Real‐Time Probe for the Efficient Sensing of Inorganic Fluoride and Copper Ions in Aqueous Media

A highly sensitive and efficient rhodamine 6G based probe ( P3 ) was synthesized for the real‐time sensing of F − and Cu 2+ ions. The probe P3 was able to show significant color change from brown to pink in the presence of F − and yellow to orange in presence of Cu 2+ ions. The UV‐vis studies confirm that the probe P3 was able to detect F − and Cu 2+ ions over other ions. Further, UV‐vis titration studies were carried out to understand the detection mechanism and stoichiometry between P3 : F − and P3 : Cu 2+ ions. 1 H‐NMR titration was performed to confirm the F − ion binding to probe P3 , where, deprotonation of hydrazone proton (‐C=N‐ NH ‐) was observed. In addition, the limit of detection for P3 :F − and P3 :Cu 2+ ions were found to be 4.02 μM and 1.64 μM respectively which is useful for practical applications. Lastly, probe P3 was used to detect and quantify the F − ions present in a commercially available mouthwash product. Furthermore, P3 was adsorbed on the surface of silica microsphere to detect Cu 2 + ions. Interestingly, the material could visually detect 1 ppm of Cu 2 + ions which is lower than the permissible limit.