Bi-8-carboxamidoquinoline derivatives for the fluorescent recognition of Zn2+

Three fluorescent sensors which were composed of a phendiol (o-, m-, p-isomers) and two carboxamidoquinolines have been synthesized and characterized. Research on the Zn(2+)-sensing properties of the three sensors was carried out, and the results showed a significant difference in the recognition performance for Zn(2+). The fluorescence intensity (I(510 nm)) of ortho isomeric sensor binding to Zn(2+) was enhanced 23-fold, the meta 15-fold, the para 8-fold. As the distance between two carboxamidoquinolines became longer, the fluorescence enhancement decreased. In addition, the selectivity of sensors got poor and the detection limit became higher with rising the distance between two receptors.