In 1901, F. Ullmann reported a new coupling reaction for the formation of sp²C-sp²C bond between two molecules of aryl iodide. In 1903, another paper of the N-arylation of aniline with aryl iodide was published. In 1905, the O-arylation of aryl bromide with the potassium salt of phenol was disclosed. These reactions, one coupling reaction and two condensations (or cross coupling reactions) played great roles in the development of aromatic chemistry during the turning from 19^th to 20^th century, especially in the field of dyestuff industry. Despite of these applications, the very harsh reaction condition, high temperature (~200℃) for long reaction time(one or two days) of the classical reaction of Ullmann condensation usually limited their applications.
By the efforts of several chemists in the end of last century, the acceleration effect of the Cu catalyzed Ullmann condensation by compounds with certain structure units or ligands was found. Thereafter, a surge of research interest was directed to this reaction. In this paper, the selection of various types of ligands, especially the oxalyldiamide type, the consideration of bases to be used especially the organic ionic bases, the immobilization of cooper sources and ligands and the green chemistry in Ullmann condensation are reviewed.
In 2004, Irina Beletskaya queried incisively and adequately a question:Is this a renaissance? Or "In the field of metal catalyzed cross coupling reactions, is the copper catalyzed reaction already a strong competitor to the palladium catalyzed reaction?" Beletskaya pointed out profoundly the five major drawbacks of copper catalyzed reaction. After more than ten years oxtensive investigation, a clear cut answer to this question was made as a result of several hundreds research papers dealing with the Ullmann cross coupling reactions.
Contents
1 Historical review
1.1 Name and scope of ullmann reaction
1.1.1 Ullmann reaction or ullmann coupling reaction
1.1.2 Ullmann condensation
1.2 Merits of Fritz ullmann
1.3 The follow-up achievements
2 The improvements of Ullmann condensation:the ligand accelerated Ullmann condensation
2.1 Acceleration effect by amino-acids
2.2 N, N-bidentate ligands——the phenanthrolines
2.3 N, N-bidentate ligands——the 1,2-diamines
2.4 O, O-bidentate ligands
2.5 O, N-bidentate ligands
2.5.1 Salicyl type-N, O-ligands and a tetra-dentate schiff base ligand
2.5.2 Amino alcohol ligands
2.5.3 The other O,N-bidentate ligands
2.6 Phosphorous containing ligands
2.7 The ligands used in the direct hydroxylation and direct amination of aryl Halides.
2.8 Is ligand necessary or is ullmann condensation really a "ligand accelerated catalysis"?
3 The improvements of Ullmann condensation by parameters other than ligands
3.1 The modification and loading of copper sources
3.2 The consideration of bases used
3.3 The technologies of micro-wave and supersonic used in the acceleration of rates of Ullmann condensations
3.4 The selection of solvent
4 The question of Irina Beletskaya
4.1 Five major points of Beletskaya's question
4.2 The re-examination of the cu-catalyzed Ullmann condensation after the query by Beletskaya
4.2.1 To moderate the reaction condition
4.2.2 To reduce the amounts of catalyst and ligands used
4.2.3 To make the reaction to be sustainable
4.3 The discovery of excellent ligands type——the oxalyl diamides
4.3.1 Breakthrough——the use of aryl chlorides
4.3.2 Broadening the scope of using aryl chlorides
4.3.3 The reduction of amounts of catalyst with oxalyl diamide
4.4 A difficult target for Ullmann condensation——the N-arylation of imidazole
4.5 Answer to the question of Beletskaya
4.5.1 Practical application of Ullmann condensation
4.5.2 The reduction of amounts of catalyst used
4.5.3 The use of aryl chloride
4.5.4 Tosylate or triflate as leaving group.
4.5.5 The advancement of green chemistry in Ullmann condensation
4.5.5.1 The reusable catalytic system
4.5.5.2 The use of water as solvent
4.6 Concluding remarks
5 Acknowledgements

