Phenanthroline-containing polyamine

A 1,10-phenanthroline-containing polyamine macrocycle (78) was designed to complex with Zn2+ ion and, because of the rigidity of the phenanthroline moiety, leave some free binding sites at the metal for ligands such as water, which easily depro-tonate to give stable hydroxo species. The hydrolysis of methyl acetate in the gas phase by such a monohydroxy-Zn(II) complex [Zn(78)(OH)]+ has been investigated by quantum mechanical procedures and some pathways delineated.78... 

Scheme 31 Proposed mechanism for LNA hydrolysis mediated by a zinc complex of a phenanthroline-containing polyamine ligand.

Complexation of Cd with a series of polyamine macrocycles, but also related open-chain polyamines, comprising or attached to the 2,2 -bipyridine (bipy) and 1,10-phenanthroline (phen) moieties, has been studied by combined UV/vis spectrometry and potentiometry.24 Formation constants and distribution diagrams of the species present have been evaluated. As a result the thermodynamic stabilities, i.e., the formation constants, are lower for the bipy- and phen-contain-ing ligands than those for Cd complexes with aliphatic oligoaza macrocycles containing the same number of N donors. The probable reason is loss of flexibility of the ligands caused by the size and stiffness of the inserted heteroaromatic moieties. 

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