An efficient Hg2+ ensemble based on a triazole bridged anthracene and quinoline system for selective detection of cyanide through fluorescence turn-off-on response in solution and live cell

•A triazole bridged anthracene and quinoline system.•Efficient Hg2+ ensemble for selective and sensitive detection of cyanide.•Fluorescence turn-off-on response.•Mimicking a sequential logic circuit and memory device.

A simple triazole bridged molecular probe containing anthracene and quinoline moieties has been designed and synthesized as a fluorescent molecular probe (7). The photophysical behavior of the probe 7 has been examined and tested for the recognition of ions in partial aqueous medium and HeLa cell. The probe 7 has shown strong affinity for Hg2+ and has been utilized to develop a stable ensemble, 7·Hg2+. The ensemble, 7·Hg2+ upon interaction with different class of anions showed high affinity for cyanide with ∼16 fold fluorescence enhancement and high limit of detection, 1.25 μM. The live cell imaging studies showed that ensemble 7·Hg2+ is capable to detect CN− intracellularly. The analytical applicability of the probe for Hg2+ and CN− has been tested on the test paper strips. Additionally, the naked eye sensitive “On-Off-On” switching behavior of 7 has been utilized to mimic the function of a sequential logic circuit at molecular level. The 1H NMR titration, ESI-MS spectroscopy and DFT calculation confirms the binding behavior between 7 and Hg2+.

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