Naphthol-based fluorescent sensors for aluminium ion and application to bioimaging

Three naphthol Schiff base-type fluorescent sensors, 1,3-Bis(2-hydroxy-1-naphthylideneamino)propane (L1), 1,3-Bis(1-naphthylideneamino)-2-hydroxypropane (12) and 1,3-Bis(2-hydroxy-1-naphthylideneamino)-2-hydroxypropane (13), have been synthesized. Their recognition abilities for Al3+ are studied by fluorescence spectra. Coordination with Al3+ inhibited the C=N isomerization of Schiff base which intensely increase the fluorescence of L1-L3. Possessing a suitable space coordination structure, 13 is a best selective probe for Al3+ over other metal ions in MeOH-HEPES buffer (3/7, V/V, pH = 6.6, 25 degrees C, lambda(em), = 435 nm). A turn-on ratio over 140 fold is triggered with the addition of 1.0 equiv. Al3+ to L3. The binding constant K-a of L3-Al3+ is found to be 1.01 x 10(6.5) M-1 in a 1:1 complex mode. The detection limit for Al3+ is 0.05 mu M. Theoretical calculations have also been included in support of the configuration of the L3-Al3+ complex. Importantly, the probe L3 has been successfully used for fluorescence imaging in colon cancer SW480 cells. (C) 2016 Elsevier B.V. All rights reserved.