Aqueous zinc ion batteries (AZIBs) as an emerging battery energy storage technology have attracted widespread attention and developed rapidly in recent years due to the merits of high safety, low price, high energy density, environmental friendliness, easy manufacturing, etc., showing good application value and prospect in large-scale energy storage and other fields. Embarking from the current scientific issues existed in AZIBs, we review the important progress in cathode and anode materials and electrolyte used in AZIBs in this article. Firstly, the characteristics of multiple cathode materials that developed and their electrochemical reaction mechanism are analyzed and summarized. Afterward, the challenge and improving strategy for metal zinc anode are discussed, and the features of different aqueous electrolytes and the optimization solution are analyzed. Finally, the scientific problems to solve and technical challenges for the practical application in the future of this novel battery technology are summarized and prospected.

Transition metal-catalyzed coupling reactions are powerful synthetic methods for the C-C bond formation. Many coupling reactions such as Heck reaction, Negishi coupling, and Suzuki coupling have been widely applied in the syntheses of pharmaceuticals, functional materials and fine chemicals. In those coupling reactions, a C(sp²)-C(sp²) bond is formed in high efficiency and selectivity. However, in contrast to the C(sp²)-C(sp²) couplings, the C(sp³)-C(sp³) couplings are more difficult and develop late. Because the C(sp³)-C(sp³) bonds are ubiquitous in organic compound, the C(sp³)-C(sp³) bond formation is the central task of research in organic chemistry. In the past two decades, a great effort has been devoted to the development of cross-coupling reactions between alkyls to construct C(sp³)-C(sp³) bonds and impressive progress has been achieved. Among the transition metal catalysts that have been used in the construction of C(sp³)-C(sp³) bonds, nickel was found to be a preferable one, exhibiting unique activity and selectivity. Nickel catalysts promote the activation of alkyl electrophiles via radical catalytic cycles and inhibit and/or manipulate β-H elimination reactions. Nickel has several variable valence states and can flexibly participate in tandem reactions and reductive cross-coupling reactions. All these characteristic natures contribute to the success of nickel catalysts in the construction of C(sp³)-C(sp³) bonds. In this review, we will describe the advances on the nickel-catalyzed C(sp³)-C(sp³) bond-forming reactions. The main contents of this review include:the cross-coupling of alkyl electrophiles with organometallic reagents; the coupling involving a C(sp³)-H bond activation in the presence of directing group; the coupling co-catalyzed by nickel and photocatalyst; the reductive coupling of two alkyl electrophiles; and the additions of nucleophiles or electrophiles to alkenes such as hydroalkylation and difunctionalization of alkenes. The review will focus on the latest developments of nickel-catalyzed alkyl coupling reactions in the past two decades. The mechanisms of each reaction are discussed in detail for understanding the reactions.

Hydrogen-bonded organic frameworks (HOFs), usually self-assembled by organic or metal-organic building blocks via intermolecular H-bonding interactions, have become a unique type of crystalline porous material. Although the weak and flexible nature of hydrogen bonds makes most HOFs fragile, the high stability and permanent porosity could be realized by the judicious selection of rigid building blocks with special spatial configuration as well as the introduction of framework interpenetration and/or other intermolecular interactions like π-π stacking and electrostatic interactions, etc. Compared with other crystalline porous materials like metal-organic frameworks (MOFs) and covalent-organic frameworks (COFs), HOFs feature mild preparation condition, high crystallinity, permissible solution processability, easy healing and regeneration, etc. These distinguishing merits make HOFs capable to be used as unique multifunctional porous materials. Herein, we first review the basic rules to design and synthesize stable and porous HOFs, and then systematically summarize the representative supramolecular synthons and backbones that have been used to build stable and porous HOFs. Emphasis is put on the potential applications of HOFs in gas adsorption and separation, proton conduction, heterogeneous catalysis, luminescence and sensing, biological applications, enantiomeric resolution and aromatic compounds separation, pollutants removal, and structure determination, etc.

Fine separation of mixture is the primary importance technology and hot topic in the petrochemical industry. In particular, high-efficiency separation of C₂ (C₂H₂/C₂H₄ and C₂H₄/C₂H₆) is a difficult issue and challenge of the high-quality production in modern chemical process. Traditional heat-driven separation processes (e.g., fine distillation separation and selective catalytic hydrogenation separation) have the shortages of high energy consumption and low economic benefits. On the contrary, the processes with non-thermal driven separations (e.g., adsorptive and membrane-based separations) can greatly overcome these weaknesses. Among these adsorptive separation materials, metal-organic framework (MOF) materials own a huge various library of components/structure units. Their characters of controllable pore structures and adjustable compositions will bring about new opportunities for the high-efficiency refined separations. In this context, the crystals and pore parameters of MOF⁺ (MOF and its composites) materials in recent years were sorted out and summarized, the researches in the high-efficiency separation of MOF⁺ materials for C₂ were analyzed, and the key issues of the design, controllable preparation, and pore size control mechanism for MOF⁺ materials were focused on. In addition, the future research trend of MOF⁺ materials were also put forward.

Room-temperature phosphorescence (RTP) can not only intuitively reflect the excited state transition process of the phosphorescent luminescence, but also has wide potential applications in optoelectronics, sensing, bioimaging and security devices. Consequently, more and more attention and interests on RTP materials have been attracted, which turned it to be one of hot topics in luminescence materials, especially, organic luminescence materials in recent years. The halogen bonds and hydrogen bonds between the molecules can fix the phosphor to suppress non-radiative transitions. A twisted donor-acceptor skeleton can promot efficient thermally activated delayed fluorescence (TADF) and also benefit to the RTP. Moreover, circularly polarized room-temperature phosphorescence (CP-RTP) also remains a daunting challenge to implant circularly polarized luminescence (CPL) in metal-free RTP materials. This review summarizes recent research progress on RTP of small organic molecules, mainly focusing on RTP materials based on hydrogen bonds, RTP materials containing halogens, RTP materials based on D-A structures and RTP materials with CPL properties.

