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Description:
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A series of seven functionalized near -infrared aza -BODIPY dyes have been synthesized and their spectroscopic properties measured . Their fluorescence emissions could be tuned by altering the electronic substituents on the aryl -groups . A through -bond energy transfer cassette featuring two fluorescein units as donor , and an aza -BODIPY dye as acceptor , was then synthesized and its preliminary spectroscopic properties examined . This cassette exhibited absorption and fluorescence characteristics that were highly dependent on the pH and the solvent polarity . Furthermore , no energy transfer was observed upon excitation of the donor . Novel near -infrared aza -BODIPY were also synthesized via a one -pot , two step reaction . Upon demethylation and intermolecular cyclization onto the B -atom , a ~ 100 nm red¬shift of both the absorption and fluorescence emission maxima could be observed .
Through -bond energy transfer cassettes based on squaraines have also been synthesized and their spectroscopic properties studied . These cassettes exhibited fast and efficient energy transfer from the donor to the acceptor . In depth experiments have also been realized to correlate the rate of energy transfer and structure on 3 different sets of through -bond energy transfer cassettes . No correlations could be made between the rate of the energy transfer and the nature of the acceptor , and the distance between the donor and acceptor .
Finally , the use of DPP (diketo -pyrrolopyrolle ) pigment as a potential donor for through -bond energy transfer cassettes was investigated . Three water -soluble DPPs dyes were prepared and studied . They all displayed weak fluorescence in water . |