Hydrophilic Truxene Derivative as a Fluorescent off-on Sensor for Copper (II) Ion and Phosphate Species

Article abstract of DOI:10.1007/s10895-019-02350-y

A new symmetrical truxene derivative (TP3) containing three dipicolylamino peripheral groups is successfully synthesized in four synthetic steps with an overall yield of 42%. This hydrophilic fluorescent compound exhibits a maximum absorption wavelength at 375?nm, an emission maximum at 474?nm with an outstanding 58% quantum efficiency in THF-HEPES buffer mixture. The compound shows a highly selective fluorescence quenching towards Cu(II) ion with a detection limit of 0.06?ppm. The results from mass spectrometry and Job plot indicate that a 1:1 complex between TP3 and Cu(II) ion is responsible for the signal quenching. Interestingly, this TP3-Cu complex can be used as a turn-on sensor for hydrogen phosphate and nucleoside phosphates. The limit of detection for hydrogen phosphate is estimated at 8.7?nM. The signal restoration involves a displacement of TP3 in the complex by the phosphates which have strong coordination abilities with Cu(II) ion.