ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 37, Number 1
JKCSEZ 37(1)
February 20, 1993 

In the presence of Ca2+ ion, the charge transfer (CT) interaction of nonionic surfactants, nonylphenol-(ethylene oxide)n LNP-(EO)n; n = 11, 40, 100] with iodine in aqueous solution were investigated by UV-visible spectrophotometer. The characteristics of spectra depended on the concentration of Ca2+ ion and the number of EO unit. Above CMC, the intensity of the CT band by the addition of Ca2+ ion for the NP-(EO)11 and NP-(EO)40 increased and then decreased, while for the NP-(EO)100 continuously increased. The increase in the intensity of CT band were attributed to the compactness of micelle in the presence of Ca2+ ion. These phenomena may be explained by the fact that the linear ethylene oxide (EO) chain, to be free configuration in aqueous solution, could form a pseudo-crown ether structures capable of forming complexes with Ca2+ ion.