Polytopic ligand

A cascade complex is one in which an additional substrate may be included between metal cations (or eventually anions) in a ditopic or polytopic ligand. 

Mechano-ionoswitching takes place, for instance, in polytopic ligands presenting ion binding induced allosteric changes [8.201, 8.276] or when an ion binds to a catenand to form a catenate [8.281, 8.282]. Modulation of the binding of a second substrate may be brought about. 

It has been found that the use, as ligands, of electron-poor phosphines, such as 1,1 -bis(diphenylphosphino)ferrocene, enhances yields ill the palladium-catalysed reaction of aiyl bromides with sodium phenoxides to yield diaryl ethers.87 Palladium-catalysed coupling of ethynylated derivatives of bipyridine or terpyridine with the corresponding bipyridine or terpyridine hahdes or triflates has been used in the synthesis of preorganized polytopic ligands.88... 

In a helicate the polytopic ligand winds around a linear array of metal ions lying on the helical axis, so that its ligation sites match the coordination requirements... 

Besides metallocycles, metallodendrimers, and metallo-supramolecular polymers [58], few examples of hollow supramolecular architectures have been obtained from polytopic ligands containing terpyridine units. Lehn et al. used heteroaromatic ligands with terpyridine type coordination sites to obtain cylindrical self-assembled architectures (Fig. 11) [60]. For synthesis of the cage 37, tris-2,4,6-(2-pyrimidyl)-l,3,5-triazine (35) was mixed with lead triflate in... 

Coordination polymers consist of long-chain polytopic ligands which are interconnected by metal-ligand bonds. Bernhard et al. reported the synthesis of a copper(l) coordination polymer using n-decane-linked bis-phenanthrolines (42), whose morphology changes reversibly... 

When the desired chiral polytopic ligands are at hand, the synthetic protocols for accessing homochiral MOCP catalysts can be quite simple. A combination of the ligand with an appropriate metal precursor in a compatible solvent under appropriate conditions, can result in the spontaneous formation of insoluble polymers by self assembly. This polymerization process involves the successive... 

The use of metalloporphyrins for the construction of multichromophore assemblies through axial binding to polytopic ligands and/or to other porphyrins is treated in detail in other chapters of this book. 

Owing to the thermodynamic and kinetic stability of the Ru-pyridyl bonds, solutions of 9Zn can be treated with excess of other N-ligands without the occurrence of decomposition or scrambling processes. Thus, 9Zn is a rigid 2D module with two central junctions that can be exploited for the construction of more elaborate supramolecular adducts upon treatment with appropriate polytopic ligands. 

The ladder topology. [2n]L (Fig. lb) can be obtained by using, as ladder sides, two linear polytopic ligands... 

Fig. 2 Linear ligands used to generate racks, ladders, and grids (a) polytopic ligands with tetrahedral pockets (b) polytopic ligands with octahedral pockets.

Mono/Polytopic Ligands A descriptive term for how many individual binding sites a ligand contains. 

The simplest of these three architectures is the rack, which consists of a single, linear polytopic ligand and several monotopic ligands (Figure 3.10(a)). Naked metal ions act as linkers between the two types of ligand so that the resulting... 

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