Macrocycles polyaza

Macrocyclic complexes of zinc have inspired interest in varied areas such as supramolecular and biomimetic chemistry including hydrolysis enzymes, such as phosphatases and esterases, and also for the fluorescent detection of zinc. The polyaza macrocycles and their A--functionalized derivatives are particularly well represented. An important aspect of macrocycle synthesis is the use of metal templates to form the ligand. Examples of zinc as a template ion will be discussed where relevant. 

Small-ring cyclic diamines have already been discussed in Chapter 1.20. The azamacrocycles offer the possibility for functionalization at the nitrogen donor groups and many examples will be presented from triazamacrocycles up to much larger polyaza macrocycles that will bind more than one zinc ion. Particular mention must be made of the large contribution of Kimura and co-workers to this area. 

Applications for Polyaza Macrocycles with Nitrogen-Attached Pendant Arms Kevin P. Wainwright... 

As for the higher oxidation states of manganese, a significant number of investigations involving pendant arm, polyaza macrocycles have been carried out. 

Polyaza macrocycle derivatives have been employed in a number of analytical applications." " For example, polymer-immobilized cyclam has been employed for the preconcentration of manganese in seawater prior to analysis." ... 

The protonated polyaza macrocycles (27-6H+ and 28-8H+) also complex metal hexacyanide anions (81CC1067). Both Fe(CN)64- and Ru(CN)64- form 1 1 complexes which are more difficult to oxidize than the uncomplexed anion. The shifts in anodic oxidation potential are independent of the M(CN)64- species involved but vary with the size of the macrocycle (+130 mV for 27-6H+ and +165 mV for 28-8H+). This suggests that the redox potential of complexed anions is controlled by electrostatic effects due to the charge of the surrounding macrocycle. 

Structural and thermodynamic properties of the complexes with saturated polyaza macrocycles 231... 

Structural awl thermodynamic properties of complexes with saturated polyaza macrocycles... 

A summary of nickel(H) complexes formed by representative saturated polyaza macrocycles is reported in Table 103, together with a concise description of the synthetic procedures and some of their physicochemical properties. Most studies are concerned with nickel(II) complexes with tetraaza macrocycles, but examples of complexes with triaza and pentaaza macrocycles are not rare. 

The redox properties of the copper(II) ion in saturated polyaza macrocyclic complexes CuN4 and CuNj have been shown1020 to vary with the chelate ring size, and the very negative E° values (Figure 62) are consistent with a macrocyclic effect , from stability constant measurements.976... 

Other Polyaza Macrocycles 21.2,5.3.3 Substitution of other ligands... 

Coronands (1) and (2) are macrocyclic species which contain various heteroatoms as binding sites. The term coronates refers to the complexes. The polyaza macrocycles were the first macro-cyclic ligands to be studied. 

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