New switch on fluorescent probe with AIE characteristics for selective and reversible detection of mercury ion in aqueous solution.

A new tetraphenylethylene derivative based fluorescenct probe (probe 2) was synthesized in a simple two-step process for selectively switch on and reversible detection of Hg2+ in aqueous solution based on aggregation-induced emission phenomenon. Probe 2 exhibited weak emission in aqueous solution due to the fast non-radiative decay of the excited singlet state facilitated by the free rotation of four phenyl rotors. While after coordination with Hg2+, the Hg2+-promoted aggregation formation will occur and restrict the intramolecular rotation, which blocks the non-radiative pathways and opens up the emission channel, resulting in the switch on response of probe 2 toward Hg2+. Probe 2 exhibited high sensitivity and good selectivity toward Hg2+ with a detection limit of 45.4 nM. Moreover, the detection can be reversible by subsequent addition of S2- into the detection system, which may be applied in the removal of toxic Hg2+ from water. Elsevier B.V. All rights reserved.