A Bis(ferrocenyl)phenanthroline Iridium(III) Complex as a Lab-on-a-Molecule for Cyanide and Fluoride in Aqueous Solution
journal contributionposted on 17.12.2012, 00:00 by Qinghai Shu, Lars Birlenbach, Michael Schmittel
The bis(ferrocenyl)phenanthroline iridium(III) complex 1 is synthesized and elaborated as a lab-on-a-molecule for the competitive and quantitative determination of cyanide and fluoride in aqueous solution. 1 exhibits a strong OFF–ON photoluminescence (PL) response upon addition of cyanide with a good selectivity over other anions. The mechanism involves nucleophilic displacement of the phenanthroline ligand, which quenches PL, to furnish a strongly photoluminescent dicyano iridium complex. In contrast, in the electrochemiluminescence (ECL) channel, cyanide undergoes oxidation and a different selectivity is observed. The strong ferrocenium–fluoride interaction is exploited for the first time in ECL to selectively monitor fluoride by a >60-fold enhancement. In both PL and ECL channels, anion selectivity is further challenged by competitive assays in the presence of other anions. Quantitative determination of CN– and F– is achieved in both channels.