Ion pair recognition receptor based on an unsymmetrically 1,1'-disubstituted ferrocene-triazole derivative.

The ferrocene-triazole derivative 4, available from 1,1'-bis(diazido)ferrocene by sequential functionalization through click-type chemistry and the Staudinger reaction, is elaborated as a lab-on-a-molecule for the selective sensing of HP(2)O(7)(3-) and Hg(2+). Receptor 4 behaves as a ratiometric fluorescent probe for HP(2)O(7)(3-) with a good selectivity over other anions, whereas in the presence of Hg(2+) it modifies the fluorescent emission of the pyrene unit, acting as a selective on-off fluorescent sensor for Hg(2+) with a low detection limit. The most salient feature of compound 4 is its behavior as an excellent electrooptical ion pair recognition receptor able to simultaneously recognize Pb(2+) cations in the presence of HP(2)O(7)(3-) anion through multichannel perturbations of the redox potential of the ferrocene unit, the emission spectrum, and a noticeable color change from yellow to green.