{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/30864"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/30864","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"Thermodynamically Driven (Reversible) End-Capping of Pseudorotaxanes to Produce Rotaxanes","abstract":"Rotaxanes can be synthesized using a thermodynamically driven approach of self-assembly. The thermodynamically driven approach is an efficient method to provide a better controlled synthesis of specific structures. This synthetic approach takes advantage of a labile bond between the guest molecule and the end stopper group. The reversibility of this bond allows for threading by the host molecule via chemical equilibrium. Intramolecular interactions such as hydrogen bonding and π-π stacking facilitate threading to form the pseudorotaxane which is endcapped to form the thermodynamically stable rotaxane. In this work, the synthesis and characterization of rotaxanes using a thermodynamically driven approach is reported. New OH-functionalized secondary dibenzyl ammonium hexafluorophosphate and tetrafluoroborate salts were synthesized and complexed with dibenzo-24-crown-8. The complexation between the salts and dibenzo-24-crown-8 was observed using 1D and 2D ¹H NMR spectroscopy. An association constant of 110 M⁻¹ was determined by integration for the pseudorotaxane from the ammonium hexafluorophospate salt and dibenzo-24-crown-8. The new guest species were endcapped in situ as trityl ethers to form new thermodynamically stable rotaxanes. Further work to pursue would include synthesis of rotaxanes using functionalized crown ethers for polymerization to make polyrotaxanes and synthesis of self-assembled polymers using this synthetic method.","abstract_html":"Rotaxanes can be synthesized using a thermodynamically driven approach of self-assembly. The thermodynamically driven approach is an efficient method to provide a better controlled synthesis of specific structures. This synthetic approach takes advantage of a labile bond between the guest molecule and the end stopper group. The reversibility of this bond allows for threading by the host molecule via chemical equilibrium. Intramolecular interactions such as hydrogen bonding and π-π stacking facilitate threading to form the pseudorotaxane which is endcapped to form the thermodynamically stable rotaxane. In this work, the synthesis and characterization of rotaxanes using a thermodynamically driven approach is reported. New OH-functionalized secondary dibenzyl ammonium hexafluorophosphate and tetrafluoroborate salts were synthesized and complexed with dibenzo-24-crown-8. The complexation between the salts and dibenzo-24-crown-8 was observed using 1D and 2D ¹H NMR spectroscopy. An association constant of 110 M⁻¹ was determined by integration for the pseudorotaxane from the ammonium hexafluorophospate salt and dibenzo-24-crown-8. The new guest species were endcapped in situ as trityl ethers to form new thermodynamically stable rotaxanes. Further work to pursue would include synthesis of rotaxanes using functionalized crown ethers for polymerization to make polyrotaxanes and synthesis of self-assembled polymers using this synthetic method.","abstract_has_math":false,"creators":["Fletcher, Amy L."],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Chemistry","degree_department":"Chemistry","school":null,"contributors":[],"advisors":[],"committee_chairs":["Gibson, Harry W."],"committee_members":["Ward, Thomas C.","McGrath, James E."],"year":2003,"date_issued":"2003-08-29","date_published":"2003-08-29","updated_at":"2026-07-24T05:56:22Z","subjects":["Supramolecular Chemistry","Self-Assembly","Pseudorotaxane","Rotaxane"],"languages":[],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-01092004-112614"],"render_values":[{"text":"etd-01092004-112614","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/30864","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Gibson, Harry W."]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Ward, Thomas C.","McGrath, James E."]},{"key":"dc:contributor.department","label":"Department","values":["Chemistry"]},{"key":"dc:creator","label":"Author","values":["Fletcher, Amy L."