Pyrene excimer-based fluorescent sensor for detection and removal of Fe and Pb from aqueous solutions.

Pyrene excimer usually serves as a chromogenic unit for developing ratiometric fluorescent sensors. But this study used excimer as a large hydrophobic group to regulate the molecular hydrophobicity, and obtained a new fluorescent sensor, N, N-bi[4(1-pyrene)-butyroyl]ornithine (1), for detection and removal of Fe and Pb from aqueous solutions. The coordination of 1 and Fe in the aqueous solution or even pure water forms removable flocculent precipitates, accompanied by obvious fluorescent quenching of emission spectra. In aqueous solutions containing 40% (v/v) acetonitrile, the special responses exhibit a high selectivity and sensitivity to Fe over other common metal ions. However, in aqueous solutions containing 40% (v/v) dimethylsulfoxide, the probe exhibits the analogous fluorescent quenching responses and the removable flocculent precipitates in the presence Fe and Pb. These results indicate that the extremely hydrophobic 1-Fe/Pb complexes are not only a supplement to the fluorescent sensing of Fe and Pb, but also a requirement to the removal of Fe and Pb from aqueous solutions.