Novel 30-membered octaazamacrocyclic ligand: synthesis, characterization, thermodynamic stabilities and DNA cleavage activity of homodinuclear copper and nickel complexes
- Additional Document Info
- View All
A new 30-membered octazamacrocyclic ligand: 4,6,9,12,20,23,26,29-octaaza-35,36-dihydroxy-16,33-dimethyl-tricyclo[29.3.1. 114,18]hexatriaconta-1(35),18(36),15,17,31,33-hexaene (L or BTBD) has been synthesized and characterized. Its coordination chemistry toward Cu(II) and Ni(II) ions has been investigated extensively by potentiometric titration in 1:1 or 1:2 (L-M) aqueous systems. L shows high complexation ability with Cu(II) and Ni(II) ions in 1:1 systems with formation constants: logK[ML]=24.01 (M=Cu), 21.04 (M=Ni), respectively. In 1:2 (L-M) systems, two metal ions were suggested to enter into the cavity separately and locate in half of the compartment without formation of μ-oxo bridged core. BTBD served as N8O2-2 ligand to divalent binuclear copper and nickel complexes with similar stability constants (logK[M2L]=15.38, 15.36, respectively). [C30H50Cu2N8O2](ClO 4)2·CH3OH·2(H2O) (1) crystallizes in the monoclinic space group P21/n, a=7.9662(7), b=14.5925(4), c=11.614(10) Å, β=105.187(4)°, V=3905.5(6) Å3 and Z=4. Each copper is complexed by half of the coordination sites of the dinucleating macrocycle, and completes square pyramidal polyhedron. [C30H50N8Ni2O2(H 2O)2](ClO4)2·CH 3OH·3(H2O) (2) crystallizes in the triclinic space group P1̄, a=10.5559(5), b=14.6947(7), c=15.3025(10) Å, α=65.5470(10), β=80.4650(10), γ=72.7392(10)°, V=2060.92(17) Å3 and Z=2. The X-ray crystallographic results demonstrate that each nickel ion resides in the N4O- site and forms six-coordinated octahedron with exogenous solvents at the apex. Dinuclear copper complexes have been found have cleavage ability toward supercoiled pBR 322 DNA in the presence of H2O2. EPR and UV results showed that the possible cleavage mechanism was via Cu(II)-O-O-Cu(II) peroxide and leads to DNA oxidative cleavage. © 2002 Elsevier Science B.V. All rights reserved.
author list (cited authors)
Kong, D., Reibenspies, J., Mao, J., Clearfield, A., & Martell, A. E.