Switchable N-pyridyl-thiourea/urea acyclic and macrocyclic compounds as anion receptors
Switchable N-pyridyl-thiourea/urea acyclic and macrocyclic compounds as anion receptors
This thesis is concerned with the synthesis of acyclic and macrocyclic N-pyridyl thiourea/urea based receptors and their tendency to switch their conformations upon protonation and subsequent binding of an anionic guest. Chapter 1 is an introduction of the basic principles of supramolecular chemistry.
Chapter 2 describes the synthesis of neutral and protonated acyclic N-pyridyl-N-phenyl thiourea receptors.
Chapter 3 describes the synthesis of neutral and protonated acyclic N-pyridyl-N-phenyl urea receptors, which showed similar conformations to their analogous neutral and protonated thioureas. Protonated ureas bind chloride by strong 1:1 and 1:2 binding modes, but are deprotonated with acetate anion. Unlike the protonated thiourea receptors, protonated ureas formed precipitation of phosphate complexes when treated with dihydrogen phosphate as confirmed by X-ray crystal structure analysis. On the other hand, NMR studies of the neutral ureas revealed their tendency to form weak to moderate complexes with halide and acetate anions. Chapter 4 describes the unsuccessful attempts to synthesise N-pyridyl-thiourea-based macrocycles and the successful synthesis of an N-pyridyl-urea-based macrocycle. The structural study of this macrocycle revealed its tendency to adopt a non-binding conformation. However, structural and NMR studies of protonated urea-based macrocycles were not performed due to low solubility of the salt in a range of solvents and attempted solubilisation in DMSO led to deprotonation of the salt giving back the neutral macrocycle.
University of Southampton
2007
Rashdan, Suad Ahmed
(2007)
Switchable N-pyridyl-thiourea/urea acyclic and macrocyclic compounds as anion receptors.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
This thesis is concerned with the synthesis of acyclic and macrocyclic N-pyridyl thiourea/urea based receptors and their tendency to switch their conformations upon protonation and subsequent binding of an anionic guest. Chapter 1 is an introduction of the basic principles of supramolecular chemistry.
Chapter 2 describes the synthesis of neutral and protonated acyclic N-pyridyl-N-phenyl thiourea receptors.
Chapter 3 describes the synthesis of neutral and protonated acyclic N-pyridyl-N-phenyl urea receptors, which showed similar conformations to their analogous neutral and protonated thioureas. Protonated ureas bind chloride by strong 1:1 and 1:2 binding modes, but are deprotonated with acetate anion. Unlike the protonated thiourea receptors, protonated ureas formed precipitation of phosphate complexes when treated with dihydrogen phosphate as confirmed by X-ray crystal structure analysis. On the other hand, NMR studies of the neutral ureas revealed their tendency to form weak to moderate complexes with halide and acetate anions. Chapter 4 describes the unsuccessful attempts to synthesise N-pyridyl-thiourea-based macrocycles and the successful synthesis of an N-pyridyl-urea-based macrocycle. The structural study of this macrocycle revealed its tendency to adopt a non-binding conformation. However, structural and NMR studies of protonated urea-based macrocycles were not performed due to low solubility of the salt in a range of solvents and attempted solubilisation in DMSO led to deprotonation of the salt giving back the neutral macrocycle.
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Published date: 2007
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Local EPrints ID: 466303
URI: http://eprints.soton.ac.uk/id/eprint/466303
PURE UUID: 423fe12d-8ad0-4736-b3bc-6f08f5435ecd
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Date deposited: 05 Jul 2022 05:08
Last modified: 05 Jul 2022 05:08
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Author:
Suad Ahmed Rashdan
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