Synthesis, crystal structure, magnetism, and biological activities of an oxo-bridged diiron(III) complex

Abstract

An unsymmetrical oxo-bridged diiron(III) complex [Fe₂L₂(μ-O)], {H₂L = trans-N,N′-bis-(2hydroxy-1-naphthalidehydene)-cyclohexanediamine} has been synthesized and characterized by various physico-chemical techniques. In the complex, each deprotonated bi-anionic L²⁻ serves as a terminal tetradentate ligand (N₂O₂) and coordinates to one Fe to form a [FeL]⁺ unit. Two [FeL]⁺ units are further linked by an oxo-bridge to construct the binuclear oxo-Fe species with intramolecular Fe–Fe separation of 3.38 Å. Variable-temperature magnetic susceptibility studies revealed a strong antiferromagnetic interaction between two iron centers with J of −112 cm⁻¹. The interaction of the complex with CT-DNA was studied by various spectroscopic and viscosity measurements, which indicated that the complex could interact with CT-DNA through intercalation. In addition, the complex is able to cleave pBR322 DNA in the presence of H₂O₂. Furthermore, the interaction of the compound with BSA was also investigated, which indicated that the complex could quench the intrinsic fluorescence of BSA by a static quenching mechanism.

Graphical abstract

An unsymmetrical oxo-bridged diiron(III) complex has been synthesized and its biological activities have been characterized by various physico-chemical techniques.

Keywords:

• Oxo-bridged binuclear iron
• Schiff base ligand
• Magnetic property
• DNA binding

Funding

This work was supported by the National Natural Science Foundation of China [grant number 21171101] and [grant number 21001066]; Tianjin Science Foundation [grant number 12JCYBJC13600]; MOE Innovation Team [grant number IRT13022] of China and NFFTBS [grant number J1103306].