Calix4pyrrole Based Ion Pair Receptors

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.

Significant efforts have been made to develop synthetic receptors with high selectivity and affinity for specific anions or ion pairs. Calix[4]pyrroles, conformationally flexible tetrapyrrolic macrocycles defined by sp3 hybridized meso bridges, have emerged as one of the essential supramolecular hosts for anion and ion pair recognition. This dissertation describes efforts to develop functional calix[4]pyrroles that might allow their eventual use as therapeutics and in environmental remediation applications. A series of calix[4]pyrroles were prepared by functionalizing the parent calix[4]pyrrole at the so–called meso bridges, including mono–walled calix[4]pyrroles, double–walled calix[4]pyrroles, and strapped calix[4]pyrroles. Chapter 1 provides a brief overview of calix[4]pyrroles, calix[4]pyrrole–based anion transporters, and hydroxide extraction based on host–guest chemistry. Chapter 2 summarizes synthetic developments focused on preparing new calix[4]pyrroles. Chapter 3 details studies devoted to establishing correlations between changes in intracellular cation concentrations and cancer cell death. Chapter 4 describes the recognition and extraction of sodium hydroxide using calix[4]pyrrole–based ion pair receptors. Chapter 5 provides the synthetic procedures and the characterization data for all new compounds used in these studies

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.

The first chapter is a review of fluorescent sensors for explosives detection and ion pair receptors. In the second chapter, two novel pyrene-appended calix[4]pyrroles are reported. Their binding properties to various guests including aromatic explosives and anions are discussed. The third chapter describes the design and synthetic attempts of two calix[4]arene-strapped calix[4]pyrroles to serve as ion pair receptor in order to be selective for potassium salts and sodium salts, respectively

Brett M. Rambo ∙ Eric S. Silver ∙ Christopher W. Bielawski ∙ Jonathan L. Sessler Covalent Polymers Containing Discrete Heterocyclic Anion Receptors Philip A. Gale ∙ Chang-Hee Lee Calix[n]pyrroles as Anion and Ion-Pair Complexants Wim Dehaen Calix[n]phyrins: Synthesis and Anion Recognition Hiromitsu Maeda Acyclic Oligopyrrolic Anion Receptors Jeffery T. Davis Anion Binding and Transport by Prodigiosin and Its Analogs Hemraj Juwarker ∙ Jae-min Suk ∙ Kyu-Sung Jeong Indoles and Related Heterocycles Pavel Anzenbacher Jr. Pyrrole-Based Anion Sensors, Part I: Colorimetric Sensors Pavel Anzenbacher Jr. Pyrrole-Based Anion Sensors, Part II: Fluorescence, Luminescence, and Electrochemical Sensors Ermitas Alcalde ∙ Immaculada Dinarès ∙ Neus Mesquida Imidazolium-Based Receptors Nathan L. Kilah ∙ Paul D. Beer Pyridine and Pyridinium-Based Anion Receptors Kevin P. McDonald ∙ Yuran Hua ∙ Amar H. Flood 1,2,3-Triazoles and the Expanding Utility of Charge Neutral CHlllAnion Interactions

El trabajo de tesis doctoral ha consistido en el diseño y síntesis de diferentes receptores moleculares. En particular, de nuevos derivados calix[4]pirrolaril-extendidos con dos y cuatro grupos fosfonatocomo receptores ditópicos para la complejación de pares iónicos, importantes para la extracción de sales y para el transporte de iones a través de las membranas celulares. Asimismo, derivados de calix[4]pirrol han sido preparados para la inclusión de N-óxidos en conformación de alta energía. La importancia de la inclusión ha sido demostrada en la modificación dela reactividad químicatípica delN-óxidoenreacciones en las queel mismo seutilizacomo co-oxidante. Por último, se presentan derivados de resorcin[4]areno con grupos etilo en la parte inferior y una pared móvil en la parte superior como potenciales ligandos para catálisis supramolecular.

