Latest ArticlesThe development of core-shell nanoclusters with controllable composition is of utmost importance as the material properties depend on their constituent elements. However, precisely tuning their compositions at the atomic scale is not easily achieved because of the difficulty of using limited macroscopic synthetic methods for atomic-level modulation. In this work, we report an interesting example of precisely regulating the core composition of an inorganic core-shell-type cobalt polyoxoniobate [Co26Nb36O140]32− by controlling reaction conditions, in which the inner Co-core composition could be tune while retaining the outer Nb-shell composition of resulting product, leading to a series of isostructural species with a general formula of {Co26-nNb36+nO140} (n = 0–2). These rare species not only can display good powder and single-crystal proton conductivities, but also might provide helpful and atomic-level insights into the syntheses, structures and composition modifications of inorganic amorphous core-shell heterometal oxide nanoparticles.
Atomization energy (AE) is an important indicator for measuring material stability and reactivity, which refers to the energy change when a polyatomic molecule decomposes into its constituent atoms. Predicting AE based on the structural information of molecules has been a focus of researchers, but existing methods have limitations such as being time-consuming or requiring complex preprocessing and large amounts of training data. Deep learning (DL), a new branch of machine learning (ML), has shown promise in learning internal rules and hierarchical representations of sample data, making it a potential solution for AE prediction. To address this problem, we propose a natural-parameter network (NPN) approach for AE prediction. This method establishes a clearer statistical interpretation of the relationship between the network's output and the given data. We use the Coulomb matrix (CM) method to represent each compound as a structural information matrix. Furthermore, we also designed an end-to-end predictive model. Experimental results demonstrate that our method achieves excellent performance on the QM7 and BC2P datasets, and the mean absolute error (MAE) obtained on the QM7 test set ranges from 0.2 kcal/mol to 3 kcal/mol. The optimal result of our method is approximately an order of magnitude higher than the accuracy of 3 kcal/mol in published works. Additionally, our approach significantly accelerates the prediction time. Overall, this study presents a promising approach to accelerate the process of predicting structures using DL, and provides a valuable contribution to the field of chemical energy prediction.
Highly enantioselective sulfa-Michael additions (SMA) between 2-alkenyl quinoxalines and aromatic thiols are accomplished using a low loading of chiral phosphoric acid catalyst (1 mol%). It was confirmed by an investigation of a lot of azaarenes that the two C=N units of quinoxalines are indispensable for controlling the reaction enantioselectivities. A series of non-terminal 2-alkenes substituted with aryls or alkyls, even other electro-withdrawing groups such as ketones, esters, or amides, selectively reacted and afforded the desired SMA products (48 examples) in good regioselectivities with high yields (up to 99%) and good ee values (up to 97%).
A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes (P1) and 3,9-diazatetracyclododecanes (P2) is reported for the first time. The types of reaction product clearly differ with solvent, regardless of the irradiation wavelength. The difference in P1 and P2 lies in the second step of the intramolecular [2 + 2] photocyclization. In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines, DFT and TDDFT theoretical calculations are performed. The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.
Because of abundant redox activity, broad tunability, and specific atomic structure, polyoxometalates (POMs or POM) clusters have attracted burgeoning interests in electrochemical especially energy storage fields. Nevertheless, due to the high solubility and fully oxidized state, they often suffer from electrically insulation as well as chemical and electrochemical instability. Traditional noncovalent loading or covalent grafting of POMs on conductive substrates have been successfully performed to overcome this problem. However, severe shedding or agglomeration of POMs arising from weak interactions with substrates or excessive entrapment or weak destruction in conductive supports cause significantly reduced availability and stability. To this end, precise confinement of POMs into conductive supports has been tried to improve their dispersibility and stability. Herein, recent progress of POMs from surface loading to precise confinement in the electrochemistry energy storage field is reviewed. Firstly, we illustrate the typical non-confinement methods (viz. covalent and non-covalent) for supported POMs in energy storage applications. Secondly, different strategies for precise confinement of POMs in organic and inorganic materials for related applications are also discussed. Finally, future research directions and opportunities for confined POMs, and derived ultrafine nanostructures are also proposed. This review seeks to point out future research directions of supported POMs in the electrochemistry-related fields.
