A. Andres et al., POLYAZACYCLOPHANES - 2,6,9,13-TETRAAZA[14]PARACYCLOPHANE AS A CATIONIC AND ANIONIC RECEPTOR, Perkin transactions. 2, (4), 1993, pp. 749-755
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.