Chemiluminescence of Lanthanide Ions Ln^(n – 1)+ during Reduction of Lnⁿ⁺ with a Solvated Electron

Abstract

The ability of lanthanide ions to luminescence due to the chemical generation of electronically excited states *Ln^(n ‒ 1)+ upon reduction of Lnⁿ⁺ by a solvated electron in ultrasound-irradiated solutions has been demonstrated for the first time using Eu³⁺ and Ce⁴⁺ as an example. A solvated electron is formed by injection of electrons from a nonequilibrium plasma periodically generated by ultrasound in a moving bubble. The key stage of the found single-bubble sonochemiluminescence (SCL) is the reduction of Eu³⁺ and Ce⁴⁺ to, respectively, the bivalent and trivalent states by an electron solvated in water and ethylene glycol. It has been found that the SCL emitters are excited ions *Eu²⁺ and *Ce³⁺, which have, along with the ability to luminescence, high reducing properties (E_ox ≤ –2.9 V). The latter factor determines the possibility of using ultrasonic generation of *Eu²⁺ and *Ce³⁺ in numerous reactions of organic synthesis and metal complex catalysis.