Highly sensitive and selective fluorescence chemosensors containing phenanthroline moieties for detection of Zn2+ and Cd2+ ions

It is extremely necessary to detect heavy metals sensitively and selectively, especially the ions that will cause great harm to humans and the environment. This work deals with two fluorescent chemosensors and their outstanding role when detecting Zn2+ and Cd2+ ions. First, a small molecular chemosensor (TPB) has been designed and synthesized via Suzuki reaction using one part of benzene-1,3,5-triyltriboronic acid and three parts of 2-bromo-1, 10-phenanthroline as starting materials. And then, its corresponding macromolecular fluorescent chemosensor (PTPB) was synthesized. The infrared spectra, mass spectrometry (MS), and 1H-NMR were used to study the structures of TPB and PTPB. From what has been studied, the TPB and PTPB were stable in a relative wide pH range. As soon as the Cd2+ and Zn2+ ions added, fluorescence of the two sensors TPB and PTPB was changed obviously. In addition, PTPB was found have better performance to both Cd2+ and Zn2+ than TPB through the ‘‘molecular wire’’ mechanism. Job’s plots were also be tested, showing that the combination ratio of TPB and PTPB to Cd2+ and Zn2+ were both 3:1 (ion/sensor). In addition, the minimum detection limits of the macromolecular chemosensor PTPB for Cd2+ and Zn2+ reached 0.424 μM and 1.27 μM, respectively.