Turn-On Fluorescent Sensors For The Selective Detection Of Al3+(And Ga3+) And Ppi Ions

Rationally designed multiple hydroxyl-group-based chemo-sensors L1-L4 containing arene-based fluorophores are presented for the selective detection of Al3+ and Ga3+ ions. Changes in the absorption and emission spectra of L1-L4 in ethanol were easily observable upon the addition of Al3+ and Ga3+ ions. Competitive binding studies, detection limits, and binding constants illustrate significant sensing abilities of these chemosensors with L4, showing the best results. The interaction of Al3+/Ga3+ ions with chemosensor L4 was investigated by fluorescence lifetime measurements, whereas Job's plot, high-resolution mass spectrometry, and H-1 NMR spectral titrations substantiated the stoichiometry between L4 and Al3+/Ga3+ ions. The solution-generated [L-M3+] species further detected pyrophosphate ion (PPi) by exhibiting emission enhancement and a visible color change. The binding of Al3+/Ga3+ ions with chemosensor L4 was further supported by density functional theory studies. Reversibility for the detection of Al3+/Ga3+ ions was achieved by utilizing suitable proton source. The multiionic response, reversibility, and optical visualization of the present chemosensors make them ideal for practical applications for real samples, which have been illustrated by paper-strip as well as polystyrene film-based detection.