科研之友
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摘要
An easily synthesizable rhodamine-based chemosensor, L-2, selectively recognizes Hg2+ and Al3+ ions in the presence of all biologically relevant and toxic heavy metal ions. Very low detection limit (47 nM for Hg2+) along with cell permeability and negligible cytotoxicity provides a good opportunity towards cell imaging of Hg2+. SEM studies reveal rod-like microstructure for L-2 in water, which changes to a porous microstructure in the presence of Hg2+. It was interesting to note that the presence of SDS solubilized the otherwise insoluble probe in pure aqueous medium. In case of Al3+ it was astonishingly observed a fluorescence quenching on increasing the SDS concentration, while a similar to 33-fold enhancement of FI of [L-2-Hg2+] complex was observed compared to that in the absence of SDS, making the prove selective towards Hg2+ over Al3+ in the aqueous SDS medium. In SDS/water system, there is a steep rise in FI, reaches a maximum at similar to 7 mM of SDS and then fluorescence intensity decreases gradually with the increase in [SDS] up to 28 mM. These observations clearly signify the SDS-assisted formation of polymer aggregates of the complex on the surface of monolayer of SDS formed in pre-micellar concentrations with higher FI, which is converted to the monomer being trapped inside the micellar cavity beyond the critical micellar concentration (cmc) with comparatively lower FI, indicating an interesting AIEE phenomenon. This proposition is further supported by the dependence of fluorescence anisotropy (r) on [SDS].
- 出版日期2017-7
