Secondary building units ligands

Figure 9.42 Secondary Building Units (SBU) using carboxylates with rigid coordination geometries that replace metal ions as vertices in MOFs. (a) Paddlewheel or lantern structure as in 9.17, (b) octahedral basic zinc acetate SBU used in MOF-5 and (c) a trigonal prismatic oxo-centred trimer. The poly-hedra use carboxylate carbon atoms as their vertices and the MOFs propagate via the linkers attached to these carbon atoms. The metal atoms are bound to only terminal ligands in addition to those shown.

Figure 1.2 A selection of MOFs based on tetranuclear Zn40(C02)6, dinuclear Cu2(C02)4 and ID Zn202(C02)2 secondary building units (left) and a range of multitopic carboxylate ligands (top). Reprinted with permission from D. Britt, D. Tranchemontagne and O.M. Yaghi, Proc. Natl. Acad. Set. U.S.A, 105, 11623.

The structural architectures of MOFs are mainly dependent on the assembly of metal-containing centers and organic ligands linkers (Fig. 3.1) [24-27]. In spite of wide utilization of single metal ions, it has been recognized that the secondary building units (SBUs) approach offers a prospective avenue toward the rational design and construction of novel MOFs [22]. As a result, the structures... 

Figure 38 Possible supramolecular architectures based on the 4,4 -bipyridine ligand, (a) Linear chain when [M] is a metal/secondary building unit forming two diagonally opposite bonds, (b) supramolecular ladder, and (c) supramolecular square.

Secondary building units Molecular complexes and clusters in which ligand coordination modes and metal coordination geometries are used to form extended networks using polytopic linkers. 

Polytopic ligands mainly contribute to define the connectivity between the nodes, generating repetitive entities also referred to as secondary building units (SBUs) [5] that form the extended structures of CPs. 

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