...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Polyoxoanion Occluded within Modified MCM-41: Spectroscopy and Structure
【24h】

Polyoxoanion Occluded within Modified MCM-41: Spectroscopy and Structure

机译：改性的MCM-41中包含的聚氧阴离子：光谱学和结构

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Polyoxoanions have enormous potential as drug delivery hosts, as catalysts, as agents for sequestering nuclear waste heavy metals, and as luminescent materials for laser and optical devices applications. We report the encapsulation of the polyoxoanion [Eu(H_2O)_3(α-1-P_2W_(17)O_(61)]~(7-) within Mobil crystalline material (MCM)-41. For proper host-guest interaction, it was necessary to functionalize the surface walls of MCM-41 through use of a silylation reagent, specifically, (aminopropy)triethoxysilane. A stable and integrated [Eu(H_2O)_3(α-1-P_2W_(17)O_(61)]~(7-) polyoxoanion was shown to be formed inside the channels of modified MCM-41. X-ray diffraction, ~(29)Si magic angle spinning (MAS) NMR, UV-vis absorption, emission and excitation spectra, and Raman scattering measurements have been used to structurally characterize the various products. Cross-polarization ~(29)Si MAS NMR has been shown to better reveal the surface structural character of the modified MCM-41 than does regular ~(29)Si MAS NMR. We find (when compared to bulk polyoxoanion) that the Raman spectrum of the polyoxoanion/MCM-41 composite system exhibits red shifts for the symmetric stretching (v_s) of the W-O_t (when O_t represents a terminal oxygen) and P-O-W bands. These latter observations are interpreted as suggesting that electrostatic interaction between the negative-charged terminal oxygen (O_t) of the polyoxoanion and the -NH_3~+ terminal functional group, associated with the silylation agent on the walls of MCM-41, leads to an increase in the lengths of adjacent W-O and P-O bonds. Given the shape and dimensions of the polyoxoanion and the diameter of the pores in MCM-41, as well as the effects of encapsulation on emission and Raman spectra, we conclude that the anion (i) is encapsulated with its long axis parallel to the pore axis an (ii) couples to the surface through interaction with terminal oxygens that are not directly bonded to the europium atom.
机译：聚氧阴离子具有巨大的潜力，可以用作药物输送主体，催化剂，螯合核废料重金属的试剂以及激光和光学设备应用的发光材料。我们报道了聚氧阴离子[Eu（H_2O）_3（α-1-P_2W_（17）O_（61）]〜（7-）在Mobil晶体材料（MCM）-41中的包封。通过使用甲硅烷基化试剂（特别是（氨基丙基）三乙氧基硅烷）使MCM-41的表面功能化是必需的，稳定且集成的[Eu（H_2O）_3（α-1-P_2W_（17）O_（61）]〜研究表明，在改性MCM-41的通道内形成了（7-）聚氧阴离子。X射线衍射，〜（29）Si幻角旋转（MAS）NMR，UV-vis吸收，发射和激发光谱以及拉曼散射测量结果已被用来表征各种产物的结构。交叉极化〜（29）Si MAS NMR比常规〜（29）Si MAS NMR能更好地揭示修饰的MCM-41的表面结构特征。 （与本体聚氧阴离子相比），聚氧阴离子/ MCM-41复合系统的拉曼光谱在W-O_t的对称拉伸（v_s）时呈现红移（当O_t代表末端氧）和P-O-W带。后面的这些观察结果被解释为表明，聚氧阴离子的负电荷末端氧（O_t）与-NH_3〜+末端官能团之间的静电相互作用与MCM-41壁上的甲硅烷基化试剂有关，导致相互作用增加。在相邻的WO和PO键的长度上。考虑到聚氧阴离子的形状和尺寸以及MCM-41中孔的直径，以及包封对发射光谱和拉曼光谱的影响，我们得出结论：阴离子（i）的长轴与孔平行轴a（ii）通过与未直接键合到atom原子上的末端氧相互作用而耦合到表面。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号