Asymmetric allylic substitution reactions involving benzyl nucleophilic reagents can rapidly construct chiral molecules containing benzyl fragments, which has attracted widespread attention from organic chemists. Formal asymmetric allylic benzylation reactions have been achieved by utilizing methylene oxazole as an equivalent of benzyl nucleophile. However, the development of highly efficient asymmetric allylic benzylation reactions remains a great challenge mainly due to the poor stability and synthetic difficulty of methylene oxazole. In this work, we have developed gold- and iridium- catalyzed alkynylamide cyclization/asymmetric allylic benzylation cascade reactions. In the presence of gold-carbene complex (Au1) and the combination of [Ir(cod)Cl]₂ and (S_a)-Carreira ligand, a wide range of enantioenriched oxazole derivatives, bearing a benzylic stereogenic center, were obtained in 49%~87% yields with 98%~>99% ee. A general procedure is described as the following: To a dried Schlenk tube were added [Ir(cod)Cl]₂ (5.4 mg, 0.008 mmol, 4 mol%), (S_a)-L1 (16.2 mg, 0.032 mmol, 16 mol%) and 1,2-dichloroethane (1 mL) under argon atmosphere. The mixture was stirred at room temperature for 15 minutes to give a chiral iridium complex solution. Under an argon atmosphere, alkynylamide (0.2 mmol, 1.0 equiv.), allyl alcohol (0.4 mmol, 2.0 equiv.), Au1 (0.02 mmol, 12.4 mg, 10 mol%), Fe(OTf)₂ (0.2 mmol, 70.6 mg, 1.0 equiv.) and 3 Å molecular sieves (80.0 mg) were added to another dry Schlenk tube, and then the above-prepared iridium catalyst was added. The reaction mixture was stirred at 40 ℃ until the starting materials were consumed (monitored by thin layer chromatography, TLC). The mixture was quenched with water (5 mL), and extracted with dichloromethane (5 mL×3). The combined organic layers were dried over anhydrous Na₂SO₄, filtered, and then concentrated in vacuo to afford the crude product. The residue was purified by column chromatography (V(petroleum ether)/V(ethyl acetate)=15/1 or 10/1) to afford product 3.

The benzyl oxidation reaction serves as a crucial functional group transformation method in the field of organic synthesis. Regrettably, traditional benzyl oxidation reactions frequently necessitate harsh conditions, such as elevated temperatures and potent oxidizing agents. In contrast, this article showcases a highly selective catalytic benzylic oxidation executed within a continuous-flow microreactor. By harnessing the previously established cerium-alcohol complex’s ligand to metal charge transfer (LMCT)-hydrogen atom transfer (HAT) activation mechanism and the anthracene-cerium synergistic catalytic system, a diverse array of aromatic ketones was synthesized from aryl alkanes with remarkable efficiency under ambient and aerobic conditions. The continuous-flow technology, endowed with unique advantages such as heightened illumination efficiency, superior gas-liquid mass transfer, repeatability, and scalability, has emerged as a powerful instrument for scaling-up photocatalytic reactions. In this process, under flow conditions, ethyl acetate solutions comprising Ce(NO₃)₃•6H₂O, tetrabutylammonium bromide (TBABr), 9,10-dibromoanthracene (DBA), trichloroethanol (TCE), and ethylbenzene encountered and mixed with oxygen within the microreactor. Subsequently, a photocatalytic aerobic oxidation reaction occurred under visible light irradiation at room temperature, achieving complete conversion within a mere 5 min, and rapidly generated a series of aromatic ketones with good to excellent yields. Mechanistic studies indicated the paramount importance of the anthracene-derived catalyst DBA in achieving the heightened efficiency. Under visible light irradiation, the excited state DBA was initially oxidatively quenched with oxygen or peroxide species generated in the system, resulting in the formation of the DBA cationic free radical. Subsequently, the DBA cationic free radical underwent a single electron transfer (SET) process with the low-valent cerium (III) complex, consequently expediting the oxidative regeneration of the cerium (IV) catalyst and markedly boosting its catalytic efficacy. Eventually, this highly efficient catalytic system is characterized by its simplicity, mild reaction conditions, elevated selectivity, minimal waste production, and extensive applicability. Furthermore, it is effortlessly scalable and amenable to continuous production.

One of the basic goals of cell biology is to identify multiple biological molecules within cells and understand the complex interactions between biological molecules in cellular life activities. Synchrotron-based X-ray microscopy has high spatial resolution and good energy (element) resolution, which has great application potential in the recognition and imaging of intracellular biomolecules. At present, the probes that have been developed for synchrotron-based X-ray microscopy are mainly immunostaining probes and genetic labeling probes. Immunostaining probes are prone to lead to cross-reactions due to their dependence on antigen-antibody reactions. The genetic labeling probes, based on gene coding tags, catalyze the generation of X-ray sensitive polymers. However, the polymers used to provide X-ray imaging signals have no fixed morphology. When it is applied to cell imaging, the positioning accuracy will be reduced due to the diffusion of tags in cells, which is an inherent defect of such imaging tags. In addition, there are few existing systems that can express each other independently and step by step for this type of probe. Therefore, both types of X-ray probes mentioned above are difficult to achieve simultaneous high-resolution imaging observation of multiple biological target molecules in cellular life activities. In this research paper, by using the characteristics of X-ray that has good energy resolution and does not interfere with each other between element spectra, we can synthesize polydopamine (PDA) nanoparticles in a controlled manner, modify azide groups on PDA nanoparticles and chelate metal ions, develop a click chemistry based synchronous X-ray imaging tag (PDA-N₃-Metal), and conduct synchrotron radition X-ray imaging on the tag with an imaging resolution of 30 nm. The research results lay a good foundation for further preparation of X-ray probes based on click chemistry, and for realizing the specific recognition and imaging of multiple biological molecules in cells at the same time.

Photochromic molecules show great potential in biological imaging, logic gates, super-resolution imaging and other fields due to the sensitivity, accuracy and penetrability of light. By utilizing their variations on physical properties upon light irradiation, the fluorescence signal of photochromic dyes can be turned on or off accurately by specific wavelength. As an important luminescent dye, organic room-temperature phosphorescence (RTP) materials have attracted great research interest of scientists by the triplet state radiation process, and have potential in sensing, anticounterfeiting, photo-dynamic therapy, and so forth. In this work, we combine the phosphorescence and photochromic properties together by connecting a classic photochromic dye (bithienylethene) with an efficient phosphor (thiochroman-4-one) via sp² and sp³ linker (BTE1oand BTE2o). These compounds show typical photochromic phenomenon in solution and polymer matrix and have good fatigue resistance. During the irradiation, a clear isosbestic point can be observed, indicating the quantified transition between two isomers. The emission quenching of derivatives is considered as the radiative energy transfer between fluorescent open form and non-fluorescent closed form. It’s interesting that the fluorescence lifetime of BTE1oand BTE2oincreases after ultraviolet (UV) irradiation, which rules out the possibility of non-radiative energy transfer mechanism of the fluorescence quenching phenomena. In the poly(vinyl alcohol) (PVA) matrix, these compounds show decent RTP emission and millisecond level lifetime. And the RTP emission can also be reversibly turned “ON” or “OFF” via irradiation of different wavelengths. It’s very interesting that the phosphorescence lifetime also increases (from 16.1 to 19.4 ms) with the irradiation of UV light, which is identified with the variation of fluorescence lifetime in solution and PVA matrix. The increase of lifetime can rule out the non-radiative energy transfer mechanism for the phosphorescence quenching phenomena. Considering the fluorescence quenching phenomena in tetrahydrofuran (THF) solution, the fluorescence and phosphorescence quenching in PVA matrix should also be attributed to the form conversion and the radiative energy transfer process between open and closed isomers.

