Turn-on selective fluorescent probe for trivalent cations

A novel fluorescent sensor 1 (1 = 10-(2-(((pyridin-2-yl)methylamino)methyl) phenol)methyl-anthracene) for trivalent cations has been synthesized and characterized. Both UV-vis and fluorescence spectroscopic studies demonstrated that the new receptor 1 was highly sensitive and selective toward trivalent cations, while there was no response to monovalent and divalent cations in methanol. Upon binding with trivalent cations, the emission bands of 1 red-shifted for all the trivalent cations from 411 nm to 421 nm and their fluorescence intensities were enhanced. In particular, Fe^{3 +} could be obviously discriminated from Fe^{2 +}. The binding modes of 1 and the trivalent cations (M^{3 +} ions) were found to be 1:1 and confirmed by Job plot, ¹H NMR titration and ESI-mass spectrometry analysis.