Stimuli Responsive Catalysis

Abstract

This thesis is centred upon the design and development of new stimuli responsive system, looking at new targets for sensing applications, and the release of new effector molecules for responsive catalytic systems.
Chapter 1 encompasses a comprehensive review of the current range of ratiometric electrochemical sensors, exploring the concepts fundamental in the design of new biosensors and highlighting strategies that improve selectivity and sensitivity. The chapter aims to provide an overview of the field and place in context the research undertaken in the thesis.
Chapter 2 reports the design, synthesis and testing of two ratiometric electrochemical chemodosimeters, and covers the development of the assays and their application towards point-of-use sensing. The chemodosimeter developed for the detection of -galactosidase exhibited a negligible background rate, which allowed for accurate detection to 0.1 U mL-1. The second chemodosimeter was selective for organophosphorus(III) compounds, sensitive to 13 ppm for triphenylphosphine, and the assay was readily compatible with a handheld potentiostat.
Chapters 3 and 4 introduce the concept of a stimuli responsive asymmetric catalytic system, with the aim of combing two ‘switch-on’ catalytic cycles that could be selectively triggered, with each cycle affording a different enantiomer product. Chapter 3 reports the development of pseudo-enantiomeric proligands for the catalytic transfer hydrogenation of ketones, covering their initial design, synthesis, and the triggered release of the proligands, which was explored via mass spectrometry. Five successful proligands are reported for a range of enzyme and small molecule triggers: b-galactosidase, fluoride, hydrogen peroxide, hydrazine, and alkaline phosphatase.
Chapter 4 focuses on the incorporation of the developed proligands into the stimuli responsive catalytic system. Firstly, three proligands are incorporated into a single pseudo-enantiomer system, with a brief substrate scope explored. Finally, two different dual pseudo-enantiomer systems are formed from the combination of two single pseudo-enantiomer systems. The selective triggering of each system is tested, and the enantioselective product formation observed.

Date of Award	14 Oct 2020
Original language	English
Awarding Institution	University of Bath
Supervisor	Christopher Frost (Supervisor) & Jonathan Williams (Supervisor)