Using 2-phenoxyethanol as starting material, two new N-pivot lariat crown ethers were synthesized, N-(2-phenoxyethyl)monoaza-18-crown-6 (18CE) and N-(2-phenoxyethyl)monoaza-15-crown-5(15CE). The structures of the new crown ethers and the intermediate compounds were characterized by FTIR, ¹H NMR and UV spectra. The coordination of Na^＋, K^＋, Ag^＋, NH₄^＋, Ni^2＋, Cu^2＋, Pb^2＋and Co^2＋with two azacrown ethers was studied respectively by conductometric titration at 25 ℃. The stability constants for the 1∶1 coordination compounds were calculated. The results show that due to the induction and participation in complexing of the azacrown ether ring of N-(2-phenoxyethyl). The stability of the complexes has been improved more distinctly than that of homologue complexes of monoaza-18-crown-6, N-(2-hydroxyethyl)monoaza-18-crown-6, N-(2-methoxyethyl)monoaza-18-crown-6 and monoaza-15-crown-5, N-(2-hydroxyethyl)monoaza-15-crown-5, N-(2-methoxyethyl)monoaza-15-crown-5. The stability constants and UV spectra for the coordination compounds gave some evidences of pivot chain phenoxy group participating in complexing．

Key words: conductometric titration, stability constant, synthesis, N-pivot lariat crown ether