Emission amplification of Ru(bpy)32+ via energy transfer from pyrene derivatives on synthesized clay

• Tetracationic pyrene derivatives (Py4+) and dicationic tris(bipyridine)ruthenium(II) (Ru2+) were hybridized on a synthetic clay (SSA) surface.
• Absorption analysis revealed fading of Ru2+; this hypochromic effect suggests that the Ru2+ and Py4+ weakly interacted on the SSA surface.
• The remarkable quenching of the emission from Py4+ by the coadsorbed Ru2+ was probably stimulated by energy transfer from Py4+ to Ru2+.
• Emission of Ru2+ was amplified 4–5 times within the Py4+/Ru2+/SSA system; the maximum emission quantum yield of Ru2+ was 30.4 ± 3.8%.
• The unique photochemical and photophysical properties might arise from the adjoined orientation of Py4+ and Ru2+ coadsorbed on the SSA surface.

Tetracationic pyrene derivatives (Py4+) and dicationic tris(bipyridine)ruthenium(II) (Ru2+) were hybridized on a synthetic clay (SSA) surface; the hybrid is denoted as Py4+/Ru2+/SSA. The photochemical properties of the Py4+/Ru2+/SSA system, especially the energy transfers from Py4+ to Ru2+, were investigated. Absorption analysis revealed fading of Ru2+; this hypochromic effect suggests that the Ru2+ and Py4+ weakly interacted on the SSA surface. The remarkable quenching of the emission from Py4+ by the coadsorbed Ru2+ was probably stimulated by energy transfer from Py4+ to Ru2+. Emission of Ru2+ was amplified 4–5 times within the Py4+/Ru2+/SSA system; the maximum emission quantum yield of Ru2+ was 30.4 ± 3.8%. Very interestingly, the three independent photochemical behaviors of Py4+/Ru2+/SSA, namely fading of Ru2+, stimulation of emission quenching of Py4+, and emission amplification of Ru2+, occurred at almost identical critical amounts of adsorbed Ru2+ (11–13% cation exchange capacity (CEC)). Molecular distribution modeling of the SSA surface suggests that Py4+ and Ru2+ adjoined on the SSA surface when the amount of adsorbed Ru2+ exceeded ca. 11% CEC. On the other hand, the unique photochemical and photophysical properties might arise from the adjoined geometrical arrangement of Py4+ and Ru2+ coadsorbed on the SSA surface.

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