Organoboronic acids and esters are highly valuable building blocks in cross-coupling reactions and practical intermediates of various functional group transformations. Additionally, organoboronic acids can be utilized directly as small molecule drugs. Therefore, development of efficient methods to synthesize organoboronic compounds is of significant importance. Traditional pathways to synthesize organoboronic compounds mainly rely on electrophilic borylation of organometallic reagent and transition-metal-catalyzed borylation. Radical intermediates have unique chemical properties which are quite different from those of polar intermediates resulted from the heterolysis of chemical bonds and those of the organometallic compounds during transition metal catalysis. As such, borylation based on radical mechanism possesses distinctive reaction process, substrate scope, reaction selectivity, etc., and have great potential in synthesis of organoboronic compounds. In 2010, the Wang's group first reported borylation via a radical mechanism. This method realized an efficient direct conversion of anilines into aryl organoboronic esters. Inspired by this innovative work, more and more borylation methods via radical intermediates have been reported and developed as new avenues for C-B bond formation in the past decade. A series of studies show that organoboronic acids and esters could be efficiently constructed by the reaction of aryl/alkyl radicals with diboron compounds. In this paper, we summarize the recent development of borylation reactions via radical mechanisms, including aryl and alkyl radical borylation. As for aryl radical borylation, the activation of substrates containing C-N, C-O, C-S, C-X (X=halogen) bonds and carboxylic acids to C-B bond is summarized respectively. As for alkyl radical borylation, the activation of substrates containing C-N, C-O, C-X (X=halogen), C-C bonds and carboxylic acids to C-B bond is summarized respectively. Finally, we provide a perspective on the future development direction of this research area.

In past decades, global warming, sea level rising, and other climate problems caused by greenhouse effect are becoming more and more serious. Considerable efforts have been paid on developing new technology that can effectively reduce the atmospheric level of carbon dioxide (CO₂), the most representative one of greenhouse gases. Solar-driven conversion of CO₂ into high value-added hydrocarbon fuels is considered as the most promising approach to alleviate the current energy crisis and the rising CO₂ level. Benefiting from their high specific surface area and novel electronic structures, two dimensional (2D) materials have drawn intense interest in the field of CO₂ photoreduction. Herein, the latest development of 2D materials for photocatalytic CO₂ reduction is presented, with special emphasis given to the structure-activity relationship in catalytic reactions. The potentials of newly emerged 2D materials including black phosphorus, graphdiyne and covalent organic frameworks as the next generation photocatalysts for CO₂ reduction are then discussed. Finally, the opportunities and challenges in the field of CO₂ photoreduction are featured on the basis of its current development.

Bioorthogonal chemistry refers to chemical reactions that can be carried out in biological systems without interfering with natural biochemical processes. During the past two decades since its emergence, the scope of bioorthogonal chemistry has been greatly expanded from ligation to cleavage reactions, with broad applications ranging from live cells to animals for biological studies, medical as well as pharmaceutical research. Chinese chemical biologists have actively participated in this exciting area, and a series of important work has been carried out with notable achievements. In particular, the creation and development of bioorthogonal cleavage reactions and its diverse applications have drawn considerable attentions. In this review, we summarize the representative work on bioorthogonal chemistry that been developed in China in recent five years. These works will be categorized into metal-, photo- and small molecule-mediated bioorthogonal ligation as well as cleavage reactions, respectively. In the end, we will discuss the future development along this exciting avenue and the further innovation of the “remote-control bioorthogonal chemistry”, which may eventually drive the bioorthogonal reactions into living animals or even human being.

Double-network (DN) hydrogels are composed of two asymmetric networks with contrasting properties, wherein the rigid and brittle network serving as sacrificial bonds effectively dissipates energy to enhance the mechanical performance. The first reconstructable physical network endows the DN hydrogels with outstanding anti-soften and mechanical stability. However, the monotonous type of physical networks and the difficulty in tailoring structure and mechanics greatly limit the development and application of DN hydrogels. Focusing on these problems, we have fabricated the rigid and brittle chitosan physical network with adjustable network type, structure and property and further constructed various chitosan-based DN hydrogels with high mechanical performance and tunable mechanics. The hydrogels were potential materials for anti-freezing dresses, biomedical materials, flexible electronics and wearable devices. The universal strategy of constructing chitosan-based DN hydrogels was beneficial for developing various functional and high-mechanical hydrogels and broadening their applications.

Nowadays malignant tumors are still one of the disastrous diseases. It is necessary to explore new strategies for the treatment of malignant tumor. Nanomaterials refer to materials with at least one dimension of the three dimensions in the nanometer range (1~100 nm). They show a wide range of applications in tumor treatment while disadvantages of low targeting efficiency, poor tumor penetration and obvious side effects still limit their applications. As a method for tumor treatment, bacterial therapy has a long history. Some facultative anaerobic and obligate anaerobic bacteria and their secretions have the characteristics of targeting hypoxic tumor tissue, strong tumor penetration and stimulating immune responses. After genetically modification or attenuation treatment, it can be used for tumor treatment. However, the safety issues and low therapeutic efficiency still needs to be solved. The combination of nanomaterials and bacteria can complement the limitation of each other, and shows great potential in tumor therapy. On one hand, bacteria could enhance the targeting efficiency of nanomaterials, and decrease the side effects. On the other hand, nanomaterials could help improve the safety and solve the problem of low therapeutic efficiency of bacterial therapy. In this review, the combination of nanomaterials and bacteria is divided into three categories based on the role of bacteria in the treatment. Firstly, the preparation of composites of nanomaterials and bacteria by chemical bonds, electrostatic interaction, and other ways to enhance tumor targeting. Secondly, bacterial enzyme could react with nanomaterials to control the release of drug. Thirdly, secretions of bacteria after plasmids were introduced and outer membrane vesicles secreted by bacteria could be combined with nanomaterials for anti-tumor therapy. The mechanisms of the combination therapy are also discussed. Finally, we summarized and discussed the current challenges, especially the safety of the combination therapy. The prospect of the combination of nanomaterials and bacterial for tumor treatment is also proposed.

