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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Organic dyes are widely applied for cloth dyeing process, paper printing, cosmetics, and food processing industries. The toxicity of industrial dyes poses serious threats to water and human health. Thus, several methods such as adsorption, degradation, and photocatalytic oxidation or reduction have been proposed to remove dyes from water. Among them, with low cost and high adsorption efficiency, porous materials become the most common materials to remove organic dyes from aqueous solutions. Notably, covalent organic frameworks (COFs) are a kind of novel crystalline porous polymers with regular pores, modifiable frameworks, high specific areas and excellent stability. Because of their outstanding properties, COFs have been used in many fields, such as gas adsorption and separation, heterogeneous catalysis, semiconductors and sensors. Especially the introduction of the nitrogen-containing functional groups to the COF skeletons provides abundant active sites to adsorb specific dyes in the field of dye adsorption. Inspired by this, a novel amide-functionalized two-dimensional COF (termed as JUC-578) was successfully prepared through Schiff-based condensation reaction of 4,4'-diaminobenzanilide (DABA) and 1,3,5-benzenetricarboxaldehyde (BT). A series of characterizations proved that JUC-578 has high crystallinity, uniform morphology and opening one-dimensional mesoporous pores. Especially the morphology of JUC-578, which was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), showed a clear spherical structure with uniform morphology distribution and smooth surface. Moreover, we studied the reversible adsorption of JUC-578 on dyes from aqueous solutions by UV-Vis spectrophotometry. The results show that JUC-578 can selectively adsorbed cationic dyes and the structure remained stable after cycling, which was attributed to the electrostatic interaction between the electron donor nitrogen in the skeleton and the electron-deficient dyes as well as other weak interactions (hydrogen bonding, coupling, etc.). Meanwhile, the crystallinity and ordered pores of JUC-578 are also important factors for reversible dye adsorption. These results indicate that COFs as functionalized porous materials have great potential in dealing with environmental problems.

Metal-organic frameworks (MOFs) are a growing class of organic-inorganic hybrid crystalline porous materials, showing high levels of structural and chemical diversity. They have a wide range of applications in gas adsorption and separation, catalysis, sensing, biomedicine and other fields. Due to their intriguing properties such as high porosity, adjustable pore size and tunable surface functionality, MOFs have been gaining popularity as a promising platform for integration of various organic/inorganic functional nanomaterials in a predictable and controllable way. The combination of MOFs and functional components offers a possibility to generate synergetic effect between functional units, thus leading to the creation of multifunctional materials with performance superior to each individual components. In this review, we summarized recent research progress on controllable synthesis of MOF composites. There are basically two strategies, including “bottle in ship” and “ship in bottle”. Following that, preparation methods including solution infiltration, deposition, solid grinding and template synthesis, were discussed in detail. Light-to-heat conversion materials have always been a research focus due to their important applications in solar powered water evaporation and near-infrared (NIR) excited bioimaging and noninvasive cancer treatment. MOFs can not only show intrinsic structure-dependent photoresponse activity, but also serve as porous supports to facilitate the stabilization and spatial distribution of photothermal nanoparticles. Recently, MOF composites with photothermal effects have aroused increasing attention in the fields like tumor diagnosis and treatment, bacterial disinfection and synergistic catalysis. This review mainly focused on the recent research progress on photothermal MOF composites. We discussed the integration of functional MOFs with various inorganic/organic photothermal nanoparticles (e.g. Au, Pt, porphyrin, polydopamine etc.), along with the structure and photothermal application of the composites. Research about MOFs based light-to-heat conversion is at the stage of rapid development. Finally, we also give a prospect to the future development of multifunctional and photothermal MOF composites.

Organic solar cells (OSCs), based on organic semiconductor materials as photoactive layers, have attracted broad interest as a promising next-generation photovoltaic technology, since they can be fabricated into low-cost, colorful, semitransparent, flexible, and large-area devices through printing process. In the past decades, enormous efforts have been dedicated to improving power conversion efficiencies (PCEs) of OSCs, such as designing high-performance photovoltaic materials, optimizing device interfacial layers, controlling active layer morphology, developing new device architectures, and elucidating device working mechanism. Nowadays, the PCEs of small-area OSCs have exceeded 18%. In addition, in order to realize commercialization of OSCs, considerable progress has been made in manufacturing large-area OSCs, reducing cost, improving lifetime, and exploring potential applications in building integrated photovoltaics and indoor photovoltaics. Chinese researchers have made pioneering and leading contributions in this field. In this review, first, we briefly introduce basic knowledge of OSCs; then, summarize important recent research progress in terms of molecular engineering, device engineering, device physics and application exploration; finally, analyze challenges and future prospects of this field.

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.

Hydrogen with remarkable energy density has attracted much attention as the green, sustainable chemical energy carrier and a substitute for traditional fossil fuels. The discovery of safe and efficient hydrogen storage materials for the transition to a hydrogen energy society is one of the biggest challenges for hydrogen energy applications today. Hydrous hydrazine (N₂H₄•H₂O), with its high hydrogen content (w=8.0%) and the advantage of CO-free hydrogen production, has significant advantages in hydrogen storage and release and is considered as a promising liquid-phase chemical hydrogen storage material. The development of efficient and highly selective catalysts is the key to release hydrogen from the decomposition of hydrous hydrazine. In the past decade, a lot of catalysts have been developed to improve the kinetic properties for hydrogen generation. In this review, we focus on the recent progress on catalyst design, synthesis and catalytic performance of the catalyst in hydrogen production from the selective decomposition of hydrous hydrazine. Ir, Rh and Ni monometallic catalysts were found to be very active toward the dehydrogenation of hydrazine. Among all the catalysts investigated, supported Pt-Ni, Rh-Ni and Pt-Co catalysts showed the highest activity. The mechanism of hydrazine decomposition was briefly analyzed. The cleavage of the N―H bond of N₂H₄ will facilitate the formation of H₂ and N₂, while N―N bond cleavage will result in the formation of NH₃ and N₂. In addition, we reviewed and discussed the strategies for promoting H₂ selectivity and activity of catalysts, such as the addition of strong base and/or alkaline carrier, formation of metal alloys, reduction of metal crystallinity and particle size, as well as the enhancement of the interaction between metal and support. The progress of this research may provide guidance for obtaining more active catalysts toward hydrogen production from nitrogen-based hydrides.

