Monolayer Properties and Ion-transportation Phenomena of Crown Ether Compound with Long-chain at Oil/Water Interface

Abstract

Monolayer properties and ion-transportation phonomena of amphiphilic crown ethers with various hydrocarbon chains were examined using a special Langmuir trough designed to measure simultaneously the transported amount of ions through an oil phase including various carries and interfacial tension at the oil/water interface.Under a polar oily condition, the transportation rate of Ba2+ was determined mainly by the distribution of a compound between the oil and water phases. In the system including a non-polar oil, the adsorbed monolayer of a crown ether compound formed at the interface was an essential factor determining ion transportation rate. The stability of the adsorbed layer was influenced by the polarity of the oil phase and structure of amphiphile compound; that is, the more lipophilic the crown ether compound, the faster was the transportation rate due to considerable solubility in the oil phase. The crown ether compound with two long hydrocarbon chains (2 C12) was extremely lipophilic, transported metal ions quite well, and could maintain a high transportation rate for a long period. However, the crown ether compound with amino acid residues and 2 C12 showed zero-transportation capacity.