Oxetanes are a class of saturated four-membered cyclic ether compounds. They are not only an important class of organic synthetic intermediates, but also crucial active structural units of natural and synthetic biological and medicinal active compounds possessing anti-cancer, inhibition of human immunodeficiency virus, as well as inhibiting glutamine synthetase in clinical practice. Thus, it is in high demand to develop efficient methods for constructing oxetane structural motifs. In this review, the intramolecular cyclization reaction via C—C bond formation, the intramolecular Williamson etherification by the formation of C—O bond, the [2+2] photocycloadditions of alkenes with aldehydes and ketones(named as Paternò-Büchi reaction), transition metal catalyzed formal [2+2] cycloadditions, sulfide ylide-mediated epoxide ring expansion, and the C—H bond oxidative cyclization are reviewed with a focus on new progress in the synthesis of oxetanes during the last five years. It is hoped that this review can provide some valuable information for the organic chemists who are interested in the construction of the oxetane skeleton and promote the development on the synthesis and application of oxetanes.

Dinitrogen is the most abundant gas in the air(approximately 78% of the total air volume), which is a precious resource endowed by nature. How to make use of dinitrogen and transform it into useful nitrogenous compounds is important for humans and sustainable development of society. Dinitrogen activation, as a very important research field, has always been a major challenge. At present, low valent uranium complexes exhibit excellent performance in the small molecule activation. This review mainly introduces and summarizes the application of uranium complexes in dinitrogen activation and transformation, and the prospect of this field is prognosticated.

Liquid crystal polymers (LCPs) are soft intelligent materials, which can change shape under external stimuli. The change of arrangement of liquid crystal molecules in microstructure induces a macroscopic shape-changing of LCP materials. Without changing environment, light irradiation allows remote and localized actuation of photo responsive LCPs, which makes photo-responsive LCPs especially attractive as soft actuators. Photo-responsive groups are introduced into liquid crystal polymers to obtain photo-deformable materials with important applications. This review focuses on recent research progress on photo-responsive shape-changing liquid crystal polymers. Different mechanisms of light-driven deformation are first discussed to understand the essence of photo-responsive behaviors of liquid crystal polymers, including photo-isomerization, photo-thermal effect and multi-stimuli-response. Their design principles are introduced in detail, especially the newly designed molecular structures. Furthermore, applications of photo-responsive liquid crystal polymers are highlighted, including bio-inspired actuator materials, energy-converted materials and soft robots. Finally, a brief outlook on the future development of this field is presented.

Chemotherapy is one of the most effective methods for cancer therapy in clinical practice, but the administration of chemotherapeutic drugs results in poor targeting of drugs to tumors and low utilization rates of drugs. While killing tumor cells, chemotherapeutic drugs also cause great damage to normal human cells, so chemotherapy is usually accompanied by serious side effects, such as nausea, vomiting, and hair loss. With the rapid development of oncology and nanomaterials, many nano-drug vectors have been used in the treatment of tumors. Nanometer drug vectors can improve the utilization rate of drugs and reduce side effects, which has become a research hotspot in the field of drug delivery. The tumor microenvironment responsive drug delivery systems have shown excellent performance in the controlled drug release, removal of the protective shell, and tumor targeting. In this paper, we discuss the common strategies for constructing tumor microenvironment responsive drug delivery systems based on abnormal biochemical indicators of tumor microenvironment or in tumor cells. The recent advances of tumor microenvironment responsive drug delivery systems are summarized. Finally, we outline the challenges and perspectives about the improvement of tumor microenvironment responsive drug delivery systems, aiming to provide a reference for the design and preparation of high-performance drug delivery systems.

Hypochlorous acid in organisms is produced from the reaction between chloride ions and hydrogen peroxide(H₂O₂) catalyzed by myeloperoxidase(MPO). It is one of the most important reactive oxygen species(ROS) in organisms and plays a vital role in physiological processes. However, excessive hypochlorite can lead to a series of physiological diseases, so the effective identification and detection of hypochlorite is favored by researchers. Compared with traditional detection methods, fluorescent probes have many advantages, such as good selectivity, high sensitivity and real-time monitoring, so they have been developed rapidly in recent years. In this paper, based on different fluorophores, the research progress and biological application of hypochlorite fluorescent probes in the last three years are reviewed.