Selective catalytic reduction of NO_x with CO technology (CO-SCR) is supposed to be a cost-effective and environmentally friendly technique for NO_x abatement in the flue gas under CO-rich conditions. As a promising class of porous hybrid inorganic-organic materials, bimetallic metal-organic frameworks exhibit great physicochemical properties in catalysis area, whereas their application in low-temperature CO-SCR system are seldom reported. In this study, a series of bimetal organic-frameworks catalysts with different Ag contents were successfully prepared by a post-synthesis method and were assessed for NO reduction by CO. The typical experimental procedure for the synthesis of bimetallic Ag-Ni-MOF-74 catalysts is as follows: First, a light yellow Ni-MOF-74 sample was prepared by a hydrothermal method. Then 250 mg Ni-MOF-74, 1 mmol of NaBH₄ and AgNO₃ with different molar ratio (0.25, 0.5, 1 mmol) were added into 40 mL N,N-dimethylformamide (DMF) solution, and were stirred for 6 h. The mixtures were further moved into a Teflon-lined autoclave at 150 ℃ for 12 h. After washing with DMF and methanol, the obtained Ag_x-Ni-MOF-74 catalysts were dried at 60 ℃ under vacuum for 12 h. Totally, bimetallic Ag-Ni-MOF-74 catalysts exhibited a better low-temperature CO-SCR efficiency than monometallic Ni-MOF-74 catalysts. Especially, Ag₁-Ni-MOF-74 achieved a nearly 100% NO conversion in the temperature range from 200 ℃ to 300 ℃. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), and hydrogen temperature programmed reduction (H₂-TPR) techniques were used to investigate the structure and properties of the samples. It was found that Ag addition not only enriched the form of more active sites, but also increased the specific surface area of the catalysts, which promote the activation and transfer of reactants. The synergistic effect between Ag and Ni species also contributed to enhancement of surface oxygen vacancies and accelerated the electron transfer in NO+CO reaction. By combining XPS and in situ FT-IR results, the mechanism of CO-SCR reaction over Ag-Ni-MOF-74 was proposed to follow Langmuir- Hinshelwood (L-H) mechanism, which exhibits a more readily low-temperature reaction rate and a lower reaction barrier than Eley-Rideal (E-R) mechanism.

The conventional separation process of olefin/paraffin with cryogenic and high-pressure distillation usually exhibits high energy consumption and low efficiency. The adsorption separation technology is widely promising in the field of olefin/paraffin separation because of its mild operation conditions and high energy efficiency. In this work, high-throughput screening was adopted to find the optimal adsorbents from 12723 real metal-organic framework (MOF) materials, which is available for adsorption separation of 1,3-butadiene from C4 olefin/paraffin mixture. Firstly, 7681 adsorbents with suitable pore size and specific surface area were selected from the total database according to their structural parameters. Then their mechanical properties were computed by molecular mechanics. The mechanical properties of UIO-66 were used as the threshold to obtain 959 candidate MOFs with stable structure. Secondly, the grand canonical Monte Carlo (GCMC) simulation was performed to calculate the selective adsorption behavior of a quinary equimolar C4 olefin mixture in different candidate MOFs at 298 K and 0.1 MPa. According to their adsorption performance scores (APS) of 1,3-butadiene, the candidate MOFs are ranked to obtain 8 MOFs with the optimal adsorption and separation performance. The structural characteristics of MOFs with high adsorption and separation performance are revealed through quantitative structure-activity relationship, adsorption isotherm and ideal adsorption solution theory. The breakthrough curve simulation further verified that 2-cis-butene could effectively separate from 1,3-butadiene in the fixed bed filled with the optimal adsorbent RIGPEE01. Finally, it is determined that the preferential adsorption mechanism of 1,3-butadiene in RIGPEE01 is mainly due to the strong adsorption sites of Cu(I), π bond coupling effect and the size sieving effect based on the radial distribution function and binding energy analysis. The high-throughput screening method and the molecule-level insights on the olefin separation mechanism of MOFs proposed in this work have laid a theoretical foundation for the further development of new adsorbents for the separation of olefin/paraffin mixtures.

In recent years, the photoelectronic conversion efficiency (PCE) of organic-inorganic halide perovskite solar cell (PSC) devices has been improved greatly. However, these devices are not very stable, and it is hard to avoid the effect of visible or ultraviolet (UV) light on the performance decay of the organic-inorganic halide perovskite devices, and there is rare report on the evolution process of the microstructure of PSCs under the light illumination, let along discussing on the different degradation mechanism of PSCs between the UV and visible light soaking. To address these scientific issues, in this study, we compared the performance evolution of CH₃NH₃PbI₃ (MAPbI₃) based PSCs during the UV and visible light irradiation. The experimental results show that the perovskite layer has been photodegraded from MAPbI₃into an amorphous phase under the white light LED soaking. Meanwhile, the migration of Au element from the electrode into the interface between MAPbI₃ and SnO₂ layers can also be captured. As comparing the kinetics of redox reaction of Au, we found that the formation rate of Au nanoparticle mass in PSCs under UV light irradiation is almost 30 times higher than that under visible light illumination. Considering on the different characteristics of microstructure evolution in PSCs under the UV and visible light irradiation, and theoretically analyzing the energy level of each functional layers in the device, the results confirm that UV light is easy to be adsorbed by electron transportation layer (ETL) of SnO₂ to excite the electron-hole pairs, while the photo-excited holes have a low energy level of –8.4 eV, which could oxidize the iodide ions (I ^–) into atomic iodine (I atom). The I atoms would diffuse into the spiro-OMeTAD layer and metal electrode interface. Due to its strong oxidation property, the I atom would not only destroy the spiro-OMeTAD layer, but also oxidize the Au metal electrode into AuI, which accelerated the generation of Au⁺. However, under the illumination of visible light, it is hard to excite the electron-hole pairs in SnO₂, which prevents the damage on the functional interfaces, and the transportation energy barrier is unchanged. So, the open circuit voltage (V_oc) has a long-term photo-stability. However, the short-circuit current density (J_sc) decreased rapidly under visible light illumination, which is mostly ascribed to the changes of charge mobility resulting from the migration of Au element and photodecomposition of MAPbI₃ layer. All these results give a new insight to understand the photo-instability of PSC.

