Metal-ligand binding interactions

Somewhat more loosely related to platinum antitumor drugs were EHMO calculations performed on heterobimetallic Pt-Pd complexes with a bridging methylcytosinate anion by Mealli, Randaccio, Lippert, and coworkers [31][32], The calculations served to elucidate the metal-metal and metal-ligand binding interactions, and yielded a qualitative interpretation of the 195Pt-NMR chemical shifts. 

The ability of the materials to differentiate between similar peptides was not assessed in these studies. This control experiment would have provided more information regarding the active site formed by metal-ligand binding interactions. For example, it is not clear that the active sites in P-16 contained one imidazole, one hydroxyl, and one carboxyl unit. Also, it was not determined what additional ligand was in place of the template during P-15 formation. This could have satisfied the rate dilemma that was observed. 

F. 9a-g. Types of binding interactions that can be exploited during templating a n-n interaction b hydrophobic or van der Waals interaction c covalent bonds d (transition) metal-ligand binding e hydrogen bonding f crown ether -ion interaction g ionic interaction... 

In this chapter, we will show how the concept of template-directed organic synthesis has expanded so that now metal-ligand binding, hydrogen bonding, n-n interactions, and covalent bonding can all be exploited to allow the synthesis of molecules with a remarkable degree of control. Several detailed reviews of molecular templates have been published [14-20]. This chapter explores the definition and classification of molecular templates and discusses how their performance can be quantified and optimized. 

A novel class of materials, which employ metal-ligand binding as a reversible, dynamic interaction, was reported in 2005 by Rowan, Beck, and Ineman. Thermoplastic elastomeric films were formed from a telecheUc poly-THF, end-capped with a terdentate ligand such as 2,6-bis(F-methylbenzimidazolyl)-4-oxypyridine (12), which enabled chain-extension by coordination to a range of metal(ll) centers (Figure 21). 

In conclusion, self-assembled molecular capsules are held together by weak inter-molecular forces such as hydrogen bonds, CH-n interactions, van der Waals forces, strong metal-ligand binding, and even dynamic covalent chemistry. Capsule formation creates an inner cavity with a unique shape that can accommodate guests with complementary shapes and binding sites. The behaviors of molecules in dilute... 

Scheme 6.4 Self-assembly of the heteroditopic monomer 16 based on two orthogonal binding interactions, metal-ligand binding, and ion-pair formation. Reprinted with the permission from Ref. [32]. Copyright 2011 American Chemical Society...

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