Fluorescence-based Investigations of the Properties and Applications of Supramolecular Host-Guest Inclusion Systems
Dr. Brian Wagner(UPEI)
Abstract: Fluorescence spectroscopy provides an excellent method for investigating supramolecular host-guest inclusion phenomena, due to its high sensitivity and the large effect of inclusion on polarity-sensitive fluorescent probe guests. In addition, the large inclusion-induced changes in emission can be exploited in fluorescent sensors and other optical devices, in both "switch-on" and "switch-off" configurations, and also in fluorescence-based trace detection. Host-guest inclusion can occur in solution (usually aqueous) or in the solid state. Our group is interested in identifying and studying polarity-sensitive fluorescent probes, with a wide range of inclusion-induced responses, wavelength ranges, sizes and shapes. We are also interested in investigating the host properties of a range of cavity-containing organic molecules (such as cyclodextrins, cucurbiturils and calixarenes) and inorganic materials (such as coordination polymers) using these fluorescent probes. In most cases in aqueous solution, host inclusion (for example by cyclodextrins) results in increased emission (fluorescence enhancement), but in rare cases, host inclusion can result in decreased emission (fluorescence suppression). The latter polarity-sensitive probe type are of great interest, because they can be used to design "switch-on" fluorescent sensors based on guest release. In this presentation, the effect of host inclusion on a range of polarity-sensitive fluorescent probe molecules in aqueous solution will be presented and discussed, in terms of the fundamental aspects of host-guest inclusion phenomena, as well as practical applications in optical sensors and trace detection (for example that of pesticides). Fluorescence-based host-guest inclusion in non-aqueous solution, as well as solids, will also be discussed.
Bio: Professor of Chemistry, University of Prince Edward Island since 1995. BSc. Honours (1985, Dalhousie), PhD (1990, Western), NSERC Postdoctoral Fellow (1990-92, University of Saskatchewan), Research Associate (1993-95, NRC Ottawa), 3M Canada National Teaching Fellow (2005)