Tetrasubstituted olefins are industrially important building blocks, which have been widely used in material and medicinal chemistry. Strategies that enable access to olefins have been developed, including the classic McMurry reactions of ketones using organotitanium reagents. The development of McMurry-type reactions using earth-abundant metals as catalysts, by the homo- and cross-couplings of two carbonyls in the deoxygenative fashion, would be a value-addition to tetrasubstituted olefins. Herein, we report the deoxygenative couplings of ketones that are enabled by cost-effective chromium catalysis. These couplings occur with low-cost Cr salt as precatalyst, 4,4'-di-tert-butyl-2,2'-bipyridyl (dtbpy) as ligand, metallic Mg as reductant, and trimethylchlorosilane (TMSCl) as additive. The protocols can be applied to achieve both homo- and cross-coupling of ketones, allowing for the efficient formation of sterically demanding tetrasubstituted olefins in one-step operation. Based on our experimental results and known reports, a plausible mechanism involving in the Cr-catalyzed deoxygenative couplings of ketones was proposed, wherein the reactive silachromate(I) might be formed by reaction of low-valent Cr species with Mg and trimethylchlorosilane, and is detected by high-resolution mass spectrometry analysis. It adds to unsaturated carbonyl of ketone in giving silyloxy-substituted (alkyl)Cr intermediate, followed by process of carbometalation by the addition of C—Cr bond to carbonyl of another ketone molecule. The C=C bond is formed by following deoxygenation in giving tetrasubstituted olefin product. Trimethylchlorosilane plays important roles in the ketone deoxygenative coupling, by the formation of reactive silachromate in responsibility for the addition and deoxygenation processes. The general procedure for the deoxygenative homocoupling is as following: in a dried Schlenk tube are placed ketone 1 (0.4 mmol), CrCl₂ (5 mg, 0.04 mmol), dtbpy (10 mg, 0.04 mmol), Mg (20 mg, 0.8 mmol) and TMSCl (50 µL, 0.4 mmol) under atmosphere of nitrogen. After the addition of freshly distilled tetrahydrofuran (THF, 2 mL) by syringe, the resulting mixture was stirred at 90 ℃ for 12 h. The volatiles were removed under reduced pressure, and the crude product was purified by silica gel chromatography to give the corresponding tetrasubstituted olefin.

In recent years, organic reactions involving difluorocyclopropenes have attracted the attention of organic chemists and have made great progress. The reactions mainly include: (1) cyclization: a) transition-metal catalyzed C—H bond activation cyclization with directing groups; b) cyclization reactions with non-directing groups; (2) hydrogenation reduction; (3) fluorination as “F” source reagents. In this paper, the synthesis methods and applications of difluorocyclopropenes in past 10 years are summarized. The conversion reactions of difluorocyclopropenes are emphasized. Additionally, difluorocyclopropenes have aroused considerable interests both from a structural standpoint and their participation in various ring-opening reactions. Given the increasing application of cyclopropyl skeleton in the development of drugs and unarguable importance of fluorinated compounds in medicinal chemistry and agrochemistry, it is no doubt that difluorocyclopropenes are encountered into bioactive molecular and at present lie among “emerging fluorinated motifs”. Although the synthesis and application of structurally diverse difluorocyclopropenes have been witnessed in the past decade, the most widely used methods for the preparation of these compounds include difluoromethylenation of alkynes and difluoromethylation of heteroatom nucleophiles (such as NaF, NaI, ⁿBuN₄X, etc.) with a difluorocarbene reagent, which can be generated from various precursors (such as TMSCF₃, TMSCF₂X, Ph₃P^＋CF₂CO₂^-, TFDA, etc.). For the transition metal-catalyzed cyclization of difluorocyclopropenes, some common metal salts (such as rhodium, ruthenium, copper, palladium, silver) are used as catalysts. Moreover, the metallic hydrogen (M—H) reduction strategy is a simple and efficient method for the hydrogenation reduction of difluorocyclopropenes leading to difluorocyclopropanes, and the asymmetric hydrogenation reduction of difluorocyclopropenes can be achieved in the presence of chiral ligands. In fluorination reactions, difluorocyclopropenes have some advantages that cannot be achieved by traditional fluorination reagents for the direct fluorination and functionalization of hydroxyl groups (such as fluorination of polyhydroxyl alcohols). Of course, the biggest disadvantage of difluorocyclopropene as a fluorine source lies in its poor atomic economy, which has been criticized. Despite the remarkable achievements in the reactions of difluorocyclopropenes, there are still many issues that need to be addressed. For instance, difluorocyclopropenes are rarely applied in traditional radical reactions, photocatalysis, electrocatalysis and flow chemistry. Hopefully, difluorocyclopropenes can gradually appear in photo- and electro-catalyzed radical chemistry, and the related asymmetric reactions will also get more attention and development in the near future.

Catalytic transformation of biomass-derived polyols into valuable chemicals has attracted attention from the viewpoint on using renewable carbon resources. Therefore, it is important for design and preparation of heterogeneous catalysts with high activity, high selectivity, and high stability for the selective conversion of biomass-derived polyols. Recently, it has been reported the selective production of mono-alcohols and/or diols by selective hydrogenolysis of sugar alcohols, where the Ir-ReO_x and Pt-WO_x as typical heterogeneous catalysts are highly efficient. In this review, we briefly summarized the routes for the selective conversion of sugar alcohols into mono-alcohols and/or diols, where the metal-metal oxide interaction for catalyst design, relationship between catalyst structure and performance, and reaction mechanism for the C—O hydrogenolysis are particularly discussed. In addition, the future trend for the selective hydrogenolysis of sugars is also prospected. This review might be helpful for design of novel heterogeneous catalysts in sugar alcohol conversion.

Since the discovery of Ziegler-Natta catalyst, great breakthrough has been made in the design of catalyst in olefin polymerization field, but the development of catalyst is still the fresh source in this field. It will always be a frontier scientific problem in this field to influence the olefin polymerization process through the structural design of catalysts. Due to the low cost of nickel and its high abundance, nickel-based catalysts have shown great prospects in the application of olefin polymerization. In this work, three kinds of unsymmetrical α-diimine nickel catalysts with different steric effects were designed, and their catalytic performances in ethylene polymerization were explored. It is found that the variety of catalysts and the change of polymerization conditions have important effects on the catalytic activity of ethylene polymerization, the molecular weight, branching density, thermodynamic parameters and mechanical properties of the prepared polyethylene. Among them, the polyolefin prepared by Ni3 catalyst with large steric hindrance is ultra-high molecular weight polyethylene, and the above materials maintain excellent mechanical properties and elastic properties at the same time. Specifically, tert-butyl substituted ketoimine intermediate B was condensed with three different anilines to synthesize ligands L1~L3 with different steric effects. The catalysts Ni1~Ni3 were successfully synthesized by efficient coordination reaction between the obtained ligands and DMENiBr₂, and the yields were over 90%. The single crystal structures of catalysts Ni1 and Ni3 were also prepared, and the steric hindrance around the nickel center was quantified utilizing the steric maps [V_bur(Ni1)=46.1%, V_bur(Ni3)=48.7%]. Under 0.8 MPa pressure of ethylene and AlEt₂Cl as cocatalyst, the ethylene polymerization performance was explored using three nickel catalysts at different temperatures. Among them, Ni2 exhibited the best catalytic activity in ethylene polymerization at 50 ℃ (up to 1.7×10⁷ g•mol^-1•h^-1), generating polyethylene with higher branching density. The polyethylene prepared by Ni3 with large steric hindrance is ultra-high molecular weight polyethylene with a molecular weight of 172×10⁴ g•mol^-1. Moreover, polyethylene materials prepared by Ni3 also showed excellent mechanical properties (breaking stress, 6~8 MPa; elongation at break, ≈600%) and elastic properties (strain recovery value up to 68%).

Organic smart materials are able to change their properties in response to specific stimuli, being a type of materials that are potential to be applied in many fields. The stimuli-responsive abilities often arise from variations of structures at the molecular level. In this study, a new type of skeleton-functionalized pillar[5]arene (N-naphthyl-phenothiazinyl-pillar[5]- arene, 6) was successfully synthesized by incorporating a quinoline structure with a naphthalene substitution into the pillar[5]arene skeleton. First, compound 2 was obtained through two-step reactions, and was further reacted with 2-aminothiophenol through an amine/carbonyl condensation followed by substitution to yield a quinone-type thiazine structure of pillar[5]arene 3. Compound 3 was further reduced to a phenol-type structure, i.e. compound 4, by sodium borohydride. Compound 4 was further functionalized with 2-bromo-naphthalene through palladium-catalyzed Buchwald-Hartwig reaction to yield compound 5. In order to improve stability, the hydroxy group of compound 5 was converted to a methoxy group by injecting iodomethane into the acetone reaction solution of compound 5, resulting in compound 6. Structure of compound 6 was characterized by ¹H NMR (nuclear magnetic resonance spectroscopy), ¹³C NMR, high-resolution mass spectra (HRMS), and X-ray single-crystal diffraction. The single crystal of this new pillar[5]arene was able to undergo a single-crystal-to-single-crystal (SCSC) conformational transformation under heating, accompanied by a change in stacking mode. Moreover, it is found that changing the guest molecule can adjust the molecular conformation in the grown single crystal. X-ray single-crystal diffraction and thermogravimetric analysis were used to verify this transformation process. This work studies the solvent-induced crystal conformation transition process from the molecular level, which provides an example for the rational construction of stimuli-responsive smart materials.

