Abstract
A μ-oxo-di-μ-carboxylato-bridged iron(III) complex containing two tridentate nitrogen ligands, {[Fe2(bpma)(bpea)(μ-CH3COO)2 μ-O)] · (ClO4)2 · 0.5CH3OH} (1) (bpma = N, N-bis(2-pyridylmethyl)methyl-amine, bpea = N,N-bis(2-pyridylmethyl)ethylamine), has been synthesized and determined by X-ray diffraction. Complex 1 crystallizes in the monoclinic space group P21/c with a = 10.9434(12) Å, b = 23.118(3) Å, c = 15.8721(18) Å, β = 92.736(2)° and Z = 4. In 1, each Fe(III) has a distorted octahedral geometry with a N3O3 donor set. The Fe(III) atoms are bridged by two carboxyl groups and one μ-oxo oxygen with Fe1–Fe2 separation of 3.064 Å. Susceptibility data of 1 indicate strong intramolecular antiferromagnetic coupling of the high-spin Fe(III) atoms with J = −121.0 cm−1 and g = 2.04. The interaction with calf thymus DNA was investigated by UV absorption and fluorescent spectroscopy. Results show that the complex binds to ct-DNA with a moderate intercalative mode. The interaction between 1 and pBR322 DNA has also been investigated by submarine gel electrophoresis; the complex exhibits effective DNA cleavage activity in the absence of activating agents under similar physiological conditions.
Acknowledgements
This work was supported financially by the National Science Foundation of China (No. 20331020, 20571056 and 20771063), the Education Science Foundation of Tianjin City (No. 20070606) and the PhD Foundation of Tianjin Normal University (No. 52LX28).