Kovár Petr, Melánová Klára, Zima Vítezslav, Benes Ludvík, Capková Pavla
Faculty of Mathematics and Physics, Charles University Prague, Ke Karlovu 3, 12116 Prague 2, Czech Republic.
J Colloid Interface Sci. 2008 Mar 1;319(1):19-24. doi: 10.1016/j.jcis.2007.10.060. Epub 2007 Dec 11.
Samples of Mg4Al2 layered double hydroxide (LDH) intercalated with p-methylbenzoate and p-bromobenzoate anions were prepared by reconstruction of calcined LDH. The interlayer arrangement of guests was investigated by molecular modeling combined with X-ray powder diffraction and thermogravimetry. Molecular modeling was carried out in a Cerius2 modeling environment. In both structures the guest anions adopt a nearly perpendicular arrangement of their long axis with respect to the host layers and they are anchored to the OH groups of the layers through COO* groups via electrostatic interactions. Molecular modeling revealed that both structures of the intercalates exhibit a certain disorder of guest anions in the interlayer space. In the case of LDH-p-methylbenzoate intercalate the anions tend to be situated in disordered rows, and the LDH-p-bromobenzoate intercalate exhibits a total disorientation of guest anions. A good agreement between calculated and measured X-ray diffraction patterns and between experimental and calculated basal spacings was obtained. In the LDH-p-methylbenzoate intercalate d exp=16.96 A and d calc=16.97 A, and in the case of LDH-p-bromobenzoate intercalate d exp=17.19 A and d calc=17.40 A.
通过煅烧层状双氢氧化物（LDH）的重构制备了插层有对甲基苯甲酸根和对溴苯甲酸根阴离子的Mg4Al2层状双氢氧化物（LDH）样品。结合X射线粉末衍射和热重分析法，通过分子模拟研究客体的层间排列。分子模拟在Cerius2模拟环境中进行。在两种结构中，客体阴离子的长轴相对于主体层几乎呈垂直排列，并且它们通过COO*基团经由静电相互作用锚定在层的OH基团上。分子模拟表明，插层物的两种结构在层间空间中均表现出客体阴离子的一定无序性。在LDH-对甲基苯甲酸插层物的情况下，阴离子倾向于无序排列成行，而LDH-对溴苯甲酸插层物则表现出客体阴离子的完全取向无序。计算得到的和测量得到的X射线衍射图谱之间以及实验和计算得到的基面间距之间取得了良好的一致性。在LDH-对甲基苯甲酸插层物中，d exp = 16.96 Å且d calc = 16.97 Å，而在LDH-对溴苯甲酸插层物的情况下，d exp = 17.19 Å且d calc = 17.40 Å。
