New ruthenium(II) complexes functionalized with coumarin derivatives: synthesis, energy-transfer-based sensing of esterase, cytotoxicity, and imaging studies

Two new bichromophoric ruthenium(II) complexes, Ru(bpy)(2)(bpy-CM)](PF(6))(2) and Ru(bpy)(2)(bpy-CM343)](PF(6))(2) (bpy=2,2'-bipyridine, CM=coumarin) with appended coumarin ligands have been designed and synthesized. The energy-transfer-based sensing of esterase by the complexes has been studied by using UV/Vis and luminescence spectroscopic methods. The cytotoxicity and the cellular uptake of one of the complexes have also been investigated.