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The work described in this thesis is inspired by natural-occurring molecules that are used throughout biology to perform specific, highly-selective tasks. This thesis illustrates the design, synthesis and investigation of novel molecular devices based on acyl hydrazones for the synthesis of a small molecule walker and light-driven molecular shuttles.Chapter One outlines a general overview of the design and synthesis of molecular devices, including molecular walkers and molecular shuttles. Some of the most important examples of walking molecules (both natural and synthetic) are described in detail, along with a comprehensive introduction of molecular shuttles and their synthetic mimics. Examples of stimuli-responsive molecular shuttles that have been developed are highlighted throughout the chapter.Chapter Two describes the design and synthetic progress towards a molecular walker, as well as detailing the optimisation of the synthetic steps achieved thus far. In this chapter, most of the work presented is based on the design and optimisation of the synthesis of an acyl hydrazone-based molecular walker, which will be able to walk directionally and repetitively along its conjugate track when the conditions are changed. A novel acyl hydrazone pyridine moiety is introduced to the system to achieve a high directional bias during the walking process. First, the concept and basis of the design is explained and further, the synthesis of the walker system is discussed in detail.Chapter Three illustrates the synthesis and operation of 1- and 2- station [2]-rotaxanes which exhibit all the requirements for a light-driven molecular shuttle. The effect of a new photo switchable binding station, an acyl pyridyl hydrazone, on the shuttling process is investigated by comparing the positional distribution of the macrocycle between the acyl hydrazone station and the succinamide-ester station, while the acyl hydrazone undergoes photo- and thermal isomerisation. The successful synthesis of this molecular architecture is described along with its operation, demonstrating high positional integrity and efficiency during the shuttling process. |
