The halogen bond is a supramolecular interaction between a Lewis‐acidic region of a covalently bound halogen and a Lewis base. It has been studied widely in silico and experimentally in the solid ...state; however, solution‐phase applications have attracted enormous interest in the last few years. This Minireview highlights selected recent developments in halogen bond interactions in solution, with a focus on the use of receptors based on halogen bonds in anion recognition and sensing, anion‐templated self‐assembly, as well as in organocatalysis.
Giving direction: The utilization of highly directional halogen bonds for anion coordination and supramolecular chemistry has become increasingly apparent. In particular, their application for selective anion interactions in solution has attracted enormous interest. This Minireview focuses on fundamental advances in receptors based on halogen bonds in the area of anion recognition and sensing, anion‐templated self‐assembly, as well as organocatalysis.
Poly(ethylene glycol) (PEG) is the most used polymer and also the gold standard for stealth polymers in the emerging field of polymer-based drug delivery. The properties that account for the ...overwhelming use of PEG in biomedical applications are outlined in this Review. The first approved PEGylated products have already been on the market for 20 years. A vast amount of clinical experience has since been gained with this polymer--not only benefits, but possible side effects and complications have also been found. The areas that might need consideration and more intensive and careful examination can be divided into the following categories: hypersensitivity, unexpected changes in pharmacokinetic behavior, toxic side products, and an antagonism arising from the easy degradation of the polymer under mechanical stress as a result of its ether structure and its non-biodegradability, as well as the resulting possible accumulation in the body. These possible side effects will be discussed in this Review and alternative polymers will be evaluated.
In the light of an ever‐increasing energy demand, the rising number of portable applications, the growing market of electric vehicles, and the necessity to store energy from renewable sources on ...large scale, there is an urgent need for suitable energy storage systems. In most batteries, the energy is stored by exploiting metals or metal‐ion‐based reactions. However, nearly every modern battery would not function without the help of polymers. Polymers fulfill several important tasks in battery cells. They are applied as binders for the electrode slurries, in separators and membranes, and as active materials, where charge is stored in organic moieties. This review concentrates on recent research on polymers utilized for every aspect of a battery, discussing state‐of‐the‐art lithium cells, current redox‐flow systems, and polymeric thin‐film batteries. The focus is on the properties of the polymers applied in different battery systems and how they affect their overall performance.
This comprehensive review covers all polymeric parts of different battery types. These range from polymeric active materials for redox flow batteries over membranes and separators for redox flow and lithium ion batteries to binders for metal ion batteries. Each topic is discussed in detail and an overview of the current literature is provided.
Research on redox‐flow batteries (RFBs) is currently experiencing a significant upturn, stimulated by the growing need to store increasing quantities of sustainably generated electrical energy. RFBs ...are promising candidates for the creation of smart grids, particularly when combined with photovoltaics and wind farms. To achieve the goal of “green”, safe, and cost‐efficient energy storage, research has shifted from metal‐based materials to organic active materials in recent years. This Review presents an overview of various flow‐battery systems. Relevant studies concerning their history are discussed as well as their development over the last few years from the classical inorganic, to organic/inorganic, to RFBs with organic redox‐active cathode and anode materials. Available technologies are analyzed in terms of their technical, economic, and environmental aspects; the advantages and limitations of these systems are also discussed. Further technological challenges and prospective research possibilities are highlighted.
Go with the flow: Redox‐flow batteries are promising candidates for storing sustainably generated electrical energy and, in combination with photovoltaics and wind farms, for the creation of smart grids. This Review presents an overview of various flow‐battery systems, focusing on the development of organic redox‐active materials, and critically discusses opportunities, disadvantages, and future challenges of these systems.
Microwave‐assisted synthesis and processing represents a growing field in materials research and successfully entered the field of carbon nanomaterials during the last decade. Due to the strong ...interaction of carbon materials with microwave radiation, fast heating rates and localized heating can be achieved. These features enable the acceleration of reaction processes, as well as the formation of nanostructures with special morphologies. A comprehensive overview is provided here on the possibilities and achievements in the field of carbon‐nanomaterial research when using microwave‐based heating approaches. This includes the synthesis and processing of carbon nanotubes and fibers, graphene materials, carbon nanoparticles, and capsules, as well as porous carbon materials. Additionally, the principles of microwave‐heating, in particular of carbon materials, are introduced and important issues, i.e., safety and reproducibility, are discussed.
Microwave radiation can be used in many different ways to prepare and modify carbon nanomaterials. Achievements in the field of carbon nanotubes and fibers, graphene materials, carbon nanoparticles and capsules, and porous carbon materials are summarized. Additionally, the principles of microwave‐heating are introduced and important issues, i.e., safety and reproducibility, are discussed.
Our society's dependency on portable electric energy, i.e., rechargeable batteries, which permit power consumption at any place and in any time, will eventually culminate in resource wars on limited ...commodities like lithium, cobalt, and rare earth metals. The substitution of conventional metals as means of electric charge storage by organic and polymeric materials, which may ultimately be derived from renewable resources, appears to be the only feasible way out.
