Lithium-triggered spontaneous formation of polyiodides in room-temperature ionic liquid-alcohol solutions.

In this study, the effect of alcohol on polyiodide formation in room-temperature ionic liquid (RTIL) was examined by time evolutions of Raman spectra in the low-frequency region and by color changes of the sample. The RTIL was 1-methyl-3-propylimidazolium iodide, [C3mim][I]. Polyiodides develop in [C3mim][I]‑lithium salt-ethanol solutions (Abe et al., Chem. Phys. 502 (2018) 72.). Without the external addition of iodine or without an external electric field, the irreversible transformation from I- to I3- indicates that charge unbalancing was promoted by lithium ion. Polyiodide formations were not induced by sodium or potassium ions. Strong alcohol effects were observed directly by the time-dependent Raman bands in the low-frequency region.