A lead selective dimeric quinoline based fluorescent chemosensor and its applications in milk and honey samples, smartphone and bio-imaging

Dimeric quinoline-based Schiff base was developed (DQS) for the specific detection of Pb(2+ )ion via fluorimetry. DQS coordinates with Pb2+, a variation in fluorescence intensity with enhanced radical blue shift was observed due to the restriction of C-N rotation, C= N isomerization, and photoinduced electron transfer (PET) mechanisms. In addition, the intramolecular charge transfer (ICT) from electron-donating morpholine to phenylene diamine acceptor linked quinoline bridge is responsible for the blue-shifted fluorescence enhancement in the DQS-Pb2+ complex. The binding stoichiometry of DQS: Pb2+ (1:2) was confirmed by host-guest titration and mass spectrometry. The limit of detection (LOD) of the DQS was found to be 1.3 x 10(-7) M for Pb2+ ion. The DQS sensing ability of Pb(2+ )was further applied into milk and honey samples, smartphone, bio-imaging and to construct of an INHIBIT molecular logic gate.