二氟尼柳/水滑石插层组装结构、氢键及水合特性的分子动力学模拟  

Molecular Dynamics Simulation on Structure, Hydrogen-Bond and Hydration Properties of Diflunisal Intercalated Layered Double Hydroxides

作　　者：潘国祥[1] 倪哲明[1] 王芳[1] 王建国[1] 李小年[1] 

机构地区：[1]浙江工业大学化学工程与材料学院,杭州310032

出　　处：《物理化学学报》2009年第2期223-228,共6页Acta Physico-Chimica Sinica

基　　金：浙江省自然科学基金(Y406069)资助项目

摘　　要：采用分子动力学方法模拟二氟尼柳插层水滑石(DIF/LDHs)的超分子结构,研究复合材料主客体间形成的氢键以及水合膨胀特性.结果表明,当水分子总数与DIF分子总数之比Nw≤3时,层间距dc保持基本恒定,约1.80nm;当Nw≥4时,层间距逐渐增大,且符合dc=1.2611Nw+13.63线性方程.随着水分子个数增加,水合能ΔUH逐渐增大.当Nw≤16时,由于ΔUH<-41.84kJ·mol-1,LDHs-DIF可以持续吸收水,从而使材料层间距不断膨胀.但当Nw≥24时,ΔUH>-41.84kJ·mol-1,此时LDHs-DIF层间不能再进一步水合,因此LDHs-DIF在水环境中膨胀具有一定的限度.水滑石层间存在复杂的氢键网络.DIF/LDHs水合过程中,水分子首先同步与层板和阴离子构成氢键;当阴离子趋于饱和后,水分子继续与层板形成氢键,并逐步发生L-W型氢键取代L-A型氢键,驱使阴离子向层间中央移动,与层板发生隔离;最后水分子在水滑石羟基表面形成有序结构化水层.The supramolecular structure of diflunisal intercalated layered double hydroxides （DIF/LDHs） was modeled by molecular dynamics （MD） methods. Hydrogen bonding, hydration and swelling properties of DIF/LDHs were investigated. The interlayer spacing dc was found to be constant （ca 1.80 nm） when Nw（the ratio of the numbers of water molecule to DIF） ≤3. The interlayer spacing dc gradually increases as Nw ≥4 and this increase follows the linear equation dc=1.2611Nw＋13.63. The hydration energy gradually increases as the water content increases. LDHs/DIF hydrates when Nw ≤16 because hydration energy △UH〈-41.84 kJ· mol^-1. At Nw≥ 24 the hydration of LDHs/DIF does not occur because △UH〉-41.84 kJ ·mol^-1. Swelling of LDHs/DIF is thus limited in an aqueous environment. The interlayer of DIF/LDHs contains a complex hydrogen bonding network. The hydration of DIF/LDHs occurs as follows： water molecules initially form hydrogen bond with layers and anions. While the anions gradually reach a saturation state and water molecules continue to form hydrogen bonds with the hydroxyls of the layers. The L-W type hydrogen bond gradually substitutes the L-A type hydrogen bond and the anions move to the center of an interlayer and then separate with the layers. Last, a well-ordered structural water layer is formed on the surface hydroxyls of DIF/LDHs.

关 键 词：分子动力学模拟 二氟尼柳/水滑石 氢键 水合 

分 类 号：O641.1[理学—物理化学]