Terphenyl-phenanthroline conjugate as a Zn2+ sensor: H2PO4− induced tuning of emission wavelength

Abstract

A new terphenyl-based macrocycle 5 incorporating phenanthroline as a fluorophore has been designed, synthesized and examined for its recognition ability toward various cations (Pb(2+), Hg(2+), Ba(2+), Cd(2+), Ag(+), Zn(2+), Cu(2+), Ni(2+), Co(2+), K(+), Mg(2+), Na(+) and Li(+)) by UV-vis, fluorescence and NMR spectroscopy. The receptor 5 showed highly selective 'Off-On' fluorescence signaling behavior for Zn(2+) ions in THF. Interestingly, the addition of H(2)PO(4)(-) ions to the [5-Zn] complex regulates the binding site for additional Zn(2+) ions and hence leads to a blue-shifted emission band.

A Phenyl Thioether‐Based Probe: Zn2+ Ion Sensor, Structure Determination and Live Cell Imaging†

“…Herein we report, a diformyl thioether based fluorescent chemosensor, H 2 ‐SAP , prepared by simple Schiff base condensation procedure ( Scheme S1 ) which displays selective fluorescence sensitivity towards Zn 2+ by chelation enhancement fluorescence effect (CHEF) process in presence of large number of ions and could identify Zn 2+ in nM level, much lower than so far reported results . The composition of the complex formed between Zn 2+ and H 2 ‐SAP has been supported by spectroscopic data (Mass, Job's plot) and single crystal X‐ray crystallography.…”

“…Chemical sensing via fluorescence signal recognition has been first established during 1980s . Since then researchers are engaged to design various types of fluorogenic sensors to detect Zn 2+ in different environment including intracellular measurements, Fluorogenic motifs like naphthyl, Diformyl derivative, terpyridyl, quinoline,, imidazoylpyridyl,, bipyridyl,, pyrenyl derivatives, terphenyl‐based motif, pyrimidinyl attached Schiff‐base, pyrazolyl,, BINOL, rhodamine,, catechol appended Schiff base, coumarinyl Schiff base, thiazolyl derivative etc. have successfully been used.…”

Switchable Optical Probes for Simultaneous Targeting of Multiple Anions

“…showed that the binding of F − /CH 3 COO − ions to the Zn 2+ center of the terphenyl‐based macrocyclic complex ( 8 ) could trigger the release of Zn 2+ ion. A rather contrasting behavior was observed with H 2 PO 4 − , which formed a ternary complex with the metal ion (Zn 2+ ) through electron‐rich oxygen centers . Irrespective to their binding modes all of these aforementioned anions (H 2 PO 4 − , F − /CH 3 COO − ) quenched the emission intensity of the preformed Zn‐complex (no discrimination was possible).…”

“…À , which formed a ternary complex with the metal ion (Zn 2 + ) through electron-rich oxygen centers. [78] Irrespective to their binding modes all of these aforementioned anions (H 2 PO 4 À , F À / CH 3 COO À ) quenched the emission intensity of the preformed Zn-complex (no discrimination was possible). However, revival of the original emission by subsequent addition of Zn 2 + was possible only in case of F À /CH 3 COO À , not with H 2 PO 4 À .…”

“…However, the specificity was found to be considerably high for F À ion in presence of Cu 2 + . [159] In a completely new strategy, Costa et al observed that the choice of indicator dye could also improve the selectivity of the flexible squaramide based receptor (78). In presence of cresol red (CR) dye, the spectral changes were observed with both sulfate and phosphate anions, whereas response was specifically observed with sulfate anion when bromocresol green (BG) was incorporated as the indicator dye.…”