Artificial intelligence (AI), especially the machine learning, is playing an increasingly important role in contemporary scientific research. Unlike the traditional computer program, machine learning can analyze a large number of data repeatedly and optimize its own model, a process which is called a "learning process". So that the AI can find the relationship underling the experiments from a large number of data, form a new model with better prediction and decisionmaking ability, and make an optimized strategy. The characteristics of chemical research just hit the strengths of machine learning. Chemical research often faces very complex material system and experimental process, so it is difficult to accurately analyze and making judgment through physical chemistry principles. Artificial intelligence can mine the correlation of massive experimental data generated in chemical experiments, help chemists make reasonable analysis and prediction, and therefore greatly accelerate the process of chemical research. This review presents the modern artificial intelligence method and its basic principles on solving chemical problems, by representative examples with specific machine learning algorithm. The application of artificial intelligence in chemical science is in a period of vigorous rise. Artificial intelligence has initially shown a powerful assist to chemical research. We hope this review can help more domestic chemical workers understand and use this powerful tool.

The levels of some biomolecules and ions in the body are usually related to the structural and functional changes of cells, tissues, organs, etc., which directly affect the prevention, diagnosis, and treatment of diseases. Therefore, in vivo bioassays of these substances are of great significance in medical and healthcare fields. The nano fluorescent probes consisted of rare earth nano materials have advantages of high sensitivity, simplicity, efficiency, and strong anti-interference ability, thus showing great potential in bioassays. The functionalization of aptamers on rare earth nanomaterials can further provide better specific recognition ability and biocompatibility for nano fluorescent probes, thereby enhancing their bioassays ability in complex samples. In this paper, the research progress of aptamer-functionalized rare earth nanomaterials as nano fluorescent probes in the field of bioassays is reviewed, and the main types, properties, detection mechanisms and detection substances are briefly introduced.

Ferroelectric materials, characterized by the reversible switching of spontaneous polarization by an applied electric field, exhibit excellent physical properties including dielectric response, pyroelectricity, piezoelectricity, electro-optics, and nonlinear optical effects, etc. All these physical properties have been widely used for diverse practical applications. In recent years, two-dimensional (2D) organic-inorganic hybrid perovskites have emerged as an important family of ferroelectrics. Benefitting from unique structural compatibility and tunability, this 2D class of ferroelectrics enable the coexistence and/or coupling of multiple functions, which become an ideal platform for the development of new multifunctional candidates. Based on the Curie symmetry principle, this work illuminates the crystallographic symmetry breaking and highlights the source of ferroelectricity in 2D hybrid perovskite ferroelectrics, as well as potential strategies to modulate their photoelectric properties. Finally, we propose the development trend and application prospects of these 2D hybrid perovskite ferroelectric materials.

The term “carbolong complexes” represents a series of novel π-conjugating aromatic frameworks, which are formed by the chelation of a carbon chain (carbolong ligand) containing not less than 7 carbon atoms with a transition metal fragment. Carbolong complexes show unique photophysical properties, thus exhibiting promising potential applications. Inspired by the efficient strategies for the construction of Os-, Ru-, and Rh-carbolong complexes by the reactions of multiynes with simple metal sources, we describe here the reasonable design of two multiyne compounds 1 and 2, which could react with the iridium precursor [Ir(CH₃CN)(CO)(PPh₃)₂]BF₄ ( 3) to produce the irida-carbolong complexes 4 and 5 with a large π conjugation system via a “one-pot” method, respectively. This is the first time to expand the carbolong complex to iridium. In addition, the ligand substitution reactions of 4 and 5have been investigated. Treatment of corresponding ligands with 4 and 5 resulted in the generation of several new irida-carbolong complexes 6~ 9. All the prepared irida-carbolong complexes were fully characterized by NMR and HRMS. The molecular structures of the irida-carbolong complexes 4~ 8 were further confirmed by single crystal X-ray diffractions. A possible mechanism was proposed for the formation of the irida-carbolong complexes on the basis of the X-ray characterization of the key intermediate Int 2. Due to the unique large π conjugation system, all the synthesized irida-carbolong complexes exhibit remarkable absorption properties in the ultraviolet visible region, and some of them even show considerable absorption characteristics in the near infrared region (NIR). The consequently photothermal property investigation indicates that complex 5 has a good NIR photothermal effect: by measuring the temperature of its solution under the NIR laser irradiation (808 nm, 1.0 W•cm ^-2), the temperature of ethanol/water solution containing 5 (0.1 mg•mL ^-1) can be increased by nearly 40 ℃ in 10 min, providing numerous possibilities for the follow-up application research based on carbolong complexes.

3,2’-Spiropyrrolidine-2-oxindole scaffold is found as a key unit in a number of pharmaceutical candidates and nature products. It is highly desirable to develop efficient synthetic strategies to access such a structural scaffold. Recently, dearomatization reactions have received considerable attention as an efficient and straightforward synthetic method to convert readily available aromatic compounds to three-dimensional organic molecules. Amongst them, the transition-metal-catalyzed dearomative functionalization of endocyclic C=C bonds of aromatic compounds initiated by dearomative migratory insertion has been extensively established. A number of dearomative Heck reactions, reductive Heck reactions, and domino Heck-anionic capture sequences have been developed. Nevertheless, the present studies are mainly focused on the dearomatization reactions of indoles and furans. In contrast, there are rare examples reported for the dearomatization of pyrroles. In this communication, we report a palladium-catalyzed intramolecular Heck reaction of the endocyclic conjugated C=C bonds of C2-tethered pyrroles through an initial migratory insertion to formal conjugate diene and subsequent hydride elimination. A range of 3,2’-spiropyrrolidine-2-oxindole derivatives are obtained in good to excellent yields, showing broad substrate scope. In addition, a preliminary study of enantioselective reaction implies that the target product could be obtained in moderateee under the help of a H₈-BINOL-based chiral phosphoramidite ligand. A general procedure for this dearomative Heck reaction is depicted as the follows: to a dried Schlenk tube were added pyrrole substrate 1 (0.20 mmol), Pd(dba)₂ catalyst (5.8 mg, 0.010 mmol), and PPh₃ ligand (5.2 mg, 0.020 mmol) under N₂ atmosphere. 2.0 mL of MeCN solvent and 83 µL of Et ₃N were then introduced through a syringe and the Schlenk tube was sealed using a Teflon cap. The resulting reaction mixture was stirred at 100 ℃ for 16 h. After the reaction was completed (monitored by TCL), the mixture was concentrated under vacuum and the residue was purified by flash column chromatography on silica gel to afford the product 2.