In the past few decades, organic solar cells (OSCs) have been extensively studied due to their advantages of semitransparency, light-weight and flexibility, which are considered to be an important renewable energy source in the future. Recently, bulk heterojunction all-small molecule organic solar cells (BHJ ASM-OSCs) composed of p-type small molecule donors and n-type non-fullerene acceptors as the active layers have achieved remarkable development and the power conversion efficiencies (PCEs) have exceeded 15%. The advantages of non-fullerene acceptors over fullerene competitors are their easily tunable energy levels, better absorption properties and proper molecular designs, which allow ASM-OSCs to achieve significantly higher open-circuit voltages, higher photocurrents and superior stability, thus extending the device lifetime of OSCs. Compared with p-type polymer donors, p-type small molecule donors have unique advantages, such as well-defined molecular structures, easy purification and low batch-to-batch variations. Although ASM-OSCs are expected to take advantages of non-fullerene acceptors and small molecule donors simultaneously, in consequence of inappropriate crystallinity and nano-scale bi-continuous interpenetrating networks in blended films resulting from similar acceptor-donor-acceptor (A-D-A) structures and physicochemical properties between small molecule donors and non-fullerene acceptors, the PCEs of current state-of-the-art ASM-OSCs are still much lower than that of polymer-based OSCs. In this review, based on the expansion of the central conjugated units of small molecular donors, we summarized the crystallinity of benzodithiophene (BDT), naphthodithiophene (NDT) and dithienobenzodithiophene (DTBDT) donors from the perspective of molecular design and provided suggestions for further molecular design and morphology improvement.

Solid oxide fuel cell (SOFC) is a clean and efficient power generation device, which has been widely used in recent years. However, its operation lifetime still needs to be improved to meet the requirements for further commercialization. The performance degradation of SOFCs is affected by many factors. It is very important to distinguish these factors and determine the dominant factor(s) for improving the operation lifetime in a more efficient manner. In this paper, the initial operation stage (<100 h) of SOFCs is mainly focused, in which the electrochemical performance changes most significantly. The electrochemical impedance spectroscopy (EIS) was periodically monitored during the operation process. Individual electrode processes of button cells and industrial-size cells were distinguished via distribution of relaxation time (DRT) method and subsequent equivalent circuit model (ECM) fitting. Through detailed time-varying analysis of EIS, the changes of different electrode processes in the initial-stage operation were obtained, and the evolution mechanism of electrochemical performance was proposed. After reduction, SOFCs go through activation stage and aging stage in turn: i) In the activation stage, the anode porosity increases and the gas-phase diffusion process is enhanced, resulting in the improvement of cell performance. ii) In the aging stage, the Ni particles in the anode agglomerate, so the effective three phase boundary (TPB) density decreases, which leads to the degradation of anode charge transfer reaction and the drop of cell performance. This evolution mechanism of electrochemical performance was partially confirmed by detailed microstructure characterization. It should be mentioned that the duration of each stage and the performance change in each stage can be affected by the initial electrode structure. Therefore, in previous studies, it was observed that some cells did not show activation process during initial-stage operation, but directly entered the aging stage. Besides, during longer-term operation of the cell (>100 h), we speculate that the dominant degradation mechanism is the continuous increase of the anode interface reaction-related resistance, which is caused by the agglomeration of Ni particles. However, since the anode structure is gradually stable, the degradation rate of cell performance decreases with respect to the operation time.

Aqueous zinc-ion batteries (ZIBs) have attracted more attention as large-scale energy storage technology due to their high safety, low cost and environmental benignity. To date, numerous cathodes based on manganese dioxide, vanadium dioxide, and polyanionic compounds have been reported. Among them, Manganese oxides have the advantages of low cost, non-toxicity, abundant materials and high working voltage, have been widely explored as promising cathodes for zinc ion batteries. Among them, MnO₂ cathodes are particularly desirable candidates for commercialization owing to their tunnel structure and affordability. α-MnO₂has (1×1) and (2×2) tunnel structures, and Zn²⁺ can rapidly inserted and deserted in the tunnel. However, the capacity of manganese dioxide is fast decaying with the cycles due to the poor conductivity of MnO₂, which limits its electrochemical performance. Herein, α-MnO₂ nanorods are uniformly distributed on the surface of porous carbon nanosheets network (PCSs) by a simple hydrothermal/dispersion method strategy. In the α-MnO₂/PCSs architecture, the α-MnO₂ nanorods and α-MnO₂/PCSs composite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), etc. The results testified that α-MnO₂/PCSs nanorods were firmly adhered on the surface of porous carbon nanosheets, which can effectively avoid the stacking of α-MnO₂nanorods, while the high conductive carbon network can improve the electrical conductivity of the composite. The porous network can provide effective electron transfer channels, provide stable hosts for fast Zn²⁺ extraction/insertion, and prevent the α-MnO₂nanorods from stacking each other. Benefiting from the unique porous structure and high conductive network, the α-MnO₂/PCSs hybrid shows high reversibility capacity, good rate performance, and outstanding cycling stability. Specifically, α-MnO₂/PCSs exhibits high reversible capacity of 350 mAh•g^–1 after 100 cycles at 0.1 A•g^–1 and maintains a capacity of 160 mAh•g^–1 at a high rate of 1 A•g^–1 after 1000 cycles, thus making it promising cathode for the high performance ZIBs.

