title: Photocontrollable cation extraction with crowned oligo(spirobenzopyran)s.
abstract: The photoinduced changes of metal-ion extractability of crown ether derivatives bearing three or four spirobenzopyran moieties and their analogues were studied using 1,2-dichloroethane as the organic solvent. Under dark conditions, these compounds extracted Cu2+, Ag+, and Pb2+ with their counteranions from the aqueous phase to the organic phase. The extraction equilibrium constants of the photochromic crown ether derivatives for Cu2+ and Ag+ were determined successfully. Under UV-light irradiation conditions, the extraction of Cu2+ by crowned tris(spirobenzopyran) was enhanced, while that of Ag+ was suppressed. During the competitive metal-ion extraction of crowned oligo(spirobenzopyran)s between Cu2+ and Ag+, the metal-ion selectivity was reversed explicitly by photoirradiation.
authors.affiliation: Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Sakae-dani 930, Wakayama 640-8510, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Nakamura
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Sakamoto
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kimura