Exosomes are nanoscale bilayer membrane vesicles actively secreted by cells, which carry abundant cell-specific substances. They can directly reflect the physiological and functional status of the secreting cells and play important roles in intercellular communication, physiological and pathological processes. In this work, we combined membrane modification technique with fluorescence imaging technique and blended CD63 aptamers into a highly stable and universal DNA tetrahedral structure to construct a cell membrane-anchored DNA sensor for real-time monitoring the secretion of exosomes. We designed four functional toes on each vertex of the tetrahedral sensor, respectively. A signal report toe on the top vertex consisted of fluorophore-modified CD63 aptamer, quencher-modified quencher probe(QP) binding part of the CD63 aptamer, and block probe (BP) binding the rest of the CD63 aptamer. The other three extended toes on the vertices were immobilized to the cell membrane by hybridizing with cholesterol-modified anchor probes(AP), which spontaneously incorporated to a lipid bilayer via hydrophobic interaction between the cholesterol moieties and the cellular membrane. In the initial state, the proposed DNA tetrahedral sensor was tethered to membrane with fluorophores quenched by QP and CD63 aptamer blocked by QP and BP. Trigger probes (TP) were add to bind to BP, resulting in the activation of the sensor. Subsequently, CD63 aptamers were specifically bound to the secreted exosomes, leading to the release of QP and concurrent fluorescence restoration of fluorophore. The intensity of the fluorescent signal in cell membrane was proportional to the amount of exosomes captured, thus realizing the real-time monitoring of the exosomes by analysis the changes of the fluorescence intensity. The experimental results showed that the sensor exhibited a good stability and a high capture efficiency for secreted exosomes. This strategy would provide a potentially useful tool for a variety of applications in biomedical research, drug discovery and tissue engineering.

Polymer solar cells (PSCs) experienced a leap forward recently due to the development of non-fullerene acceptors. These novel acceptor materials possess improved photon absorption ability as well as readily tunable band structures compared to the conventional fullerenes. Perylene diimide (PDI) derivatives were among the first investigated non-fullerene acceptors for PSCs. PDI is widely adopted as building blocks for acceptor materials for its high photon absorption and electron transporting abilities, suitable and tunable energy levels, ease of synthesis and excellent photon stability. However, PDI derivatives are well known for their aggregation tendency to result in poor blend morphology, which leads to lower device efficiency than the acceptor-donor-acceptor type fused ring small molecular acceptors. To address this issue, we designed and synthesized three PDI based small molecular acceptors with a diketopyrrolopyrrole (DPP) core. The c-PDI2 and nc-PDI2 were two-PDI-armed molecules with PDI substituents attached on the carbon or nitrogen atoms of the DPP skeleton, respectively, while PDI4 was a four-PDI-armed molecule. The PDI units were predicted by molecular simulations to be positioned in altered planes forming the twisted 3D structures, which would reduce the intermolecular aggregation. Based on optical absorption, energy level, blend morphology and photovoltaic performance studies, all three molecules were found with amorphous morphology, which indicated that the aggregation tendency was efficiently suppressed. Among the three molecules, the four-armed PDI4 displayed the flatter structure with broadened electron delocalization which led to significantly increased extinction coefficient and electron transport mobility. The faster electron transport of PDI4 assured the balanced charge transport which yielded into a higher field factor (FF) over 65% in contrast to the two-armed molecules with FFs under 55% in the respective PSC devices. With additional aids from the increased photon absorption, PSCs containing PDI4 also generated substantially higher photocurrent. These improvements afforded the highest power conversion efficiency (PCE) as high as 8.45% among the three PDI derivatives, which was twice and 1.5 times of those of c-PDI2 and nc-PDI2, respectively. In comparison between the two two-armed PDI derivatives, the nitrogen-position-substituted nc-PDI2 delivered higher device performances than the carbon-position-substituted c-PDI2, also thanked to its flatter molecular arrangement and broader intra- and intermolecular electron delocalization. In our study, we successfully prevented aggregation of PDI derivatives by constructing 3D molecular structures with multiple PDI units. The numbers and substituting positions of PDIs on the DPP core were also investigated in detail, which provided valuable insights for designing of high performance PDI derivatives for PSCs.

As the third-generation emitters for organic light-emitting diodes (OLED), thermally activated delayed fluorescence (TADF) materials have attracted widespread attention from both academic and industrial communities in recent years. In TADF molecules, the triplet excitons can be upconverted to the singlet state with the aid of ambient thermal energy by virtue of the reverse intersystem crossing (RISC) owing to the small singlet-triplet splitting energy (ΔE_ST). Therefore, 100% exciton utilization efficiency can be theoretically realized by harvesting both singlet and triplet excitons. Consequently, the external quantum efficiencies of OLEDs can be significantly improved compared with the first-generation devices based on conventional fluorophores. TADF materials are regarded as an effective potential solution to break through the bottleneck of highly efficient and stable blue organic electroluminescence (EL). Generally, TADF molecules is a purely organic push and pull system containing at least an electronic donor and acceptor. The Δ E_ST, frontier orbital distributions, aggregation structures, EL colors and device performance can be effectively tuning by changing the structures and quantities of the donor and the acceptor, the substituents and their substituted positions. Meanwhile, the substituents of TADF molecules play a crucial role in the regulation of the strengths of donor and acceptor, molecular configurations, aggregation structures, stabilities and other physical and chemical properties. The substituent effects of purely organic blue TADF molecules from D-A type and multiple-resonance type blue TADF molecules are summarized, in the hope of providing effective reference for the design and synthesis of high-efficiency and stable blue light TADF molecules.

The origin of life attracts more and more attentions of researchers. Synthetic biologists are devoting to construct a simple and rational system which can exist in primitive earth. Coacervate is a phase separation system which is formed by the interactions of polyelectrolyte. It's a rational protocell model. So far, coacervate has been found to present as membraneless organelles in natural cells. Therefore, the construction of coacervate as artificial organelles is emerging. The formation mechanism, characteristics and categories of coacervate are reviewed in this paper. Additionally, the applications of coacervate as protocell and artificial organelles are summarized. The existing scientific problems and the future development directions are provided at the end of this paper.

