An acyclic, dansyl based colorimetric and fluorescent chemosensor for Hg(II) via twisted intramolecular charge transfer (TICT) Original Research Article

An efficient fluorescent chemosensor for Hg2+ ion, based on 5-(dimethylamino)-N-(2-mercaptophenyl)naphthalene-1-sulfonamide, has been developed. It exhibits Hg2+-selective on–off fluorescence quenching behavior via twisted intramolecular charge transfer (TICT) mechanism, which is rationalized by time dependent density functional theory (TD-DFT) calculations. The system exhibits visible color change from colorless to gray upon Hg2+ binding with very high selectivity and sensitivity (as low as 5.0 × 10−10 mol L−1) over other metal ions such as K+, Na+, Ag+, Mn2+, Ca2+, Ba2+, Fe2+, Zn2+, Pb2+, Cu2+, Sn2+, Cd2+, Ni2+ and Co2+. The present sensing system is also successfully applied for the detection of Hg2+ ion in real samples.