Molecular Dynamics Simulation on Structure, Hydrogen-Bond and Hydration Properties of Diflunisal Intercalated Layered Double Hydroxides
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.
Keywords: Diflunisal/layered double hydroxide; Hydration; Hydrogen-bond; Molecular dynamics simulation
Document Type: Research Article
Publication date: 15 February 2009
- Acta Physico-Chimica Sinica, founded in 1985, is sponsored by the Chinese Chemical Society and organized by the College of Chemistry and Molecular Engineering, PekingUniversity. Since 1997, Acta Physico-Chimica Sinica has been indexed in SCI of ISI (US). Acta Physico-Chimica Sinica is devoted to reporting new and original experimental and theoretical basic research of interest to physical chemists, biophysical chemists, and material physical chemists. Manuscripts that are essentially reporting data, applications of data, or reviews of the literature are not suitable for publication in Acta Physico-Chimica Sinica.
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