Due to their advantages of low cost, flexibility and light weight, organic solar cells (OSCs) are considered to be a promising photovoltaic technology for practical applications and have received great attentions. The active layers of OSCs are the blends of conjugated small molecule/polymer electron donors and electron acceptors. Before 2013, the most-widely used electron acceptors are fullerene derivatives. Nevertheless, the weak absorption in the visible region, limited electronic tunability, and poor morphological stability hinder their further application in OSCs. Non-fullerene electron acceptors with good light harvesting ability and tunable energy levels have developed rapidly in past few years. Based on the types of electron donor and acceptor materials, non-fullerene OSCs may be classified into four types, including polymer donor/polymer acceptor blend (P_D/P_A), polymer donor/small molecule acceptor blend (P_D/M_A), small molecule donor/polymer acceptor blend (M_D/P_A), and small molecule donor/small molecule acceptor blend (M_D/M_A). Among various kinds of OSCs, M_D/P_A-type OSCs possess the excellent morphology stability under thermal stress, which is worthy of further study. Although the advantages of M_D/P_A-type OSCs, there are still large challenges in their development. The power conversion efficiencies (PCEs) of M_D/P_A-type OSCs are still much lower than that of other type OSCs, due to the limited material combination of small molecule donors and polymer acceptors and undesirable phase separation morphology of the active layers. In this review, we summarize the research progress of OSCs based on small molecule donors and polymer acceptors, and introduce the active layer material systems from three type polymer acceptors, i.e.the imide group, cyano group and boron-nitrogen coordination bond (B←N) unit based polymer acceptors. Benefiting from the development of both donor and acceptor materials as well as the manipulation of phase-separation morphology in active layers, the good match between small molecule donors and polymer acceptors is achieved. This not only boosts the large improvement in PCE from 0.29% to 9.51%, but also contributes to a high-temperature tolerant photovoltaic device. Finally, we also present an outlook of the future development of high-performance M_D/P_A-type OSCs.

Aerogel is a kind of nanoporous materials with important scientific research significances and great engineering application values. Its preparation process involves basic scientific issues such as sol-gel chemical transformation, structure control, and interfacial tension elimination. Aerogels are ideal lightweight super thermal insulation materials due to their ultra-low density and ultra-low thermal conductivity, which are attractive properties for the applications in aerospace, transportation, and other applications with strict weight requirements. Thanks to the characteristics of high specific surface areas, high porosity, and continuous open pore structure, aerogels also have important potential applications in the fields of adsorption, catalysis, drug carrier, energy and environmental remediation. Recent years, great research interests in aerogels have gained from both academic and industrial fields. This review gives a brief overview of the relevant literatures and intellectual property rights since the first report of aerogels, and systematically summarizes the preparation methods of aerogels, types of aerogels, dimensional structure designs, and novel applications of aerogels developed in the past five years. For example, supramolecular aerogels, stimuli-responsive aerogels, aerogel fibers, additive manufacturing of aerogels have subverted traditional materials to a certain extent and broke through the limitations of traditional preparation methods. Finally, a brief summary of aerogels in recent years and prospect for the development of aerogels in the future are made.

Binding free energy is the most crucial physical quantity for describing recognition-association of protein-ligand hybrids. Accurate estimation of protein-ligand binding free energies is of paramount importance in the field of drug design and biological engineering. However, the association process of protein-ligand hybrids is usually coupled with complex conformational changes of molecular objects, which is not amenable to the timescale of classical molecular simulations. This limitation makes it difficult to accurately estimate the protein-ligand binding free energies using classical free-energy calculation strategies. An effective solution is to apply geometric restraints to reduce the configurational space needed to be sampled, so as to boost up the convergence rate of simulations, and then calculate and deduct the contribution of these restraints to the binding free energy by post-processing. In this review, we firstly introduce the recent developments of three geometric restraints, namely, funnel, spherical, and seven-degree-of-freedom restraints, used in accurate binding free-energy calculations, with emphasis on the latest progress of the third one. Specifically, the theoretically rigorous seven-degree-of-freedom restraint describes translational, orientational, rotational, and conformational degrees of freedom by means of a center-of-mass distance, spherical angles, Euler angles and the root-mean-square deviation. Moreover, we demonstrate the theoretical backgrounds and methods of how to achieve accurate protein-ligand binding free-energy estimation by combination of geometric restraints and importance-sampling or alchemical algorithms. In the geometric routes, the degrees of freedom of the relative movement of the protein-ligand complex are addressed in a stepwise fashion by one-dimensional importance-sampling simulations. In the alchemical routes, a special thermodynamics cycle is designed, in which additional simulations are performed to address the contribution of the restraints. A general suggestion for how to choose a suitable strategy for a given molecular assembly based on our experience is provided. Last but not least, we discuss the applications and challenges of using accurate protein-ligand binding free-energy calculation methods in fields such as drug design, and present the possibility of extending these methods for investigating complex protein-protein interaction.