Detection of mercury ions (Hg2+) in actual samples is of significant importance due to the toxicity of Hg2+ to human health. In this work, a simple tetraphenylethene (TPE) derived fluorescent probe TPE-Hg based on aggregation-induced emission (AIE) mechanism was synthesized. TPE-Hg can visually recognize Hg2+ in THF/HEPES (1:9, v/v, HEPES 20 mmol/L, pH 7.3) system with rapid response, strong anti-interference ability, large Stokes shift (203 nm), and low detection limit (7.548 × 10−7 mol/L). The results show that Hg2+ triggered elimination of TPE-Hg lead to releasing of an AIE-active compound 2 is responsible to the sensing mechanism. TPE-Hg is applicable to detect Hg2+ in actual water samples and image Hg2+ in living MCF-7 cells. In addition, TPE-Hg is suitable to assay the Hg2+ level in seafood and tea samples, and it is also applicable in test strips.
Three isomorphic polytungstates, Cs9K18H10{[Sm2(H2O)4W4O10(AsW9O33)3]2(N(CH2PO3)2)}·46.5H2O (1), Cs10K9H18{[Eu2(H2O)4W4O10(AsW9O33)3]2(N(CH2PO3)2)}·41.5H2O (2), Cs10K9H18{[Gd2(H2O)4W4O10 (AsW9O33)3]2(N(CH2PO3)2)}·46H2O (3), have been successfully synthesized and characterized by routine methods, and demonstrated excellent catalytic activities in Knoevenagel condensation reaction as heterogeneous catalysts. Notably, catalyst 1 achieved higher reaction activity than catalysts 2 and 3, where a satisfactory reaction yield (95%) and high TON value (6380) could be obtained at moderate reaction condition. In addition, in the scale-up experiment, with the help of catalyst 1, 7.8 g benzaldehyde and 5.7 g ethyl cyanoacetate could transform into corresponding condensation product with a satisfactory yield (83%) and impressive TON value (13,883).
Herein, we report a semi-synthetic strategy affording a nitrophorin 2 (NP2) variant with a N,N′-bis(2-pyridylmethyl)amine (Dpa) ligand as sidechain selectively installed at position 27, which was assembled from a synthetic peptide thioester bearing the Dpa ligand and an expressed protein segment via native chemical ligation. The semi-synthetic NP2 was able to accept the natural heme b cofactor and the Dpa ligand was able to bind Cu(Ⅱ)/Fe(Ⅲ) ions, leading to heteronuclear active site.
Following our previous work on human immunodeficiency virus-1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTIs), a series of novel biphenyl-pyridone derivatives were synthesized and evaluated for their anti-HIV-1 activity to expand their structure–activity relationship. Some of them exhibited low nanomolar activity toward wild-type HIV-1 and clinically relevant single/double mutant strains. The most active compound B1 was 231-fold more potent (EC50 = 17 nmol/L) than the lead compound 2 (EC50 = 3.93 µmol/L) against wild-type (WT) HIV-1. This compound was approximately 3.5-fold less cytotoxic (CC50 = 100.58 µmol/L) than compound 2 (CC50 = 28.24 µmol/L), presenting a higher selectivity index (SI) value of 5923. Compared with 2, the antiviral potency of B1 was significantly increased against five single mutant strains (L100I, K103N, E138K, Y181C and Y188L) and two double mutant strains (F227L+V106A and K103N+Y181C). Especially, K103N, Y181C and K103N+Y181C were more sensitive to B1 than both 2 and doravirine. Besides, the enzymatic inhibitory activity of B1 against wild-type HIV-1 reverse transcriptase was approximately 32-fold higher (IC50 = 100 nmol/L) than 2 (IC50 = 3.21 µmol/L). Molecular docking studies and dynamic simulations were conducted to explain their potent activity. Taken together, this research represents an important step toward the discovery of novel biphenyl-pyridone drug candidates for HIV therapy.
Superlattices in crystals, particularly in perovskite oxides with strong correlation effects, can create new states of matter and produce peculiar physicochemical phenomena. However, the newfangled perovskite superlattices depend on physical deposition with unit-cell precision. It has been challenging to explore a new suitable chemical method to tailor perovskite superlattices. Herein, we present a new bottom-up strategy to precisely prepare atomic-scale oxide superlattices of (LaMnO3)1-(La1-x-yCaxKyMnO3)2 in a monodispersed perovskite La0.66Ca0.29K0.05MnO3 (LCKMO). The special atomic-scale perovskite superlattices are demonstrated using SAED, HAADF-STEM, XRD, and atomic-resolution elemental mapping. Our experiments reveal that the perovskite superlattices can be fabricated under extreme hydrothermal conditions utilizing ultra-high concentrations of KOH. An approximate molten salt system in the hydrothermal process can induce the disproportionation reaction of MnO2 solids, which is vital to the growth of ordered perovskite superlattices. This work not only clarifies the hydrothermal growth process of perovskite oxides in extreme conditions, but also proposes a novel engineering route toward perovskite superlattices.
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