Highly selective and sensitive fluorescent chemosensor for Hg2+ in aqueous solution

A new indole-based fluorescent chemosensor 1 was prepared and its metal ion sensing properties were investigated. It exhibits high sensitivity and selectivity toward Hg2+ among a series of metal ions in H2O-EtOH (7:1, v/v). The association constant of the 1:1 complex formation for 1-Hg2+ was calculated to be 9.57 × 103 M−1, and the detection limit for Hg2+ was found to be 2.25 × 10−5 M. Computational results revealed that 1 and Hg2+ ion formed with a central tetrahedron-coordinated Hg2+.