Structure determination of two intercalated compounds VOPO₄·(CH₂)₄O and VOPO₄·OH-(CH₂)₂-O-(CH₂)₂-OH; synchrotron powder diffraction and molecular modelling

The crystal structures of two intercalated compounds have been determined using a combination of synchrotron powder diffraction and molecular mechanics simulations: (1) vanadyl phosphate intercalated with tetrahydrofuran, VOPO₄·(CH₂)₄O, and (2) vanadyl phosphate intercalated with diethylene glycol, VOPO₄·HO(CH₂)₂O(CH₂)₂OH. Both intercalates preserve the tetragonal space group P4/n, as found in the host structure VOPO₄·2H₂O. (1): a = 6.208, c = 8.930 Å, Z = 2, D_x = 2.51 g cm^-3; (2): a = 6.223, c = 11.417 Å, Z = 2, D_x = 2.66 g cm^-3. Both intercalates exhibit the same type of orientational disorder in the arrangement of guest molecules, as observed in the same host compound intercalated with water. These two intercalates also exhibit, rather surprisingly, perfect ordering in layer stacking without the displacement disorder, characteristic of many intercalated layered structures. Thanks to this regularity in the arrangement of guests and layers, synchrotron powder diffraction could be used in the present structure determination. The present results also enabled the analysis of the effect of geometrical parameters characterizing the mutual host-guest complementarity and the effect of host-guest and guest-guest interaction on the crystal packing of intercalates.