Extraction Spectrophotometry of Lithium Ions Based on Cation- and Photo-Induced Isomerization of Crowned Spirobenzopyran

Abstract

A spirobenzopyran derivative incorporating monoaza-12-crown-4 moiety was applied as a reagent for extraction spectrophotometry of alkali metal ions, taking advantage of the cation-complexation-induced Isomerization of its spiropyran moiety to the corresponding colored merocyanine form. The present spectrophotometry is quite selective for lithium ion against the other alkali metal ions. Photoisomerization of the crowned spirobenzopyran promoted the lithium extraction; especially, it increased the extraction rate remarkably.