Metal is an essential material foundation on which human society depends on survival and development. It is a supporting material that constitutes a modern civilized society. Increasing the unique properties of metal materials and expanding the scope of application of metal materials has become a hotspot in the cross-study of natural sciences. Inspired by nature, the researchers have investigated the ultra-slip behaviour of the pitcher plant of nepenthes, injecting low surface energy lubricating liquid into the micro/nano structure substrate, forming a solid-liquid composite structure, and prepared a slippery liquid-infused porous surface(SLIPS) with special wettability. SLIPS has excellent self-healing, anti-icing, anti-fouling, anti-corrosion, anti-bioadhesion and self-cleaning properties. The method designs and constructs a SLIPS on a metal substrate and realizes its surface versatility, thereby providing the possibility for it to achieve a wider range of applications in the fields of marine anti-fouling, biomedical, aerospace, refrigeration, and industrial production. This article is divided into four parts to review the research progress of metal-based SLIPS manufacturing and its application, and summarize the design principle, preparation process, application of metal-based SLIPS, and future development trends and challenges.

Micro-structured elastomer films are elastomer films endowed with pores or patterned arrays of specific structures on the top layer or in the bulk. Such films have been extensively used as dielectric layers for flexible electronics. In this review, both the fabrication techniques and the applications of the micro-structured elastomer dielectric layers are introduced. Different types of elastomers used as dielectric layers are firstly introduced. Fabrication methods of micro-structured elastomer dielectric layers with porous and non-porous arrays are summarized, including sodium chloride template method, sugar template method, bicarbonate template method, microsphere template method and silicon template method. The applications of the micro-structured elastomer dielectric layers in stress-strain sensors and nano-generators are also illustrated.

The polymer electrolytes are mainly divided into gel polymer electrolytes and solid polymer electrolytes, and both of them can improve the performance of Li rechargeable batteries. Gel polymer electrolytes include a plasticized or gelled polymer matrix, wherein the addition of plasticizer results in a 3D polymer matrix swollen in a liquid electrolyte, which can incorporate both diffusive property of liquids and the mechanical property of solids. Solid polymer electrolytes are solvent-free systems where the polymer host is used as solid solvent to dissolve the lithium salts, and the ions are transported by the polymer chain dynamics. Compared with the traditional ex-situ prepared polymer electrolyte, the polymer electrolytes synthesized by in-situ reaction can effectively improve the interface compatibility of electrolyte and electrode, simplify the assembly process and reduce cost. Therefore, this paper reviews the state-of-art of in-situ polymerization electrolytes in view of their electrochemical and physical properties for the applications in lithium batteries. The prospects and challenges toward the practical applications of in-situ polymerization polymer electrolyte for lithium rechargeable batteries are further summarized.

The heavy metals in sludge, especially flue gas desulphurization wastewater sludge, exceed the standard seriously, which belongs to hazardous solid waste. The annual production of sewage sludge in China has exceeded 50 million tons. It is calculated that only the annual production of flue gas desulphurization wastewater sludge in coal-fired power plants reaches 90 million tons. The heavy metals in sludge, if not disposed of properly, will cause very serious secondary pollution to the ecological environment. This paper introduces the present situation of sludge treatment at home and abroad and the determination and estimation methods of heavy metals in sludge. The advantages and disadvantages of chemical process, electrokinetic treatment, bioleaching process, thermal treatment and stabilization are summarized in detail from the aspects of principle, reaction device, research progress, and hot spot. Furthermore, the authors shed light on the existing problems and development prospects of each method. In the end, the paper puts forward the prospect of economical and efficient implementation device and technical scheme with strong application.