Chiral triptycene acridine (TpAc) has unique 3D structure, homoconjugation effect and two separate reaction sites. By using the design strategy of chiral electron donor-acceptor (D*-A) copolymerization, the triptycene-based non-conjugated chiral red thermally activated delayed fluorescence (TADF) polymers (R,R)-pTpAcBTZ and (S,S)- pTpAcBTZ were directly polymerized by using TpAC as chiral electron donor and 4,7-dibromobenzo[c][1,2,5]thiadiazole (BTZ) as the strong electron acceptor. The molecular weights of these chiral polymers were characterized by gel permeation chromatography (GPC), and the GPC analysis indicated that the number-average molecular weight (M_n) ranged from 37.9 kDa to 39.3 kDa with the polydispersity index (PDI) values from 1.99 to 2.02. The chiral polymers exhibited good solubility in common organic solvents, such as chlorobenzene, tetrahydrofuran, dichloromethane and chloroform, ensuring good film quality during solution processing. In addition, the chiral TADF polymers showed excellent thermal stability with thermal decomposition temperature (T_d) (corresponding to a 5% weight loss) around 440 ℃, and glass transition temperatures (T_g) were also detected in these chiral polymers when they were heated to 300 ℃, which could be ascribed to their highly rigid and twisted structures. According to the onset of the oxidation curve, the highest occupied molecular orbital (HOMO) energy levels of the chiral polymers were estimated to be -5.27 eV. Their corresponding optical energy band gaps were estimated to be 2.21 eV from the onset of their ultraviolet-visible (UV-Vis) absorption spectra in toluene. Consequently, the corresponding lowest unoccupied molecular orbital (LUMO) energy levels were calculated to be -3.06 eV. The S₁ and T₁ values of pTpAcBTZ were 2.13 eV and 2.05 eV, respectively, which were determined at 77 K, and the corresponding ΔE_ST was 0.08 eV which were favorable for reverse intersystem crossing of excitons from T₁ to S₁ states. The chiral TADF polymers showed efficient red TADF (λ_toluene=663 nm) activity, and they also displayed mirror-image red circularly polarized luminescence (CPL) signals, with the |g_lum| of approximately 1.4×10^-3. By using the chiral red polymers as emitters, the obtained solution-processed red OLEDs displayed maximum electroluminescence peak of about 658 nm, and its turn-on voltage is 3.6 V at a brightness of 1.0 cd/m². The device exhibited well device efficiency, with a maximum external quantum efficiency of 2.0%, maximum current efficiency of 1.1 cd/A, maximum power efficiency of 0.8 lm/W. The design of the non-conjugated chiral polymers and their red TADF activity are conducive to promoting the development of related research fields such as chiral luminescent materials and red luminescence devices.

CO₂ emission is a serious global problem. CO₂ capture technology is indispensable to achieve the strategic goals of carbon peaking and carbon neutrality in China. Ionic liquids as new media have attracted much attention in the field of CO₂ capture and separation due to their unique advantages of low volatility, good gas solubility and structure designability. This review focuses on research progresses of amino and non-amino functionalized ionic liquids, ionic liquid hybrid solvents, ionic liquid modified adsorbents and membranes for CO₂ capture and separation reported in the past five years. The influence of amino groups and electronegative functional sites on CO₂ separation performance and mechanism, and the role of functionalized ionic liquids in hybrid solvents, adsorbents and membranes were summarized. Finally, the future development direction and prospect of ionic liquid-based CO₂ capture technologies were also proposed.

Chiral C—X (X=N, O, P, B, F, etc.) bond fragments are present in a wide variety of natural and pharmaceutically active molecules. Transition metal-catalyzed asymmetric hydrogenation is one of the most attractive strategies for the synthesis of these chiral compounds. Among the many transition metal catalysts, earth-abundant transition metals (iron, cobalt, nickel, and copper) have been used in asymmetric hydrogenation to replace rare metals (rhodium, ruthenium, iridium and palladium) due to their abundant reserves, low toxicity, and environmental friendliness. At present, this method for the construction of chiral C—X bonds has become a prominent trend in modern organic chemistry. Among them, the development of nickel catalysts has been relatively rapid. Based on this, the article will review the latest research in the preparation of compounds with chiral C—X bonds via nickel-catalyzed asymmetric hydrogenation using hydrogen. It is divided into five sections consisting of the construction of chiral C—N, C—O, C—P, C—B and C—F bonds by nickel-catalyzed asymmetric hydrogenation.

Metal-organic frameworks (MOFs) are characteristic of high specific surface area, abundant metal nodes, diverse organic ligands, and ordered pore structure. More importantly, its composition and structure are easy to be designed and controlled, so it is very promising to become a new class of catalytic carrier materials. In recent years, the composites of metal nanoparticles encapsulated by MOFs have attracted great attention in the field of catalysis due to their unique structural features. However, more in-depth and systematic research is still needed in terms of its precise preparation and the relationship of the structure and catalytic performance. Based on above, the recent research progress on the preparation methods of metal nanoparticles encapsulated by MOFs and their catalytic applications are systematically summarizd. First, the synthesis methods of metal nanoparticles encapsulated by MOFs are summarized. Then, the catalytic applications are discussed in term of synergy among metal nanoparticles, pore structure, organic ligands or/and metal nodes of MOFs. Moreover, the relationships among active component, structure and their properties are illustrated. Finally, the challenges, opportunities and future development prospects of this research direction are discussed from the aspects of synthesis methods and catalytic applications.

Compared to traditional thiolated DNA probes, poly-adenine-based DNA probes (polyA DNA probes) are free of special chemical modifications, and thus exhibit unique advantages of easy synthesis, low economic cost, and excellent stability. Using their intrinsic polyA fragments, polyA DNA probes are combined onto the gold surface to form a compact and ordered monolayer with both anchoring and recognition capabilities. As a result, polyA DNA probes have attracted numerous research interests in biosensing. In this review, we first presented the mechanism of interaction between polyA DNA probes and the gold surface and then reviewed the applications of the polyA DNA probes in the development of biosensors, including colorimetric biosensors, fluorescence biosensors, surface-enhanced Raman scattering (SERS) biosensors, and electrochemical biosensors. We concluded with a discussion of the opportunities and challenges for polyA DNA probes and expected this review to be informative for the development of biosensors in food safety, environmental monitoring, and biomedicine.