Photoredox catalysis is a practical and efficient synthetic technique that enables previously challenging or even impossible chemical transformations proceeding effectively. As one of the most prominent contribution to green chemistry, it provides a sustainable platform to the generation of high reactive radical species under mild reaction conditions. On the other hand, β-fluoro α-amino acids are significant structural units present in enzyme inhibitors, drugs and probes. Catalytic β-C(sp³)―H fluorination of α-amino acid represents a direct synthetic approach, but the harsh reaction conditions and the limited substrate scopes lead to high difficulty for these methodologies to being generalized to industrial application. Here, we report a novel and modular protocol that is via photoredox catalytic radical coupling. By using a dicyanopyrazine-derived chromophore (DPZ) as the photoredox catalyst, two readily accessible starting substrates, that are N-aryl glycine esters and α-fluoro-aryl acetic acid-derived redox-active esters (RAEs), can undergo single-electron oxidation and reduction, respectively. The resulting ester-substituted α-amino radicals and α-fluoro benzylic radicals then experience cross coupling, a highly reactive process in radical chemistry. As a result, a series of β-fluoro-α-amino acid derivatives were obtained in high yields. In this transition metal-free catalytic system, no extra oxidant or reductant is required, representing a redox neutral platform. General procedure for the synthesis of β-fluoro-α-amino acid derivatives is: to a flame dried Schlenk tube was sequentially added N-aryl substituted glycine esters 1 (0.4 mmol), RAEs 2 (0.2 mmol), DPZ (0.004 mmol, 1.42 mg), tetra-n-butyl- ammonium bromide (0.04 mmol, 12.9 mg), sodium dihydrogen phosphate (0.40 mmol, 48 mg) and cyclopentyl methyl ester (CPME) (4 mL). Then degassed three times by freeze-pump-thaw method. The reaction mixture was stirred under an argon atmosphere at 25 ℃ irradiated by a 3 W blue LED for 48 h. After completion of the reaction, the reaction mixture was directly loaded onto a short basified silica gel column, followed by gradient elution with petroleum ether/ethyl acetate (V/V, 8/1). Removing the solvent in vacuo, afforded products.

Cryopreservation is a science and technology of using ultra-low temperatures for the long-term storage of cells, tissues, or organs; also it ensures a recovery in function after thawing. Cryopreservation is currently the only effective method to realize long-term storage of biological samples, and it plays a critical role in areas of biomedicine such as cell therapy, regenerative medicine and organ transplantation. As the water content of cells and tissues can be as high as 70%~90%, ice formation inevitably occurs both intracellularly and extracellularly, which can be lethal because of the mechanical damage, the osmotic shock and excessive solute accumulations. Therefore, the scientific challenge of cryopreservation is to inhibit or control ice formation in the freezing/thawing processes. Traditional cryopreservation strategies use large amounts of small molecules, such as dimethyl sulfoxide (DMSO), as cryoprotectant (CPA) to permeate into the cells and prevent intracellular ice formation; which to some extends are successful in the cryopreservation of cells. However, these molecules are chemically and epigenetically toxic to cells. Meanwhile, these strategies have proved refractory for the cryopreservation of tissues and organs. Therefore, great efforts have been made for effective ice-controlling materials to regulate the ice formation during cryopreservation. In nature, many cold-acclimated species can avoid cold damage and survive in the subzero environment due to the existence of ice-regulating proteins, i.e., ice nucleating proteins (INPs) and antifreeze (glyco) proteins (AF(G)Ps). Inspired by these proteins, intensive investigations have been made to reveal the protection mechanism of the ice-regulating proteins in order to develop their mimics. It has been reported that the bio-inspired ice-controlling materials are more effective and safer CPA in cryopreservation in comparison to small organic molecules. Therefore, the present review will briefly summarize the history of cryopreservation for cells and tissues, and focus on the development of bio-inspired ice-controlling materials and their application in the cryopreservation of cells and tissues. At last, the challenges and possible directions of bio-inspired ice-controlling materials as cryoprotective agents will be briefed.

NAD(P)H:quinone oxidoreductase-1 (NQO1) is a cytosolic two-electron-specific reductase whose abnormal expression is associated with breast cancer, and NQO1 has been regarded as an important biomarker for monitoring the occurrence and development of breast tumors. Although there are some research reports involving fluorescent probes for imaging NQO1 in vivo, they generally suffer from the strong light scattering by tissues which would cause the spatial resolution of fluorescent signals degrade rapidly with imaging depth. On the other hand, as an emerging detection and imaging modality, optoacoustic tomography (OAT) is capable of providing more detailed information in deep biological tissues than fluorescent imaging, since in OAT ultrasound signals are the reporting signals. To overcome the inherent defects of fluorescent imaging, in this work, we developed a novel near-infrared (NIR) NQO1-activatable optoacoustic (OA) probe TPA-X-Q based on the push-pull internal charge transfer (ICT) scaffold. TPA-X-Q consists of a NQO1-responsive moiety, quinone propionate group and a NIR chromophore TPA-X-OH. In the absence of the enzyme NQO1, the probe displays nearly no noticeable OA signal upon NIR excitation. Whereas in the presence of NQO1, the quinone propionate group of TPA-X-Q is reduced and cleaved by the enzymatic reaction triggered by NQO1, and thus TPA-X-Q is transformed into TPA-X-OH, consequently evident OA signal is generated, thereby realizing the detection and imaging of NQO1. As for the probe, the limit of detection (LOD) is determined to be 0.193 μg·mL ^–1. Furthermore, the probe TPA-X-Q displays several advantages, such as quite good selectivity towards NQO1, low cytotoxicity and excellent photostability. Moreover, the probe has been successfully utilized to detect and image the overexpressed NQO1 in the breast cancer-bearing mouse model. Orthogonal-view three-dimensional (3D) images can also be obtained by using multispectral optoacoustic tomography (MSOT), and thus precise localization of the breast cancer tumors can be achieved. This probe holds great potential for being employed as an efficacious tool for diagnosing breast cancer via responding to NQO1.

