A novel and fast responsive turn-on fluorescent probe for the highly selective detection of Cd2+ based on photo-induced electron transfer

A novel, highly sensitive and fast responsive turn-on fluorescence probe, 2,2 '-((1E,1 ' E)-((1,10-phenanthroline-2,9-diyl)bis(methanylylidene)) bis(azanylylidene)) diphenol (ADMPA), for Cd2+ was successfully developed based on 2,9-dimethyl-1,10-phenanthroline and o-aminophenol. ADMPA showed a remarkable fluorescence enhancement toward Cd2+ against other competing cations, owing to the suppression of the photo-induced electron transfer (PET) and CH & xe001;N isomerization. A good linear relationship (R-2 = 0.9960) was obtained between the emission intensity of ADMPA and the concentration of Cd2+ (0.25-2.5 mu M) with a detection limit of 29.3 nM, which was much lower than that reported in literature. The binding stoichiometry between ADMPA and Cd2+ was 2 : 1 as confirmed by the Job's Plot method, which was further confirmed by a H-1 NMR titration experiment. Moreover, the ADMPA probe was successfully applied to detect Cd2+ in real water samples with a quick response time of only 6.6 s, which was about 3-40 times faster than the reported cadmium ion probe.