In this context, the novel class of organic radical batteries (ORBs) excelling in rate capability (i.e., charging speed) and cycling stability (>1000 cycles) sets new standards in battery research. This review examines stable nitroxide radical bearing polymers, their processing to battery systems, and their promising performance.
For over a hundred years, rechargeable batteries have facilitated the evolution from a mains‐operated to a mobile society. During this process, our society's dependency on limited resources such as lithium, cobalt, and rare earth metals grew steadily. With the recent development of electroactive nitroxide‐radical‐bearing polymers, a new and seminal class of electrode material is evolving quickly.
In times of spreading mobile devices, organic batteries represent a promising approach to replace the well‐established lithium‐ion technology to fulfill the growing demand for small, flexible, safe, ...as well as sustainable energy storage solutions. In the last years, large efforts have been made regarding the investigation and development of batteries that use organic active materials since they feature superior properties compared to metal‐based, in particular lithium‐based, energy‐storage systems in terms of flexibility and safety as well as with regard to resource availability and disposal. This Review compiles an overview over the most recent studies on the topic. It focuses on the different types of applied active materials, covering both known systems that are optimized and novel structures that aim at being established.
The search for the green battery is at the center of numerous efforts during the last years. In particular, the replacement of environmentally questionable metals by more sustainable organic materials is on the current research agenda. This review presents recent results regarding the developments of organic active materials for electrochemical energy storage.
Asymmetric flow field-flow fractionation (AF4) is a widely used and versatile technique in the family of field-flow fractionations, indicated by a rapidly increasing number of publications. It ...represents a gentle separation and characterization method, where nonspecific interactions are reduced to a minimum, allows a broad separation range from several nano- up to micrometers and enables a superior characterization of homo- and heterogenic systems. In particular, coupling to multiangle light scattering provides detailed access to sample properties. Information about molar mass, polydispersity, size, shape/conformation, or density can be obtained nearly independent of the used material. In this Perspective, the application and progress of AF4 for (bio)macromolecules and colloids, relevant for “nano” medical and pharmaceutical issues, will be presented. The characterization of different nanosized drug or gene delivery systems, e.g., polymers, nanoparticles, micelles, dendrimers, liposomes, polyplexes, and virus-like-particles (VLP), as well as therapeutic relevant proteins, antibodies, and nanoparticles for diagnostic usage will be discussed. Thereby, the variety of obtained information, the advantages and pitfalls of this emerging technique will be highlighted. Additionally, the influence of different fractionation parameters in the separation process is discussed in detail. Moreover, a comprehensive overview is given, concerning the investigated samples, fractionation parameters as membrane types and buffers used as well as the chosen detectors and the corresponding references. The perspective ends up with an outlook to the future.
2,2′:6′,2′′‐Terpyridine (tpy) and its derivatives represent highly versatile ligands for the complexation of transition metal ions. Today, such complexes are employed in a highly diverse fashion – ...including inter alia materials science, opto‐electronics, pharmacy or catalysis. Concerning the latter one, a vast development has led to new or improved applications in both “conventional” organic chemistry (i. e., catalysis of functional‐group interconversions, CH‐activation or cross‐coupling reactions) as well as energy‐related applications (e. g., CO2 reduction, artificial photosynthesis, dye degradation). In this respect, not only homogeneous catalysts (i. e., molecular complexes) but also heterogeneous and recyclable ones have moved to the focus of interest. These heterogeneous structures include 1D metallopolymers, metal‐organic frameworks (MOFs), organic‐inorganic hybrids and bio‐inspired catalysts. We gave a first overview on this topic already in 2011; in here, the methods and implementations established within the last decade as well as relevant contributions from earlier works are presented and discussed.
Old terps, new tricks: Metal complexes with terpyridine (tpy) ligands have found application in various fields of research, catalysis represents a notable example in this respect. A wide range of organic reactions are catalyzed by such complexes, homogeneous as well as heterogeneous ones. Furthermore, the CO2 reduction and the artificial photosynthesis are facilitated by tpy complexes. In here, these catalytic processes, under the umbrella of tpy complexes, are summarized with a strong focus on the literature published in the last decade.
Poly(ethylene imine)s (PEIs) are widely used in different applications, but most extensively investigated as non-viral vector systems. The high ability of cationic PEIs to complex and condense ...negatively charged DNA and RNA combined with their inherent proton sponge behavior accounts for the excellent efficiency in gene delivery. Further chemical modifications of the polymer expand the application potential, primarily aiming at increased transfection efficiency, cell selectivity and reduced cytotoxicity. Improvements in the synthesis of tailor-made PEIs in combination with new in-depth analytical techniques offer the possibility to produce highly purified polymers with defined structures. The contemporary strategies towards linear and branched poly(ethylene imine)s with modified surface characteristics, PEI-based copolymers as well as conjugates with bioactive molecules will be discussed. In this regard, the versatile branched PEIs have been successfully modified in a statistical manner, whereas the linear counterparts open avenues to design and synthesize well-defined architectures, in order to exploit their high potential in gene delivery.
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