With the awareness of human and public health increasing, biomedical research has been paid more and more attention. 2D intercalation materials with versatile physicochemical advantages have attracted extensive interest in biomedical applications. Layered double hydroxides (LDHs), as a class of typical 2D materials, have been widely utilized as various multi-function materials and exhibited great promise in biomedical applications. The general chemical formula of LDHs can be described as [M2+ 1–x M3+ x (OH)₂]^q+(A^n–)_q/n·yH₂O, where M²⁺ and M³⁺ refer to divalent and trivalent mental cations, respectively, and A^n– is an exchangeable anion, including inorganic, organic, biological compound, and even gene. LDHs have attracted a great attention in the field of biomaterials due to their good biocompatibility, pH sensitivity, biodegradability, high intracellular delivery efficacy and low cost, etc. In this review, we summarize the development of LDHs and related nanocomposites for biomedical applications including sterilization, cancer therapy, bioimaging, etc. In general, the LDH-based sterilization materials can be divided into four categories. The first type is the pristine LDHs and their derivatives named mixed mental oxides (MMO). The second type is organo-modified LDHs nanostructures, including surface modified LDHs and interlayer assembled biomaterials, which embed antibacterial agents or other biomolecules in the interlayer spaces. The last two are enzyme immobilized LDHs and Ag NPs deposited LDHs, respectively. In addition to sterilization, LDHs have also been applied to cancer diagnosis and therapy. We mainly introduce three types of cancer monotherapy, including photodynamic, photothermal and chemodynamic therapy. Moreover, cancer combination therapy and bioimaging for cancer diagnosis are also discussed. Furthermore, the large-scale synthesis of LDH-based materials plays a fundamental role in the potential biomedical applications in the future. Therefore, we summarize the feasible methods of large-scale production of LDHs reported in recent years. Among them, the SNAS (separate nucleation and aging steps) method with a simple and quick operation, and has realized the industrial scale-up production of LDHs. Finally, we also discussed the future challenges and opportunities of LDH-based biomaterials.

The third-generation energy electro-optical technology, perovskite solar cells (PSCs), have risen fast over the past decade. In view of the characteristic of intrinsic-semiconductor of organic-inorganic hybrid perovskite materials, as well as the multilayer planar architecture of PSC devices, the hole transport materials (HTMs) based on organic small molecules were introduced PSCs to make up of p-type layer, by which not only full-solid state PSCs were established, but also the highly efficient and stable PSC devices were attained. Currently, spiro-OMeTAD (2,2′,7,7′-tetrakis[N,N-di(4-methoxy- phenyl)amino]-9,9′-spirobifluorene) is still used as an universal benchmark material in the hole-transporting layer of PSCs, meanwhile the researches have make great effort to analyze and to improve the spiro-OMeTAD. For the prevailing molecule, the three-dimensional core of spirofluorene (SBF) offers a platform to integrate more hole-transporting units with less occupied space, and arylamine groups act as high electroactivity units due to their excellent p-type property. However, the classical SBF core has two major drawbacks: expensive preparation cost and monotonous modification positions, therefore the improvement orientation of spiro-OMeTAD is focused on the arylamine moieties. Along with the developments of molecular design of HTMs and corresponding synthetic methodology, a series of SBF-like aromatic-skeletons have been springing up and stepping into the field of HTMs in recent five years, e.g. spiro[fluorene-9,9′-xanthene], spiroacridine, spirothioxanthene and so on. These advancements expand the design space of HTM molecules, and enhance the efficiency and stability of PSCs. In consequence, we put eyes on the HTMs containing spiro aromatic-skeleton, and seek the structure elements of highly efficient materials. In this review, the high performance HTMs have been classified and summarized according to the type of spiro structure, further, their design solution and structure-performance relationship have also been refined. It is expected that the summarization and condensation would provide valuable strategies for HTMs design and promote the development of highly efficient and long-life PSCs towards practical application.

Enantioselective desymmetrization is a powerful strategy in asymmetric synthesis. By differentiating two identical enantiotopic functional groups through simple transformations, asymmetric desymmetrizations provide efficient protocols for the synthesis of chiral compounds from easily available starting materials. The strategy has been successfully applied in a broad range of organocatalytic and transition metal-catalyzed asymmetric reactions. Copper-catalyzed coupling reactions are one of the most important methods for the construction of aryl or alkenyl carbon-heteroatom bonds. But the asymmetric coupling reactions remain a great challenge. It may be because that the bonds are generally formed between sp²-hybrized carbon and heteroatoms like N or O, and no chiral carbon centers were involved in the bond formation process. By utilizing desymmetrization strategies, we have developed a variety of copper-catalyzed enantioselective aryl carbon-heteroatom bond coupling reactions. However, the research on copper-catalyzed asymmetric alkenyl C-heteroatom coupling is rarely reported, and only one example of enantioselective copper-catalyzed alkenyl C—O bond coupling was achieved recently by Liu and co-workers via the desymmetrization strategy. In a previous work, we reported a desymmetric intramolecular aryl C—N coupling reaction of 2-(2-iodobenzyl)malonamides for the synthesis of chiral 2-oxo-1,2,3,4-tetrahydroquinoline-3-carboxamides. During the course, we believed that such a desymmetrization strategy should also be applicable to alkenyl C—N bond coupling reactions. To explore this idea, in this work, an enantioselective alkenyl C—N coupling is developed. It is a copper- catalyzed intramolecular desymmetric reaction with 2-(3-iodoallyl)malonamides as the substrates. Under the catalysis of 10 mol% CuI and 15 mol% of chiral diamine ligand, the reactions of 2-(3-iodoallyl)malonamides proceeded smoothly at room temperature inN,N-dimethylformamide (DMF), with K₃PO₄ as the base. It afforded the desired 2-oxo-1,2,3,4-tetrahydro- pyridine-3-carboxamide products bearing quaternary stereogenic carbon centers in high yields and moderate enantioselectivities. An example of double alkenyl C—N coupling for the synthesis of chiral 2,8-diazaspiro[5.5]undeca-3,9-diene-1,7-dione spirocyclic product was also demonstrated. Although the enantioselectivity is unsatisfactory, the reactions expanded the scope of copper-catalyzed asymmetric C—N coupling from aryl to alkenyl C—N coupling. It may find further applications in the synthesis of chiral heterocycles.