Trifluoromethyl group has strong electron-withdrawing ability and stable C—F bond, and its introduction into organic molecules could often significantly modify the acidity, dipole moment, lipophilicity and metabolic stability of parent compounds. Therefore, the incorporation of trifluoromethyl group into bioactive molecules has become a common strategy for drug development. Trifluoromethylated arene moiety is the important unit of many drugs and related candidates, such as Nilotinib, Radotinib, Ponatinib, Regorafenib, Pexidartinib, Bimiralisi, and Defactinib. Therefore, it is of great interest to design new compounds containing trifluoromethyl group and explore their potential applications in the development of protein kinase inhibitors. Imatinib is the first-generation tyrosine kinase inhibitor and the first small molecule targeting anti-tumor drug that inspires the synthesis of a large number of excellent anti-tumor drugs. Therefore, in this study, we aimed to design new trifluoromethyl-containing tyrosine kinase inhibitors via combining the aniline-pyrimidine structure of Imatinib with 1,2,4-triazines. In particular, we developed a one-pot [3＋3] cycloaddition sequence to construct a series of 3-ester-5-aryl-6- CF₃-1,2,4-triazines in good yields. Subsequently, a series of new compounds containing the trifluoromethyl 1,2,4-triazine skeleton were obtained via a sequence of hydrolysis, chlorination, and amidation reactions. Finally, a preliminary evaluation of biological activity was conducted and a hit compound 4a was found with good activity in promoting apoptosis protein Caspase 9. A representative procedure for the synthesis of model product 4a is described as following: Starting from trifluoroethylamine (9.91 g, 100 mmol), tert-butyl nitrite (11.34 g, 110 mmol) and AcOH (1.2 g, 20 mmol) were used to generate trifluorodiazoethane in situ in tetrahydrofuran (THF, 20 mL) at 55 ℃ for 30 min. Then the CF₃CHN₂ solution was added to the mixture of glycine imine 1 (50 mmol), silver fluoride catalyst (0.64 g, 5 mmol) and cesium carbonate (20.36 g, 62.5 mmol) in THF (80 mL), and the reaction mixture reacted at 0 ℃ for 24 h to give the corresponding 6-CF₃-tetrahydrotriazine 2. Afterwards, 2,3-dichloro-5,6-dicyanophenoquinone (DDQ) (2.72 g, 12 mmol) was used as oxidant for compound 2 (3 mmol) to produce the corresponding 3-ester-5-aryl-6-trifluoromethyl-1,2,4-triazine 3. The obtained trifluoromethyl-1,2,4-triazine 3 (3 mmol) was hydrolyzed under the promotion of lithium hydroxide (0.15 g, 3.6 mmol) in THF/H₂O (5 mL THF, 10 mL H₂O) at r.t. for 1 h to give the corresponding carboxylic acid. The carboxylic acid intermediate reacted with oxalyl chloride (0.31 mL, 3.6 mmol) under the catalysis of N,N-dimethylformamide (DMF, 1~2 drop) in CH₂Cl₂ at r.t. for 2 h to give the corresponding acyl chlorides. Finally, in a mixture of CH₂Cl₂ (5 mL) and DMF (2 mL), acyl chloride intermediates reacted with the corresponding aniline-pyrimidine intermediate (0.92 g, 3.3 mmol) to give the desired product 4.

The introduction of heteroatoms into metal nanoclusters is an effective strategy to regulate the physical and chemical properties of clusters. Most of the doped clusters reported are binary metal nanoclusters via one metal heteroatom doping into a metal nanocluster, while the preparation and properties of ternary metal nanoclusters via two heteroatoms doping into a metal nanocluster are rarely studied. In this work, we report the Pd and Hg co-doped ternary metal nanocluster HgPdAu₂₃(PET)₁₈ (PET=2-phenylethanethiol) using the Au₂₅(PET)₁₈ nanocluster as an ideal template that can be viewed as a Au₁₃ icosahedral core protected by the exterior 12 Au atoms as a shell. The structural framework of the HgPdAu₂₃(PET)₁₈ nanocluster is similar to that of its parent Au₂₅(PET)₁₈ nanocluster, determined by single-crystal X-ray crystallography and electrospray ionization mass spectroscopy (ESI-MS), which shows a 13-atom icosahedral core and a 12-atom shell capped by 18 thiolate ligands. It indicated that the doping strategy might destroy the total structure (core plus surface) of the parent nanocluster, which will offer an excited opportunity for the correlation of the structure with properties of the doped nanoclusters. More notably, the possible doping location of the Pd and Hg atoms in the HgPdAu₂₃(PET)₁₈ nanocluster can be determined by the combination of single-crystal X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy (i.e., ¹H NMR and two-dimentional NMR). It is suggested that the Pd atom is possibly located on the center of the icosahedron of the HgPdAu₂₃(PET)₁₈ nanocluster, while the Hg atom is possibly located on the surface of the icosahedron of the HgPdAu₂₃(PET)₁₈ nanocluster. The electronic configuration of HgPdAu₂₃(PET)₁₈ nanocluster is distinct from those of the parent Au₂₅(PET)₁₈ and one-metal doped PdAu₂₄(PET)₁₈ and HgAu₂₄(PET)₁₈ nanoclusters, which can be implied by the X-ray photoelectron spectroscopy (XPS) and UV-Vis absorption spectroscopy. This study provides a new design rule for the two-metal-heteroatom doped nanoclusters.

Electrical double layer capacitors (EDLCs) with the merits of high power density and fast charging/discharging have been widely used in the different fields, e.g. green energy and national defense, which is however limited by the unsatisfied energy density. The factors dominating the EDLCs performance mainly include the specific surface area, pore structure (i.e., ion transport channel), conductivity and wettability of the electrode material, the working voltage window and ionic conductivity of the electrolyte. In recent years, mesostructured carbon nanocage have been attracting more and more attention as advanced platform materials for energy storage and conversion, which have a particularly broad application prospect in the field of supercapacitors. Based on the rule of solubility product and the carbothermal reduction method, herein we have developed a new route to regulate the pore size distribution of hierarchical carbon nanocages (hCNCs) and effectively increased the number and size of the channels across the shells of hCNCs. The optimized sample exhibits excellent supercapacitive performances in KOH and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF₄) electrolytes: the specific capacitance of 255 and 220 F•g^－1 at 1 A•g^－1 (50% and 25.7% higher than those of the pristine hCNCs); 179 and 129 F•g^－1 at a high current density of 200 A•g^－1 (68.9% and 33.0% higher than those of the pristine hCNCs); energy density of 12.8 Wh•kg^－1@0.3 kW•kg^－1 and 116 Wh•kg^－1@0.97 kW•kg^－1, respectively. Such excellent electrochemical performances can be attributed to the introduction of small-sized mesopores and the increase in number and size of micropores on the shells of hCNCs, which much increases the specific surface area and benefits the rapid transport of ions through the microchannels on the nanocage shells. This study provides a new thought to develop the advanced supercapacitor electrode materials.

Because of the open-shell electronic structures, organic radicals have many special properties and can be applied to various fields, such as molecular magnets, spintronics, organic rechargeable batteries, electron paramagnetic resonance imaging and field-effect transistors. Specifically, organic radicals provide an alternative method to overcome the efficiency limitation of organic light-emitting diodes (OLEDs) based on conventional fluorescent organic molecules. They have doublet- spin properties arising from unpaired electronics and can be designed to have rapid emission on nanosecond timescales for exploitation in OLEDs with up to 100% internal quantum efficiency. However, luminescent radicals are still rare and often have narrow highest occupied molecular orbital (HOMO)-singly occupied molecular orbital (SOMO) gap, so the luminescent colors are mainly focused on the long wave range of visible light, such as orange and red. It is difficult to obtain luminescent radicals with blue emission. In this work, to further enrich the types of luminescent radicals and broaden the luminescence range of radicals, we design and synthesize novel radical precursors [2a]I and [2b]I by palladium-catalyzed coupling reaction of N-heterocyclic carbenes (NHCs) and 9-(4-iodophenyl)-9H-pyrido[2,3-b]indole, which was characterized by nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization mass spectrometry, and single-crystal X-ray diffractometry analyses. Subsequently, two neutral luminescent radicals 3a and 3b were successfully prepared by single electron reduction using KC₈ as a reducing agent. The experimental results show that radicals 3a and 3b have blue emission in tetrahydrofuran solution, and their maximum emission wavelengths are 450 and 428 nm, respectively. In addition, it is found that the fluorescence emission energy of radicals 3a and 3b is much higher than the maximum absorption energy given by the absorption spectrum, indicating an obvious Anti-Kasha emission phenomenon. Theoretical calculations further confirm that the fluorescence originates from the higher energy electronic excited state (D₃) rather than the lowest energy-excited state (D₁). This work shows that luminescent radicals with blue emission can be constructed by using NHCs as the skeleton unit, which provides a new research idea for the controlled synthesis of stable luminescent radicals.

