Laser photolysis studies of quaternary ammonium ionic liquids aqueous solution

The reactions between quaternary ammonium ionic liquids ([Me3NC2H4OH]+[Zn2Cl5]−, abbrev. Ch-Zn2Cl5) and one-electron oxidant (SO4•−), have been studied by nano-second laser photolysis techniques. The mechanism of monophotonic ionization by 266 nm laser excitation was suggested and the quantum yield was estimated to be 0.04. The second-order decay rate constant of SO4•− oxidation reactions at 460 nm, 1.3 × 109 M−1 s−1, was almost equal to the product rate constant of 1.5 × 109 M−1 s−1 at 320 nm in Ch-Zn2Cl5 aqueous solution showing that the decay and the product were synchronic. Comparison of Ch-Zn2Cl5 with chloride choline and ZnCl2 showed that the anion Zn2Cl5− played an important role in photoionization while choline cation had little function on its photolysis and radiolysis. The present study would be helpful for understanding the application of ionic liquids in the field of electrochemical deposition.