Interpenetration 3D networks

Fig. 10 (a) Coordination environment of Co, showing the building unit of [Co3(bpdc)3(bpy)] (8). (b) Packing diagram of one of the two nets of 8 viewed down the b axis, (c) Twofold interpenetrating 3D networks viewed down the a axis, (d) Space-filled model of 8 viewed perpendicular to the (001) plane... 

An alternative approach to catalytically active homochiral MOFs is to incorporate directly chiral metal complexes which are either active catalysts or precatalysts into the framework structures. For example, Hupp and coworkers have combined Ls and H2bpdc with Zn(N03)2 and obtained twofold interpenetrating 3D networks [Zn2G3pdc)2Ls]10DMF-8H2O (17) (Scheme 12) [46]. While the channels along... 

The 4,4 -bipy and bpe derivatives display a similar crystal structure to that of Cd(4,4 -bipy)2[Ag(CN)2]2 reported by Iwamoto et al. [89]. It consists of the interpenetration of two identical 3D networks. The knots of the networks are defined by the iron(II) and silver(I) atoms. Each iron(II) atom located on an inversion centre defines an elongated octahedron whose axial positions are occupied by the nitrogen atoms of two 4,4 -bipy ligands. In addition, each 4,4 -bipy ligand binds a silver atom so that it is three-coordinated. This is the reason why the [Ag(CN)2] group is bent (see Fig. 18). 

The diamond structure, see Fig. 7.14 below, is a 3D network in which every atom is surrounded tetrahedrally by four neighbours. The eight atoms in the unit cell may be considered as forming two interpenetrating face-centred cubic networks. If the two networks are occupied by different atoms, the derivative cF8-ZnS (sphalerite) type structure is obtained. As a further derivative structure, the tI16-FeCuS2 type structure can be mentioned. These are all examples of a family of tetrahedral structures which have been described by Parthe (1964). 

Two major categories of interpenetrating 2D network can be discerned - one we shall refer to as parallel interpenetration and the other as inclined interpenetration . Inclined interpenetration inevitably leads to a 3D interlocked composite, whereas in all cases but one very recent one, parallel interpenetration yields a 2D composite. 

Blatov, V. A., Carlucci, L., Ciani, G., Proserpio, D. M., Interpenetrating metal-organic and inorganic 3D networks a computer-aided systematic investigation. Part I. Analysis of the Cambridge structural database. Crystengcomm 2004, 6, 377-395. 

Figure 20 Part of the four-fold interpenetrated 3D diamondoid network formed by [Cu(L)4]+ [L = 3-cyano-6-methylpyrid-2(l//)-one] as its PF6 salt [58], Hydrogen-bonded links are provided by R2(8) synthons involving all amide groups. Oxygen, nitrogen and key hydrogen atoms are shaded.

Fig. 7 2D sheets of Tb(III) centers interconnected by bpdo linkers leading to 3D networks 5 as viewed down the a axis (a) b axis (b) and c axis (c). (d) Tb coordination environment in 5. (e) Simplified schemes of the networks (onefold shown) of 5. (f) Schematic representation of the twofold interpenetrating networks of 5... 

Fig. 3 Interpenetration of 3D nets (a) two interpenetrating diainondoid networks and (b) two interpenetrating a-Po nets in the structure of a-M(dca)2(pyz). (View this art in color at WWW. dekker. com.)...

More often, geometrical approaches prove useful. Molecules or metal ions in crystals may be considered as nodes and the intermolecular interactions as connectors. This widely accepted concept facilitates a design of one-dimensional (ID), two-dimensional (2D), and three-dimensional (3D) networks by the "building block" principle (Fig. la)." However, there is a significant problem associated with this concept. Because of a gain in lattice energy by n-fold interpenetration, many attempts result in densely packed structures. 

D network. Here,. SiFf, anions connect layers, preventing interpenetration. Channels with pore sizes of 8x8 A along the c-axis. and 6 X 2 A along the h-axis are formed (Fig. 3a).f2ii... 

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