Rhodamine‐Based Chromo‐/Fluorogenic Dual Signalling Probe for Selective Recognition of HgII with Potential Applications for INHIBIT Logic Devices and Cell‐Imaging Studies

Abstract

AbstractA new rhodamine‐based dual signaling probe (L3) has been found to display quick responses through visible colorimetric changes as well as fluorogenic properties on selective 1:1 binding to Hg2+, as delineated by absorption and fluorescence titrations as well as by Job′s method and ESI‐MS+ studies. The fluorescent probe L3 displays a 252‐fold fluorescence enhancement on binding to Hg2+. A Benesi–Hilderband fit of the absorption titration data gives Kd = (32.01 ± 0.74) μM and a 1:1 binding stoichiometry. Owing to its solubility in mixed organic/aqueous solvents as well as its cell permeability, L3 could be used for in vitro/in vivo cell imaging of Hg2+ with no or negligible cytotoxicity. The detection limit of Hg2+ was calculated by the 3σ method to be 9.28 ng L–1. Moreover, the fluorescence of the L3–Hg2+ system was turned off and its red colour disappeared when KI was added. Thus, the “OFF–ON–OFF” fluorescence sensing behaviour of L3 observed in the presence of Hg2+ and I– may find applications in devices with logic gate functions.