Lithium metal batteries (LMBs) are regarded as one of the most promising candidates for next-generation high-energy-density devices, due to the high theoretical specific capacity and low electrochemical potential of lithium metal anode. However, the uncontrollable growth of Li dendrite, unstable Li/electrolyte interface and infinite volume fluctuation during charge/discharge process give rise to low Coulombic efficiency, poor cycle stability and even serious safety hazard from internal short-circuit via dendrite penetration through separators. These multifaceted problems severely hinder the practical applications of LMBs. Featured by high specific surface area, low density, controllable pore structure, and flexible molecular design of pore surface/skeleton functionality, porous polymers have received growing attention in electrochemical energy storage, especially for lithium anode protection. The nanopores and tailored functionalities could allow for facilitated Li ion transport, while inhibiting anions and regulating the grain size and distribution of LiF. The large pores are conducive to accommodating lithium deposition and lowing of local current density. Consequently, porous polymers have become the “new favorite” in the field of “dendrite-free” LMBs recently, which show great potential for stabilizing Li metal anode. However, explorations in this field still remain in their infancy, and the objective of this review is to briefly summarize the research progress of porous polymers, especially crystalline covalent organic frameworks for lithium metal anodes protection, by means of constructing the artificial solid electrolyte interphase layer, coating separator with functional layers and designing metal anode structure.

To form “bridge” via the self-assembly of block copolymer provides a useful way for the fabrication of network structures of excellent mechanical properties, which is promising in applications. However, previous work has hardly paid attention to the impact of “bridge” on the self-assembly behavior of block copolymers. This account provides a review of a recent progress about the control of the self-assembly behaviors of block copolymers via the stretching degree of the bridging block. Accordingly, we have purposely designed BABCB linear multiblock copolymer. When BABCB copolymer self-assembles into binary mesocrystal structures (sphere or cylinder), the middle B-block connects a pair of A and C domains (“macromolecular atom” aggregated by blocks) naturally forming bridge. The stretching degree of the middle bridging B-block can be increased by reducing its length relative to the other two B-blocks, lowering the coordination numbers (CNs) of mesocrystal. Moreover, the asymmetry of CNs between A and C “macromolecular atoms” can be tuned by the asymmetry between the two end B-blocks. Abiding by the two principles, using self-consistent field theory (SCFT) we have predicted rich binary mesocrystals of equal and unequal CNs. Furthermore, we have extent the concept of “stretched bridge” into AB-type block copolymers. We have proposed the effect of combinatorial entropy to realize high-ratio bridging configurations in the self-assembled structures by AB-type block copolymers. By increasing the stretching degree of bridging blocks, we have successfully predicted nonclassical square array and graphene-like array of cylinders instead of the usual hexagonal array of cylinders. In future, it is hopeful to recast most of known atomic/ionic binary crystal structures or even beyond by considering topology and blending during the design of ABC-type block copolymers.

In recent years, flexible organic and perovskite photovoltaic devices, organic thin-film transistors and medical sensors have been become popular fields of scientific research due to their advantages of wearable, flexible and semi-transparent properties. Employing conductive polymer with excellent mechanical properties is one of the effective pathways to realize these high-performance devices. In conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and its aqueous dispersion poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) have been demonstrated to be the most promising alternative flexible materials of conventional metal oxides. It can be used as transparent electrode, hole transport layer, interconnects, electroactive layer, or motion sensing conductor in the device. This review focused on recent research advances of flexible devices for PEDOT and PEDOT:PSS applications, including various strategies to improve electrical conductivity, mechanical tolerance and long-term stability, and reveals the potential mechanisms of performance enhancement.

Axially chiral compounds represent an important class of chiral molecules. In this regard, many methods have been developed to access these compounds. However, efficient methods for the synthesis of axially chiral styrenes are limited to date, mainly due to their relative instability compared to axially chiral biaryl compounds. Iridium-catalyzed asymmetric allylic substitutions have evolved as a powerful tool in constructing C―C or C―X bonds at the allylic position. We developed an efficient sequential strategy to access a series of axially chiral styrenes by iridium-catalyzed allylic substitution and central-to-axial chirality transfer via olefin isomerization. With the iridium complex derived from [Ir(cod)Cl]₂ and Alexakis ligand L1 as catalyst, and β-naphthol as nucleophiles, a broad range of axially chiral styrenes were obtained with moderate to excellent yields (28%~97% yields) and enantioselectivity (59%~98% ee). A general procedure for the asymmetric allylation of β-naphthol is described as 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 (2.6 mg, 0.004 mmol, 2 mol%), (S,S,S_a)-L1 (4.8 mg, 0.008 mmol, 4 mol%), freshly distilled tetrahydrofuran (THF, 0.5 mL) and propylamine (0.5 mL). The mixture was stirred at 50 ℃ for 30 min and then the low-boiling solvents were removed in vacuo to give a pale yellow solid. The solid was stirred at 50 ℃ again under vacuum until it became a powder. After that, β-naphthol 1 (0.22 mmol, 1.1 equiv.), allyl carbonate 2 (0.2 mmol, 1.0 equiv.), 1,4-diazobicyclo(2.2.2)octane (DABCO) (67.3 mg, 0.6 mmol, 3.0 equiv.) and freshly distilled Et₂O (2.0 mL) were added to this flask under argon atmosphere. The reaction mixture was stirred at 20 ℃ until the starting material was consumed (monitored by thin layer chromatography, TLC). The crude reaction mixture was diluted with water (5 mL), and extracted with dichloromethane (DCM, 5 mL×3). The organic layers were collected, dried over Na₂SO₄ and then concentrated in vacuo to afford the crude product. The residue was purified by preparative TLC to afford the product.