Boron nitride nanosheets (BNNSs), also known as “white graphene”, is an important nanofiller with excellent mechanical properties, thermal conductivity, abrasion resistance, barrier properties, and hydrophobicity. It is also a new type of excellent performance insulation materials. It is widely used in heavy-duty anti-corrosion coatings, lubricants, sensors and other fields. Based on the huge application prospects of BNNSs in the field of metal corrosion protection, this article systematically summarizes the preparation and surface functionalization of BNNSs, boron nitride thin film protective coatings, BNNSs/organic protective coatings, BNNSs-inorganic materials/organic protective coatings, and focuses on the detailed analysis and existing problems of BNNSs uniformly dispersed in organic coatings and used for metal corrosion protection. The future development of BNNSs-based anticorrosive coatings is prospected.

Nitric oxide (NO) is a ubiquitous physiological signal messenger, but the use of NO as a trigger event to delicately tune the self-assembly behaviors of biomimetic polymers has been far less exploited. In this work, a single primary amine-containing 2-(3-(2-aminophenyl)ureido)ethyl methacrylate (APUEMA) monomer was first synthesized by the reaction between o-phenylenediamine and 2-isocyanatoethyl methacrylate. Then, the well-defined double hydrophilic block copolymer (DHBC), poly[oligo(ethylene glycol)methyl ether methacrylate]-b-poly[2-(3-(2-aminophenyl)ureido)ethyl methacrylate-co-4-(2-methylacryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole)] (POEGMA-b-P(APUEMA-co-NBD)), was synthesized via sequential reversible addition-fragmentation chain transfer (RAFT) polymerization. Since there is a free amine group in the APUEMA monomer, it can be competent to quench the fluorescence of dyes and react with NO showing NO-responsiveness property. The reaction product of APUEMA and NO was purified by column chromatography, and ¹H and ¹³C NMR results displayed the formation of urea-functionalized benzotriazole residual. The pK_a values of APUEMA monomer and POEGMA-b-P(APUEMA-co-NBD) block polymer were measured to be 3.36 and 2.15, respectively, indicating that APUEMA monomer and PAPUEMA moieties of POEGMA-b-P(APUEMA-co-NBD) showed hydrophilic ability at acidic medium and hydrophobic ability at neutral medium. The aqueous solution of POEGMA-b-P(APUEMA-co-NBD) block copolymer exhibited a small diameter with about 5.0 nm at pH 2.0, which illustrates that block copolymer can dissolve into water with a unimer state. After changing the solution pH value to 7, the solution diameter increased to about 10 nm recorded by dynamic light scattering (DLS). Transmission electron microscope (TEM) results displayed micelles of POEGMA-b-P(APUEMA-co-NBD) block copolymer aqueous solution with spherical structures at pH 7.4. Furthermore, the fluorescence intensity of the block copolymer solution was decreased quickly after the pH value increased from 2 to 7. The NO-responsive property of block copolymer POEGMA-b-P(APUEMA-co-NBD) was also detected by DLS and fluorescent spectrometry methods. At pH 2.0, the diameter of the block copolymer aqueous solution increased from 5 nm to about 150 nm upon sparging with NO for 24 h. At pH 7.0, the diameter of block copolymer micelles increased from 10 nm to about 100 nm after exposure to NO for 24 h. The transmittance of POEGMA-b-P(APUEMA-co-NBD) block copolymer aqueous solution at pH 2.0 or pH 7.0 decreased upon NO addition, which were in accorded with DLS results. Moreover, the fluorescence intensity of the block copolymer solution at pH 2.0 improved rapidly upon sparging with NO for 0.5 h, implying that the NO-triggered self-assembly of micelles decreased environmental polarity. The fluorescence intensity decreased with further addition. The fluorescence intensity of block copolymer micelles at pH 7.0 exhibited 15-fold increased after addition with NO for 24 h. The in vitro study of block copolymer POEGMA-b-P(APUEMA-co-NBD) was conducted in normal MRC-5 cells. The block copolymer showed negligible cytotoxicity even at the block copolymer concentration of 100 g/mL. We herein report on a novel pH-responsive DHBC with unique NO-reactive feature, where NO can spontaneously trigger the self-assembly and morphological transformation in acidic and neutral milieus, respectively. After the introduction of fluorophores, these transitions are also associated with significant fluorescence turn-on due to eliminations of photoinduced electron transfer (PET) process in the presence of NO, imparting the opportunities to visualize intracellular NO.

Layered double hydroxides (LDHs) has played an important role in the field of catalysis because of its high dispersion of active sites, adjustable layer elements, and exchangeable interlayer anions. LDHs show excellent catalytic activity in oxygen evolution reaction (OER), due to the specific synergistic effect of double metals site. Thus, it is crucial to reveal the role of synergistic effect for promoting catalytic performance of photocatalyst and electrocatalyst. Although great efforts from experimental workers have been devoted to exploring the types and ratios of bimetals in LDHs, the role of synergistic effect on OER is still unclear. In this work, we systematically investigated the synergistic mechanism and the role of synergistic effect on OER performances based on density functional theory calculation plus U (DFT+U) method. Five kinds of LDHs (MN³⁺-LDH (M²⁺=Co²⁺, Ni²⁺; N³⁺=Al³⁺, Cr³⁺, Mn³⁺, Fe³⁺)) were built to study the synergistic effect from different bimetal. The results showed that oxygen species is bridged by one M²⁺and one N³⁺metal, forming a stable adsorption structure. For electrocatalytic OER, the synergistic effect of the bimetallic sites decreased the free energy change of the potential-determining step, and further reduces the overpotential of the electrocatalytic oxygen evolution reaction. Therein, Ni₃Fe-LDH has the lowest overpotential, exhibiting superior electrocatalytic OER activity among the five LDHs. This is not the case in photocatalytic OER, the synergy of bimetals affects the band gap, work function and driving force of LDHs, which determine the ability of LDH photocatalytic OER. The five types of LDH studied are all visible light response, and Ni₃Cr-LDH is predicted to be a good OER photocatalyst in view of its higher driving force than the overpotential. This work reveals the synergistic effect of bimetal in LDH on OER activity from a micro-atomic level, which will provide theoretical insights for the design of novel LDH-based catalysts.

