Ligand macrocyclic hgand

Thioether coordination chemistry has undergone a renaissance with the development of general syntheses of poly-thioether macrocyclic hgands. Scheme 29 illustrates some of the ligands that have been reported. The tridentate ligand... 

These examples not only indicate an interesting chemistry of arsenic(ni) rings but also illustrate their versatility as macrocyclic hgands. It is important to underscore that the coordinated ligand is formed in a metal induced ring... 

A tetradentate macrocylic ONNO-type ligand was used recently by the same authors for Ir-catalyzed ATH reactions. The reaction of l,3-bis(2-formylphenoxy)-2-propanol with chiral 1,2-diaminocyclohexanes gave (S,S)- or (R,R)-macrocyclic C6O2N2 Hgands (85) (Scheme 4.36), while the catalysts generated in situ in the... 

A more preorganized ligand system is derived from the self-condensation of o-aminobenzaldehyde. The tridentate form of the hgand (25) (TRT) imparts considerable inertness toward substitution. For example, the salts of the [Ni(TRl)(H20)3] + ion can be resolved into optical isomers. A copper(ll) complex of the methyl-substituted tetradentate macrocycle Me4TAAB, in which bis-coordination occurs, displays a dynamic Jahn Teller distortion based on crystallographic evidence. ... 

Compartmental ligands (16) provide extensive opportunities for multiple metal ion complexation. An example of a mixed donor ligand incorporating different metal ions is the macrocyclic trinucleating hgand (63), which is capable of complexing two soft donor metal centers in addition to a hard alkali or alkaline earth metal. ... 

Tlie basic study of intermolecular interactions is facihtated by one-bead-one-stRicture libraries which can be powerful tools for the discovery of hgands to synthetic receptors and vice versa. Encoded combinatorial libraries have been useful for disclosing ligands for well-designed macrocyclic host molecules and to elucidate their specificities for peptide sequences. These studies led via receptors with more flexibility to simple host molecules without elaborate design that ai e accessible to combinatorial synthesis. One application is the development of chemical sensors for analytes that are otherwise difficult to detect or only non-specificaUy detected. Such hbraries have been used to find new catalysts and enzyme mimics. 

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