Exploring the Ability of Luminescent Metal Assemblies to Bind and Sense Anionic or Ionizable Analytes A Ru(phen)2bipy-Based Dizinc Complex for Bisphenol A (BPA) Recognition

The synthesis of a new Ru-II complex, in which the metal is coordinated by two 1,10-phenanthroline ligands and a 2,2 '-bipyridyl unit linked, via methylene bridges in its 4 and 4 ' positions, to two 1,4,7,10-tetraazacyclododecane (cyclen) macrocycles ([Ru(phen)(2)L](2+)) is reported. Protonation and Zn-II binding by [Ru(phen)(2)L](2+) have been analyzed by potentiometric titration, evidencing the formation of mixed hetero-binuclear and hetero-trinuclear Zn-II/Ru-II complexes. These complexes were tested as bis-phenol A (BPA) binders. Only the dizinc complex with [Ru(phen)(2)L](2+) is able to bind BPA in aqueous solution, affording a remarkably stable {Zn-2[Ru(phen)(2)L]BPA(H-2)}(4+) adduct at neutral pH, in which BPA is bound in its doubly deprotonated form to the two Zn-II ions. BPA binding was found to quench the luminescence emission of the Ru-II(phen)(2)bipy core. Although the quenching effect is modest, this study demonstrates that appropriately designed dizinc complexes can be used for binding and optical sensing of BPA in water.

Automated summary

A new Ru-II complex was synthesized and tested for its ability to bind BPA in water, demonstrating potential for optical sensing applications.