The ent-kaurane diterpenoids, widely distributed in terrestrial plants, represent an important group of tetracyclic diterpenes with diverse scaffolds and varied bioactivities. More and more studies have revealed that these compounds possess potent antitumor, antibacterial and anti-inflammatory activities. The tetracyclic ent-kaurane diterpenoids have attractive structural diversity owing to intramolecular cyclization, oxidative cleavage and rearrangements of their parent compounds. As a result, the total synthesis of ent-kaurane diterpenoids has received great attention from synthetic community during the past decades. This review describes the recent progress in this field, which includes total synthesis of C-20 non-oxygenated ent-kauranes such as(+)-lungshengenin D and pharicins A-C; total synthesis of C-20 oxygenated ent-kauranes such as maoecrystal P, eriocalyxin B, neolaxiflorin L and xerophilusin I; total synthesis of seco-ent-kauranes such as sculpomeatin N, trichorabdal A, maoecrystal Z, enmein, isodocarpin, sculponin R, londirabdiol, longirabdolactone and effusin; and total synthesis of nor or rearranged-ent-kauranes such as jungermannenones B and C, maoecrystal V, jungermatrobrunin A and kauradienone.

In this paper, the separation, synthesis and biological activities of glycosylated iminosugars are systematically summarized. The naturally occurring glycosylated iminosugar products can be classified into five types according to their iminosugar units. Most of them have important biological activities, especially glycosidase inhibitory activities. Potential pharmacological activities of these compounds promote the study of synthetic strategies. According to the construction methods of glycoside bonds, these strategies can be roughly divided into enzyme catalyzed transglycosylation and chemical synthesis, of which the main difference is reaction condition. Enzyme catalyzed transglycosylation features mild reaction conditions and possible avoidance of protection groups, but the reaction efficiency and selectivity still need further improvement. Many synthetic strategies for ordinary glycosides can be used in chemical synthesis of glycosylated iminosugars, and are applicable for almost all synthetic targets. However, burdensome protection-deprotection procedures pull down the efficiency of chemical synthesis. The development of synthetic strategies have promoted the design and synthesis of the natural products and their analogues, which greatly enriches the variety and biological activities of glycosylated iminosugars. Generally, biological activities of glycosylated iminosugars are influenced by both the glycosyl groups and the iminosugar units. As the cross-domain of traditional carbohydrate chemistry and iminosugar chemistry, the structural diversity of glycosylated iminosugars provides excellent parent skeletons for the development of highly active and selective lead compounds, which endows these compounds with potential applications in drug discovery.

As fluorescent sensing materials, fluorescent polymers not only have many sensing units, high brightness and good light stability, but also facilitate the fabrication of fluorescent sensing films, which are easy to implement devices. Therefore, fluorescent polymers have been widely studied and applied in fluorescence detection of explosives. In recent years, a large number of fluorescent polymers with various functional units have been developed, and their structures have evolved from common linear structures to branched and porous network structures, which have effectively improved the sensitivity, selectivity and response rate of explosive detection. This review is aimed to summarize the research progress on fluorescent polymers used for detection of explosives, including linear polymers, branched polymers and porous polymers. The emphasis of this review is especially focused on the structure design strategies, functional characteristics and sensing performances of typical linear conjugated and non-conjugated polymers, dendrimers and hyperbranched polymers and amorphous and crystalline porous polymers. Finally, the future opportunities and challenges of fluorescent polymers in application of explosive detection are presented.

Azo compounds are a class of trans-cis(E/Z) photoisomerization compounds which have advantages of simple synthesis, high isomerization rate and efficiency, and resistance to photobleaching. Due to their outstanding photoisomeric properties and ability to form stable inclusion complexes with macrocyclic hosts, azo compounds have shown great potential application in many fields. In this review, we show the design principles, assembly mechanism, application and development of the photo-controlled supramolecular assemblies in topologically morphological regulation, drug delivery, smart materials and so on, which are constructed by host-guest interaction using azo modified cyclodextrin, bis-cyclodextrin bridged by azobenzene, crown ether derivatives, azo aromatic macrocyclic compounds as the hosts or azobenzene or azobenzene derivatives as guests. At the same time, we also discuss the opportunities and challenges of the development of such supramolecular assemblies, and hope to further promote the development of intelligent supramolecular assemblies.

Supramolecular self-assembly provides a new strategy for the development of drug delivery systems from molecular components. With non-covalent interactions as driving forces, supramolecular drug delivery systems(SDDSs) can realize precise component control at the molecular level, increased predictability of the self-assembled structures, tunable control of morphologies and sizes, controlled release of delivered drugs. In this review, we first concisely introduce the background for the design of SDDSs and then describe important advances in SDDS development that involves the applications of cyclodextrin, calixarene, pillararene and cucurbituril based on host-guest interactions. Following these popular design principles, we further present the applications of water-soluble supramolecular organic frameworks as SDDSs. Finally, the challenges that need to be addressed for the practical translation of SDDSs are discussed.

The lithium ion(Li-ion) batteries, known for their high energy density and high energy conversion efficiency, have been widely applied in portable electronics and electric transportation. With reversible capacities over 300 mAh·g^-1, the Li-rich layer-structured oxides are important candidiates of the cathode materials for the Li-ion batteries with energy densities of 350 Wh·kg^-1 or higher. However, the issues related to the structural degradation during long-term cycling and the high surface/interface sensitivity(dissolution of the transition metal ions and the side reactions with the electrolyes) have to be well addressed before these materials can be commercially applied. This review is to present some of our efforts in stabilizing the structure and electrochemical performances of these materials by way of elemental substitution in the bulk and on the surface and by designing new structures, on the basis of comprehensive understandings on their crystalline and electronic structures and the structural evolution. Meanwhile, for the purpose of providing the audience with some overview about the world-wide research progress on these oxide materials, some important achievements are introduced including homogeneous elemental substitution in the lattice, structurally integrated surface modification(such as multilayer modification and construction of concentration-gradient materials), surface coating and surface doping. We will share our thinking on the research directions of these materials before ending this review.

Efficient, precise and controllable separation of target compounds in low concentration and large volume complex solutions is a world frontier in the field of chemical separation science. Solid phase extraction technology currently faces two challenges in industrial separation of low-concentration complex systems. On the one hand, it is difficult to give consideration to both of the high selective precision capture and the mild green desorption. On the other hand, solid phase extraction technology lacks efficient separation process and equipment for large scaled continuous separation. This review summarizes the research progress of new environmental responsive solid phase extraction technology, magnetic field responsive solid phase extraction technology, electric field- and ultrasound field- assisted solid phase extraction technology in order to solve the problems of current solid phase extraction technology, and achieve the efficient and precise separation for low concentration complex systems. Finally, the research and development direction of solid phase extraction technology in this application field is prospected. In this review, the key scientific issues of external field enhanced environmental responsive solid phase extraction technology, including environmental responsive problems, controllable separation problems and process amplification problems, are further discussed. Besides, measures and suggestions are proposed for the development of related fields.