An improved one‐step method to prepare some diaza‐crown ethers and the cation complexation properties of 4,10‐diaza‐18‐crown‐6 with two transition metal ions

Abstract 4,10‐Diaza‐15‐crown‐5, 4,10‐diaza‐18‐crown‐6, 4,13‐diaza‐21‐crown‐7, and 4,16‐diaza‐24‐crown‐8 were prepared by an improved method from the appropriate oligothylene glycol diiodides and diamines. The thermodynamic values of log K, ΔH and ΔS for the interaction of 4,10‐diaza‐18‐crown‐6 with Pb2+ and Ag+ were determined by a calorimetric titration method and compared with thermodynamic values for interactions of 4,13‐diaza‐18‐crown‐6 with the same cations. The thermodynamic values were found to be different for the two diaza‐crown ligands. 4,10‐Diaza‐18‐crown‐6 and its 4,13‐diaza‐crown analog formed precipitates when treated with Co2+, Cd2+, Cu2+, and Ni2+ so that no thermodynamic data are reported for these interactions.