Electrocatalytic biomass conversion, which utilizing the electrical energy generated by intermittent energy, drive biomass into high value-added organic chemicals, and usually can be coupled with water splitting for the production of high-purity hydrogen. It has the potential to significantly decrease fossil fuel consumption, optimize energy structure and solve environmental issues. However, because biomass possess multiple groups and its conversion involves multiple electrons, electrocatalytic biomass conversion suffer from low conversion efficiency, bad selectivity and poor stability. Surface and interface chemistry engineering, such as regulating intrinsic structure, generating vacancies, introducing heteroatom, and constructing synergistic interface, can design and modify two-dimensional electrocatalysts to optimize their electronic structure and geometric structure, and effectively improve the electrocatalytic efficiency, selectivity and stability. This review provides an overview of recent advances about the role of surface and interface chemistry played on electrocatalytic biomass conversion of two-dimensional materials. In addition, the authors also give some perspectives on the challenges and prospects in this field.

Electrocatalytic carbon dioxide reduction is the focus and nodus of energy chemistry and catalytic science. As a basic concept in physical chemistry, gas-solid-liquid triphase interface model has been widely studied in electrocatalytic carbon dioxide reduction reaction in recent years, showing many advantages compared with traditional solid-liquid biphase systems. In this review, we discuss the research progress of triphase interface eletrocatalytic carbon dioxide reduction, focused on the classification as well as the principle of triphase interface eletrocatalytic systems. Then, carbon dioxide electroreduction properties of various triphase systems including underwater superaerophilic and gas diffusion layer systems are discussed, with special attention on the influence factors, such as the interfacial diffusion and interfacial wettability of reactants. Finally, we summarize and prospect the existing problems and the future development direction of electrocatalytic carbon dioxide reduction based on triphase systems.

Aqueous sodium-ion batteries recently have been widely and deeply studied in the energy field due to their prominent advantages such as high safety, low cost and environmental friendliness. Remarkable progresses of aqueous sodium-ion batteries gradually encourage their process of industrialization. However, compared with the organic secondary ion batteries, the development of aqueous sodium-ion batteries is limited by the narrow stable voltage window of the electrolyte and the poor cycle stability of the electrode material. How to solve these problems is still the key to the development of aqueous sodium-ion batteries. The latest developments in electrode materials, electrolyte and current collector of aqueous sodium-ion batteries, as well as challenges and possible solutions for developing high-performance aqueous sodium-ion batteries are mainly summarized in this review. Furthermore, the development prospects of aqueous sodium-ion batteries are discussed.

Carbon dots (CDots) not only possess the characteristics of strong luminescence and small size similar to traditional quantum dots, but also show the advantages of good water dispersibility and biocompatibility beyond traditional quantum dots. As an emerging branch of the quantum dots family, the structure, synthetic chemistry and photoelectric properties of CDots are quite different from those of traditional quantum dots, which also provide new opportunities and challenges for the development of quantum dots. With the rapid development and deepening of the field of CDots, it is more and more necessary to compare them with traditional quantum dots on some basic concepts, and to clarify the unique characteristics and key challenges of CDots from the view of traditional quantum dots. In this review, we focus on the aspects of basic structure, synthetic chemistry, optical properties and application research, in an effort to reexamine the research progress and challenges in CDots from the view of fundamental concepts of traditional quantum dots.

Furin, the most characteristic member of the proprotein convertase (PCs), has important biological functions. The expression level of furin is related to many diseases, for example, the occurrence and development of cancer is closely related to the expression level of furin. Although several small-molecule fluorescent probes for furin have been developed, which were designed based on near-infrared dye or one-photon dye. These probes exhibit low Stocks' shift or shallow penetration depth, which leading to self-quenching and strong interference. Two-photon fluorescent probes, which utilize two near-infrared photons as the excitation source, can overcome these problems. Herein, a furin-activatable two-photon fluorescent probe (Nap-F) was developed firstly that allowed for detection and imaging of furin in live cells and tumor tissues. Nap-F consists of a classical two-photon fluorophore (1,8-naphthalimide), a furin-particular polypeptide sequence RVRR and a self-eliminating linker. Nap-F is water-soluble and in a fluorescence-off state itself due to the inhibited intramolecular charge transfer (ICT). In the absence of furin, no noticeable fluorescence enhancement was detected, even over 3 days in buffer solution, indicating its good stability. Upon the conversion by furin, it displayed a dramatically fluorescence enhancement at 545 nm, and exhibits high specificity and sensitivity to furin. Nap-F was applied for visualizing the difference in the expression level of furin in various cells, demonstrating its capacity of distinguishing some cancer cells from normal cells. Furthermore, Nap-F was utilized to visualize the variation of furin expression level efficiently after immobilization of hypoxia-inducible factor-1 (HIF-1) by CoCl₂, with the results indicating that there is a positive correlation between the expression level of furin and the degree of hypoxia in tumor cells. Owing to the excellent property of Nap-F, the probe was also successful utilized to imaging furin activity in tumor tissues. Thus, Nap-F is able to serve as a potential tool for better exploring the intrinsic link between hypoxic physiological environment and cellular carcinogenesis and detecting cancer in preclinical applications.

