Germanates of 1D 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 blocks (Ge7X19 (X = O, OH, or F) or Ni@Ge14O24(OH)3) and span the full range of dimensionalities from 1D chains of Ge7O13(OH)2F3 x Cl x 2 [Ni(dien)2] (FJ-6) to 2D layers of Ge7O14F3 x 0.5 [In(dien)2] x 0.5 H3dien x 2 H2O (1) and 3D frameworks of Ni@ Ge14O24(OH)3 x 2 [Ni(L)3] (FJ-1 a/FJ-1 b) (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 GeX5 trigonal bipyramids, and one GeX6 octahedron with a mu3-O atom at the center of the cluster, whereas the Ni@ Ge14O24(OH)3 cluster in FJ-1 a/FJ-1 b is formed by condensation of nine peripheral GeO4 tetrahedra and five interior GeO3Ni units with one mu5-Ni atom at the center of the cluster. FJ-6 is characterized by a pair of racemic Ge7O14(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-1 a/FJ-1 b with large 24-membered-ring channels is the first example of porous materials that contain metal-metal bonds (Ge2+-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.