Microwave Assisted Crystal Growth of a New Organic—Decavanadate Assembly: [V10O27(OH)] · 2(C6N2H14) · (C6N2H13) · (C6N2H12) · 2H2O

Microwave synthesis was used to grow single crystals of a new organic–inorganic supramolecular assembly, [V₁₀O₂₇(OH)] · 2(C₆N₂H₁₄) · (C₆N₂H₁₃) · (C₆N₂H₁₂) · 2H₂O, in a very short time compared to the conventional solution technique. In order to generate crystals suitable for single crystal experiments, an equimolar mixture of reactants and a few hours of microwave heating are required. Although non-merohedral twinning is an inherent problem, the crystal structure can be solved and refined in the orthorhombic space group Pna2 ₁ with a = 20.972(4) Å, b = 10.3380(14) Å, c = 20.432(3) Å, Z = 4, with an excellent result, R(F²) = 0.0431. The assembly is hydrogen bond-assisted and built up of the monoprotonated decavanadate and 1,4-diazabicyclo[2.2.2]octane of various degrees of protonation. The number and location of protons on both the inorganic and organic motifs govern the formation of the extensive hydrogen bonding network, which in turn regulates the assembly architecture.     

A Flexible Hexacarboxylate-Samarium(III) Metal–Organic Framework: Synthesis, Structure and Spectroscopic Properties

A new flexible triazine-based polycarboxylate metal–organic framework, [Sm₂(TTHA)(H₂O)₄]·9H₂O (I) (TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetate), has been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis and FT-IR spectroscopy. Crystal data for I are monoclinic C2/c, a = 12.6974(13) Å, b = 16.7309(12) Å, c = 14.8076(15) Å, β = 91.452(8)°, V = 3,144.7(5) Å³. Each Sm^III ion is 9-coordinate in a distorted tri-capped trigonal prismatic geometry; but, the principal inorganic building block is {Sm₂O₁₆}, which comprises two of these polyhedra that share an edge. The complex exhibits a three-dimensional open-framework structure of approximately 31 % void volume, which comprises two types of channels oriented in three directions; [0 0 1], [1 1 0] and [?1 1 0]. The network can be simplified into either the cooperite (pts) or anatase (ant) topologies depending on the choice of nodes. The UV–Vis spectra of the compound are dominated by the absorption of the TTHA ligand. Thermogravimetric analysis shows that the loss of channel and coordinated water upon heating occurs in two distinct steps.