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

摘要

A new rhodamine-based dual signaling probe (L~3) has been found to display quick responses through visible colorimetric changes as well as fluorogenic properties on selective 1:1 binding to Hg~(2+), as delineated by absorption and fluorescence titrations as well as by Job's method and ESI-MS~+ studies. The fluorescent probe L~3 displays a 252-fold fluorescence enhancement on binding to Hg~(2+). A Benesi-Hilderband fit of the absorption titration data gives K_d =(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, L~3 could be used for in vitro/in vivo cell imaging of Hg~(2+) with no or negligible cytotoxicity. The detection limit of Hg~(2+) was calculated by the 3σ method to be9.28 ngL-1. Moreover, the fluorescence of the L~3-Hg~(2+) system was turned off and its red colour disappeared when KI was added. Thus, the "OFF-ON-OFF" fluorescence sensing behaviour of L~3 observed in the presence of Hg~(2+) and I- may find applications in devices with logic gate functions.