CSIRO Molecular and Health Technologies (CMHT), Private Bag 10, Clayton South MDC, VIC 3169, Australia.
J Phys Chem B. 2009 Dec 10;113(49):15949-59. doi: 10.1021/jp906344u.
Eight lanthanide(III) oleates have been prepared and characterized. The chelation and self-assembly structures of these rare-earth oleates have been studied by elemental analysis, Fourier transfer infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD) analysis. Elemental analysis and FTIR results indicate that three oleate anions are complexed with one lanthanide cation and, with the exception of anhydrous cerium(III) oleate, form either a mono- or a hemihydrate. The X-ray analysis showed that the neat lanthanide soaps have a lamellar bilayer structure at room temperature. The thermal behavior has been investigated by cross-polarized optical microscopy (POM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). POM scans showed that all the lanthanide oleates form a lamellar phase in the presence of excess water. Small-angle X-ray scattering (SAXS) and XRD were used to investigate the internal structure of the bulk lanthanide oleates in excess water, and these X-ray results confirmed that the lanthanide oleates do not swell in water. Select lanthanide oleates were dispersed in water to form nonswelling lamellar submicrometer particles, confirmed by dynamic light scattering (DLS) and synchrotron SAXS measurements. NMR results indicated that colloidal dispersions of lanthanide oleates containing paramagnetic ions, such as gadolinium(III), terbium(III), and dysprosium(III), have a significant effect on the longitudinal (T(1)) and transverse (T(2)) relaxation times of protons in water. Time-resolved fluorescence measurements have demonstrated that colloidal dispersions of europium(III) oleate exhibit strong luminescence. The rare earth metal soaps exemplify the potential of self-assembled chelating amphiphiles as contrast agents in medical imaging modalities such as magnetic resonance imaging (MRI) and fluorescence imaging.
已经制备并表征了八种镧系元素（III）油酸酯。通过元素分析、傅里叶变换红外光谱（FTIR）和 X 射线粉末衍射（XRD）分析研究了这些稀土油酸酯的螯合和自组装结构。元素分析和 FTIR 结果表明，三种油酸根阴离子与一个镧系元素阳离子配位，除无水三价铈（III）油酸酯外，形成单水合物或半水合物。X 射线分析表明，在室温下，纯镧系元素皂具有层状双层结构。通过偏光显微镜（POM）、差示扫描量热法（DSC）和热重分析（TGA）研究了热行为。POM 扫描表明，所有镧系元素油酸酯在存在过量水的情况下均形成层状相。小角 X 射线散射（SAXS）和 XRD 用于研究过量水中块状镧系元素油酸酯的内部结构，这些 X 射线结果证实镧系元素油酸酯在水中不溶胀。选择的镧系元素油酸酯在水中分散形成不溶胀的层状亚微米颗粒，通过动态光散射（DLS）和同步加速器 SAXS 测量得到证实。NMR 结果表明，含有顺磁性离子（如三价钆、三价铽和三价镝）的镧系元素油酸酯胶体分散体对水中质子的纵向（T1）和横向（T2）弛豫时间有显著影响。时间分辨荧光测量表明，铕（III）油酸酯胶体分散体具有强荧光。这些稀土金属皂是自组装螯合两亲分子作为磁共振成像（MRI）和荧光成像等医学成像模式造影剂的潜力的范例。
