Topotactic desolvation and condensation reactions of 3D Zn3TiF7(H2O)2(taz)3·S (S = 3H2O or C2H5OH).

Crystals of two new 3D hybrid compounds, trans-Zn3TiF7(H2O)2(taz)3·3H2O and cis-Zn3TiF7(H2O)2(taz)3·C2H5OH, have been obtained by solvothermal synthesis ((taz)- = 1,2,4-triazolate C2H2N3 ligand). Their structures, determined from X-ray single crystal diffraction data in Cm and Pnma space groups, respectively, are based on Zn3N9(H2O)2F3 trimers linked by TiF6 octahedra that build trans- or cis-chains ∞[Zn3TiN9(H2O)2F7]. Water or ethanol in the structure cavities is released below 110 °C to give trans- or cis-Zn3TiF7(H2O)2(taz)3 and, on further heating, these intermediate phases dehydrate and lead to anhydrous trans- or cis-Zn3TiF7(taz)3. At 110 °C, the loss of ethanol concerns only ≈1/3 of the weight of cis-Zn3TiF7(H2O)2(taz)3·C2H5OH while the remaining part subsists up to 180 °C. This behaviour is attributed to a core-shell type configuration. Rehydration in humid air occurs at room temperature for the anhydrous cis-phase. All desolvated, dehydrated or rehydrated phase structures have been determined by X-ray powder diffraction and ab initio Rietveld refinements. All transformations from solvated or hydrated to anhydrous phases are realised without any symmetry change and the trans or cis connection of the TiF6 octahedra is maintained together with the overall features of the 3D networks. The final loss of water molecules induces a condensation reaction that implies the connection of the trimers by fluorine atoms; the structures of the anhydrous phases Zn3TiF7(taz)3 are then described by Zn3N9F4 trimers. 1H and 19F MAS NMR studies, coupled with DFT calculations of NMR parameters, confirm the water loss and support the strutural models while evidencing both the positional disorders, more likely of the organic parts, and the F motions within TiF6 octahedra.

Which physical activities and sports can be recommended to chronic low back pain patients after rehabilitation?

BACKGROUND: Physical exercise is widely prescribed in rehabilitation programmes for low back pain (LBP). The LBP patient often asks whether this physical activity should be maintained and, in some cases, whether he/she should resume or take up a sport. PURPOSE: To answer these two questions by performing a review of literature on the efficacy and safety of post-rehabilitation physical activities and sport in LBP. METHOD: A systematic search of computerized databases from 1990 to 2011 was performed using grade 1 to 4 studies articles in English or French. RESULTS: Of the 2583 initially identified articles, 121 articles were analysed. Globally, physical activities like swimming, walking and cycling, practiced at moderate-intensity help to maintain fitness and control pain. Inconsistent results were found for avoiding recommendations according to the nature of PA. Sport activities, except ballgames, can be easily resume or take up as tennis, horse riding, martial arts, gymnastics, golf and running which can be performed at a lower intensity or lower competitive level. DISCUSSION AND CONCLUSION: Moderate but regular physical activity helps to improve fitness and does not increase the risk of acute pain in chronic LBP patients. The resumption of a sport may require a number of adaptations; dialogue between the therapist and the sports trainer is therefore recommended.

Bis(butane-1,4-diammonium) di-µ-oxido-bis[trifluoridooxidomolybdate(V)] monohydrate.

The title compound, (C4H14N2)2[Mo2O4F6]·H2O, was obtained by solvothermal reaction at 443 K for 72 h from a mixture of MoO3, HF, 1,4-diamino-butane (dab), water and ethyl-ene glycol. The structure consists of [Mo2O4F6](4-) anionic dimers containing strongly distorted MoO3F3 octa-hedra (with twofold symmetry), diprotonated dab cations and water mol-ecules (twofold symmetry) in the ratio 1:2:1. The cohesion of the three-dimensional structure is ensured through N-H⋯O, N-H⋯F and O-H⋯F inter-actions.

2,4,6-Triamino-1,3,5-triazine-1,3-diium aqua-penta-fluoridoaluminate.

The title compound, (C(3)H(8)N(6))[AlF(5)(H(2)O)], was obtained by solvothermal synthesis from the reaction of aluminium hydroxide, 1,3,5-triazine-2,4,6-triamine (melamine), aqueous HF and water at 323 K for 48 h. The structure consists of [AlF(5)(H(2)O)](2-) octa-hedra and diprotonated melaminium cations. Cohesion is ensured by a three-dimensional network of hydrogen bonds.