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Topic

Sulfo-pillar[n]arenes and their applications in complex sensing systems and the molecular recognition of illicit drugs

Department of Chemistry

Date & location

• Wednesday, April 15, 2026
• 2:00 P.M.
• Elliott Building, Room 226

Examining Committee

Supervisory Committee

• Dr. Fraser Hof, Department of Chemistry, ̽��ϵ�� (Supervisor)
• Dr. David Leitch, Department of Chemistry, UVic (Member)

External Examiner

• Dr. Jay Cullen, School of Earth and Ocean Sciences, UVic

Chair of Oral Examination

• Prof. Michael Eby, School of Earth and Ocean Sciences, UVic

Abstract

Host-guest systems are increasingly relevant in chemical sensing and therapeutic applications. Sulfo-pillar[n]arenes are a recently developed class of highly anionic macrocyclic hosts that exhibit very strong binding affinities (K_a = 10⁷–10¹¹ M^-1) toward multiple cationic small molecules in biological media, enabling their applications in drug sensing and drug reversal. This thesis explores how the unique properties of sulfo-pillar[n]arenes can be used to create complex, information‑rich sensing systems and how structural modifications to these hosts influence their molecular recognition of illicit drugs.

In Chapter 2, we demonstrate that sulfo-pillar[6]arene (sP6) forms a highly emissive co‑assembly with the fluorescent DimerDye 13 (DD13) sensor. This mixed host system produces enhanced and diversified fluorescence responses to a broad range of illicit drugs, including exceptionally bright ternary complexes formed with cocaine. The co‑assembly significantly lowers limits of detection for illicit drugs relative to DD13 alone and enables a minimalist two‑component sensor array to discriminate structurally similar drugs. We further demonstrate that a single DD13-sP6 co‑assembly, deployed as two sensors by preparing solutions with the two components at different ratios, can reliably differentiate complex whole-tissue biological samples such as locally foraged wild mushrooms.

In Chapter 3, we synthesize three pseudo sulfo-pillar[6]arenes in which selective removal of sulfate groups modulates host charge and therefore binding properties. These new hosts display altered affinities and selectivities towards DAPI, fentanyl, cocaine, and acetylcholine, demonstrating that binding strength is strongly influenced by subtle differences in charge distribution and host shape. Notably one of these new hosts (sPABD) retained strong affinity for fentanyl while exhibiting improved selectivity over acetylcholine. NMR studies further show that these hosts adopt distinct guest binding geometries.

Overall, these studies show how co‑assembly and specific host modifications can tune sulfo-pillar[6]arene molecular recognition, enabling improved sensor performance and more selective binding of illicit drugs.