In order to develop a novel sugar hybrid material with self-actuated micromotor and immune function, we designed and prepared a dumbbell micromotor modified with mannose (Zinc oxide/Polydopamine/Mannose micromotor, ZnO/PDA/Man micromotor for short), which combines the kinetic properties of ZnO active colloid and visible light absorption properties of PDA materials. X-ray diffraction (XRD) and Raman spectroscopy results showed that the introduction of PDA and Man does not change the crystal shape of ZnO, which ensures that the photocatalytic activity of ZnO is unaffected in ZnO/PDA/Man. The dumbbell structure of the micromotor can cause an uneven distribution of ions, the ion gradient will drive micromotor to move. The micromotor energy source is non-toxic and can move itself in solution with pure water as fuel under visible light. The simulation verified that the motion mechanism of dumbbell micromotor is ionic self-diffusiophoresis, which keeps the head in front and pulls the colloid to move. The motion behavior of the micromotor under different intensities of visible light was observed and recorded by the microscope. It was found that the micromotor changed from translational motion to circular motion with the enhancement of light intensity, and the micromotor's motion speed also increased gradually. Meanwhile, by adjusting the direction of incident light, the motion direction of ZnO/PDA/Man micromotor can be accurately adjusted to make it move according to the predetermined route. In order to preliminarily explore whether the mannose-modified micromotor can regulate the phenotype of macrophages, the ZnO/PDA/Man micromotor was incubated with macrophages, and the morphological changes of macrophages were observed with a microscope. The results showed that the micromotor could be used as an immune activator to polarize macrophages. What'more, cytotoxicity experiment indicated that ZnO/PDA/Man micromotor has good biocompatibility. Compared with traditional immune activators, ZnO/PDA/Man micromotor is expected to realize free movement in tumor tissues under visible light irradiation, so as to promote their deep penetration into tumor tissues, which has potential application in the field of tumor immunotherapy.

Here we reported temperature-controlled moisture responsive wrinkled patterns based on bilayer system, and explore its regulation mechanism and applications. The bilayer wrinkling system is comprising a copolymer P(IMAN-co-NIPAM-co-OEGMA) containing 1-vinyl-3-anthracenemethyl imidazolium chloride (IMAN), N-isopropylacrylamide (NIPAM) and poly(ethylene glycol) methyl ether methacrylate (OEGMA) as the skin layer and poly(dimethylsiloxane) (PDMS) as the substrate. After photodimerization of the AN group, the polymer network is crosslinked, and the modulus of the top film increases. According to the linear buckling theory, random wrinkles are formed under thermal treatment and subsequent cooling to room temperature owing to the mismatch in the moduli and thermal expansion coefficients between the stiff skin layer and the soft substrate. First, the photodimerization of AN group endows the system with the ability of region selective wrinkling. If the irradiation process is performed with a photomask, the exposed regions are rigid enough for wrinkles forming, while the unexposed areas are not. Furthermore, surface wrinkles caused strong light scattering while the flat surface limit it, which affects the visibility of an object. Thus, we could fabricate various images utilizing the selective wrinkled patterns. Second, the NIPAM-containing polymer chain endows the wrinkles with temperature-controlled moisture response. Under room temperature, the wrinkles can be eliminated by moisture, which is caused by the decreasing modulus and stress relaxation during absorbing moisture; while under a higher temperature, the wrinkles cannot be driven by moisture because the copolymer of top layer becomes hydrophobic, which is demonstrated by experimental results such as the laser scanning confocal microscope images. Furthermore, the wrinkled images and the transparence can be controlled by moisture and temperature during the switch between wrinkled and flat states. Besides, the poly(ethylene glycol) methyl ether methacrylate (OEGMA) is involved to tune the mechanical properties. The photosensitive and temperature- controlled moisture responsive wrinkled patterns may find potential applications in moisture sensing, smart display or smart windows.

Throughout the history of transition-metal catalysis, almost every breakthrough is closely related to the development of ligands. Therefore, the history of transition-metal catalysis roughly parallels the development history of ligands. Therefore, ligand development lies in the heart of transition metal catalysis. Since the beginning of homogeneous catalysis, transition metals have been accompanied by phosphine ligands (Wilkinson's catalyst). Till now, phosphine ligands are one of the most widely used ligand types. There are several key factors for the popularity of phosphine ligands, among which the backbone of ligand plays a decisive role in supporting their stability, activity and selectivity. Many privileged phosphine ligands contain five- or six-membered rings in their core structures, possibly due to their ready-availability, low ring strain, and high stability. Seven- and above membered cyclic structures have flexible frameworks, many stable conformations, and are difficult to synthesize, making them unsuitable as ligand backbones. The cyclobutane structure has relatively strong ring strain, but its conformation can be flipped, and it is difficult to synthesize, making it inappropriate to be used as a ligand skeleton, too. As the smallest all-carbon ring, the three carbon atoms of cyclopropane are located in the same plane. Because of the unique electronic structure and rigidity of cyclopropane, changing a substituent on any one of the carbon atoms of the ring will affect the conformation of the substituents on the other two carbons. And cyclopropane structure is relatively simple to synthesize and modify, making it a promising ligand skeleton. However, it is surprising that phosphine ligands with cyclopropane as the core structure have been rarely studied so far, and their applications need to be further explored, too. Based on types of ligands, this perspective systematically summarizes reported phosphine-containing ligands (including monophosphines, diphosphines, phosphine-heteroatoms and triphosphines) with cyclopropane backbone, and their applications in transition metal catalysis. We hope to draw researchers' attention to the cyclopropane-based phosphine ligands and thus promote the development of transition metal catalysis.

Covalent organic frameworks (COFs) are a class of crystalline organic porous materials formed by molecular building blocks via covalent bonds. According to the dimensions of the framework extended in space, COFs can be divided into two-dimensional and three-dimensional COFs. Owing to their high specific surface area, good stability and strong designability, COFs have broad prospects in the fields of gas adsorption and separation, catalysis, sensing, optoelectronics, and energy storage. In the field of photocatalysis, COFs have the following advantages. First, COFs are highly designable, which can achieve efficient photocatalysis by introducing different functional units to adjust the band gap energy and light absorption range. Secondly, the ordered structure of COFs improves the electron-hole separation efficiency. In addition, the high specific surface area and abundant active sites of COFs can promote the photocatalytic reaction and improve the reaction rate. Finally, COFs are connected by covalent bonds, which make them highly stable and facilitate the maintenance of catalytic activity in the photocatalytic process. Porphyrins are a class of 18 π-electron conjugated macrocyclic compounds formed by the interconnection of four pyrroles, which can be involved in photosynthesis as the core part of chlorophyll and other biomolecules. As a kind of functional units with large π-conjugated structure and good photophysical properties, porphyrins usually have strong absorption in the 400~450 nm (Soret band) and 500~700 nm (Q band) regions, and their photocatalytic properties can be regulated by coordination with metal ions and modification of functional groups, which has unique advantages in the field of photocatalysis. By introducing porphyrins into COFs, combined with their unique advantages, porphyrin-based COFs have been found great potential in the field of photocatalysis due to the exceptional optical absorption in a broad spectral range, multiple active sites and effective electron-hole separation ability. As a new type of photocatalyst, porphyrin-based COFs have attracted much interest and have been rapidly developed in the field of photocatalysis. In this review, we focus on the discussion of porphyrin-based COFs in the photocatalytic CO₂ reduction, photocatalytic water splitting, photocatalytic organic transformation, and photocatalytic reduction of hexavalent uranium. Finally, the prospects and challenges of porphyrin-based COFs in photocatalysis are discussed.

o-Hydroxyphenyl substituted p-quinone methides (p-QMs) belong to a class of p-QMs with unique advantages. They not only maintain the high reactivity of p-QMs, but also have more reactive and activation sites owing to the introduction of hydroxyl group. Therefore, o-hydroxyphenyl substituted p-QMs have wide applications in synthetic and medicinal chemistry. The catalytic asymmetric 1,6-conjugate addition and [4＋n] cycloaddition of o-hydroxyphenyl substituted p-QMs have developed very rapidly in recent years, which have become efficient strategies for the synthesis of chiral oxygen-containing heterocycles and arylmethanes with potential bioactivity. This review summarizes the catalytic asymmetric reactions involving o-hydroxyphenyl substituted p-QMs and points out the remaining challenges in this research area, which will open a new window for the design of new type of o-hydroxyphenyl substituted p-QMs and their involved catalytic asymmetric reactions.