Considerable efforts have been made to develop the supramolecular systems being capable of selectively binding and recognizing specific chemical species. Within this context, particular has been put towards nuclear waste remediation, environmental chemistry, and biology. Calix[4]pyrroles are non-conjugated tetrapyrrolic macrocycles capable of binding anions and neutral substrates via concerted and directional hydrogen bonding. Moreover, functionalization of the calix[4]pyrrole meso position allows the incorporation of additional binding sites for both cations and anions. Due to the ease of preparation and functionalization, elaborated calix[4]pyrroles have been employed as various anion and ion pair receptors as well as potential extractants for species present in high-level liquid waste (HLLW) and transporters for biological important ions in connection with therapeutic aims. These studies reported herein are primarily focused on the discovery in meso-substituted calix[4]pyrrole-functionalized extended molecular systems and applications for environmental concerns. Chapter 1 provides a brief overview regarding the historical perspective and inherent properties of calix[4]pyrroles, as well as outlines recent contributions for capturing, extracting and sequestering chemical species with environmental concerns. Chapter 2 describes the extraction of the sulfate anion via bipyrrole-strapped calix[4]pyrroles. Through these studies, we have discovered such cryptand-like receptors could extract the highly hydrophilic sulfate anion into an organic solvent from aqueous solutions when A336Cl was used as a coextractant. Chapter 3 depicts a novel meso-functionalized calix[4]pyrrole-based three dimensional networked molecular cage. Interestingly, upon treatment of fluoride, the resultant framework could be disassembled, which serves to release the inner molecules. Moreover, multiple lone pairs and hydrogen bonding donors provided by the calix[4]pyrrole building units allow for a highly selective adsorption for CO2 over other gaseous guest, such as N2, O2, H2 and CH4. Chapter 4 describes two novel calix[4]pyrrole-based uranyl complex cages, cage-1 and -2. The transformation from a tripodal cage (cage-1) to a tetrapodal system (cage-2) was achieved by a sunlight induced photochemical oxidation or via simple addition of hydrogen peroxide. Chapter 5 details the synthetic procedures and characterizations of all compounds used in these studies.

Comprehensive Supramolecular Chemistry II, Second Edition, Nine Volume Set is a ‘one-stop shop’ that covers supramolecular chemistry, a field that originated from the work of researchers in organic, inorganic and physical chemistry, with some biological influence. The original edition was structured to reflect, in part, the origin of the field. However, in the past two decades, the field has changed a great deal as reflected in this new work that covers the general principles of supramolecular chemistry and molecular recognition, experimental and computational methods in supramolecular chemistry, supramolecular receptors, dynamic supramolecular chemistry, supramolecular engineering, crystallographic (engineered) assemblies, sensors, imaging agents, devices and the latest in nanotechnology. Each section begins with an introduction by an expert in the field, who offers an initial perspective on the development of the field. Each article begins with outlining basic concepts before moving on to more advanced material. Contains content that begins with the basics before moving on to more complex concepts, making it suitable for advanced undergraduates as well as academic researchers Focuses on application of the theory in practice, with particular focus on areas that have gained increasing importance in the 21st century, including nanomedicine, nanotechnology and medicinal chemistry Fully rewritten to make a completely up-to-date reference work that covers all the major advances that have taken place since the First Edition published in 1996

Provides deep insight into the concepts and recent developments in the area of supramolecular chemistry in water Written by experts in their respective field, this comprehensive reference covers various aspects of supramolecular chemistry in water?from fundamental aspects to applications. It provides readers with a basic introduction to the current understanding of the properties of water and how they influence molecular recognition, and examines the different receptor types available in water and the types of substrates that can be bound. It also looks at areas to where they can be applied, such as materials, optical sensing, medicinal imaging, and catalysis. Supramolecular Chemistry in Water offers five major sections that address important topics like water properties, molecular recognition, association and aggregation phenomena, optical detection and imaging, and supramolecular catalysis. It covers chemistry and physical chemistry of water; water-mediated molecular recognition; peptide and protein receptors; nucleotide receptors; carbohydrate receptors; and ion receptors. The book also teaches readers all about coordination compounds; self-assembled polymers and gels; foldamers; vesicles and micelles; and surface-modified nanoparticles. In addition, it provides in-depth information on indicators and optical probes, as well as probes for medical imaging. -Covers, in a timely manner, an emerging area in chemistry that is growing more important every day -Addresses topics such as molecular recognition, aggregation, catalysis, and more -Offers comprehensive coverage of everything from fundamental aspects of supramolecular chemistry in water to its applications -Edited by one of the leading international scientists in the field Supramolecular Chemistry in Water is a one-stop-resource for all polymer chemists, catalytic chemists, biochemists, water chemists, and physical chemists involved in this growing area of research.