Polymeric oxygen/nitrogen donor

Metal Ion Binding at Polymeric Oxygen/Nitrogen Donor... 

Lanthanide ions have a high affinity for hard donor atoms, and ligands containing oxygen or oxygen-nitrogen atoms may be employed in the preparation of lanthanide polymeric complexes. Lanthanide ions present only little preference in bond direction, due to the inner positioning of their 4f valence orbitals. 

The second group already contains donor groups (usually oxygen or nitrogen) and, thus, requires no further chemical modification. These include polyacrylic acid (82, 83), polyvinyl alcohol (60), polymeric Schiff s bases (65), poly-L-methylethylenimine (52), poly-2-vinylpyridine (78, 79, 98), poly-4-vinylpyridine (24), and polyvinylamine (54, 59). 

Thus the grafting reaction onto soft tissues is highly versatile. It takes place with many monomers and different initiator systems such as CAN, persulfate-bisulfite, and donor-acceptor monomers. Although the polymerization is inhibited by oxygen and thus air, it is conducted readily in a nitrogen or carbon dioxide atmosphere. 

In fact, hardly any donor atoms other than nitrogen have been used to create multiporphyrin assemblies. Using hard Lewis acids as central metal opens the possibility to bind two axial ligands on either side of the porphyrins. With ditopic Ugands such as diols this can lead to polymerization. However, a few examples can be found in the Uterature, where the central metal of the porphyrin is axially coordinated by oxygen, sulfur or selenium to assemble porphyrins. The use of (non-porphyrinic) phosphine ligands apparently has so far not been successful in the construction of supramolecular multiporphyrin arrays. 

---