Photonics crystals are structures composed of materials with different refractive indices arranged periodically. Due to their unique optical properties and excellent color saturation, they have become the most important type of structural color materials. In the past few decades, the fabrication of photonic crystals using self-assembly of nanoparticles has attracted widespread research attention due to its precision, low cost, and ease of large-scale production. The recent research progress on photonic crystal structural color materials, including their basic color production mechanisms, fabrication methods, and practical applications in displays, color sensing, and information anti-counterfeiting encryption is reviewed with focuses on the fabrication of photonic crystal structural colors using a “bottom-up” self-assembly approach. And the methods for producing photonic crystal patterns and large-area structural color films are emphasized. Finally, the challenges faced by current self-assembly fabrication of photonic crystal structural color materials and prospects for future development directions are discussed.

Ultrasound is a kind of mechanical wave, whose frequency exceeds the upper limit of human hearing. Ultrasound has high energy and penetration, which can pierce the barrier of biological soft tissue and induce the occurrence of chemical reactions. In recent years, sonochemistry has been increasingly used in biomedical research, providing a new focus for the development of biomedicine. This review is mainly divided into three parts, the mechanochemistry of ultrasound, the sonochemistry assisted by sonosensitizers, and the cavitation effect of ultrasound, to describe the research progress in sonochemistry for biomedical applications.

Photothermocatalysis provides a green approach to convert solar energy to chemical energy. In previous studies, the most catalysts were powdered particles, which faces a problem that the light irradiation cannot reach the underlying catalysts, thereby making these catalysts not exhibit activity. A possible resolution to this difficulty is to load active phase on a thin substrate. In this study, a photothermocatalytic film of Ru/quartz filter paper (abbreviated as QFP) was designed, in which the Ru particles were loaded on a QFP with a thickness as thin as 0.36 mm. A photothermal synthesis was adopted to load the Ru particles. A 5 μL of precursor of RuCl₃ ethanol solution was dripped on the QFP and then the QFP was dried under the irradiation of Xe lamp; this operation was repeated until all the precursor were loaded. After that, the QFP with Ru precursor was reduced in an atmosphere of H₂/Ar mixture [V(H₂)∶V(Ar)=1∶9] at photothermal 400 ℃ for 30 min. The loading mass of Ru particles were optimized by loading 1, 2, 3, and 4 mg of Ru on QFP to fabricate four samples. The X-ray diffraction (XRD) measurement revealed that the QFP was amorphous while the loaded Ru particles were metallic. The scanning electronic microscopy (SEM) indicated that the Ru particles were loaded on the SiO₂ fiber of QFP steadily and most of Ru particles possessed a size less than 200 nm. Next, the photothermocatalytic CO₂ methanation was carried out over the as-prepared catalysts to assess their catalytic activity. The catalyst with 2 mg Ru loading showed the highest performance; it delivered an 85.5% of CO₂ conversion during 2 h of light irradiation. Although the four samples exhibited different CO₂ conversion, the selectivities for CH₄ product over these samples were all close to 100%. The stability of optimal catalyst was tested in a flow-type reaction system; under a 5 mL•min^－1 flow rate of reactant gases, the CO₂ conversion over the catalyst could remain around 51% during 12 h and the apparent CH₄ yield rate reached 478.1 mmol•g_Ru^－1•h^－1. This study demonstrates a photothermal synthesis of recyclable Ru/QFP film and its application of photothermocatalytic CO₂ methanation, which provides an energy-efficient process to achieve decarbonization and therefore is of great potential for practical application.

Supported Au-based catalysts have been attracting continuous attention owing to their outstanding performance in various catalytic applications. However, the complicated environment on the catalyst surface severely hampered the unambiguous illustration of the structural-function relationship for Au-based catalysts. In this work, we developed a facile strategy to fabricate various Au species [Au^n＋ (n>1), Au^δ＋ (0<n<1) and Au⁰] onto the CeO₂ support, which the Au/CeO₂ interaction was distinctively modulated by the CeO₂-x with different calcination temperatures. As-prepared Au/CeO₂-x were valued as catalysts for CO oxidation reaction, which is important for both environmental application and model catalysis. The as-formed clustered Au with δ＋ oxidation state on CeO₂-400 demonstrates the best catalytic performance at 50 ℃, while the Au nanoparticles with dominant Au⁰ atoms are superior for catalyzing CO oxidation at room temperature. However, the monodispersed Au^n＋ single-sites with the highest dispersion are almost inactive for CO oxidation below 50 ℃. On the basis of structural characterizations and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) results, we reasonably speculated that the electronic state of Au species plays a predominant role at room temperature for catalytic performance owing to the differentiated CO adsorption ability. This speculation is well in line with our former research finding that the Au^n＋ sites are weak in capturing CO molecules and Au⁰ is favorable for CO adsorption. The surficial O atoms, especially the lattice O atoms, play a minor role in catalyzing CO oxidation for the Au particles within Au/CeO₂-700, implying that the reactant molecules might prefer a L-H pathway at room temperature. In contrast, the clustered Au^δ＋ with moderate CO adsorption ability and abundant interfacial site was apt to participate in the surface reaction with a MvK pathway, in which the reaction between surficial lattice O atoms and adsorbed CO molecules significantly contribute to the catalytic activity. Therefore, the Au/CeO₂-400 catalyst coupling with moderate CO adsorption ability and abundant active O atoms displayed the best catalytic efficiency at elevated temperatures. These findings in this work provided a facile route for the fabrication efficient Au/CeO₂ catalyst, and shed light on the molecular understanding of the reaction path over various Au sites.

With the extensive utilization of fossil fuels in industrial development, the energy crisis and environmental issues have become crucial challenges for current scientific development. The development of sustainable and clean energy is of great importance for sustainable human progress. Fuel and metal-air batteries have emerged as promising alternatives to fossil fuels, providing environmentally friendly and sustainable clean energy. Improving the efficiency of the oxygen reduction reaction (ORR) is crucial for energy generation and storage processes of batteries. Therefore, the development of efficient and stable ORR electrocatalysts is a key task to improve battery performance. Noble metal-based materials are known for their excellent ORR catalytic performance, but their high cost and instability have limited their applications. Hence, it is essential to develop low-cost, low-pollution, and high-efficiency electrocatalysts as noble metal-based alternatives. Transition-metal (TM)-based materials, metal alloys, and metal-free carbon nanomaterials have been reported as alternatives, but their properties are not as good as those of noble metal-based materials. In addition, their complex processes and difficult-to-identify active sites make it challenging to elucidate the intrinsic mechanisms. Rational design and precise synthesis of electrochemical catalysts are critical strategies. Covalent organic frameworks (COFs) have several advantages, including high crystallinity, high specific surface area, high stability, and regular pore channels. Besides, the construction of COFs has the advantages of pre-design and precise synthesis. Reasonable design and construction unit is an important strategy to realize the functional application of COFs materials. Many new products with structural characteristics have been reported since the introduction of COFs, and they have demonstrated excellent performance in several fields. In this study, we investigated the application of a highly stable sp²-carbon-linked COF (JUC-557) based on a bicarbazole building block for electrocatalytic oxygen reduction. We performed various characterizations of JUC-557, which demonstrated its high crystallinity, high specific surface area (870.64 m²/g), and regular structure. Moreover, JUC-557 exhibited excellent thermal and chemical stability. In the ORR performance test, JUC-557 showed good ORR catalytic performance, with an onset potential of 0.80 V vs. RHE, a half-wave potential of 0.68 V vs. RHE, a Tafel slope of only 62.20 mA•cm^－2, and a C_dl of 5.79 mF•cm^－2. Moreover, the Zn-air battery assembled with JUC-557 as an air-cathode electrode catalyst has a stable open-circuit voltage of 1.29 V and can easily light up the “COF” LED board. In conclusion, the rational construction of COFs as ORR catalysts has great potential in energy device application.

