Environment

A combination of nuclear resonance vibrational spectroscopy (NRVS), FTIR spectroscopy, and DFT calculations was used to observe and characterize Fe?H/D bending modes in CrHydA1 [FeFe]‐hydrogenase Cys‐to‐Ser variant C169S. Mutagenesis of cysteine to serine at position 169 changes the functional group adjacent to the H‐cluster from a ‐SH to ‐OH, thus altering the proton transfer pathway. The catalytic activity of C169S is significantly reduced compared to that of native CrHydA1, presumably owing to less efficient proton transfer to the H‐cluster. This mutation enabled effective capture of a hydride/deuteride intermediate and facilitated direct detection of the Fe?H/D normal modes. We observed a significant shift to higher frequency in an Fe?H bending mode of the C169S variant, as compared to previous findings with reconstituted native and oxadithiolate (ODT)‐substituted CrHydA1. On the basis of DFT calculations, we propose that this shift is caused by the stronger interaction of the ‐OH group of C169S with the bridgehead ‐NH‐ moiety of the active site, as compared to that of the ‐SH group of C169 in the native enzyme.     

P2-type Na0.6[Mg(II)0.3Mn(IV)0.7]O2 as a new model material for anionic redox reaction

In this work, P2-Na_0.6[Mg(II)_0.3Mn(IV)_0.7] O₂ with inoxidizable elements (Na⁺, Mg²⁺ and Mn⁴⁺) except O^2- was synthesized and investigated, which exhibited high reversible capacity (~210 mAh/g) with highly reversible ARR characteristic.     

Poly(styrene-4-sulfonate)-protected copper nanoclusters as a fluorometric probe for sequential detection of cytochrome c and trypsin

Stable copper nanoclusters (CuNCs) were prepared by utilizing D-penicillamine as both the stabilizer and reductant. The emission of the CuNCs (with excitation/emission peaks at 390/645 nm) is largely stabilized by coating with poly(sodium-p-styrenesulfonate) (PSS). Cytochrome c (Cyt c) quenches the fluorescence of the PSS-coated CuNCs, and this effect was exploited to design a quenchometric fluorometric assay for Cyt c. If trypsin is added to the loaded CuNCs, it will hydrolyze Cyt c to form peptide fragments, and fluorescence is gradually restored. A highly sensitive and fluorometric turn-off-on assay was constructed for sequential detection of Cyt c and trypsin. The linear ranges for Cyt c and trypsin are from 8.0 nM to 680 nM, and from 0.1 to 6.0 μg mL^?1, and the lower detection limits are 0.83 nM and 20 ng mL^?1 for Cyt c and trypsin, respectively.

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Graphical abstract Schematic illustration of the fluorometric assay for trypsin based on the electron transfer between poly(p-styrenesulfonate)-protected copper nanoclusters (PSS-CuNCs) and cytochrome c (Cyt c).