Exploring 1,4-dihydroxyanthraquinone as long-range emissive ratiometric fluorescent probe for signaling Zn2+/PO43−: Ensemble utilization for live cell imaging

• Long-range emissive ratiometric molecular probe for selective detection of Zn2+.
• The probe possesses dual wavelength excitation properties.
• The probe absorbs in yellow region and emits in orange.
• Cellular imaging of intracellular zinc.
• Resultant probe-Zn2+ ensemble was utilized as ratiometric signaling platform for PO43−.

Fluorescent 1,4-dihydroxyanthraquinone 1 was found to demonstrate its ratiometric signaling property upon interaction with divalent zinc (Zn2+). While the probe itself exhibited fluorescence emission in the yellow region (λem = 544 nm and 567 nm), binding with Zn2+ induced strong emission in the orange region (λem = 600 nm) which was mainly due to a combination of CHEF and ICT mechanism. The probe was found to be highly sensitive toward the detection of zinc and the limit of detection (LOD) was calculated to be 9 × 10−7 M. The possibility of using this probe for real-time analysis was strongly supported by the striking stability of fluorescence signal for more than five days with similar fluorescence intensity as observed during instant signaling. The present probe works within physiological pH range and is devoid of any interference caused by the same group elements such as Cd2+/Hg2+. The probe possesses excellent excitation/emission wavelength profile and can penetrate cell membrane to image low concentration of zing inside living system. The in situ formed zinc-probe ensemble was further explored as ratiometric sensing platform for detecting another bio-relevant analyte phosphate anion through a zinc-displacement approach.

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