Heterometallic complex formation on p-sulfonatothiacalix[4]arene platform resulting in pH- and redox-modification of [Ru(bpy)3]2+ luminescence

The pH-dependent heterometallic complex formation with p-sulfonatothiacalix[4]arene (TCAS) as bridging ligand in aqueous solutions was revealed by the use of spectrophotometry, nuclear magnetic relaxation and fluorimetry methods. The novelty of the structural motif presented is that the appendance of emission metal center ([Ru(bpy)3]2+) is achieved through the cooperative non-covalent interactions with the upper rim of TCAS. The second metal block (Fe(III), Fe(II) and Mn(II)), bound with the lower rim of TCAS in the inner sphere coordination mode is serving as quencher of [Ru(bpy)3]2+ emission. The difference between the complex ability of Fe(III) and Fe(II) ions provides pH conditions for redox-dependent emission of [Ru(bpy)3]2+.

Graphical abstractHeterobimetallic complex formation with p-sulfonatothiacalix[4]arene as bridging ligand, where [Ru(dipy)3]2+ is appended through the upper and second metal block Fe(III) (Fe(II) and Mn(II)) is bound with the lower rim was revealed in aqueous solutions. The different complex ability of Fe(III) and Fe(II) provides pH conditions for redox-dependent emission of [Ru(dipy)3]2+.Figure optionsDownload full-size imageDownload as PowerPoint slide