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T20:30:19Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T20:30:19Z","2005-01-15"]},{"key":"dc:date.issued","label":"Date","values":["2003-08-29"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Supramolecular Chemistry","Self-Assembly","Pseudorotaxane","Rotaxane"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-01092004-112614"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/30864"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Rotaxanes can be synthesized using a thermodynamically driven approach of self-assembly. The thermodynamically driven approach is an efficient method to provide a better controlled synthesis of specific structures. This synthetic approach takes advantage of a labile bond between the guest molecule and the end stopper group. The reversibility of this bond allows for threading by the host molecule via chemical equilibrium. Intramolecular interactions such as hydrogen bonding and π-π stacking facilitate threading to form the pseudorotaxane which is endcapped to form the thermodynamically stable rotaxane. In this work, the synthesis and characterization of rotaxanes using a thermodynamically driven approach is reported. New OH-functionalized secondary dibenzyl ammonium hexafluorophosphate and tetrafluoroborate salts were synthesized and complexed with dibenzo-24-crown-8. The complexation between the salts and dibenzo-24-crown-8 was observed using 1D and 2D ¹H NMR spectroscopy. An association constant of 110 M⁻¹ was determined by integration for the pseudorotaxane from the ammonium hexafluorophospate salt and dibenzo-24-crown-8. The new guest species were endcapped in situ as trityl ethers to form new thermodynamically stable rotaxanes. Further work to pursue would include synthesis of rotaxanes using functionalized crown ethers for polymerization to make polyrotaxanes and synthesis of self-assembled polymers using this synthetic method."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["Master of Science"]},{"key":"dc:title","label":"Title","values":["Thermodynamically Driven (Reversible) End-Capping of Pseudorotaxanes to Produce Rotaxanes"]}]}],"canonical_facts":{"dc:contributor.committeechair":["Gibson, Harry W."],"dc:contributor.committeemember":["Ward, Thomas C.","McGrath, James E."],"dc:contributor.department":["Chemistry"],"dc:creator":["Fletcher, Amy L."],"dc:date.accessioned":["2014-03-14T20:30:19Z"],"dc:date.available":["2014-03-14T20:30:19Z","2005-01-15"],"dc:date.issued":["2003-08-29"],"dc:description.abstract":["Rotaxanes can be synthesized using a thermodynamically driven approach of self-assembly. The thermodynamically driven approach is an efficient method to provide a better controlled synthesis of specific structures. This synthetic approach takes advantage of a labile bond between the guest molecule and the end stopper group. The reversibility of this bond allows for threading by the host molecule via chemical equilibrium. Intramolecular interactions such as hydrogen bonding and π-π stacking facilitate threading to form the pseudorotaxane which is endcapped to form the thermodynamically stable rotaxane. In this work, the synthesis and characterization of rotaxanes using a thermodynamically driven approach is reported. New OH-functionalized secondary dibenzyl ammonium hexafluorophosphate and tetrafluoroborate salts were synthesized and complexed with dibenzo-24-crown-8. The complexation between the salts and dibenzo-24-crown-8 was observed using 1D and 2D ¹H NMR spectroscopy. An association constant of 110 M⁻¹ was determined by integration for the pseudorotaxane from the ammonium hexafluorophospate salt and dibenzo-24-crown-8. The new guest species were endcapped in situ as trityl ethers to form new thermodynamically stable rotaxanes. Further work to pursue would include synthesis of rotaxanes using functionalized crown ethers for polymerization to make polyrotaxanes and synthesis of self-assembled polymers using this synthetic method."],"dc:description.degree":["Master of Science"],"dc:identifier.other":["etd-01092004-112614"],"dc:identifier.uri":["http://hdl.handle.net/10919/30864"],"dc:publisher":["Virginia Tech"],"dc:rights":["In Copyright"],"dc:rights.uri":["http://rightsstatements.org/vocab/InC/1.0/"],"dc:subject":["Supramolecular Chemistry","Self-Assembly","Pseudorotaxane","Rotaxane"],"dc:title":["Thermodynamically Driven (Reversible) End-Capping of Pseudorotaxanes to Produce Rotaxanes"],"dc:type":["Thesis"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["masters"],"thesis:degree_name":["Master of Science"],"thesis:institution_name":["Virginia Polytechnic Institute and State University"]},"updated_at":"2026-07-24T05:56:22Z"}