Xanthene/Benzoxanthene Dyes: Novel Synthetic Metholologies, Applications in Molecular Recognition, Cellular Imaging and the Design of a Tunable White (RGB) Light Emitter
My graduate work has focused on the development of new fluorophore materials towards addressing several interdisciplinary research problems. Selective detection of sialic acid via a boron-amide interaction. Concentration changes of sialic acid can be monitored ratiometrically in the visible region using a boronic acid based chemosensor. The technique shows great promise for the detection of sialic acid, a critical cell surface residue involved in cancer, graft rejection and virulence in certain bacteria. There is no interference from commonly occurring oligosaccharides, aminosugars and most carboxylic acid-containing compounds. Improved synthetic methodology and studies of novel molecular probe architectures. I have developed a unique synthesis of xanthene dyes. It involves the initial formation of methylated carbinol intermediates, followed by demethylation and concomitant condensation. I successfully applied the methodology to the synthesis of hitherto unavailable type [a] and [b] benzoxanthene architectures. Importantly, the new dyes can display three emission maxima of approximately equal intensities, in the blue, green and red spectral regions, or in the blue, orange and near infra-red regions. When excited at ca. 300 nm, one of the fluorophores emits near white light, which resembles the white light from an incandescent light bulb. Discovery of a novel boron mediated 1-2 aryl shift reaction on substrates bearing a leaving group at a remote benzylic position. During the course of my work involving xanthene dye synthesis I discovered a new reaction (Scheme 1) reminiscent of the prototypical 1,2-alkyl shift involving R-haloalkyl borates discovered by Matteson in 1963.
Benzoxanthene, Xanthene, Sensing, Near infrared (NIR), Synthesis, Dye
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