New Tritopic Terpyridine‐based Fluorescent Probe for the Efficient Determination of Th 4+ , Zn 2+ and F − Ions

The present work demonstrates the determination of thorium ( Th 4+ ), zinc ( Zn 2+ ) and fluoride ( F − ) ions by employing a substituted tripodal terpyridine ( TP ) as a fluorescence sensor. The distinct fluorescence intensities of the free TP and TP ‐M complexes (M= Zn 2+ or Th 4+ ) with the same emission wavelength at 468 nm were observed in steady‐state photoluminescence (PL) spectra at pH 7.0 with a 1 : 3 ratio of metal to the ligand. A ratiometric dual fluorescence signals for Zn 2+ and Th 4+ were displayed by the probe TP at varied concentrations. Furthermore, the quantitative determination of F − ions was achieved through the addition of F − to the tripod‐terpyridine‐zinc complex ( TP‐Zn 2+ ) where the fluorescence intensity decreases gradually. Notably, the present work facilitates the LOD (limit of detection) as 1.1×10 −10 M, 1.01×10 −8 M and 3.18×10 −10 M and further LOQ (limit of quantification) as 0.37×10 −9 M, 0.33×10 −7 M and 5.26×10 −9 M for Zn 2+ , Th 4+ and F − ions, respectively. The predicted absorption spectra of TP show HOMO to LUMO+2 electronic excitation at 358 nm whereas the complex TP‐Th 4+ exhibits HOMO to LUMO+1 electronic excitation at 568 nm.