White organic light-emitting diodes (OLEDs) are promising candidates for novel solid-state lighting devices, and high-performance orange light-emitting materials are one of the key factors to realize high-performance complementary color white OLEDs. In this work, we designed a new bipolar cyclometalating ligand by incorporating carbazole moiety with hole-transport ability into 2-phenyl-4-methylquinoline with a large torsion angle. Based on this carbazole-bearing cyclometalating ligand, a pair of orange emissive iridium(III) complexes (Ir1 and Ir2) showing bipolar transport ability are prepared by selecting 2,2,6,6-tetramethylheptane-3,5-dione and picolinic acid as ancillary ligands. Two complexes and the corresponding cyclometalating ligand are well characterized by ¹H and ¹³C nuclear magnetic resonance spectrometry, and mass spectrometry, and the new bipolar cyclometalating ligand and complex Ir1 are also confirmed by X-ray diffraction analysis. The single crystals of Ir1 crystallized in the orthorhombic space group P2₁2₁2₁. Its unit cell parameters are α=β=γ=90°, a=1.271 nm, b=1.522 nm, c=3.161 nm. In O₂-free toluene solution at room temperature, both complexes exhibit intense orange phosphorescence (587 nm for Ir1, 570 nm for Ir2) with high photoluminescent quantum yields of 69% and 74% and with short lifetimes of 1.50 and 1.62 μs. Most importantly, they not only show relatively broad full width at half maximum (FWHM) of 83 nm for Ir1 and 88 nm for Ir2 in their emission spectra but also possess bipolar transport ability, which will be beneficial to realize high-performance electroluminescence. Complex Ir2 is selected as the dopant to fabricate orange OLEDs. The as-prepared OLED realizes a broad orange emission at 569 nm with FWHM of 86 nm, maximum brightness of 4826 cd•m^－2, external quantum efficiency (EQE) of 15%, current efficiency of 35.7 cd•A^－1, and power efficiency of 23.4 lm•W^－1. The results demonstrate that the new bipolar orange emissive iridium(III) complexes designed by incorporating carbazole moiety with hole-transport ability into the cyclometalating ligand with a large torsion angle will be the promising candidates for the future design of high-performance white organic light-emitting diodes.

Pyrrolo[3,2-d]pyrimidin-4-ones are valuable structural motifs in many bioactive compounds and pharmaceuticals. Such structures have received extensive attentions from synthetic community. Two general strategies have been developed for the formation of the fused pyrimidine-pyrrole structure: one is to construct the pyrimidine ring from substituted pyrroles, and the other is to construct the pyrrole ring from 5,6-functionalized pyrimidines. However, these methods have generally required multiple synthetic steps and the use of starting materials with uncommon functional groups, and also suffered with other drawbacks such as harsh reaction conditions and limited substrate scope. Thus, it is highly desirable to develop facile and practical approaches for the construction of structural diversified pyrrolo[3,2-d]pyrimidin-4-ones. Very recently, we have developed an alkyne-isocyanide [3＋2] cycloaddition/Boulton-Katritzky rearrangement/ring expansion reaction for the synthesis of 9-deazaguanines from 1,2,4-oxadiazole-derived propiolamides with isocyanides. Different from traditional Boulton-Katritzky rearrangement (BKR), which is to form stable five-membered rings, the method provides a facile access to fused heterocycles via forming an unstable BKR spirocyclic intermediate and followed by a spontaneous ring expansion via acyl migration. In this work, to further expand the scope of this method, the [3＋2] cycloaddition/BKR-ring expansion reactions of isoxazole-derived propiolamides with isocyanides were developed. The reactions were performed with CuI as the catalyst and Cs₂CO₃ as the base in toluene/N,N-dimethylformamide (DMF) (1∶3, V∶V) at room temperature for the alkyne-isocyanide [3＋2] cycloaddition and then at 110 ℃ for the BKR-ring expansion process. A variety of isoxazole- derived propiolamides and isocyanides were well tolerated in the reactions and afforded the desired pyrrolo[3,2- d]pyrimidin-4-one products in satisfactory yields. The control experiments were performed to elucidate the reaction process: copper catalyst is used only for the alkyne-isocyanide [3＋2] cycloaddition, but no necessary for the base-promoted BKR-ring expansion process. Compared to the traditional methods for such skeletons, the approach features readily available starting materials, broad substrate scope, short steps, and structural diversification.

Nanopore-based single molecular analysis technique usually uses time-domain features such as time-current scatter plots of blocking currents for event recognition. However, as the time-domain features overlap with each other, the substances with extremely similar molecular structures are difficult to be accurately discriminated using traditional nanopore recognition methods. The differences in the deep feature representations need fully explored to obtain credible recognition results, thus improving the recognition accuracy of nanopore ionic current signals. Here, a time-series signal classification algorithm is proposed in this paper: firstly, the original signal is framed with overlapping sliding windows to generate sub-signals and extract their shallow feature information; then a time-series signal classification network based on Emphasized Channel Attention, Propagation and Aggregation in time delay neural network (ECAPA-TDNN) is proposed to develop a multi-branch inter-layer feature fusion model for deep feature extraction, where the multi-branch multi-level attention module of this model (RepVGG-SE-Res2Block, RSR-Block) obtains multi-scale features by constructing a feature pyramid structure within each residual block, reduces the inference speed based on structural reparameterization techniques while ensuring the model performance, and introduces Adaptively Spatial Feature Fusion (ASFF) to fuse the features of different layers in the network; finally, a credible statistical prediction strategy is used to obtain reliable classification results by counting the classification probabilities of sub-signals. The experimental results show that for the peptide sequences N'-DDFFIFFDD-C' (DF_I) and N'-DDFFLFFDD- C' (DF_L) containing only the different amino acids I (isoleucine) and L (leucine), which are isomers of each other, the algorithm achieves a recognition accuracy of 99.00%, obviously improving the sensing capability of nanopores for single molecules with similar or even identical molecular weights.

The engineering and regulation of electrode interfaces are of great significance for accurate analysis of specific analyte in complex samples. Covalent organic frameworks (COF), as a class of crystalline polymers formed precisely and periodically by building blocks, have provoked exponential interest due to their pre-designable and adjustable pore sizes, hydrophobicity, geometry and so on. Therefore, varying the structures of monomers is able to modulate the molecular permeability of COF and achieve selective detection of different analytes. In this work, the polycondensation reaction between the amine monomer, namely 1,3,5-tris(4-aminophenyl) benzene (TAPB), and two different aldehyde monomers, namely terephthalaldehyde (PDA) and 2,5-dibromoterephthalaldehyde (BrPDA), at the liquid/liquid interface was conducted to prepare continuous and uniform imine-linked covalent organic framework (COF) membranes. The membranes were subsequently transferred onto the surface of indium tin oxide (ITO) glass electrodes and then the electrochemical responses of hydrophobic vitamin A (VA) and hydrophilic vitamin C (VC) at two COF modified electrodes were investigated. Due to the existing of Br groups on the pore walls of TAPB-BrPDA COF, it is hydrophobic with a contact angle of 122°, while the TAPB-PDA COF membrane is hydrophilic with a contact angle of 73°. The electrochemical responses of two COF modified electrodes towards hydrophobic VA and hydrophilic VC were studied in 1 mol/L NaCl solution. The results of cyclic voltammetry revealed that TAPB-BrPDA COF could prohibit effectively the permeability of VC whereas allow that of VA, eventually achieving the selective electrochemical detection of the latter with a detection linear range of 5~100 μmol/L and a limit of detection at 1.32 μmol/L. In contrast, TAPB-PDA COF/ITO electrode can reject the access of VA whereas permit that of VC, thus showing good electrochemical selectivity toward VC and yielding a linear detection range of 5~200 μmol/L and a limit of detection at 1.35 μmol/L. Finally, two electrodes were successfully used for the quantitative determination of VA and VC in multivitamin tablets with recoveries of 104% and 101%, respectively. This work constitutes a step in the surface engineering of electrodes by COF to realize pre-designed composition and functions and thus excellent selectivity towards specific molecules.

The multivalent or multilevel supramolecular assembly of macrocyclic compounds and its applications in biology, chemistry and materials is one of the current research hotspots, among which the supramolecular assembly of amphiphilic cupric aromatic hydrocarbons is notable. The recent studies on the secondary supramolecular assembly of calixarenes and their biological applications are reviewed, including: (1) the secondary assembly of amphiphilic calixarenes bonded guest molecules with macromolecules and its biological applications; (2) the secondary assembly of cucurbiturils bonded guest molecules with amphiphilic calixarenes and its biological applications. Compared with the primary assembly, the secondary assembly of amphiphilic calixarenes can improve the hydrophobicity of the microenvironment of supramolecular assemblies, while it can co-assemble with dye molecules, drug molecules, and light-controlled smart molecules to form supramolecular assemblies such as nanorods, nanoparticles, and nanofibers, which can not only further regulate guest molecules to promote luminescence behavior, but also promote energy transfer and cascade energy transfer. The secondary supramolecular assemblies constructed based on amphiphilic calixarenes with light-responsive, pH-responsive, and redox-responsive properties can be used in research fields such as bioimaging, targeted drug delivery, and information anti-counterfeiting, which have broad application prospects. We hope that this review will provide new ideas to conduct research on multidimensional and multilevel assembly of supramolecules and their biological applications, which will further promote the development of supramolecular chemistry.

