A highly sensitive and selective visible-light excitable luminescent probe for singlet oxygen based on a dinuclear ruthenium complex

Abstract

A dinuclear Ru(II) complex of [(bpy)₂Ru(H₂ipaip)Ru(bpy)₂]Cl₄ {bpy = 2,2′-bipyridine, H₂ipaip = 2-(9-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)anthracen-10-yl)-1H-imidazo[4,5-f][1,10]phenanthroline} is newly synthesized and characterized. Singlet oxygen sensing and ground- and excited-state acid–base properties of this complex are studied. The results indicated that the complex acted as a highly sensitive and selective luminescent probe for singlet oxygen (¹O₂) in neutral and alkaline aqueous media under visible light excitation at 458 nm, resulting in 5.2- and 7.6-fold emission enhancement, respectively. This probe has advantages of visible light excitation, low singlet oxygen detection limits of 2.7–3.1 nM and high water solubility, thus holding great potential for applications in biological systems.