Activation of Ru(bpy)32+ multibubble sonochemiluminescence in alkaline aqueous solutions by a hydrated electron

G L Sharipov; A M Abdrakhmanov; L R Yakshembetova

doi:10.1016/j.ultsonch.2018.12.022

Activation of Ru(bpy)₃²⁺ multibubble sonochemiluminescence in alkaline aqueous solutions by a hydrated electron

Ultrason Sonochem. 2019 May:53:55-58. doi: 10.1016/j.ultsonch.2018.12.022. Epub 2018 Dec 13.

Authors

G L Sharipov¹, A M Abdrakhmanov¹, L R Yakshembetova¹

Affiliation

¹ Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, Ufa, Russian Federation.

PMID: 30595488
DOI: 10.1016/j.ultsonch.2018.12.022

Abstract

The sonochemiluminescence in 10^-4 M aqueous solutions of Ru(bpy)₃Cl₂ was studied in the presence of NaOH and KOH (up to 0.4 M). The observed increase in the steady-state emission intensity from Ru(bpy)₃²⁺ as compared with the intensity in neutral solutions was attributed to conversion of H resulting from water sonolysis to e_aq. As a result, there is a multiple (>10⁶) change in the concentrations of the sonochemical intermediates Ru(bpy)₃⁺ and Ru(bpy)₃³⁺. The reduction of the Ru(bpy)₃³⁺ ion with H, which is of low efficiency for the formation of the excited *Ru(bpy)₃²⁺ ion, is replaced by reduction with hydrated electron, in which *Ru(bpy)₃²⁺ is generated in a high yield. The participation of e_aq provides a fivefold increase in the sonochemiluminescence intensity in a key disproportionation reaction: Ru(bpy)₃⁺ + Ru(bpy)₃³⁺ → Ru(bpy)₃²⁺ + *Ru(bpy)₃²⁺. It was shown that chemiluminescence from reduction of intermediate Ru(bpy)₃³⁺ with the OH^- ion does not make a pronounced contribution to the sonochemiluminescence intensity.

Keywords: Hydrated electron; Multibubble sonochemiluminescence; Tris-bipyridyl ruthenium(II) complex.