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A series of molybdenum(VI) oxide-organic solids were prepared by hydrothermal reactions employing N-donor tectons, which combine two 1,2,4-triazol-4-yl sites separated by representative aliphatic spacers (ethylene, tr(2)eth; 1,3-propylene, tr(2)pr; trans-1,4-cyclohexanediyl, tr(2)cy; diamondoid 1,3-adamantanediyl, tr(2)ad; 1,6- and 4,9-diamantanediyls, 1,6-tr(2)dia and 4,9-tr(2)dia) and heterofunctional 5-[4-(1,2,4-triazol-4-yl)phenyl]tetrazole (trtz). In all the compounds the 1,2,4-triazol-4-yl group acts as a short-distance N(1),N(2)-bridge between two Mo ions (Mo-N 2.36-2.50 A). The 3D framework structure is based upon pseudo-4(1) helices ([Mo(4)O(12)(tr(2)eth)(2)] 1, [Mo(2)O(6)(tr(2)cy)] 3) or sinusoidal chains ([Mo(2)O(6)(tr(2)pr)] 2, [Mo(2)O(6)(tr(2)ad)].6H(2)O 4, [Mo(2)O(6)(4,9-tr(2)dia)].0.5H(2)O 5) of vertex-sharing MoO(4)N(2) octahedra, while the bitopic organic ligands manifest a dual role as connectors for two adjacent octahedra and as links between separate 1D inorganic subtopologies. For linear, lengthy tectons tr(2)cy and 4,9-tr(2)dia two identical frameworks interpenetrate. In [MoO(3)(trtz)] 7, the 4(1) helices aggregate into 3D tetragonal framework (five-fold interpenetrated) by hydrogen bonding between the tetrazole groups. The 2D structure of [Mo(4)O(12)(1,6-tr(2)dia)].2H(2)O 6 is influenced by the very bulky aliphatic portion of the ligands, which connect chains of edge-shared octahedra MoO(5)N (Mo-N 2.346(2), 2.456(2) A).

Syntheses and comprehensive characterization of two closely related series of isomorphous metal-organic frameworks (MOFs) based on triazolyl isophthalate linkers with the general formula ∞(3)[M2(R(1)-R(2)-trz-ia)2] (M = Cu, Zn) are presented. Using solvothermal synthesis and synthesis of microcrystalline materials on the gram scale by refluxing a solution of the starting materials, 11 MOFs are readily available for a systematic investigation of structure-property relationships. The networks of the two series are assigned to rutile (rtl) (1-4) and α-PbO2 (apo) (5-9) topology, respectively. Due to the orientation of the triazole substituents toward the cavities, both the pore volume and the pore diameter can be adjusted by choice of the alkyl substituents. Compounds 1-9 exhibit pronounced microporosity with calculated porosities of 31-53% and show thermal stability up to 390 °C as confirmed by simultaneous thermal analysis. Systematic investigation of adsorption properties by CO2 (298 K) and N2 (77 K) adsorption studies reveal remarkable network flexibility induced by alkyl substituents on the linker. Fine-tuning of the gate opening pressure and of the hysteresis shape is possible by adjusting the substitution pattern and by choice of the metal ion.

As a basis for the evaluation of hydrogen storage by physisorption, adsorption isotherms of H 2 were experimentally determined for several porous materials at 77 K and 298 K at pressures up to 15 MPa. Activated carbons and MOFs were studied as the most promising materials for this purpose. A noble focus was given on how to determine whether a material is feasible for hydrogen storage or not, dealing with an assessment method and the pitfalls and problems of determining the viability. For a quantitative evaluation of the feasibility of sorptive hydrogen storage in a general analysis, it is suggested to compare the stored amount in a theoretical tank filled with adsorbents to the amount of hydrogen stored in the same tank without adsorbents. According to our results, an ''ideal'' sorbent for hydrogen storage at 77 K is calculated to exhibit a specific surface area of >2580 m 2 g À1 and a micropore volume of >1.58 cm 3 g À1 .