POLYAZACYCLOPHANES - 2,6,9,13-TETRAAZA[14]PARACYCLOPHANE AS A CATIONIC AND ANIONIC RECEPTOR

The synthesis and characterization of the new azacyclophane, 2,6,9,13- tetraaza[14]paracyclophane, is described. The acid-base behaviour and the metal and anion coordination capabilities of this compound have be en studied by potentiometry at 298.15 K in 0.15 mol dm-3 NaClO4, as we ll as by H-1 and C-13 NMR spectroscopy. The protonation patterns show stabilization effects produced by the presence of the aromatic ring. T he aromatic spacer prevents simultaneous involvement of all four nitro gens in the coordination to the metal ions Cu2+ and Zn2+. Stable mono- hydroxylated species have been detected for both metal ions. The tripr otonated species is the main one over a wide pH range around neutralit y making this ligand a good coordinating agent for such anionic specie s as ATP4- and P2O74-. Formation of complexed anionic species with deg rees of protonation varying from three to six has been detected.