Germanates of ID chains, 2D layers, and 3D frameworks built from Ge-O clusters by using metal-complex templates: Host-guest symmetry and chirality transfer

The self-assembly of Ge-O polyhedra by metal-complex templates leads to initial examples of open germanate structures under mild solvothermal conditions. These materials are constructed from Ge-O cluster building bocks (Ge₇X₁₉ (X = O, OH, or F) or Ni@Ge₁₄O ₂₄(OH)₃) and span the full range of dimensionalities from 1D chains of Ge₇O₁₃(OH)₂F₃· Cl·2[Ni-(dien)₂] (FJ-6) to 2D layers of Ge₇O ₁₄F₃·0.5[In(dien)₂]·0.5H ₃dien· 2H₂O (1) and 3D frameworks of Ni@Ge ₁₄O₂₄(OH)₃·2[Ni(L)₃] (FJ-1a/FJ-1b) (dien = diethylenetriamine, L = ethylenediamine (en) or 1,2-diaminopropane (enMe)). The Ge₇X₁₉ cluster in FJ-6 and 1 is formed by condensation of four GeX₄ tetrahedra, two GeX ₅ trigonal bipyramids, and one GeX₆ octahedron with a μ₃-O atom at the center of the cluster, whereas the Ni@Ge ₁₄O₂₄(OH)₃ cluster in FJ-1a/FJ-1b is formed by condensation of nine peripheral GeO₄ tetrahedra and five interior GeO₃Ni units with one μ₅-Ni atom at the center of the cluster. FJ-6 is characterized by a pair of racemic Ge₇O ₁₄(OH)₂F₃ cluster chains and represents only one example of 1D germanates; 1 exhibits unique germanate layers with uniform 10-membered-ring apertures encapsulating an unknown indium complex, and the framework structure of FJ-1a/FJ-1b with large 24-membered-ring channels is the first example of porous materials that contain metal-metal bonds (Ge ²⁺-Ni⁺). These initial examples of germanates from metal-complex templates provide a useful model system for understanding the mechanisms of host-guest interactions, which may further facilitate the design and development of new porous materials "on demand". It is shown that the symmetry and configuration of the guest metal complex can be imprinted onto the host inorganic framework through hydrogen bonding between host and guest.