Epigenetic inheritance is a heritable change in gene function independent of alterations in nucleotide sequence. 5-Hydroxymethylcytosine (5hmC), which is called “the sixth base”, is an epigenetic modification discovered after 5-methylcytosine (5mC). 5hmC is widely distributed in mammalian tissues and cells, and its abnormality is closely related to tumorigenesis, developmental diseases, and nervous system diseases. Because the structure of 5hmC is similar to that of 5mC and its abundance is much lower than that of 5mC, it is much difficult to accurately detect 5hmC by using the traditional methods. Recently, scientists have developed a series of new methods for the detection of 5hmC, including liquid chromatography tandem mass spectrometry, fluorescent method, electrochemical method, photoelectrochemical method, single base-resolution sequencing, and single-molecule detection technology. These emerging technologies have their own unique advantages and greatly promote the advance of epigenetic research. The recent advance in the detection of 5hmC is reviewed in this paper, and the challenge and trends of this area is highlighted as well.

As a kind of sophisticated dynamic DNA nanomachine, DNA walker has shown powerful application ability in many aspects due to its excellent structural designability and programmability. Taking advantage of stochastic DNA tracks on surface and adaptable DNA outputs of the well-known catalytic hairpin assembly (CHA) circuits, the DNA walkers that move along DNA-coated three-dimensional particle surfaces have attracted much interests. On the other hand, in the field of DNA-mediated nanoparticle assembly, self-assembly of nanoparticles is a thermodynamically driven nonequilibrium process, which is easily trapped at intermediate local free-energy minima, resulting in a disordered structure. Therefore, effective strategies to evade each local free-energy minimum are highly desired. In addition to the traditional annealing strategy, the time-dependent strategy relied on toehold-mediated strand-displacement DNA circuit recently reported by our group has been proven an alternative solution, where interactions between nanoparticles can be tuned in a time-dependent manner for programming dynamic pathway to achieve a free-energy minimum. Through integrating a CHA-based bipedal DNA walker with a DNA-functionalized gold nanoparticle (i.e., spherical nucleic acid; SNA) assembly, a time-dependent strategy for assembly of SNAs programmed by DNA walker at constant temperature was developed in this work. In our strategy, the active sticky ends used for assembly of SNAs can be gradually generated on nanoparticle surface after the walking of the bipedal DNA walker driven by the CHA reaction to induce the synchronization of assembly and bonding between SNAs, thereby obtaining ordered nanoparticle superlattice structure. Take a one-component SNA assembly system for example, the dynamic walking process of the bipedal DNA walker on the surface of SNA was proved to be stable with good walking ability and persistence at first. Then, the SNA assembly kinetics results showed that the bipedal walker concentrations and DNA linker ratios could greatly influence the aggregation of SNA conjugates. Finally, the performance of the integrated SNA assembly system driven by the bipedal DNA walker was investigated under varied concentrations of bipedal walker. In the presence of lower concentrations of the walker strand, the assembly process of SNAs could have a long residence time to switch between the binding and unbinding of the generated sticky ends and achieved a series of near-equilibrium states. Thus, as the interaction between particles grows, the dynamic pathway of nanoparticles assembly can be programmed to achieve a free-energy minimum to form ordered face-centered cubic (FCC) superlattice structure. Based on similar design principle, an asymmetric two-component SNA assembly system programmed by the bipedal DNA walker was constructed to obtain CsCl superlattice structure. Our DNA walker-programmed SNA assembly strategy will have great potential in the creation of functional nanoscale superlattice materials and in the construction of SNA structures with complex phase behaviors.

Micro/nano materials have unique properties that are different from macro materials because of their small scale, and these materials have diverse applications in many fields. In recent years, with the unique advantages of low consumption, high efficiency, high throughput, miniaturization, integration and automation, microfluidic technique has aroused widespread concerns in the synthesis field of micro/nano materials. In this review, the commonly used microreactors are classified from two perspectives of structural form and reaction method, and the application of microfluidic technique in the synthesis of micro/nano materials including inorganic materials, organic materials and composite materials are introduced. In addition, the main development trends in the future are prospected in this review. Microfluidic technique has provided new ideas and methods for the synthesis of micro/nano materials, which has rich possibilities and great potentials in both industrial production and academic research.

Cyclopentadithiophene (CPDT) derivatives, as a class of fluorene-like molecular building blocks that have a wide range of applications in the design of organic optoelectronic materials due to their easily molecular tailoring, electron-rich, low band gap, high electrical conductivity and good charge transport properties in the field of plastic electronics. At the same time, cyclopentadithiophene is easy to carry out structural modification, which can introduce various functional groups conveniently and quickly, and can expand a variety of derivatives. Cyclopentadithiophene can be divided into six structural isomers based on the position of the S atom on thiophene. Among these structural isomers, there are many reports on 4H-cyclopenta[2,1-b:3,4-b']dithiophene derivatives. In this article, we review mainly the synthesis and properties of 4H-cyclopenta[2,1-b:3,4-b']dithiophene derivatives and applications in organic solar cells (OSCs), organic field-effect transistors (OFETs). The research progress in organic light-emitting diodes (OLEDs) and other fields is also comprehensively summarized. The perspectives of the gridochemistry of CPDT-based organic semiconductors will be made finally.