Rhodamine–Pyridyl Probe: A Selective Optical Reporter for Biologically Important Zn2+

Abstract

A new Rhodamine-based probe, Rhoda-P affords remarkably selective chromo- and fluorogenic responses in the presence of Zn2+ with the color turning from colorless (λmax=302 nm) to orange (λmax=528 nm) and the fluorescence output increased by 160-fold at 1.5×10−3 M of Zn2+. In contrast, Li+, Na+, K+, Ba2+, Ca2+, Mg2+, Co2+, Ni2+, Cu2+, and Cd2+ did not significantly alter the photophysical properties of the probe even at relatively higher concentrations than Zn2+.

Tricolor Emission of a Fluorescent Heteroditopic Ligand over a Concentration Gradient of Zinc(II) Ions

“…The emission color of compound 1 , which undergoes excited state internal charge transfer (ICT), , changes from blue to green upon Zn 2+ coordination (Scheme A) . The nonfluorescent 2 was designed by the addition of a 1,2,3-triazolyl ring on the spirolactam ligand developed by Shiraishi et al The triazolyl ligand acts as both an additional metal coordination ligand for enhancing the coordination affinity and a linker for tethering other functional groups (as in compound 4 ). − The spirolactam precursor of rhodamine has been incorporated in fluorescent sensor structures targeting various substances, − including Zn 2+ . ,− The analyte-induced spirolactam ring-opening reaction affords rhodamine of a bright orange emission.…”

Fluorescent Chemosensors Based on Spiroring-Opening of Xanthenes and Related Derivatives

“…Mashraqui et al have synthesized a rhodamine-based chromo- and fluorogenic probe, 101 , which can detect micromolar concentrations of Zn 2+ by turning the color of the solution from colorless to orange and also by changing the corresponding absorption maximum from 302 to 528 nm. The detection is very selective over other competitive cations such as Li + , Na + , K + , Ba 2+ , Ca 2+ , Mg 2+ , Co 2+ , Ni 2+ , Cu 2+ , and Cd 2+ .…”

A Highly Selective Turn-On Colorimetric, Red Fluorescent Sensor for Detecting Mobile Zinc in Living Cells

“…The mechanism of fluorescent turn-on for these compounds typically involves opening of a spirolactam ring by external reagents, including Cr 3+ , Fe 3+ , Cu 2+ , Hg 2+ , Pb 2+ , Au 3+ , and Ag + . − The spirocyclic forms of these dyes, which are colorless and nonfluorescent, become colorful and strongly fluorescent when cations react with the sensors. To our knowledge, there are only two examples of zinc sensing based on such a rhodamine dye spirocyclic ring-opening mechanism. , One, termed Rhoda-P, is selective for zinc, but its properties were investigated only in organic solvents and there was no information about its reversibility or applicability for live cell imaging . Moreover, we find that Rhoda-P evokes no appreciable turn-on response to zinc ions in buffered aqueous solution (Figure S1, Supporting Information, SI).…”

“…10–20 The spirocyclic forms of these dyes, which are colorless and nonfluorescent, become colorful and strongly fluorescent when cations react with the sensors. To our knowledge, there are only two examples of zinc sensing based on such a rhodamine dye spirocyclic ring-opening mechanism 21,22. One, termed Rhoda-P, is selective for zinc but its properties were investigated only in organic solvents and there was no information about its reversibility or applicability for live cell imaging 21.…”

“…To our knowledge, there are only two examples of zinc sensing based on such a rhodamine dye spirocyclic ring-opening mechanism 21,22. One, termed Rhoda-P, is selective for zinc but its properties were investigated only in organic solvents and there was no information about its reversibility or applicability for live cell imaging 21. Moreover, we find that Rhoda-P evokes no appreciable turn-on response to zinc ions in buffered aqueous solution (Figure S1, Supporting Information, SI).…”