Acta Phys. -Chim. Sin. ›› 2009, Vol. 25 ›› Issue (02): 223-228.doi: 10.3866/PKU.WHXB20090205

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

PAN Guo-Xiang; NI Zhe-Ming; WANG Fang; WANG Jian-Guo; LI Xiao-Nian   

  1. College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310032, P. R. China
  • Received:2008-08-01 Revised:2008-10-08 Published:2009-01-16
  • Contact: NI Zhe-Ming E-mail:jchx@zjut.edu.cn

Abstract: The supramolecular structure of diflunisal intercalated layered double hydroxides (DIF/LDHs) was modeled bymolecular 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-Wtype 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.

Key words: Molecular dynamics simulation, Diflunisal/layered double hydroxide, Hydrogen-bond, Hydration

MSC2000: 

  • O641