Over the past few years, the external quantum efficiency (EQE) of organic-inorganic hybrid perovskite light-emitting diodes (LEDs) has experienced a tremendous progress. The reported highest EQE of infrared and green perovskite LEDs has reached 21.6% and 20.3%, respectively, which is comparable to commercial organic light-emitting diodes. Even the slightly inferior blue perovskite LEDs have a recorded EQE of 12.3%. However, poor device stability is the biggest problem hindering the commercial application of perovskite optoelectronic devices, which is a severer problem in LEDs because the higher operating voltage will trigger acute ion migration. Encouragingly, however, the lifetime of perovskite LEDs has increased from the initial several seconds to over 200 hours, presenting a dramatic progress. The outstanding performance of perovskite LEDs is closely related with the excellent material properties, including tunable bandgaps, narrow full width at half maximum (FWHM), high defect tolerance, high electron/hole mobility and solution processibility. Moreover, the diversity of components and structure of perovskite makes the addition of various additives effective, enabling optimizing device performance through kinds of chemical methods. In this review, we analyzed the impacts of component and structure designing on the efficiency and stability of perovskite LEDs from the perspective of compositional designing, defect passivation and interfacial modification. We analyzed how compositional designing affects the optoelectronic properties through altering the ratio between organic and inorganic components or adding other molecules and ions to adjust the dimension of perovskites. As for defect passivation, we discussed various passivating reagents and their working mechanism. In addition, we summarized the significance of interfacial modification between different functional layers, including improving the wetting property of the substrates, achieving higher crystal quality of perovskite films, passivating the defects at the interfaces, blocking leakage current and reducing hole/electron injecting barrier. Finally, we discussed the scientific and technological challenges yet to be resolved before perovskite LEDs can be considered for commercial applications.

Carbon monoxide (CO), an extremely important gasotransmitter, plays a critical role in a variety of physiological and pathological events, thus having been considered as a pharmaceutical activity compound with broad medical application. The physiological effects of CO are determined by its dose and spatial location. Therefore, the specific recognition of CO and its controllable supplying are of great significance for understanding and effectively utilizing its physiological and pathological effects. Fluorescence detection and photocontrolled releasing have been widely applied to track and carry active molecules in cells, tissues and in vivo in view of their unique spatiotemporal controllability and noninvasive capacity. Herein, the research progress of CO organic fluorescent probes and photocontrolled releasers in recent years is reviewed, focusing on their recognition mechanism, release mechanism and biological applications. Finally, the application prospects and challenges are discussed.

Chiral metal-organic frameworks have shown important applications in the identification and separation of enantiomers and asymmetric heterogeneous catalysis, owing to their structural diversities and multifunctionalities. Recently, the applications of chiral metal-organic frameworks have been expanded to other research fields, such as circularly polarized luminescence and chiral ferroelectrics. Compared with achiral metal-organic frameworks, it is highly challenging to synthesize chiral metal-organic frameworks, because the chirality introduction usually results in the difficulty of the crystallization and purification process for the design of chiral metal-organic frameworks. In this review, we discussed three main strategies that have been utilized to construct chiral metal-organic frameworks, including direct synthesis by chiral ligands, spontaneous resolution with achiral ligands or in the presence of chiral-template, and post-synthetic modification of achiral metal-organic frameworks. Moreover, the recent research progresses of chiral metal-organic frameworks in chiral molecular recognition, enantiomer separation, asymmetric catalysis, circularly polarized luminescence, and chiral ferroelectrics are discussed.

Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are representative crystalline porous polymers. Due to their high surface area, high porosity, open channels, abundant functional groups and easy functionalization, they show great applications in gas storage and separation, catalysis, energy storage, photovoltaic devices, etc. Amino acids are the basic structural units that constitute peptides and proteins, which not only have important biological functions, but also play an important role in industrial applications such as pharmaceutical production, biodegradable plastics, and chiral catalysts. The introduction of amino acids into MOFs and COFs could endow them with diverse and flexible frameworks, special pore environment, and chiral sites, improving their biocompatibility and degradability to some extent and enriching their functions and applications. This review focuses on the progress of the amino acid functionalized MOFs and COFs, including their synthetic strategies, such as employing amino acids and their derivatives as building unit, covalent modification of amino acids onto the framework, and utilizing amino acids as modulators. The advantages and disadvantages of these strategies are compared and their challenges are discussed. In addition, we also introduce their applications in chiral separation, catalysis, adsorption and proton conduction. Finally, we summarize the current challenges in the preparation of amino acid functionalized crystalline porous polymers and outlook the future research direction in this field.

Doping is an effective method to improve the carrier densities and charge transport capabilities of organic semiconductors. In recent years, n-doping of organic semiconductors via Lewis base anions has attracted much attentions of researchers, which takes place under mild condition and controllable fashion, hence exhibiting broad applications in optoelectronics. This perspective focuses on discussing the mechanism of anion-induced electron transfer to semiconductors, summarizing its recent progresses in interfacial materials and doped active layers for optoelectronic devices, as well as analyzing the future development of this field.

The development of new synthetic methodology and reagent is always a hot topic in organic synthesis community. Among the strategies used, chemical property investigation of synthetic intermediates with multifunctional groups represents a direct and efficient way. In this paper, as a systematic continuation of α-aminomalononitrile based synthetic application studies, α-aminomalononitrile has been developed for the first time as a surrogate for carbamoyl anions and applied to the synthesis of tertiary amides via a copper-catalyzed decyanation reaction. This strategy features simple reaction conditions, scalability, and wide substrate scope. This work not only further enriches the reaction model of aminonitrile compounds, but also provides an alternative synthetic strategy for the synthesis of substituted amides from simple formamides. In this process, the substrates could be readily synthesized through the nucleophilic addition or substitution reaction of α-aminomalononitriles, and they would be converted to corresponding tertiary amide in the presence of CuF₂ in DMSO. As an example, the formal hydrocarbamoylation reaction of unsaturated bonds could be achieved. A general procedure for the strategy is as follows:α-aminomalononitrile derived from formamide is used to undergo nucleophilic addition or substitution reaction with electrophilic reagents. Next, the two cyano groups of the synthesized substrates could be removed under the catalysis of CuF₂ to form a C=O double bond in situ, thereby achieving the synthesis of corresponding tertiary amide. During the reaction, the α-aminomalononitrile substrate (0.4 mmol), CuF₂ (5 mol%), DMSO (3 mL) were placed in a sealed reaction tube at 100℃ at an argon atmosphere for about 32 hours. Then, the reaction system was washed out with ethyl acetate, and the organic phase was washed with water to remove DMSO. Next, the aqueous phase was extracted with ethyl acetate. Finally all organic phases were combined, washed once with saturated brine. After drying the organic phase over anhydrous sodium sulfate, it was concentrated by a vacuum pump. Finally, the residue was purified by flash column chromatography to give amide product.

