Abstract
Naphthazarin(5,8-dihydroxy-1,4-naphthoquinone) exhibited high selectivity for F-, as compared with CN-, Cl-, Br-, HSO4-, H2PO4-, ClO- and NO3- in DMSO, which was attributed to the formation 1:1 complex. Interestingly, the blue color of the naphthazarin-F- complex could be recovered after the addition of Cr3+. We have investigated the ability of complex formation based on the association constant, Kass; the binding ability for the complex formation of naphthazarin-F- and Cr3+ is much greater in DMSO (Kass =5.3 × 104 M-1) than that of the naphthazarin with F- (Kass = 2.0 × 103 M-1).
