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. / text

The study of the binding and recognition of anions has emerged as a significant branch of supramolecular chemistry over the past 20 years. Of particular interest is the binding in aqueous media of industrially or biologically relevant anions including fluoride, pyrophosphate, and terephthalate. To date, most anion recognition using synthetic systems has been accomplished with small molecule receptors operating in organic media. We believe the challenge of sensing and binding anionic species in aqueous media could be addressed through polymers. This is due to their solubility, which can be tuned by judicious selection of the appropriate polymer backbone. Further, polymers can be cross-linked (forming interchain bonds) to produce insoluble materials that are attractive for use as filter materials for liquids and gases. The polymer network can also act as a net to strip away the solvent shell of the anions, leading to increased sensitivity toward hydrated analytes. In addition, the multi-valency due to multiple binding sites in a polymer can lead to increased affinities for analytes. This dissertation details the author’s work focused on the preparation of anion receptor-containing polymers and their subsequent evaluation as both sensors for the fluoride anion and as extractants for bisanions under conditions of liquid-liquid extraction. Chapter 1 gives a brief review of the challenges of anion binding and a primer on the field of sensing and extracting anions using polymeric systems. Chapter 2 describes our work incorporating three quinoxaline-based anion receptors into poly(methyl methacrylate) polymers and their sensing of anionic targets. Chapter 3 describes our work incorporating calix[4]pyrrole anion receptors into poly(methyl methacrylate) polymers. These polymeric systems were found to undergo reversible crosslinking in organic media when combined with certain ditopic anions. Chapter 4 describes our work to investigate chemopreventives of prostate cancer based on the phytochemicals 6-gingerol and 6-shogaol. The mechanism of action was linked to the inhibition of inflammation pathways. Derivatives of 6-shogaol were synthesized and their ability to inhibit prostate cancer cell growth was evaluated. Chapter 5 details all the syntheses and characterization data of the compounds discussed in this dissertation, as well as spectra from titrations and extraction studies. / text

La presente tesis consta de dos vertientes interrelacionadas. La primera se centra en intentar cuantificar experimentalmente la contribución energética en disolución de la interacción anión-, mediante el uso de calix[4]pirroles aril substituidos en las posiciones meso- como moléculas modelo. El trabajo realizado muestra que la interacción anión- es repulsiva para anillos con valores de ESP negativos y a medida que el efecto electrón atrayente de los sustituyentes aumenta la interacción se vuelve menos repulsiva, hasta que, cuando el valor de ESP en el centro del anillo aromático es positivo la interacción se vuelve ligeramente atractiva. La segunda en el uso de estos receptores simples para obtener arquitecturas supramoleculares más complejas, y su autoensamblaje en capsulas. Los estudios muestran que calix[4]pirroles sustituidos con grupos urea en sus anillos aromáticos se autoemsamblan en capsulas diméricas en presencia de un huesped adecuado como los N-óxidos de alquil aminas y piridinas en disolventes apolares. / This thesis consists of two interrelated aspects. The first one pretends to quantify experimentally the energetic contribution in solution of the anion- interaction, using aryl extended calix[4] pyrroles substituted in their meso- positions as a model system. The work performed shows that the anion- interaction is repulsive for aromatic rings with negative ESP values, as the electron withdrawing character of the substituent increases the interaction becomes less repulsive, until eventually, when the ESP value in the center of the aromatic ring is positive the interaction turns into slightly attractive.The second one is based on the use of these simple receptors as scaffolds to obtain complex structures and their self-assembly into capsules. The studies performed show that aryl extended calix[4]pyrroles substituted with urea functions on their upper rim self-assemble into dimeric capsules in the presence of a suitable guest like the N-oxides of alkyl amines and pyridines in non-polar solvents.