胆红素及其两亲衍生物的Langmuir-Blodgett膜研究

研究了亚相酸度和金属离子对胆红素(1)及其两个两亲衍生物胆红素二(十八烷基)酯(2)和胆红素二(十八烷基)酰胺(3)的单分子膜和LB膜性能的影响.通过π-A等温线、X射线光电子能谱、紫外-可见光谱等方法,研究了它们在有序分子膜中的分子伸展及与金属离子的配位方式.胆红素及其两亲衍生物与金属离子在有序分子膜中的配位(生成1:1型配合物)明显不同于其在本体溶液中的配位(1:1,1:2或2:1型配合物).小角X射线衍射表明1,2和3形成双层膜间距分别为2.15,5.55和5.65nm的Y型LB膜.

Studies on Langmuir-Blodgett Films of Bilirubin and Its Amphiphilic Derivatives

Monolayer formation, LB film fabrication of bilirubin(1), its two kinds of amphiphilic derivatives, bilirubin dioctadecyl ester［B(COOC18H37)2, 2］ and dioctadecyl bilirubinamide ［B(CONHC18H37)2, 3］ at an air-water interface on subphases with different pH values and subphases containing different metal ions were investigated and compared with 1. Some information regarding the packing density in monolayers, molecular orientation and complexation by metal ions has been obtained by means of many physical measurements such as the π-A isotherms, X-ray photoelectron spectroscopy, UV-visible spectroscopy and low-angle X-ray diffraction. At the air-water interface the amphiphilic ligands with their complexing head groups in contact with the aqueous phase can form metal complexes with many metal ions present in the aqueous phase. The formation of ligand-metal complexes leads to changes in the area per molecule and in the collapse pressure, as well as to changes in the XPS and UV-visible absorption spectra of the monolayer assemblies. Low-angle X-ray diffraction indicates that the LB films of 1, 2 and 3 were Y-type with bilayer spacing of ca. 2.50, 5.60 and 5.65 nm. The coordination in ordered molecular films are much different from that in bulk solution. It can help us to understand the formation and prevent and cure of gallstones.