Effect of electron donors on the photophysical and theoretical properties of BODIPY dyes based on tetrazolo[1,5-a]quinoline

Abstract

Novel tetrazolo[1,5-a] quinoline-based BODIPY dyes (6b-d) were synthesized and characterized by photophysical and theoretical methods. Except for 6c, fluorescence quantum yield of the dyes increased parallelly with the solvent viscosity due to hindrance of free rotation at meso position. Fluorescence quantum yield of 6c is higher than 6d, although the number of electron-donating groups of the former is less than that of the latter. The fluorophores exhibited apparent responses in the fluorescence intensities with increasing water ratio in ethanol owing to their aggregation-induced emission (AIE) characteristics. In a separate study, NBO analysis and DFT calculations were also performed for dyes 6a-d. Various quantum chemical parameters from frontier orbital energies to polarizability were calculated and discussed in detail. The theoretical calculations showed that compound 6d is the most stable. These results demonstrate that tetrazolo[1,5-a] quinoline-based fluorophores would have potential application in water detection systems.