A single fluorescent chemosensor for detecting Ag+ ion in DMF and common trivalent metal ions in ethanol

•A fluorescent chemosensor (PAOP) was synthesized and well characterized.•PAOP exhibited highly selective fluorescence quenching response towards Ag+ in DMF.•PAOP can identify Al3+, Fe3+ and Cr3+ in ethanol via fluorescent color change.•PAOP coordinated with metal ions in 2:1 stoichiometric ratio.•PAOP has been successfully applied to the detection of Cr3+ in real water samples. A fluorescent chemosensor PAOP based on pyrene formaldehyde and o-phenylenediamine was successfully synthesized, and its molecular structure was characterized by NMR and mass spectrometry. PAOP exhibits excellent fluorescence sensing ability for Ag+ in DMF with high selectivity and sensitivity. In addition, PAOP can selectively identify common trivalent metal ions (Al3+, Fe3+, Cr3+) in ethanol solution. After the addition of common trivalent metal ions, the fluorescence of PAOP ethanol solution changed from blue–violet to blue–green. The results of the reversible fluorescence change, mass spectra, FT-IR and DFT calculations proved that the selective fluorescence response towards the special metal ions was attributed to formation of stable 2:1 complex PAOP@Mn+. PAOP has good recovery in detection of Cr3+ in real water samples and shows great potential application as a chemosensor. [Display omitted]