Colorimtric and "turn-on" fluorescent for Hg²⁺ based on rhodamine-3,4-ethylenedioxythiophene derivative

We designed a novel fluorescent chemosensor for Hg²⁺ imaging in living cells based on rhodamine hydrazone and 3,4-ethylenedioxythiophene (EDOT). The selective fluorescence response of 1 to Hg²⁺ is due to the Hg²⁺-promoted desulfurization of the thiocarbonyl moiety, leading to the ring-opening of rhodamine B moiety of 1. The titration results show a 2:1 complex formation between 1 and Hg²⁺. The reversibility of chemosensor 1 is verified through its spectral response toward Hg²⁺ and S^2- titration experiments. Chemosensor 1 can be utilized as an inhibit logic gate at molecular level.