As a kind of classic perovskite type oxide, BiFeO₃ possesses a certain visible light catalytic and heterogeneous Fenton-like catalytic performance. Under the irradiation of visible light and in the presence of hydrogen peroxide, BiFeO₃ could activate H₂O₂ and generate abundant strong oxidizing species, which attack the molecules of pollutants, therefore inducing the degradation of them. However, the problems of low quantum efficiency and easy recombination between photogenerated electrons and holes during the visible light catalytic process of BiFeO₃ still exist. It could hardly degrade the stable organic pollutants effectively under the irradiation of visible light. Except that, its ability of activating H₂O₂ still needs enhancing. The research progress of BiFeO₃ and its modifier which are used as a kind of visible light and heterogeneous Fenton-like catalyst in almost two decades is summarized in this paper. And the methods and effects to improve the environmental catalytic performance of BiFeO₃ (such as morphology control in preparation, noble metal deposition, ion doping, semiconductor recombination and load on the surface of other materials) are introduced emphatically. Through the modification, it was found that the visible light catalytic performance and heterogeneous Fenton-like catalytic ability of BiFeO₃ are strengthened. And a large number of pollutants could be degraded effectively by BiFeO₃ and its modifiers. At last, the research direction of BiFeO₃ compound catalyst in future is prospected.
Contents
1 Introduction
2 Fenton-like catalytic ability of BiFeO₃
3 Fenton-like catalytic ability of BiFeO₃ modifiers
4 Visible light catalytic ability of BiFeO₃ and its modifiers
4.1 Visible light catalytic ability of BiFeO₃
4.2 Visible light catalytic ability of BiFeO₃ modifiers
5 Visible light and Fenton-like catalytic performance of BiFeO₃ and its modifiers
5.1 Visible light and Fenton-like catalytic performance of BiFeO₃
5.2 Visible light and Fenton-like catalytic performance of BiFeO₃ modifiers
6 Conclusion and outlook

Metal-organic frameworks (MOFs) materials have attracted much attention in the field of photocatalysis, as compared with conventional porous materials, which are structurally ordered and diverse, with adjustable pore size and ultra-high specific surface area. At the same time, quantum dots (Quantum Dots, QDs) of nano-fluorescent materials have good optical properties and can convert near-infrared light into visible light, which can promote the absorption of visible light, which accounts for a large proportion of the solar spectrum, and the emergence of QDs has also contributed to the development of photocatalysis. But as a single phase catalyst, they have autologous shortcomings, limiting their use as a photocatalyst for future application and development. In recent years, researchers have found that the effective combination of QDs and MOFs materials to form a composite photocatalyst is one of the ways to improve the photocatalytic performance of single phase catalysts, and a preliminary study has been carried out. The results show that catalytic performance is greatly improved and it has broad application prospect in solving environmental problems. This paper combines the status quo at home and abroad, and a series of studies on the preparation of QDs@MOFs composite photocatalyst as well as its application and development in the field of photocatalytic degradation are reviewed. This paper also puts forward the key problems that should be paid attention to in the process of QDs@MOFs composite photocatalyst and the future development trend.
Contents
1 Introduction
2 Preparation of QDs@MOFs materials
2.1 The method of ship in the bottle
2.2 The method of bottle around the ship
2.3 The method of photochemical deposition
2.4 The method of direct surface functionalization
2.5 Other methods
3 Application of QDs@MOFs materials in the field of photocatalytic degradation
3.1 Application of MOFs materials in the field of photocatalytic degradation
3.2 Application of QDs in the field of photocatalytic degradation
3.3 Application of QDs@MOFs materials in the field of photocatalytic degradation
4 Conclusion and outlook

Transition-metal-catalyzed C—H bond activation is currently one of the most extensively studied research topics in organic synthesis. Recently, the directing group assisted C—H functionlization has drawn more attention from the researchers. The directing groups could enhance the reactive speed, selectivity and catalysis efficiency, which usually contain the nitrogen or oxygen atom. The review aims to summarize the methods of construction of C-C bond, C-O bond or C—N bond by C—H bond activation via introducing a directing group, including carboxyl, pyridnyl groups and so on during the past 3 years. The reaction mechanisms, the existing problems and limitations of this field are also included in this review. Finally, the development trend of this area is prospected.
Contents
1 Introduction
2 Recent advances in directing group C—H activation
2.1 Nitrogen-containing groups as the directing group
2.2 Oxygen-containing groups as the directing group
3 Conclusion

