A rhodamine hydrazide–4-nitroindole-3-carboxaldehyde based turn on Hg2+ chemosensor: cytoplasmic live cell imaging, logic gate and memory device applications and computational studies
A new, highly sensitive probe L2 for the selective detection of Hg2+ in organo-aqueous (H2O:CH3CN, 1:1, v/v, HEPES buffer, pH 7.2) medium has been synthesized from rhodamine 6G-hydrazide and 4-nitroindole-3-carboxaldehyde. It was thoroughly characterized by physicochemical techniques including single crystal X-ray diffraction studies. The reaction of L2 with Hg2+ gives a 1:1 stoichiometry resulting in a 146 fold fluorescence enhancement and a binding constant (K f) of 3 × 104 M−1. The spirolactam form of the probe is non-fluorescent; however, it shows dual channel (absorbance and fluorescence) recognition of Hg2+ via CHEF effect through the opening of the spirolactam ring. The quantum yields of L2 (0.00045) and L2 -Hg2+ (0.29) show the higher stability of complex in the excited state over the free ligand. The 44.5 nM LOD value demonstrates the detection of Hg2+ at a very low concentration range. Cell imaging studies show the cytoplasmic recognition of Hg2+ by L2 . Experimental results are comparable with theoretical values obtained by DFT studies. The fluorescence emission of the complex was completely quenched by I- and from the reversibility studies an advance level INHIBIT logic gate and memory device can be framed.
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Document Type: Research Article
Affiliations: 1: Department of Chemistry, Jadavpur University, Kolkata, India; 2: Department of Biochemistry, University of Lausanne, Epalinges, Switzerland
Publication date: July 3, 2018