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Dalton Transactions

The international journal for inorganic, organometallic and bioinorganic chemistry



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Dalton Trans., 2009, 9870 - 9880, DOI: 10.1039/b912676g

Novel 1D chain Fe(III)-salen-like complexes involving anionic heterocyclic N-donor ligands. Synthesis, X-ray structure, magnetic, 57Fe Mössbauer, and biological activity studies

Radovan Herchel, Zdenk indelá, Zdenk Trávníek, Radek Zboil and Ján Vano

The iron(III) salen-type complexes [Fe(salen)(L)]n ( 1–6) involving heterocyclic N-donor ligands HL {HL = 1H-imidazole (Himz), 1H-tetrazol-5-amine (Hatz), 5-methyl-1H-tetrazole (Hmtz), 1H-benzimidazole (Hbimz), 1H-1,2,4-triazole (Htriz) and 1H-benzotriazole (Hbtriz)} have been prepared and characterised by elemental analysis, FT IR, CI mass and 57Fe Mössbauer spectroscopies, and variable temperature magnetic measurements. Single crystal X-ray analysis of [Fe(salen)(btriz)]n ( 6) revealed a 1D chain-polymeric structure of the complex with the btriz anion as a bridging ligand. Magnetic data for all complexes were fitted using Fisher's model (for S = 5/2) and also using a heptanuclear closed ring model showing a weak antiferromagnetic interaction (J-1 to -2 cm-1), and moreover, molecule-based magnet properties have been observed in the case of [Fe(salen)(atz)]n ( 2). The exponential correlation between the magnetic properties (the isotropic exchange parameter J) and the basicity of the free ligands (Kb) has been found. The antiferromagnetic ordering as well as a moderate structural dissimilarity in the vicinity of iron atoms has been proved by the 57Fe Mössbauer low-temperature (2 K) in-field (7 T) experiments in the case of ( 2), in which two sextets with the line intensities (3/4/1/3/4/1) have been observed. The compounds have been tested for their SOD-like activity, DNA cleavage activity, and in vitro cytotoxicity against two human cancer cell lines: chronic myelogenous erythroleukemia (K562) and breast adenocarcinoma (MCF7). The best result regarding the cytotoxicity has been achieved for the complex of [Fe(salen)(atz)]n ( 2), where IC50 = 6.4 M against K562.

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