Continuous flow polymerizations in the microreactors have attracted great research interest from both academia and industry. Remarkable advantages have been achieved by using microflow technology due to its superior mixing and heat transfer performance. This review focused on the recent progress in highly exothermic ionic polymerizations in microreactors. Compared with the traditional batch reactors, continuous flow anionic/cationic polymerizations show tremendous benefits, including but not limited to improvement of reaction conditions, good control of the molecular weight and the molecular weight distribution, and highly efficient construction of block structures. Moreover, the applications of continuous flow ionic polymerizations in the industry are discussed and prospected.
Contents
1 Introduction
2 Cationic polymerization in continuous flow
2.1 Controlled/living cationic polymerization of vinyl ethers in continuous flow
2.2 Controlled/living cationic polymerization of diisopropenylbenzenes in continuous flow
2.3 Controlled/living cationic polymerization of isobutylene in continuous flow
3 Anionic polymerization in continuous flow
3.1 Controlled/living anionic polymerization of styrenes in continuous flow
3.2 Controlled/living anionic polymerization of alkyl methacrylates in continuous flow
3.3 Controlled/living anionic block copolymerization of styrenes and alkyl methacrylates in continuous flow
4 Conclusion and outlook

Nanomaterials for drug delivery have become a hot issue in the field of modern medicine since the successful improvement of the physicochemical and biological properties to drugs. Among them, peptides, as an emerging class of building block for nanomedicine, have attracted an extensive research interest due to their excellent properties such as good biocompatibility, easy self-assembly and chemical diversities, which point out a new direction for researchers to construct the novel and intelligent drug delivery systems. Herein, we report that the self-assembly peptides are driven by the integrated roles of noncovalent forces, including hydrophobic interaction, hydrogen bonding, electrostatic interaction and π-π stacking, to form a variety of well-defined nanostructures, such as micelles, vesicles, nanospheres, nanofibers, nanotube, disc and so on. Furtherly, the basic concept of peptide drug conjugates (PDCs) and their advantages of high drug loading, high bioavailability and specific targeting are introduced. The research in recent years on the construction of PDCs nanomedicine for drug delivery based on the functional peptide is summarized. We mainly focus on the most recent five-year report to construct the smart drug delivery system with the multifunction involved in self-assembly, enhancing solubility, long-term acting, targeting, stimulating response and cell transmembrane function.
Contents
1 Introduction
2 Self-assembling peptides
2.1 Classification of self-assembling peptides
2.2 The driving force of peptide assembly
3 Peptide drug conjugate for drug delivery system
3.1 Self-assembling peptide drug conjugates
3.2 Long-term acting peptide-drug conjugates
3.3 Targeting peptide drug conjugates
3.4 Responsive polypeptide drug conjugates
3.5 Transmembrane polypeptide drug conjugates
4 Conclusion

Graphene/polyaniline nanocomposites have attracted tremendous attention of the researchers because of their significant potential in the energy storage filed, especially supercapacitors. Polyaniline(PANI)is one of ideal electrode materials, due to high theoretical specific capacity and facile synthesis. However, its drawback is poor cycling life. Graphene(GN)possesses a high theoretical specific surface area and composites of polyaniline with graphene derivatives are used to acquire excellent electrochemical capacitive properties on account of the synergistic effect between the two components. In this feature article, new research results and important advances over the past few years on the synthesis of graphene-polyaniline based nanocomposite for electrochemical supercapacitors are reviewed. And we discuss how to improve the structure and performance of electrodes. In the meantime, the application of electrode materials blended with graphene-polyaniline for organic supercapacitors is introduced. Eventually, the application prospects of graphene-polyaniline nanocomposites are briefly described. The progress of graphene/polyaniline nanocomposites in the fields of supercapacitor depends on the appropriate microstructure design of the composites. The construction of an ideal 3D porous structure is one of research interests which is used to avoid the expansion and contraction of polyaniline. Furthermore, it is still difficult to find the balance between the performance and functionalization of graphene while improving the weak interfacial interaction between graphene and polyaniline. PANI-based nanocomposites with excellent mechanical properties can also play a vital role in the study of flexible quasi-solid-state supercapacitors.
Contents
1 Introduction
2 Preparation of graphene/polyaniline nanocomposites
2.1 In-situ chemical oxidative polymerization
2.2 Electro-polymerization
2.3 Interfacial polymerization
2.4 Solution mixing
2.5 LBL self-assembled
3 Structural optimization of graphene/polyaniline nanocomposites
3.1 Microstructure control of polyaniline
3.2 Composite film
3.3 3D hierarchical structure
4 Application of graphene-polyaniline nanocomposites for organic supercapacitors
5 Conclusion and outlook

