Thermodynamic Studies of Complexation of Rub idium and Cesium Cations by Azobenzene-calix [4] bis-crown-6

in this study the binding abilities of 1,3-di(2,2-azobenzene)-calix [4] bis-crown-6 toward Rb+ and Cs cations have been perfomed in methanol using spectrophotometric measurments at 25±0.1°C and 0.01 M ionic strength, and Specifit computer program. Stability constants for 2:1, metal: ligand complexes have been estimated. The results reveal that L is capable to complex cesium and rubidium ions with a 2:1 metal to ligand ratio. Taking into account a 1:1 complex alone or together with the binuclear one doesn't improve the fit and even leads to the rejection of the model.