Fluorometric dual sensing of Hg2+ and Al3+ by novel triphenylamine appended rhodamine derivative in aqueous media

Triphenylamine appended rhodamine (named probe TR) was built as a selective fluorescent probe for Al3+ and Hg2+ ions through different sensing mechanisms. TR demonstrated a distinct fluorescence enhancing at 501 and 580 nm towards Al3+ and Hg2+ ions due to the PET-off (Photoinduced electron transfer-off) and FRET-on (Fluorescence resonance energy transfer-on) processes, respectively. The binding modes between TR with Al3+ and Hg2+ were found to be 1:1 by job plot analysis. The limits of detection of TR for sensing Al3+ and Hg2+ are down to 71.8 nM and 0.48 mu M, respectively. At the same time, the complexation details between the probe TR with Al3+ and Hg2+ ions were investigated by FTIR, (HNMR)-H-1 experiments and DFT calculations. Moreover, simple test papers coated probe TR were successively developed for the rapid monitoring of Al3+ and Hg2+ ions.