This article reports the hydrothermal synthesis and characterization of two new series of porous tin(IV) phosphonophenoxyphenylphosphonates with controlled pore size distributions, using as precursor the 4-(4′-phosphonophenoxy)phenyl phosphonic acid, [H2O3P–C6H4]2–O. Supermicroporous solids (SBET, 300–400 m2 g−1) were obtained employing n-alcohol (C1-C6)–water mixtures (solvents ratio 1 : 1), in the presence of hydrofluoric acid. X-Ray powder diffraction shows that these compounds are semi-crystalline and the local environments around the phosphorus and tin elements have been studied by 31P and 119Sn MAS-NMR spectroscopy, respectively. The microstructure (particle sizes and shapes) of these phosphonates has been analyzed by scanning and transmission electron microscopy. This study shows that the microstructures of single-ligand (for instance tin(IV) phenylphosphonate) and cross-linked tin(IV) bisphosphonates are different. Tin(IV) phenylphosphonate crystallizes as micron-sized spheres, ∅
∼ 1–2 µm, formed by the aggregation of nanospheres, whereas tin(IV) bisphosphonates crystallize as microparticles larger than 20 µm. The textural properties of these porous solids were characterized by N2 and CO2 sorption isotherms. The key result of this work is that maxima of pore size distributions smoothly shift from 12 to 16 Å upon increasing the chain length of the alcohol. The microporosity of tin(IV) bisphosphonates is compatible with a double role played by the phosphonate groups acting as a pillar between adjacent layers and as a component of the hybrid organic–inorganic layers.
本文以 4-(4′-膦酰基苯氧基)
苯基膦酸 [H2O3P-C6H4]2-O 为前驱体,报道了两种具有可控孔径分布的多孔
锡(IV)膦酰基苯氧基
膦酸新系列的
水热合成和表征。在
氢氟酸的存在下,使用正
丙醇(C1-C6)-
水混合物(溶剂比 1:1)获得了超微孔固体(SBET,300-400 m2 g-1)。X 射线粉末衍射显示这些化合物为半晶体,
磷元素和
锡元素周围的局部环境分别通过 31P 和 119Sn MAS-NMR 光谱进行了研究。扫描和透射电子显微镜分析了这些
膦酸盐的微观结构(颗粒大小和形状)。这项研究表明,单
配体(例如
苯基膦酸
锡(IV))和交联
双膦酸
锡(IV)的微观结构是不同的。
苯基膦酸
锡(IV)结晶为微米大小的球体,∅∼ 1-2 µm,由纳米球聚集而成,而
二膦酸
锡(IV)结晶为大于 20 µm 的微颗粒。N2 和
CO2 吸附等温线表征了这些多孔固体的质地特性。这项研究的主要结果是,当醇的链长增加时,孔径分布的最大值会从 12 Å 平滑地转移到 16 Å。
锡(IV)
双膦酸盐的微孔性与
膦酸盐基团作为相邻层之间的支柱和有机-无机混合层的组成部分所发挥的双重作用是一致的。