Naphthyl-functionalized ninhydrin-derived receptor for 'CHEF'-based sequential sensing of Al(III) and PPi: Prospective chemosensing applications under physiological conditions

An easy-to-prepare naphthyl-functionalized ninhydrin-based multi-analyte probe, L-1 displayed a 'turn-on' emission response towards Al3+ via chelation-enhanced fluorescence (CHEF) process in a mixed medium. This selective probe featured the fluorescence sensing of Al3+ with similar to 20 nm red-shift. A limit of detection (LOD) 1.97 mu M, considerably lower than the USEPA standard for Al3+ in drinking water. The probe was also capable of selectively and colorimetrically detecting Cu2+ (LOD 0.34 mu M) with a considerable red-shift (similar to 130 nm) in the UV-vis spectra. The in situ prepared L-1- Al3+ complex could selectively sense phosphate ions, particularly pyrophosphate (PPi). The suggested detection pathway is the complexation with aluminum, followed by the decomplexation of the ensemble by PPi anions. Interestingly, the interaction between L-1- Al3+ ensemble and ctDNA elicited a distinctive systematic emission 'turn-off response from the highly emissive ensemble. The probe also found applications in testing actual aqueous samples.