Macrocyclic ligands polyaza

Virtually all types of metal ions have been complexed with macrocyclic ligands.2-7 Complexes of transition metal ions have been studied extensively with tetraaza macrocycles (Chapter 21.2). Porphyrin and porphyrin-related complexes are of course notoriously present in biological systems and have been receiving considerable investigative attention (Chapter 22).8 Macrocyclic ligands derived from the Schiffbase and template-assisted condensation reactions of Curtis and Busch also figure prominantly with transition metal ions.6,7 The chemistry of these ions has been more recently expanded into the realm of polyaza, polynucleating and polycyclic systems.9 Transition metal complexes with thioether and phosphorus donor macrocycles are also known.2... 

Wainwright, K.P. Synthetic and structural aspects of the chemistry of saturated polyaza macrocyclic ligands bearing pendant coordinating groups attached to nitrogen, Coord. Chem. Rev. 166 (1997), 35-90. 

Transition metal complexes of the larger polyaza macrocyclic ligands have been less extensively studied than for the smaller ring systems. For the pentaaza macrocycles, [ISJaneNs with ethylene bridges appears to form the most stable complexes with most metal ions. Structural data for a variety of pentaaza macrocyclic complexes have been reviewed. The N-H bonds as well as the different sized chelate rings must be considered in calculating the... 

Recent reports also describe the use of fer -butyloxycarbonyl (Boc) protecting groups in the preparation of a number of bis(polyaza-macrocyclic) ligands of general type 37 62, 63). As discussed above, a... 

There is evidence that the coordination of metal ions by macrocyclic ligands can be accelerated by the attachment to the macrocycle of a coordinating pendant arm capable of capturing the metal ion with subsequent transfer of the metal ion to the macrocyclic cavityEntry of metal ions into the cavities of macrocycles lacking such pendant arms can be slow partly as a consequence of conformational changes which often accompany the coordination of the metal ion. A spec-trophotometric SF study of the coordination of metal ions by two polyaza... 

Ogden, M. Spencer, P. New polyaza and polyammonium 33. ferrocene macrocyclic ligands that complex and electro-chemically recognize transition metal cations and phosphate anions in water. Chem. Commun. 1993, 13, 1046. 

Smith, D.K. Spencer, P. Transition metal cation and phosphate anion electrochemical recognition in water by new polyaza ferrocene macrocyclic ligands. Inorg. Chim. 35. Acta 1996, 246, 143. 

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. 

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. 

Thioether analogs of the crowns have been known since the 1930s,103 but metal ion complexes of these ligands have not been investigated with the intensity found for the crowns and polyaza macrocycles. As anticipated from the soft nature of the heteroatom, the sulfur macrocycles show a preference to bind transition metals rather than alkali and alkaline earth ions. Studies have... 

Polyaza-, polythia-ligands. Recognition of transition metal ions. Replacing the oxygen sites with nitrogen or sulphur yields macrocycles and cryptands that show marked preference for transition metal ions and may also allow highly selective complexation of toxic heavy metals such as cadmium, lead and mercury [2.41-2.44, A.14]. 

Carbonyl compounds are commonly used precursors for the polyaza macrocycles, as in the classic synthesis of the Curtis ligand from the condensation of acetone with Ni(en)3 (Scheme 2). 2,6-Diacetylpyridine has provided the... 

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