Multi-functional fluorescent probe for Hg²⁺, Cu²⁺ and ClO^- based on a pyrimidin-4-yl phenothiazine derivative

A multi-functional fluorescent probe based on PzDPM (10-ethyl-3,7- di(pyrimidin-4-yl)-10H-phenothiazine) for Hg²⁺, Cu²⁺ and ClO^- has been synthesized and characterized. The probe comprises an electron-donating fluorophore core of 10-ethylphenothiazine and two Hg ²⁺-specific chelating arms of pyrimidin-4-yl. The 10-ethylphenothiazine also acts as a Cu²⁺/ClO^--specific reactive moiety. PzDPM exhibits green fluorescence and selectively senses Hg²⁺/Cu²⁺ upon coordination/reaction in acetonitrile (MeCN), and behaves as a turn-off chemosensor or ratiometric chemodosimeter, respectively. On the other hand, PzDPM is very weakly emissive in aqueous solution but acts as an excellent turn-on chemodosimeter for ClO^- in 1:4 (v/v) MeCN:Tris-HCl (10 mM, pH = 7.0) with a maximum fluorescent intensity increase of over 110-fold. The probe PzDPM allows the determination of Hg ²⁺, Cu²⁺ and ClO^- at 10^-7 M levels with satisfactory selectivity.