New visible light excitable donor-acceptor 7-hydroxy-coumarins as blue fluorescent probes for selective staining of vacuoles in yeasts and L. donovaniElectronic supplementary information (ESI) available: Spectroscopic characterization data, 1H and 13C NMR spectra, and absorption, excitation and fluorescence spectra of all of the compounds, 4a-d, 5, 6 and 8, in HEPES. Computed TD-DFT data and Cartesian coordinates, materials and methods. See DOI: 10.1039/c6tb03257e

In order to address the existing limitations of the commercially available fluorescent probe CMAC (7-amino-4-chloromethylcoumarin), a new series of highly fluorescent donor-acceptor 7-hydroxy-coumarin derivatives was prepared and these derivatives were used as vacuole specific fluorescent probes for live cell imaging of unicellular parasitic protozoa L. donovani promastigotes and yeast cells S. pombe and S. cerevisiae . The synthesized 7-hydroxy-coumarins exhibited interesting photophysical properties and have advantages such as excitation in the visible region, good water solubility, photo-stability, good quantum yield and low cytotoxicity. New 3-cyano-7-hydroxy-4-methylthio-coumarins ( CHMC s) were discovered as blue fluorescent probes for staining vacuoles.