IRMOF-16, structure

Telfer and coworkers showed that the same nitrobenzyl groups could be incorporated into bpdc linkers and that the resultant zinc MOF [Zn40(bpdc-0CH2CgH4N02-2)3] has an IRMOF structure. Photolysis of powdered samples of this 2-nitrobenzyl ether with... 

Figure 9.43 Single crystal X-ray structures of IRMOF-n (n = 1 — 7,8,10,12,14, and 16), labelled respectively. MOF-5 is re-designated IRMOF-1 as part of this series. IRMOFs 9,11,13, and 15 are doubly interpenetrated. Zn (II) tetrahedral shown as polyhedra. The large spheres represent the largest van der Waals spheres that fit in the cavities without touching the frameworks (reprinted from [47] with permission from AAAS).

Figure 7.3 Single-crystal X-ray structures of IRMOF-n (n — 1-8, 10, 12, 14, and 16). All the hydrogen atoms have been omitted, and only one orientation of the disordered atoms is shown for clarity.74 (Reprinted with permission from M. Eddaoudi et al., Science 2002, 295, 469-472. Copyright AAAS.)...

Comparison of cubic fragments in the respective three-dimensional extended structures of IRMOF-1 (= MOF-5), IRMOF-6, IRMOF-8, IRMOF-11, and IRMOF-16. From M. Eddaoudi, J. Kim, N. Rosi, D. Vodak, J. Wachter,... 

In other similar structures, such as IRMOF-6 and IRMOF-8, the specific hydrogen uptake is approximately doubled and quadrupled, respectively, compared to MOF-5 at room temperature and 2.0MPa pressure [244], The hydrogen absorption capacity of these structures at room temperature is comparable to that of carbon nanotubes at cryogenic temperatures and can be fine-tuned by modifying the porosity of the structure with suitable linkers [244],... 

Figure 1 Examples of two topologically distinct isoreticular MOF structures, (a) A cubic fragment of IRMOF-1. Each corner of the cubes is built up of a connector (b) and linked by a linker (c) (here 1,4-benzenedicarboxylate). The linkers form the edges of the cube. The connector can be described as four distorted tetrahedra Zn(01)30 connected by a central 02. (d) A cubic fragment of Cu-BTC (Cu3(BTC)2(H20)3 BTC 1,3,5-benzene-tricarboxylate) The structure is built up of the so-called paddle-wheels (e). Each metal atom completes its pseudo-octahedral coordination sphere, Cu(COO)2, with an aqua ligand.

To analyze the differences in the densities of states for IRMOFs with different linkers IRMOF-MO was chosen as a reference system. The IRMOF-MO PDOS (for different states of a given atom) shows that the valence band is composed of Zn 3d, 0 2p and C 2p states. The unoccupied band is determined by 5 and p orbitals of Zn, and p orbitals of O and C. Similar electronic properties have been found for IRMOF-1 being in agreement with the earlier work of Fuentes-Cabrera et al Fig. 4 (left) shows the PDOS of exemplary structures with different sizes of the linker. The results are compared with the PDOS of the reference system and IRMOF-Mll (cage-like linker). In Fig. 4 (right) the PDOS of the Cu-BTC stracture is shown. 

The results of the partial densities of states show that the band gap is dominated by the k states of sp carbon atoms within the linkers. It can be noticed in Fig. 4 that with increasing number of sp carbon atoms in the linker the band gap decreases. This is due to the larger contribution of k states, which means the top of the valence band is dominated by the n states of the C3, C4, etc. atoms. A similar tendency is observed for unoccupied bands, where a big influence of k states of Cl is observed for structures with a small number of sp C atoms (e.g. IRMOF-MO and IRMOF-Ml 1). 

Figure 9.14 Single-crystal x-ray structures of IRMOF-n n = through 7, 8, 10, 12, 14, and 16), labeled respectively. Color scheme is as follows Zn (blue polyhedra), O (red spheres), C (black spheres), Br (green spheres in 2), amino groups (blue spheres in 3). The large yellow spheres represent the largest van der Waals spheres that would fit in the cavities without touching the frameworks.

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