Selective recognition of Cr2O72- anion in water by anthracene phenylpyridine fluorescent probe

A unique phenypyridine derivatives fluorescent probes ( G1, G2, G3 and G4) were constructed and the detection performance of Cr 2 O 7 2- anion was studied. In aqueous solution, we found that the fluorescence emission of anthracene phenypyridine derivatives can be quenched by the non-covalent interaction (NCI) of anthracene phenypyridine with Cr 2 O 7 2- , and other common anions and cations do not interfere with the quenching process. Theoretical calculation shows that the LUMO energy level of Cr 2 O 7 2- is similar to that of anthracene phenylpyridium molecules, so that after G1 and Cr 2 O 7 2- molecules combine to form an ion pair (Cr 2 O 7 2- @ G1 ), the LUMO orbital of G1 is delocalized toward Cr 2 O 7 2- , which makes the HOMO electron of the probe easily captured by Cr 2 O 7 2- when it is photo excited. Intermolecular charge transfer (CT) occurs, which is resulting in fluorescence quenching of dye molecules. The discovery of this phenomenon provides a reference for the design of water-soluble anionic fluorescent probes.