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DC Field | Value | Language |
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dc.contributor.advisor | Vargas-Baca, Ignacio | - |
dc.contributor.author | Ho, Peter | - |
dc.date.accessioned | 2021-11-10T02:47:08Z | - |
dc.date.available | 2021-11-10T02:47:08Z | - |
dc.date.issued | 2021 | - |
dc.identifier.uri | http://hdl.handle.net/11375/27161 | - |
dc.description.abstract | Noncovalent interactions have attracted significant attention in the recent decades, both seeking a fundamental understanding and pursuing a wide range of applications. One particular case that has been studied in great detail is halogen bonding (XBs). The use of chalcogen bonding (ChBs) is only beginning to thrive but already has made a mark in the chemical community. In this thesis, we intended to augment the study of ChBs by examining 1,2-chalcogenazole 2-oxides. These N-oxides of C3NCh (Ch = Se, Te) heterocycles spontaneously assemble supramolecular structures through reversible Te…O ChB interactions. In solution, their macrocyclic tetramers and hexamers exist in equilibrium. These rings as well as supramolecular polymers (infinite chains in crystalline phase) have been authenticated by single-crystal X-ray diffraction. Despite the reversibility of the Te…O link, the macrocycles display properties typical of covalent macrocycles, including ability to coordinate metal ions, host small molecules, and form adducts with fullerenes. The compounds are stable to tellurium halogenation and unreactive to Lewis bases. However, they are readily cleaved by Brønsted and Lewis acids. Transformation of the structure of iso-tellurazole N-oxides by formal insertion of an aromatic bridge between the nitrogen and oxygen atoms led to a new family of supramolecular building blocks. A disubstituted benzene bridge yielded three isomers, all of which display signs of aggregation in solution and crystallize in either polymeric or macrocyclic aggregates. Among the latter, the ortho compound assembled a calixarene-like trimer while the para derivative built a macrocyclic tetramer akin to a molecular square. | en_US |
dc.language.iso | en | en_US |
dc.title | Te…O Chalcogen Bonding in Supramolecular Chemistry | en_US |
dc.title.alternative | Te…O CHALCOGEN BONDING | en_US |
dc.type | Thesis | en_US |
dc.contributor.department | Chemistry and Chemical Biology | en_US |
dc.description.degreetype | Thesis | en_US |
dc.description.degree | Doctor of Philosophy (PhD) | en_US |
dc.description.layabstract | Supramolecular chemistry is a rapidly growing field of research that uses non-covalent interactions to spontaneously build well-organized structures. Among such interactions, hydrogen bonds are the most investigated and highly utilized in chemical and biological systems such as in DNA self-assembly, protein folding, cellulose, synthetic polymers and more. In recent years, much attention has been given to other non-covalent interactions, in particular bonding interactions that occur between electron-rich centres with electron-poor covalently bonded atoms of elements in groups 14 to 17 on the periodic table. These bonding interactions are named according to the group of the electron-deficient elements such as halogen bonds (XBs, group 17), chalcogen bonds (ChBs, group 16), “tetrel bonds” (group 14) and “pnictogen bonds” (group 15), as alternatives to hydrogen bonding. The purpose of this thesis is to augment our knowledge of ChBs by investigating the supramolecular chemistry of iso-chalcogenazole N-oxides and related compounds. Such molecules spontaneously assemble robust supramolecular structures, like infinite chains (polymers), and macrocyclic tetramers hexamers through Te…O ChB interactions that are strong and yet reversible. The macrocyclic aggregates coordinate to transition metal ions, form adducts with fullerene and host small molecules. The unusual stability of these tellurium-containing supramolecular building blocks, in addition to their strong ChBs, facilitated these investigations. The solubility of these compounds was improved by installing non-polar bulky groups. The macrocyclic cavity can be enlarged by replacing the oxygen atom with phenoxides groups, creating a new family of supramolecular building blocks. | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
Files in This Item:
File | Description | Size | Format | |
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Ho_Peter_Cheng-Wei_2021Nov_PhD.pdf.pdf | PhD Thesis | 25.98 MB | Adobe PDF | View/Open |
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