A benzimidazole based tripodal fluorescence derivative (L1) is synthesized and characterized. Combining L1 with Cu2+ shows excellent selectivity toward sulfide anions. The binding stoichiometry of L1 with Cu2+ is established by jobs plot analysis and mass spectral evidence and the binding mode is established by synthesis of a control compound L2. The initial fluorescence of L1 is lost on complexation with Cu2+ and is regained in presence of sulfide. The “OFF-ON” behavior of L1 is studied by Fluorescence, UV/vis and mass spectroscopic method.