Modeling in Structure Analysis of Vanadyl Phosphate Intercalated with 1-Alkanols

Abstract

IntroductionVanadyl phosphate-and zirconium phosphate-alkanol intercalates may be considered as very good starting materials for the intercalation of other polar organic molecules. [1,2] Previous X-ray diffraction studies of vanadyl phosphatealkanol intercalate [3] revealed irregularities in basal spacing increments depending on the alkyl chain length. Comparing the experimental basal spacing for VOPO 4 -ethanol d = 13.17 Å, VOPO 4 -propanol d = 14.36 Å and VOPO 4 -butanol d = 17.90 Å, one can see that one additional carbon atom causes the increment of basal spacing ∆d = 1.19 Å in the case of propanol and 3.54 Å in the case of butanol. In the present work we have used molecular mechanics simuAbstract Molecular mechanics simulations supported by X-ray powder diffraction measurements have been used to investigate the structure of vanadyl phosphate intercalated with 1-alkanols C n H 2n+1 OH for n = 2, 3, 4. Modeling revealed the specific features and differences in arrangement of alkanol molecules with different chain length, depending on the relation between the parameters of active sites network and size of guest molecules. This result enabled us to explain the irregularities in dependence of basal spacing on the chain length. The comparison of experimental d exp and calculated d calc values of basal spacing showed the good agreement of modeling with x-ray powder diffraction. While we obtained d calc (Univ) = 13.05 Å for vanadyl phosphate-ethanol using the Universal force field (d exp =13.17 Å), for vanadyl phosphate-propanol and vanadyl phosphate-butanol better agreement with experiment was obtained using the Tripos force field. In the case of vanadyl phosphate-propanol the calculated basal spacing d calc (Tripos) = 14.49 Å, compared with an experimental value of d exp =14.36 Å. For vanadyl phosphate-butanol d calc (Tripos) = 17.71 Å and d exp =17.90 Å.

Intercalation chemistry of layered vanadyl phosphate: a review

“…The intercalate with methanol shows lower content of alcohol (x = 1.33) and the basal spacing indicates a monolayer of the methanol molecules. Molecular mechanics simulations supported by powder X-ray diffraction have been used to investigate the structure of vanadyl phosphate intercalated with ethanol, 1-propanol, and 1-butanol [68,69]. As follows from the calculations, the alcohol molecule coordinated to the vanadium atom is nearly perpendicular for all three guests.…”

Intercalates of Vanadyl Phosphate with Unsaturated Alcohols

“…The intense band at about 1104 cm −1 in the spectrum of the intercalate is assigned to the asymmetric stretching vibration ν(PO 4 ) of the phosphate tetrahedron. This band is due to the hydrogen bonds between the alcohol hydroxyl and the phosphate oxygen, analogous to the saturated 1‐alkanols 31. The strong hydrogen bonding of the alcohol in the intercalate leads to broad OH stretching vibration bands centered at about 3403 and 3582 cm −1 .…”

“…the distance from C 1 to C n ) 20,31. This means that they are arranged in two layers and the angle, α, at which they are tilted to the plane of the host sheets, increases with an increasing number of carbon atoms, as in the homologous series of ethanol, 1‐propanol and 1‐butanol intercalates 31. Half of the guest molecules are anchored to V host by donor−acceptor bonds with O guest .…”

Crystal packing of intercalated layered structures

“…Using combination of molecular mechanics simulations with experiment (X-ray and synchrotron powder diffraction and IR spectroscopy) we determined the structure of the following intercalates with various organic guest species: phyllosilicates 2 , vanadyl phosphates 3,4 and zirconium phosphate 5 . This structure analysis based on the combination of modeling with experiment enables the structure determination, including the characterization of possible disorder.…”