Molecular Design of the Electron-Donating Sidearm of Lariat Ethers: Effective Coordination of the Quinoline Moiety in Complexation toward Alcali-Metal Cations

Article abstract of DOI:10.1021/ja00210a037

The electron-donating sidearm of alkyl-substituted lariat ethers based on 15-crown-5, 16-crown-5, and 18-crown-6 was modified to clarify the contribution to the complexation of the sidearm toward alkali-metal cations.A specific coordination property of the quinoline sidearm was shown by measuring the complexing ability in methanol at 25 deg C, the change of the chemical shift in the 1H NMR spectrum, a characreristic absorption in the UV spectrum, the exrtactability, and the transport ability.The methyl-substituted lariat ether based on 15-crown-5 or 18-crown-6 displayed an excellent selectivity toward Na⁺ or K⁺, resoectively, comparedwith the unsubstituted ethers.