F^- has a very significant impact on human life and ecological environment. Bone and teeth contain the majority of fluoride in the human body, which is closely related to human life activities and metabolism of teeth and bone tissue.Dietary deficiency or excessive intake of fluoride has been related to serious health problems. Moreover, soil and groundwater are contaminated by the use of fluoridated wastewater for irrigation, the settling of fluoridated dust, and the exchange of air in the soil with fluorinated air. Therefore, it is of vital importance to the quantitative detection and control of fluoride. Due to the advantages of good selectivity, in-situ visual and nondestructive detection compared with limitations of traditional methods, the design routine of luminescent probes of fluoride have attracted great interest of researchers,and it also can be used in biological detection or real life productions This review summarizes the research progress in luminescent fluoride probes with various kinds and recognition mechanisms in recent five years. The composite probes based on supported polymers and functionalized nanoparticles are also discussed. Finally, the development trend of luminescent fluoride probes is forecast.
Contents
1 Introduction
2 One-component probes
2.1 Probes based on the interaction of fluoride ion and Lewis acid
2.2 Probes utilizing weak interactions
3 Composite probes
3.1 Organic luminophor
3.2 Inorganic luminophor
4 Conclusion and outlook

Au nanostars (AuNSs) with the complex three-dimensional structure have become a new type of nanomaterials with a rapid development of nanotechnology. AuNSs have unique physical and chemical properties such as tunable optical properties of localized surface plasmon resonance (LSPR), surface-enhanced Raman scattering (SERS) effect, photothermal properties, and the large surface-to-volume ratio. For this reason, there's great potential for their applications in the fields of nanomaterials and biomedicine. In this article, we firstly evaluate the optical properties of AuNSs and explain their theoretical basis. Then two main methods of preparing AuNSs in recent years are summarized, including seed-mediated synthesis method and one-step method. At the same time, a discussion of the merits and drawbacks of each method is also made. In terms of functionalized probes' assembly, two principal ways of surface modifications are introduced, including silica-coated AuNSs and modification of AuNSs using polymer or biomolecules. In the way of application, the recent progress of AuNSs applied in biomolecular detection, medical imaging, diagnosis and photothermal therapy of tumors, delivery and controlled release of drug is reviewed. In the end, we discuss some problems in the preparation and application of AuNSs. What's more, the future research content and research direction in this field are prospected.
Contents
1 Introduction
2 Optical properties of Au nanostars and their theoretical basis
3 Preparation of Au nanostars
3.1 Seed-mediated growth method
3.2 One-step method
4 Surface modifications of Au nanostars
4.1 Silica-coated Au nanostars
4.2 Modification of Au nanostars using polymer or biomolecules
5 Applications of Au nanostars in biomedical field
5.1 Biomolecular detection
5.2 Medical imaging
5.3 Diagnosis and photothermal therapy of tumors
5.4 Delivery and controlled release of drug
6 Conclusion and outlook

Nanosilver is one of the most commercialized nanomaterials in the world. Due to its unique surface plasma resonance performance and excellent antibacterial activities, nanosilver has been widely used in many fields, such as medical area, health care, industrial products and our daily supplies. Meanwhile, the increasing application of nanosilver has drawn more and more attention to its biosafety. Previous toxicological studies have revealed diverse deleterious effects nanosilver may cause, wherein, neurotoxicity is highly concerned. This review mainly focuses on the neurotoxicological effects of nanosilver, and three aspects, including the bioaccumulation of nanosilver in brain and its penetration routes, neurotoxicological effects and the underlying molecular mechanisms, and the influencing factors, are comprehensively discussed. The administration of nanosilver through diverse ways could cause brain silver accumulation, and its penetration routes to the brain were mainly involved with the direct nasal olfactory nerve transfer and the translocation of the blood-brain barrier. The neurotoxicological effects of nanosilver were evidenced by neurobehavioral changes in the exposed animals, histopathological alteration in the brain or cellular morphological changes in neurons and neuroglia cells, and the disturbance in the neurontransmitter secretion. The underlying mechanisms were related with oxidative damage and inflammatory responses. The factors, including particle size, surface coating and silver ion release, would potentially determine nanosilver induced neurotoxicity. Finally, the existing problems in neurotoxicological studies on nanosilver are pointed out, and the future perspectives in this area are proposed. The review would be of great help to risk assessment of the production, application and disposal of nanosilver.
Contents
1 Introduction
1.1 Overview
1.2 The synthesis of nanosilver
1.3 The environmental release of nanosilver
1.4 The toxicological effects of nanosilver
2 The bioaccumulation of nanosilver in brain and its penetration routes
2.1 The bioaccumulation of nanosilver in brain
2.2 The penetration routes of nanosilver to brain
3 The neurotoxicological effects of nanosilver and its molecular mechanisms
3.1 Neurobehavioral changes
3.2 Histopathological effects
3.3 Neurotransmitter changes
3.4 The underlying molecular mechanisms
4 The key factors influencing the neurotoxicity of nanosilver
4.1 Particle size
4.2 Surface coating
4.3 Release of silver ions
5 Conclusion and perspective

