The Synthesis and Study of Functionalised Catenanes and Rotaxanes for Supramolecular Chemistry Applications
Creators: name: Barlow, Sean
Publisher: name: Lancaster University
Year: 2024
Subjects: Chemistry
Supramolecular
Rotaxanes
CATENANES

description: A key pillar of supramolecular chemistry is located in the field of
 mechanically interlocked molecules. Interlocked systems, such as rotaxanes
 and catenanes, offer bespoke and desirable properties due to the
 architecture arising from the mechanical bond. This thesis explores the
 design, synthesis, and properties of such systems for a host of
 supramolecular chemistry applications. 
 
 
 Chapter 1 provides an introduction into the field of mechanically
 interlocked molecules, exploring routes to their synthesis through
 directed self-assembly. A review of the main properties and applications
 such systems possess are also discussed and the potential routes of
 further investigation are considered. 
 
 
 Chapter 2 begins with the development of a rapid hydrogen bond templated
 synthesis towards novel [2]catenanes and [2]rotaxanes, with several high
 yielding catenane substrates being subsequently isolated. Their
 characterisation is then discussed. Further investigations into the
 improved templated synthesis of single amide-containing [2]rotaxanes is
 then explored by incorporating PNO and thioamide motifs. In the final part
 of the chapter, the application of rapidly synthesised PNO-[2]catenane
 which demonstrated moderate binding selectivity towards lithium cations is
 detailed. 
 
 
 Chapter 3 explores the hydrogen bond templated synthesis developed in
 Chapter 2 for the synthesis of exotic interlocked architectures. In the
 first instance, the successful synthesis of two handcuff [2]rotaxanes are
 discussed and their characterisation is detailed. Following on from this,
 efforts to incorporate 1,3-substituted cubanes as a structural isostere in
 interlocked architecture is explored. This led to the isolation and
 characterisation of the first examples of cubane containing interlocked
 molecules. 
 
 
 Chapter 4 describes the synthesis and study of Raman-active [2]rotaxanes
 with the intent of applying them for in vivo applications. An overview of
 the synthesis describing the means of incorporating specific Raman-active
 functional groups (tags) is presented and, following this, four potential
 [2]rotaxane candidates were successful prepared and characterised. Initial
 Raman spectroscopy studies, which showed detection of the expected tag
 signals, and fluorescence interference arising from the most promising
 rotaxane candidate are then presented. 
 
 
 Chapter 5 details efforts towards the successive ring expansion of
 [2]catenanes through the SuRE and CARE methodologies. Investigations
 utilising the novel [2]catenanes synthesised from Chapter 2 were first
 explored, however, acylation attempts under the literature and modified
 conditions were sadly unsuccessful. In the second half, the synthesis and
 attempted ring expansion of a novel single amide containing [2]catenane is
 presented. Following a moderate redesign, isolation of the [2]catenane was
 achieved in high yield, however, follow-up ring expansion studies were
 unsuccessful due to failed acylation attempts. 
 
 
 Chapter 6 focus on the synthesis of hydrogen bond and chloride anion
 templated mechanically chiral interlocked systems. Initially,
 investigations focused on the separation of the enantiomers via separation
 of the corresponding diastereomeric salts or via chiral-HPLC for both the
 hydrogen bond and chloride anion templated [2]catenanes system. Whilst
 their synthesis and characterisation in a racemic form was successful,
 subsequent attempts to separate the enantiomers came to no avail. With
 minimal success, investigation turned towards the synthesis and separation
 of the enantiomers of a chloride anion templated mechanically chiral
 [2]rotaxane. In this instance, synthesis of the [2]rotaxane and subsequent
 separation of its enantiomers via chiral-HPLC was successful and has
 opened a new avenue of investigation into this style of rotaxane
 architecture.
 
 
 Chapter 7 provides a discussion of the overall conclusions from this
 thesis with reflection on the outlook and contextualisation of the
 research. This highlighted the importance and application of the rapid
 hydrogen bonded templated methodologies and designs developed in this
 thesis. Further work and future avenues of investigation are also
 suggested. 
 
 
 Chapter 8 provides the synthetic procedures and characterisation details
 for the compounds listed in this thesis broken down by chapter.
 
 
 Bibliography contains all the citations referenced in this thesis.
 
 
 Appendix reports the supplementary experimental information for titration
 protocols and X-ray crystal structure data.