Indolizine is an important N-containing heterocyclic nucleus and their derivatives display interesting biological activities. The development of synthetic methods towards indolizine derivatives has attracted extensive attention. Despite the rapid growth in this area, asymmetric synthesis of indolizine derivatives has been rarely reported. Ir-catalyzed asymmetric allylic substitution reaction is an efficient method for the enantioselective construction of C-C or C-X bonds, furnishing terminal olefins bearing a stereogenic center at the allylic position with excellent regio- and enantioselectivities. In this regard, various electron-rich arenes, including indoles, pyrroles, naphthols, have been applied as the nucleophiles via Friedel-Crafts type process in the allylic substitution reactions. As a class of constitutional isomers of indoles, indolizines are now demonstrated as suitable nucleophiles in transition-metal-catalyzed allylic substitution reactions. Herein, an iridium- catalyzed enantioselective allylic substitution of allylic alcohol with indolizine is reported. A broad range of 3-allylindolizines were accessed with high yields (83%~95%) and excellent enantioselectivities (95%~>99%ee). A general procedure for the asymmetric allylation of indolizines is described in the following: A flame-dried Schlenk tube was cooled to room temperature and filled with argon. To this flask were added [Ir(cod)Cl]₂ (4.0 mg, 0.006 mmol, 3 mol%) and (S)-L1 (12.1 mg, 0.024 mmol, 12 mol%). After the flask was evacuated and refilled with argon for three times, freshly distilled dichloromethane (DCM) (2 mL) were added. After the mixture was stirred for 15 min at room temperature, indolizines (0.2 mmol, 1.0 equiv.), allylic alcohols (0.4 mmol, 2.0 equiv.) and (PhSO₂)₂NH (18.0 mg, 0.06 mmol, 30 mol%) were added under argon atmosphere. The reaction mixture was stirred at room temperature and monitored by thin-layer chromatography (TLC). Once indolizines were consumed, the reaction was diluted with water (5 mL), and the mixture was extracted with EtOAc (10 mL×3). The organic layer was collected, dried over Na₂SO₄ and then concentrated in vacuo to afford the crude product. This crude material was purified by column chromatography to afford the product.

Ammonia is not only an important chemical for fertilizer and industrial chemical, but also an ideal carrier of clean energy. Current ammonia synthesis is mainly based on Haber-Bosch process that suffers from some problems such as high energy consumption, low conversion and large amount of greenhouse gas emission, so the solar ammonia synthesis from N₂ and H₂O has recently attracted extensive attention. However, both conversion and Faradaic efficiency via the solar-based catalysis have been still retarded by poor surface catalysis process. Accordingly, development of efficient electrocatalysts for N₂ reduciton reaction (NRR) as well as their coupling with photoadsorbers is highly desirable. The recent research progress in the following areas is summarized in this review: i) main electrocatalysts for NRR, including thermal catalyst, transition metal catalyst, noble metal catalyst and non-noble metal catalyst, ii) typical strategies to improve the NRR performance and iii) other routes using different nitrogen sources such as NO₃ ^– and NO. Finally, the remaining challenges and perspectives will be outlined.

This perspective summarizes the research progress of metal-organic frameworks (MOFs) materials used in lithium-ion battery/lithium-metal electrolytes. By summarizing several long-standing defects of lithium-ion batteries/lithium- metal batteries, MOFs materials are subsequently used as ion sieves, artificial electrode protective layers, quasi-solid electrolytes and used to adjust electrolytes’ configuration, the performance of batteries has been significantly improved. Finally, based on the characteristics of MOFs materials themselves, this perspective also makes a reasonable forward-looking outlook on the subsequent applications of MOFs materials in the field of electrochemical energy storage.

The photocage is a light sensitive substance for photo-controlled release, which is formed by combining the target substance with photosensitive group and other functional groups through physical and chemical methods. Under the irradiation of the specified band, the photocage releases the target substance. It is widely concerned because it can realize space-time control, which means that the time and place of release are controllable. The advantages of simple operation, easy control, strong modification ability and small body damage make it widely used in chemistry, biology, materials science and medicine. In this paper, we introduced and discussed the research progress of photocages in photo-controlled release of metal ions, gases, fluorescent substances, amino acids, peptides, enzymes, proteins, drugs and other target substances in recent 10 years.

Lithium-rich manganese-based oxides (LRMO) are promising cathode materials to build next generation lithium-ion batteries because of high capacity and low cost. However, the severe capacity fade and voltage decay, which originate from surface oxygen loss, side reactions and irreversible phase transformation, restrict their practical application. Proposed approaches to address these issues include electrolyte modification, synthesis condition optimization, tuning elemental composition, bulk doping and surface coating. Surface coating has been proved to be an effective method to stabilize the interface between LRMO and electrolyte. Herein, we report a facile approach to synthesize Li₃PO₄-coated LRMO (LRMO@LPO) by in-situ carbonate-phosphate precipitate conversion reaction. The formation of Li₃PO₄ layer and its contribution to enhanced electrochemical performance are investigated in detail. Transmission electron microscopy (TEM) reveals that the surface of carbonate precursor converts to Ni₃(PO₄)₂ after reacting with Na₂HPO₄ solution, which finally transforms to Li₃PO₄ coating layer with thickness below 30 nm during calcination process. Quinoline phosphomolybdate gravimetric method gives the optimal Li₃PO₄ coating content of 0.56%. The modified LRMO@LPO sample exhibits improved cycling stability (191.1 mAh·g^-1 after 175 cycles at 0.5C between 2.0~4.8 V and 81.8% capacity retention) and suppressed voltage decay (1.09 mV per cycle), compared with bare LRMO material (72.9% capacity retention, 1.78 mV per cycle). The electrodes are studied by galvanostatic intermittent titration technique, electrochemical impedance spectroscopy, TEM and inductively coupled plasma atomic emission spectrometry. The results suggest efficient mitigation of phase transformation and dissolution of transition metal in LRMO@LPO. As a coating material with lithium-ion conductivity, Li₃PO₄ not only acts as a physical barrier to inhibit side reaction between the electrolyte and LRMO, but also promotes lithium ion transport at the surface region of cathode. The in-situ surface modification approach simplifies the traditional post coating process, and may provide new insight to build stable and low cost Li-rich cathode for lithium-ion batteries.