Photodynamic therapy(PDT) is a cancer therapeutic modality that utilizes photosensitizers(PSs) and molecular oxygen upon irradiation with light to generate cytotoxic reactive oxygen species leading to damage of the target tissues and cells. Activatable photosensitizers(aPSs)that are inactivated initially, can only be activated by tumor-associated stimuli, such as tumor-associated specific enzymes, acidic pH, nucleic acid, to achieve targeting diagnosis and treatment. The aPSs have become a hot spot in the field of medical photosensitizers because of its higher selectivity. In this paper, we will summarize the recent development of aPSs, and analyze their structure-activity relationships, expecting to provide a reference for the future studies.
Contents
1 Introduction
2 pH-activatable photosensitizers
3 Enzyme-activatable photosensitizers
3.1 Cathepsin-activatable photosensitizers
3.2 Urokinase type plasminogenactivator(uPA)-activatable photosensitizers
3.3 Fibroblast activation protein-α(FAPα)-activatable photosensitizers
3.4 Matrix metalloproteinase(MMP)-activatable photosensitizers
3.5 Hyaluronidase-activatable photosensitizers
3.6 Other enzyme-activatable photosensitizers
4 Nucleic acid-activatable photosensitizers
5 Other activatable photosensitizers
6 Perspective

Using chemical method to efficiently hydrolyze cellulose into sugar is a key support technology for converting renewable non-food biomass into energy and materials, which has great significance to maintain the sustainable development of resources and the environment in the future. In recent years, with the development of the research on the hydrolysis of cellulose, the research content has been shifted from exploring the feasibility of hydrolysis into building a technology of highly efficient (i.e., high conversion rate, high selectivity and high conversion speed) hydrolysis of cellulose into sugar. The principle and method of highly efficient hydrolysis of cellulose into sugar are systematically reviewed. On basis of the relationship between the crystalline structure of cellulose and the high efficiency of hydrolysis, the advantages and disadvantages of various technical methods are discussed in detail. Combining with the latest progress of hydrolysis research, some ideas and suggestions are also provided with the aim to successfully achieve highly efficient hydrolysis of cellulose into sugar in the future.
Contents
1 Introduction
2 Mechanism of highly efficient hydrolysis of cellulose into sugar by chemical catalytic method
2.1 Dissociation of glycosidic bond
2.2 Inhibition of highly crystalline structure
2.3 Recrystallization in hydrolysis
3 Technology and methods to hydrolyze cellulose into sugar
3.1 Catalyst
3.2 System of hydrolysis
3.3 Hydrolytic and driving methods
4 Conclusion and outlook

