Modified Calix4arene Receptors For Anion And Cation Recognition

Anion recognition plays a critical role in a range of biological processes, and a variety of receptors and carriers can be found throughout the natural world. Chemists working in the area of supramolecular chemistry have created a range of anion receptors, drawing inspiration from nature as well as their own inventive processes. This book traces the origins of anion recognition chemistry as a unique sub-field in supramolecular chemistry while illustrating the basic approaches currently being used to effect receptor design. The combination of biological overview and summary of current synthetic approaches provides a coverage that is both comprehensive and comprehensible. First, the authors detail the key design motifs that have been used to generate synthetic receptors and which are likely to provide the basis for further developments. They also highlight briefly some of the features that are present in naturally occurring anion recognition and transport systems and summarise the applications of anion recognition chemistry. Providing as it does a detailed review for practitioners in the field and a concise introduction to the topic for newcomers, Anion Receptor Chemistry reflects the current state of the art. Fully referenced and illustrated in colour, it is a welcome addition to the literature.

Compared with simple ion receptors, ion pair receptors display significantly enhanced affinity to ions through allosteric effects and additional electrostatic interactions between the bound ions, as well as host-guest interactions. Taken in concert, these necessarily permit a higher level of control over ion recognition and transport than that obtainable from simple ion binding. However, in spite of their potential applications in various fields, such as salt solublization, extraction, and membrane transport, ion pair receptors, which are able to form simultaneous complexation with an anion and a cation, still remains in a relatively unexplored area in supramolecular chemistry. This dissertation describes efforts to develop such systems on the basis of calix[4]arenes and calix[4]pyrroles. Calix[4]pyrroles and calix[4]arene derivatives bearing crown ethers or ester groups are known to act as efficient receptors for anions and cations, respectively. Therefore, the synthetic combination or modification of these two macrocyclic subunits provides an entry into novel ion pair receptors. The focus of this dissertation is on matched systems that form strong and specific complexes with cesium or potassium salts, depending on the exact structure in question. The selectivity demonstrated by these receptors is ascribed to a tuning of the cation recognition sites and control of the calix[4]arene conformation. Solid state structural and 1H NMR spectroscopic analyses reveal that potassium and cesium cations are bound to different sites within these ion pair receptors. A strong dependence on the counter anion (e.g., fluoride, chloride and nitrate) is also seen. In some cases this dependence is near-absolute, thus mimicking AND logic gates. Noticeably, the ion pair receptor consisting of a 1,3-alterate calix[4]arene crown-5 and a calix[4]pyrrole is able to extract various cesium and potassium salts from a water phase into an organic phase in various binding modes, depending on the counter anions. Furthermore, the extraction behavior of this ion pair receptor towards such ion pairs can be controlled by cation switching and the use of different solvents.

with contributions by numerous experts

This volume will capture transformational changes in both the chemistry and engineering side of solvent extraction, creating new directions and deepening our understanding of the structure and dynamics of liquid-liquid systems from the molecular- to nano- to meso- to bulk-scale. Reviews will cover advances in microfluidics, new tools for understanding the structure and dynamics of the liquid-liquid interface, ionic liquids in liquid-liquid extraction, molecular dynamics to visualize interactions in the solvent phase, liquid-liquid electrochemistry to interrogate the energetics of interfacial transport and complexation, design of new extractants, and the streamlining of process applications.

Calixarenes in Action is unique among books devoted to this interesting class of synthetic macrocycles. Rather than emphasizing the molecular properties of calixarenes, it covers in depth their supramolecular functions, enlightening the reader as to the peculiar features of calixarenes as hosts and as platforms for the synthesis of more complex receptors and catalysts. Topics covered in detail include the use of calixarenes in:molecular modeling of calixarenesnon-covalent interactionscrystal engineeringcation recognitionanion recognitionsupramolecular devicesnew materialsself-assembly processessupramolecular catalysisThe interest in calixarenes has grown tremendously in the last few years and this book reports, for each topic, the most recent literature critically evaluated by active researchers in the field. Calixarenes in Action is a valuable reference book for researchers in organic, inorganic, analytical and environmental chemistry and can serve as a graduate-level text for students of supramolecular science and technology.

Polymers are substances containing a large number of structural units joined by the same type of linkage. These substances often form into a chain-like structure. Starch, cellulose, and rubber all possess polymeric properties. Today, the polymer industry has grown to be larger than the aluminium, copper and steel industries combined. Polymers already have a range of applications that far exceeds that of any other class of material available to man. Current applications extend from adhesives, coatings, foams, and packaging materials to textile and industrial fibres, elastomers, and structural plastics. Polymers are also used for most composites, electronic devices, biomedical devices, optical devices, and precursors for many newly developed high-tech ceramics. This new book presents leading-edge research in this rapidly-changing and evolving field.

The book is designed to highlight the utility of supramolecular systems in diverse areas such as sensing of ionic and molecular analytes, aggregation, artificial molecular machines, biology, and medicine. The synthetic chemistry of a diverse set of supramolecules encompassing various supramolecular interactions involved in driving macrocyclic architectures is discussed. Attempts have been made to cover unique features of macrocycles viz. control over shape, size, and valency along with supramolecular interactions, which direct complex supramolecular systems. The book also provides a discussion on the similarity between macrocyclic host-guest systems and biomolecules, which lay the foundation of building modern artificial molecular motors and switches like protein machines for application in diverse areas. The authors hope that the book will appeal to a wider audience of students and researchers in academics and/or industries.