Dinuclear Zn II Complexes of Polydentate Polyamines as Minimalist Models of Hydrolytic Reactions

The synthesis of the novel macrocycle 2,6,9,12,16-pentaaza[17](2,9)(1,10)phenanthrolinophane (L3) is reported. Speciation studies on the systems ZnII−L3 and ZnII−L2 (L2 =2,6,10,13,17,21-hexaaza[22]metacyclophane) performed in aqueous solution show the formation of mono- and dinuclear ZnII complexes. In the two systems, the dinuclear complexes readily hydroxylate, with the hydroxo species being the main ones in solution at relatively low pH values. This feature makes these complexes promising hydrolytic agents for carboxy and phosphate esters. The hydrolytic ability of the L1−L3 dinuclear complexes toward the carboxy and phosphate ester bond was tested by addition of p-nitrophenyl acetate (N…