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Details of Grant 

EPSRC Reference: EP/F026382/1
Principal Investigator: Richardson, Dr TH
Other Investigators:
Hunter, Professor CA
Researcher Co-Investigators:
Project Partners:
Department: Physics and Astronomy
Organisation: University of Sheffield
Scheme: Standard Research
Starts: 01 August 2008 Ends: 30 September 2011 Value (£): 421,338
EPSRC Research Topic Classifications:
Materials Characterisation Materials Processing
Materials Synthesis & Growth
EPSRC Industrial Sector Classifications:
Related Grants:
Panel History:
Panel DatePanel NameOutcome
15 Nov 2007 Materials Prioritisation Panel November (Tech) Announced
Summary on Grant Application Form
The identification and measurement of pollutant or contaminant vapours present in or entering the atmosphere has never been more important than today. Current interest in our environment has resulted from overwhelming scientific data confirming global warming and associated climate change. Furthermore, the threat posed by terrorism of toxic vapours introduced criminally into our air supply highlights the urgent need for highly responsive sensing materials that can form the active ingredients in efficient sensing systems. Many monitoring devices utilise semiconductor-based or electrochemical sensing elements but these are often non-specific and usually require high operating temperatures. Organic materials have most notably attracted attention in the form of the electronic nose in which conducting polymers act as chemi-resistors. However, problems with reproducing the behaviour of these polymers from batch to batch have hindered their commercial development. Our previous research has produced a family of porphyrins which exhibits most of the characteristics of useful sensing materials for application with a wide range of analytes and at low concentrations (typically in the region 0.5 / 10ppm). Porphyrins are highly conjugated organic molecules which display a rich UV-visible absorption spectrum . These transitions are readily modified by the adsorption of a wide range of gaseous analyte molecules. Close study of the absorption spectrum shows that the detailed changes resulting from vapour exposure are different from analyte to analyte. The current availability of sophisticated, high resolution, portable and, most importantly, inexpensive (<2-3k) UV-visible spectrophotometers now means that even very small variations in the modified spectra arising from interactions with different analytes can be detected easily. Thus, by using several members of a family of sensing materials in an array configuration, one can expect to identify and quantify the concentration of a particular analyte. Our porphyrins are processable as Langmuir-Schaeffer (LS) films although our work has shown that the use of a host component / for example, a fatty acid or a calix[n]arene acid / aids film formation and leads to high reproducibility of samples. In this proposed research programme, we wish to develop a family of porphyrins ( calixporphs ) in which the porphyrin monomer is grafted around the edge of a calix[n]arene carboxylic acid ring to form a molecule possessing the vapour /sensitive functionality of the porphyrin coupled to the superb film-forming properties of the calix[n]arene acid species. Furthermore, calix[n]arenes are known to be relatively thermally stable compounds compared to many other host materials with melting points usually in the range 250 / 300oC. Importantly, we wish to invoke the interaction properties of calix[n]arenes themselves which are known to bind a wide range of small molecules such as NO2, toluene and various metal ions in such a way that the optical properties of the adduct are significantly modified in the UV-visible region. The principal aim of this programme is to realise a molecular system in which the optical properties of resulting thin films are affected dramatically by the presence of interactions between the analyte and the porphyrin moieties and / or the calix[n]arene cavities. The bifunctionality of these molecules would be expected to enhance selectivity beyond our present achievements and lead to extremely useful sensing materials. The versatile properties of the calixarene carrier (binding ability, porosity, film-forming ability, thermal stability) coupled to the vapour sensitivity of the porphyrins should allow us to develop sensing materials displaying fast response rate, high sensitivity, high identification power (selectivity / with the use of arrays) and most probably materials showing suppressed temperature dependence.
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Organisation Website: http://www.shef.ac.uk