Analytical Sciences

Abstract − Analytical Sciences, 21(4), 403 (2005).

Photocontrollable Cation Extraction with Crowned Oligo(spirobenzopyran)s
Makoto NAKAMURA, Hidefumi SAKAMOTO, and Keiichi KIMURA
Department of Applied Chemistry, Faculty of Systems Engineering, Wakayama University, Sakae-dani 930, Wakayama 640-8510, Japan
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.