Polyaza[n]paracyclophanes as synthetic models of Zn containing enzymes. The role of a non coordinated nitrogen atom in the proximity of the metal
作者:Belen Altava、M.Isabel Burguete、Santiago V. Luis、Juan F. Miravet、Enrique García-España、Victor Marcelino、Conxa Soriano
DOI:10.1016/s0040-4020(97)00144-0
日期:1997.3
2,6,9,13-Tetraaza[14]paracyclophane (3, B323) represents a simple model for Zn containing enzymes like HCAII which possess additional reactive groups in the proximity of the metal center. The Zn2+.3 complex shows notable catalytic activity for the hydrolysis of p-nitrophenyl acetate. Structural modifications of 3 which affect to the non coordinated nitrogen atom greatly modify the catalytic activity
Polyazacyclophanes. 2,6,9,13-Tetraaza[14] paracyclophane as a cationic and anionic receptor
作者:Antonio Andrés、M. Isabel Burguete、Enrique García-España、Santiago V. Luis、Juan F. Miravet、Conxa Soriano
DOI:10.1039/p29930000749
日期:——
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 been studied by potentiometry at 298.15 K in 0.15 mol dm-3 NaClO4, as well as by H-1 and C-13 NMR spectroscopy. The protonation patterns show stabilization effects produced by the presence of the aromatic ring. The aromatic spacer prevents simultaneous involvement of all four nitrogens in the coordination to the metal ions Cu2+ and Zn2+. Stable mono-hydroxylated species have been detected for both metal ions. The triprotonated species is the main one over a wide pH range around neutrality making this ligand a good coordinating agent for such anionic species as ATP4- and P2O74-. Formation of complexed anionic species with degrees of protonation varying from three to six has been detected.