Syntheses of calix[4]pyrrole functionalized extended molecular systems and applications for environmental concerns




Lee, Juhoon

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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.



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