Zeolite molecular sieve is by far the most widely used porous material with the greatest contribution to society. Hierarchical zeolites, which possess dual advantages of large diffusion coefficient and high activity, are increasingly important as catalysts and adsorbents in many chemical processes. A class of organic mesoporogens named organic mesopore generating agents (OMeGAs), such as amino acids, phenols, and azoles were found to produce intracrystalline mesopores by one pot method, wherein the nucleophilic etching effect of the in-situ generated anions, including oxyanions, nitranions, or carbanions, plays the key role. By adding mild OMeGAs in-situ into the reaction solution of zeolite synthesis, the nucleophilic etching assisted growth could overcome the energy-intensive mesoscale template calcination associated with the “bottom-up” strategy and the zeolite structure destruction of the “top-down” post-synthetic strategy. The interplay between in-situ etching and growth on the early precursor or nuclei has enabled effective control over crystallinity, size, morphology, mesopores, and performance of zeolites. In this account, the existing preparation strategies of hierarchical zeolite are first briefly introduced. Then, the in-situ etching-assisted growth strategies are discussed in detail, including the selection of mild etchant OMeGAs, mechanism and advantages of the etching-assisted zeolite crystallization process. Finally, the application of in-situ etching-manipulated hierarchical zeolite is summarized.

The spinel oxides have various elements, flexible cations, variable valence states and rich electronic structure, which bring about rich physical and chemical properties. In recent years, as important inorganic nano therapeutic agents in tumor, they had shown excellent potential in the field of tumor labeling, diagnosis and treatment. The ratio of A-O tetrahedron to B-O octahedron is fixed in the structure composition of spinel oxide AB₂O₄, and the occupancy ratio of e_g orbital calculated by d orbital splitting in B-O octahedron can be used as a descriptor of various catalytic reactions. Therefore, it shows a unique advantage in establishing the structure-activity relationship between the electronic state structure of spinel oxides and the diagnostic and therapeutic performance in the treatment of various tumors.

Enantioselective desymmetrization of diols is an important method for the synthesis of complex enantioenriched alcohols, which has broad application prospects in medicinal chemistry, total synthesis, and materials science. In recent years, the use of copper catalysis to achieve diols’ enantioselective desymmetrization has progressed rapidly because copper is inexpensive and readily available compared with other noble metal catalysts. Besides, copper undergoes a two-electron or single-electron transfer process in the catalytic cycle, and the rich oxidation states of copper provides the opportunity to solve some challenging problems. This review summarizes the research progress in this field according to the types of diols (meso diol and prochiral diol) and reactions together with a brief perspective.

Diffusion behavior in life system involves important life processes such as nutrient uptake and drug delivery. A deeper understanding about diffusive behavior of particles in complex biomacromolecular media will facilitate the understanding of relevant life phenomena as well as the development of novel medical materials. The diffusion behavior in biomacromolecular media is often anomalous and cannot be described simply based on the conventional diffusion constant equation. This is usually attributed to the continuous correlation of diffusion caused by crowded environment and complex interactions in biological medium, which leads to the central limit theorem no longer applicable. The mechanism and physical characteristics of anomalous diffusion were analyzed from three aspects: diffusion coefficient, mean square displacement, and displacement probability distribution function. The recent progress of anomalous diffusion in biomacromolecular media was summarized. The physical model and existing theoretical framework of anomalous diffusion are then outlined. Finally, the future direction of anomalous diffusion dynamics in biomacromolecular media is discussed.

The excessive discharge of oxyanions (i.e., nitrate, bromate, perchlorate) into water has caused more and more serious environmental pollution problems. Oxyanions are generally persistent, refractory, teratogenic and carcinogenic, posing a great threat to ecosystems and human health. Therefore, they have increasingly attracted widespread attention. Electrochemical reduction is regarded as one of the most promising water treatment technology, because it could employ either electrons or strong reductive species (atomic H*) generated by dissociating water molecules to realize the efficient, green and safe removal of toxic oxyanions. Herein, the electrochemical reduction mechanism for removing pollutants is briefly introduced, the advancements of electrochemical reduction of nitrate, bromate and perchlorate are summarized and their possible reaction pathways are discussed, the effect of catalysts (i.e., structure, types) on the performance of electrochemical reduction is further analyzed. Finally, the possible challenges of electrochemical reduction technology to remove oxyanions are deeply discussed and prospected.

Electron microscopy (EM) is one of the most important techniques to characterize the morphology and structure of micro- and nano-particles. However, conventional procedures for sample preparation often alter the structure and morphology of samples with high water contents, causing distortions and misinterpretations for EM characterizations. The invention of Cryo-electron microscopy (Cryo-EM) has largely solved this problem. Via rapidly freezing the hydrated samples at low temperatures, cryogenic techniques instantaneously transform liquid water into amorphous ice to ensure high vacuum and reduce electron radiation damage, allowing researchers to observe hydrated samples in their native state with high resolution. For example, applications of Cryo-EM during the COVID-19 pandemic have demonstrated the amazing ability of Cryo-EM to visualize the detailed structure of SARS-CoV-2 viruses, which provides vital knowledge for rapid and reliable detection and diagnosis of the disease, transmission mitigation, and vaccine development. So far, Cryo-EM technology has been widely used in materials, biology, pharmaceuticals, and other fields of research, successfully broadening and deepening the understanding of the interactions between micro- and nano-particles. This review summarizes the recent development of Cryo-EM from aspects of electronic components, imaging technology, and resolution and introduces the sample preparation methods. Furthermore, the three-dimensional reconstruction method is highlighted to advance the EM method from 2D to 3D. As most environmental samples are highly hydrated, Cryo-EM will likely become an essential tool to investigate microscopic particles in the environmental field. This review gives examples of the applications of Cryo-EM in the formation of aerosol particles in the atmosphere, observing biofilm morphology in the water treatment process, the pore structure of activated sludge flocs, and the potential mechanism of soil microorganisms on heavy metal remediation. Finally, the prospects of Cryo-EM are summarized and discussed. We expect that with software, hardware, and artificial intelligence development, Cryo-EM technology can achieve faster data acquisition and higher resolution and make breakthrough contributions to environmental chemistry research.

Based on the well development of diazo compound transformations in organic synthesis, it is expected to extend its applications to the field of polymer synthesis. It is of vital importance to transform efficient organic reactions of diazo compounds into new polymerization methodology in order to afford polymers with new structures and functions. Currently, there is still great development potential in the application of diazo compounds in polymer synthesis. This review highlights the recent advancements of polymer synthesis chemistry with diazo compounds, including chain-growth polymerization, step-growth polymerization, end-group functionalization and post-polymerization modification. Transition-metal-catalyzed chain-growth polymerization of diazoacetates constructs C—C main chain from one carbon unit. Through the development of catalytic diazoacetate polymerization, the synthesis of high molecular weight polymers, stereocontrol polymerization and living/controlled polymerization can be realized successively. The stepwise polymerization of diazo compounds originated from their efficient organic conversions. The insertion reaction of diazo compounds into O—H and N—H bonds can be extended to stepwise polymerization to afford polyethers, polyesters and polyamines that are not easily accessible through other synthetic methods, while cross-coupling polymerization of diazo compounds via metal carbene insertion-migration mechanism can realize the synthesis of polymers with novel structures. Diazoacetates and diazomalonates can be employed to regulate the terminal structures of polymers synthesized through metal-catalyzed vinyl addition polymerization or ring-opening metathesis polymerization of olefins, and successively end-capped by metal carbene. The post-polymerization modifications based on diazo compounds can be applied to the introduction of polar functional groups into polyolefin. Compared to the copolymerization of polar olefins, the post-polymerization functionalization strategy avoids the depressed reactivity of varied monomers, and can be applicable to a broad scope of functional groups. The thermal and mechanical properties of polymers can be improved by this method. Finally, the future challenges in expanding the approaches on polymer chemistry of diazo compounds are prospected in this review.