Environmental Sulphide Anion Sensing

Lead Research Organisation: University of Oxford
Department Name: Oxford Chemistry

Abstract

Hydrogen sulphide is a corrosive and poisonous gas present in biology and plays a pivotal role in a variety of physiological processes, including the relaxation of vascular smooth muscles and the inhibition of insulin signalling. Additionally, in the form of sulphide it is found naturally in the environment - particularly as a contaminant in ground water. As a contaminant, sulphide poses a threat to living organisms and human industry; the corrosion of infrastructure or more specifically, and also alarmingly, nuclear waste canisters has sparked major concerns. Hence, in particular the importance of detecting sulphide in the environment has recently gained much interest. The current favoured methods of detection, electrochemical sensing and the methylene blue test, both have drawbacks that hamper their efficiency - one specific example being the poisoning of reference electrodes. These methods also provide irreversible detection routes only, thus limiting their scope for adaptation to provide real-time information on biological and environmental processes. As a consequence, the development of an effective, fast and reversible method with a greater operational lifetime for the accurate detection of sulphide is of much interest and stands to benefit a wide range of industries. Supramolecular host systems have been shown to bind a variety of anionic guest species. The potential for these types of molecules to recognise and sense sulphide has yet to be fully explored. This project's aim is to design and develop novel supramolecular host systems that can selectively bind and detect sulphide in organic and aqueous media. To achieve this aim, a range of acyclic, macrocyclic and interlocked supramolecular hosts will be constructed. The increase in host design complexity will come from the synthesis of rotaxane and catenane host molecules that contain unique three dimensional cavities. These interlocked host systems have been demonstrated to display exceptional levels of selectivity towards anions such as the halides. Additionally, highly directional non-covalent halogen bond donor motifs, together with redox- and photo-active reporter groups will be integrated into these mechanically bonded host structural frameworks to produce electrochemical and optical sensors for sulphide. Alignment to EPSRC's strategies and research areas: Energy (Nuclear Energy), Healthcare, Manufacturing, Global Uncertainties, Physical Sciences (Grand Challenge 'Directed Assembly of Extended Structures and Targeted Properties'; priority themes 'Synthetic Coordination Chemistry and Synthetic Supramolecular Chemistry'). Nuclear energy is a sub-theme of EPSRC's energy area. Implementing geological disposal is government policy in this area and is an enabler for the future nuclear landscape as dealing with the nuclear legacy as well as the future wastes is part of the 'social licence'. The ability to rapidly and cost-effectively characterise critical hydrogeological parameters is necessary in identifying a suitable candidate site for the Geological Disposal Facility (GDF). Aqueous sulphide content in deep groundwaters is one such parameter as it affects the safety functions provided by the envisioned multi-barrier system comprising the GDF. The industrial partner in this project is Radioactive Waste Management Limited.

Publications

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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/R512333/1 01/10/2017 30/09/2021
1950241 Studentship EP/R512333/1 01/10/2017 30/09/2020 Edward Joseph Mitchell