Akcakayiran D, Mauder D, Hess C, Sievers T K, Kurth D G, Shenderovich I, Limbach H-H, Findenegg G H
Institut für Chemie, Technische Universität Berlin, Berlin, Germany.
J Phys Chem B. 2008 Nov 20;112(46):14637-47. doi: 10.1021/jp804712w. Epub 2008 Oct 8.
The adsorption of a metallo-supramolecular coordination polymer (Fe-MEPE) in the cylindrical pores of SBA-15 silica with pure and carboxylic acid (CA) carrying pore walls has been studied. Fe-MEPE is an intrinsically stiff polycation formed by complexation of Fe(II)-acetate with an uncharged ditopic bis-terpyridine ligand. The adsorption affinity and kinetics of the Fe-MEPE chains is strongly enhanced when the pore walls are doped with CA, and when the pH of the aqueous medium or temperature is increased. The initial fast uptake is connected with a decrease of pH of the aqueous solution, indicating an ion-exchange mechanism. It is followed by a slower (presumably diffusion-controlled) further uptake. The maximum adsorbed amount of Fe-MEPE in the CA-doped material corresponds to a monolayer of Fe-MEPE chains disposed side-by-side along the pore walls. The stoichiometry of Fe-MEPE in the pores (determined by XPS) was found to be independent of the loading and similar to that of the starting material. The mean chain length of Fe-MEPE before and after embedding in the CA-doped matrix was studied by solid-state 15N NMR using partially 15N-labeled Fe-MEPE. It is shown that the average chain length of Fe-MEPE is reduced when the complex is incorporated in the pores.
研究了金属超分子配位聚合物（Fe-MEPE）在具有纯孔壁和带有羧酸（CA）孔壁的SBA-15二氧化硅圆柱孔中的吸附情况。Fe-MEPE是由醋酸亚铁与不带电荷的双齿双吡啶配体络合形成的本质上刚性的聚阳离子。当孔壁掺杂CA以及水介质的pH值或温度升高时，Fe-MEPE链的吸附亲和力和动力学显著增强。最初的快速吸收与水溶液pH值的降低有关，表明存在离子交换机制。随后是较慢的（可能是扩散控制的）进一步吸收。CA掺杂材料中Fe-MEPE的最大吸附量对应于沿孔壁并排排列的单层Fe-MEPE链。发现孔中Fe-MEPE的化学计量（通过XPS测定）与负载量无关，且与起始材料的化学计量相似。使用部分15N标记的Fe-MEPE通过固态15N NMR研究了Fe-MEPE嵌入CA掺杂基质前后的平均链长。结果表明，当络合物掺入孔中时，Fe-MEPE的平均链长会缩短。
