巨轮型多金属氧酸盐纳米超薄多层膜的制备

首次将巨轮型纳米多孔多金属氧酸盐Na₁₅［Mo^VI₁₂₆Mo^V₂₈O₄₆₂H₁₄(H₂O)₇₀］_0.5［Mo^VI₁₂₄Mo^V₂₈O₄₅₇H₁₄(H₂O)₆₈］_0.5·ca.400H₂O通过层层自组装的方法，与聚乙烯基亚胺（PEI）通过静电作用自组装形成纳米超薄多层膜。该膜的制备过程通过紫外可见光谱进行监测，巨轮型纳米多孔多金属氧酸盐的特征吸收峰的吸收值随着层数的增加呈线性增长关系，表明在纳米超薄多层膜的组装过程中巨轮型多金属氧酸盐的结构没有被破坏，自组装成膜的过程是一个层层均一、反复生长的过程，每层吸附循环沉积的聚电解质和多金属氧酸盐的量相等。对纳米超薄多层膜的偏振紫外光谱的研究表明巨轮型纳米多孔多金属氧酸盐分子在纳米超薄膜中不是杂乱无章随意排列堆积的，而是在带高负电荷的巨轮型纳米多孔多金属氧酸阴离子间存在的静电排斥作用下彼此平行倾斜在基片表面并且与基片表面成一定的取向角从而减低整个体系的能量达到最稳定状态。

Fabrication of organic-inorganic ultrathin multilayer films of a giant-wheel nanoporous polyoxometalate

Ultrathin multilayer films based on the giant wheel nanoporous polyoxometalate Na₁₅［Mo^VI₁₂₆Mo^V₂₈O₄₆₂H₁₄(H₂O)₇₀］_0.5［Mo^VI₁₂₄Mo^V₂₈O₄₅₇H₁₄(H₂O)₆₈］_0.5·ca.400H₂O({Mo₁₅₄}) and polyethyleneimine (PEI) have been fabricated for the first time by layer by layer self assembly techniques (LBL). UV-visible spectroscopy showed that the absorbance values at the characteristic wavelengths of the multilayer films increased almost linearly with the number of {Mo₁₅₄}/PEI bilayers, suggesting that each adsorption cycle incorporates an equal amount of {Mo₁₅₄} into the thin films. This provides persuasive evidence for the regular growth of the multilayers and for the high reproducibility of the layer-by-layer assembly method. Polarized UV-visible spectroscopy suggested that the giant-wheel nanoporous polyoxometalate anions in the multilayers were tilted with respect to the substrates and were parallel with each other in order to minimize the electrostatic repulsion between adjacent anions. 