Synthesis, crystal structure, DNA-binding and magnetism of copper 15-metallacrown-5 complexes based on glycinehydroxamic acid ligand

Abstract

Six metallacrown complexes {La(OAc)(H₂O)₂[15-MC_Cu(N)glyha-5](H₂O)₄}·2NO₃·5H₂O (1), {Gd(OAc)(H₂O)[15-MC_Cu(N)glyha-5](H₂O)₃}·2NO₃·5H₂O (2), {Tb(OAc)(H₂O)[15-MC_Cu(N)glyha-5](H₂O)₄}·2NO₃·4H₂O (3), {Pr(NO₃)(H₂O)₂[15-MC_Cu(N)glyha-5](H₂O)}·2NO₃·8H₂O (4), {Nd(NO₃)(H₂O)₂[15-MC_Cu(N)glyha-5](H₂O)₂}·2NO₃·7H₂O (5) and {Sm(NO₃)(H₂O)₂[15-MC_Cu(N)glyha-5](H₂O)₂}·2NO₃·6H₂O (6) (glyha²⁻ = dianion glycinehydroxamic acid) have been synthesized and structurally characterized by X-ray single crystal diffraction, IR spectroscopy and elemental analysis. Spectroscopic studies show that these complexes bind to CT-DNA via an intercalative mode and cause a more B-like to a more C-like conformational change. Magnetic measurements indicate that complexes 1, 3, 4, 5 and 6 dominantly show antiferromagnetic interactions between metal centers, whereas complex 2 reveals ferromagnetic interactions.