Synthesis of new fluorescent bichromophoric compounds as ratiometric pH probes for intracellular measurements

Vanessa Saura, Maria Marin Altaba, M. Isabel Burguete, David Russell, Francisco Galindo, Santiago V. Luis

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Three different bichromophoric compounds (1-3) containing an aminomethyl anthracene moiety linked to a second chromophore (pyrene, 4-nitrobenzo-2-oxa-1,3-diazole (NBD) and dansyl) through a valine-derived pseudopeptidic spacer have been prepared and their fluorescent properties studied. The results obtained show that upon irradiation the photophysical behavior of these probes involves electronic energy transfer from the excited anthracene to the second chromophore and also intramolecular photoinduced electron transfer. The X-ray structure obtained for 3 reveals that the folding associated to the pseudopeptidic spacer favours a close proximity of the two chromophores. The emissive response of 3 is clearly dependent on the pH of the medium, hence this bichromophoric compound was shown to be an excellent ratiometric pH fluorescent sensor. The emission intensity due to the anthracene moiety exhibits a decrease at neutral-basic pH values that is concomitant with an increase in the intensity arising from the dansyl fluorophore. These properties make this compound a good candidate for biological pH sensing as has been confirmed by preliminary studies with RAW 264.7 macrophage cells imaged by means of confocal fluorescence microscopy with an average pH estimation of 5.4-5.8 for acidic organelles.
Original languageEnglish
Pages (from-to)7736-7749
Number of pages14
JournalOrganic & Biomolecular Chemistry
Issue number28
Early online date19 Jun 2015
Publication statusPublished - 28 Jul 2015


  • Ratiometric pH probe
  • intracellular
  • analysis

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