High-density jet fuels are advanced fuel synthesized to improve the performance of aerospace vehicles. As response to the sustainable development, the development of high-density biofuels becomes extremly necessary, which can also extend the sources of fuels. Herein, the progress in synthesis of high-density jet fuels using biomass-derived feedstock has been reviewed. Biofuels with different structure, such as paraffins, branched monocycloalkanes, and polycycloalkanes, and the feedstock including pinenes and lignocellulose-derived platform molecules such as cyclic ketones/alcohols, furanic aldehydes/alcohols, aromatic oxygenates, etc. are covered. The propulsion performance of the engine is deeply dependent on the properties of the applied fuel, for which the most important features are density and low-temperature properties. Specially, the properties of typical biofuels are summarized to discuss the effect of molecular structure. Increasing the number of the ring in fuel molecular improves the fuel density, with undesirable variation in low-temperature properties. Fortunately, introducing the branched chain will improve the low-temperature properties. And several reactions such as alkylation, condensation, cyclic addition, and hydrodeoxygenation are discussed from the aspects of catalyst and reaction condition. An outlook on further development of high-density biofuels is also given. This review will be helpful to explore and develop better approach and process for high-density biofuel synthesis and upgrade for advanced aerospace vehicles.
Contents
1 Introduction
2 Synthesis of paraffin biofuels
3 Synthesis of branched monocycloalkane biofuels
4 Synthesis of polycycloalkane biofuels
4.1 Terpene-derived biofuels
4.2 Lignocellulose-derived polycycloalkane biofuels
4.3 Lignocellulose-derived fused-ring biofuels
5 Conclusion

In the process of producing hydrogen by water electrolysis with Solid Polymer Electrolyte(SPE), anodic oxygen evolution reaction(OER) is the rate-determining step of the whole electrochemical reaction. The progress of the state-of-the-art for the SPE technology in terms of oxygen evolution reaction(OER) mechanism, catalyst materials and its synthesis method are recommended. It is pointed out that new detection methods can analyze OER reaction mechanism and study the intermediate activity products at atomic level. Optimization of the traditional synthesis method and the development of the new method can improve the catalysts performance. In addition, introducing high stability, low cost and high activity carrier material can also improve the performance of catalyst and reduce its cost accordingly. It is hoped that our paper will give a clear direction for the future research of anode catalysts and promote the commercialization of the SPE electrolysis.
Contents
1 Introduction
2 SPE catalyst
2.1 OER mechanism
2.2 Catalyst materials
2.3 Preparation methods
3 Conclusion and outlook

Given the environmental risk and valuable metal containing nature of spent lithium-ion batteries, it is of great significance to harmlessly dispose of spent lithium-ion batteries and recycle the valuable resources therein. At present, the spent lithium-ion batteries recycling technology is realized mainly through enhanced chemical conversion under high temperature or normal temperature conditions. High temperature boosts the chemical conversion rate of valuable elements in the spent lithium-ion battery, results in a short flow and releases material dependence. Therefore, high temperature chemical conversion is easy to implement in industry, and the related technologies have become one of the hotspots for the recycling of spent lithium-ion batteries. Based on the chemical conversion differences of various phases, this study systematically analyzes and evaluates the physicochemical mechanisms, technical characteristics, and research status of high temperature chemical reduction, roasting with molten salt, and direct regeneration. The advantages and problems of various technologies are compared. Based on this, it is advised that the future research needs in-depth study of its chemical conversion mechanism and takes into account the short flow clean regeneration of materials. It is necessary to develop a low energy-consuming and environmentally-friendly approach to enable the green treatment and recycling of spent lithium-ion batteries based on the principle of green chemistry.
Contents
1 Introduction
2 Pyrometallurgy recovery technology
2.1 High temperature reduction
2.2 Sulfation roasting
2.3 Direct regeneration
2.4 Discussion
3 Challenges and Prospects
4 Conclusion

Catalytic coal gasification technology is essential to improve the efficiency of coal gasification. At present, alkali metals, alkaline earth metals and transition metal catalysts have poor application induced by their high cost and difficulty in recovery except for CaCO₃. Disposable catalysts have got a multitude of attention on research and application of coal gasification in recent years, which have the advantages of being cheap, disposable, environmentally friendly, and capable of adjusting the ash melt characteristic and sulfation reaction. In this paper, the progress of several kinds of disposable catalysts in the field of coal gasification is reviewed, including the catalytic properties and mechanism of catalysts such as calcium based catalysts, waste water catalysts, waste solid catalysts and biomass ash catalysts, the problems in practical application are discussed, and the challenges and perspectives of the coal gasification catalysts are also prospected.
Contents
1 Introduction
2 Types of disposable catalysts and their catalytic mechanism
2.1 Calcium based catalysts
2.2 Industrial waste water catalysts
2.3 Industrial waste solid catalysts
2.4 Biomass catalysts
3 Conclusion and outlook