In recent years, with the rapid development of industry, the water pollution crisis is one of the major threats facing the world. The development of new environmentally functional materials and technologies to achieve efficient removal of water pollutants is a hot topic in the current research. Double network hydrogels are high molecular polymers with a three-dimensional network structure. They have superior mechanical properties with high strength, can withstand high levels of tensile and compression deformation. The low swelling rate allows the hydrogels to hold a large amount of water, but still maintains the stable morphological and network structures. In addition, due to their unique cross-linking, the hydrogels also have fast self-healing property and significant fatigue performance. The application effect of double network hydrogels as an adsorbent in the removal of heavy metal ions and other pollutants is significantly effective. Therefore, they are adsorption materials with great potential and have attracted widespread attention in the field of water treatment. This paper reviews the physicochemical properties and classifications of the double network hydrogels adsorbents, and their latest application progress to remove heavy metals, antibiotics, dyes and other pollutants from water. Through this review, new ideas, new methods and new technologies are provided for the in-depth development of double network hydrogels adsorbents and engineering applications in water purification.

The pollutants in the wastewater are hazardous to human health due to their complex composition, high biological toxicity and difficult degradation. Therefore, finding and developing some adsorbents that can effectively remove highly toxic and refractory pollutants in wastewater have become an urgent problem to be solved. Metal-organic frameworks(MOFs) materials have the characteristics of orderly and diverse structure, rich topology, ultra-high porosity, large specific surface area, stable framework structure and easy doping with other components, which have attracted wide attention in the field of adsorption. Compared with pure MOFs, the new hybrid materials POMs@MOFs are created by incorporating polyoxometalates(POMs) onto metal-organic frameworks(MOFs). They not only have their unique set of properties, but also combine the strong acidity, oxygen-rich surface, and redox capability of POMs. At the same time, they have overcome shortcomings of POMs and MOFs, such as difficult handling, low surface area, and high solubility. In recent years, researchers have discovered that the composites of POMs and MOFs have excellent performance as adsorbents in the field of wastewater treatment. In this paper, the synthesis and preparation of POMs@MOFs, especially the advantages and disadvantages of various preparation methods, are summarized and analyzed based on the reported researches and the works of our group. This article focuses on the application and development of POMs@MOFs in wastewater treatment. Finally, the development direction and research prospect of POMs@MOFs composite materials are also proposed.

Small-molecule fluorescent probes are widely applied in the fields of life science, medicinal chemistry and environmental science, due to their characteristics of high sensitivity and specificity, good stability and economic applicability. In pesticide chemistry, small-molecule fluorescent probes are frequently utilized in the detection of pesticide residues and heavy metal pollutions. With global strategic needs and rapid technological progress in green pesticide development, fluorescent probes are urgently desired as important molecular tools for design, screening and development of environmentally benign agrichemicals. This article aims to review the key updates of small-molecule fluorescent bioprobes in green pesticide R&D by covering their chemical design, molecular targeting, and screening mechanisms against different green pesticide biotargets, and to provide the current status on their research and application as well as future perspectives.

With the rapid development of detection system and the improvement of detection accuracy, the demand for stealth technology is increasingly urgent. As the traditional infrared stealth materials are facing the severe challenge of multi-channel target detection, it is of great significance to develop new compatible stealth materials which can meet the requirements of infrared stealth, radar stealth, visible light stealth and laser stealth. The infrared stealth materials mainly aim at the infrared radiation characteristics of the target to design the material and structure, so as to reduce the prominence of the thermal infrared radiation signal in the background and the hit probability of the target by the thermal infrared guided weapon. This review summarizes the working principle, preparation methods and latest research progress of infrared stealth and compatible materials. Firstly, the structural characteristics, stealth mechanism and research results of the most promising infrared stealth materials, including photonic crystals, doped semiconductors, phase change materials and nano materials, are introduced. The materials to achieve infrared stealth and the specific stealth characteristics are focused. Secondly, infrared/radar compatible, infrared/visible light compatible, infrared/laser compatible and multi band compatible materials are discussed. In addition, the latest research progress is systematically summarized. Finally, the shortcomings and difficulties of infrared stealth materials and compatible materials are summarized, and the future research direction is prospected.