Hexaphenylbenzene-based fluorescent probes for the detection of fluoride ions

Novel hexaphenylbenzene derivatives (HPB-1 and HPB-2) were synthesized and their structural and optical properties were characterized using H-1 NMR, C-13 NMR, HRMS, absorption and fluorescence spectroscopies. The effect of various anions (AcO-, NO3-, HSO4-, ClO-, ClO4-, SCN-, CN-, F-, Cl-, Br-, I- and H2PO4-) on the optical properties of these new compounds was investigated in THF. Among the different anions, significant changes in the fluorescence spectra of HPB-1 and HPB-2 were observed in the presence of only F- ions. The interaction ratios of HPB-1 and HPB-2 with F- ions were determined to be 1 : 1 and the binding constants (K-A) were found to be 0.0417 M-1 and 0.982 M-1 for HPB-1 and HPB-2, respectively. The LOD values were calculated as 2.79 mu M and 1.04 mu M for HPB-1 and HPB-2, respectively. The mechanism of F--ion sensing was investigated via(1)H NMR titration. The obtained results show that the newly synthesized HPB-1 and HPB-2 compounds can be a turn-on fluorometric sensor with high selectivity for F- ions.