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Crystal structure of a Tb^III-Cu^II glycine-hydroxamate 15-metallacrown-5 sulfate complex.

ABSTRACT: The core of the title complex, bis-[hexa-aqua-hemi-aqua-penta-kis-(μ₃-glycine-hydroxamato)sulfato-penta-copper(II)terbium(III)] sulfate hexa-hydrate, [TbCu₅(SO₄)(GlyHA)₅(H₂O)_6.5]₂(SO₄)·6H₂O (1), which belongs to the 15-metalla-crown-5 family, consists of five glycine-hydroxamate dianions (GlyHA^2-; C₂H₄N₂O₂) and five copper(II) ions linked together forming a metallamacrocyclic moiety. The terbium(III) ion is connected to the centre of the metallamacrocycle through five hydroxamate oxygen atoms. The coordination environment of the Tb³⁺ ion is completed to an octa-coordination level by oxygen atoms of a bidentate sulfate and an apically coordinated water mol-ecule, while the copper(II) atoms are square-planar, penta- or hexa-coordinate due to the apical coordination of water mol-ecules. Continuous shape calculations indicate that the coordination polyhedron of the Tb³⁺ ion in 1 is best described as square anti-prismatic. The positive charge of each pair of [TbCu₅(GlyHA)₅(H₂O)_6.5(SO₄)]₂ ²⁺ fragments is compensated by a non-coordinated sulfate anion, which is located on an inversion center with 1:1 disordered oxygen atoms. Complex 1 is isomorphous with the previously reported compounds [LnCu₅(GlyHA)₅(SO₄)(H₂O)_6.5]₂(SO₄), where Ln ^III = Pr, Nd, Sm, Eu, Gd, Dy and Ho.

SUBMITTER: Pavlishchuk AV

PROVIDER: S-EPMC8647751 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The three complexes [Fe(opo)3], [Cu(opo)2], and [Zn(opo)2] containing the non-innocent anionic ligand opo- (opo- = 9-oxido-phenalenone, Hopo = 9-hydroxyphenalonone) were synthesised from the corresponding acetylacetonates. [Zn(opo)2] was characterised using 1H nuclear magnetic resonance (NMR) spectroscopy, the paramagnetic [Fe(opo)3] and [Cu(opo)2] by electron paramagnetic resonance (EPR) spectroscopy. While the EPR spectra of [Cu(opo)2] and [Cu(acac)2] in dimethylformamide (DMF) solution are very similar, a rather narrow spectrum was observed for [Fe(opo)3] in tetrahydrofuran (THF) solution in contrast to the very broad spectrum of [Fe(acac)3] in THF (Hacac = acetylacetone, 2,4-pentanedione; acac- = acetylacetonate). The narrow, completely isotropic signal of [Fe(opo)3] disagrees with a metal-centred S = 5/2 spin system that is observed in the solid state. We assume spin-delocalisation to the opo ligand in the sense of an opo- to FeIII electron transfer. All compounds show several electrochemical opo-centred reduction waves in the range of -1 to -3 V vs. the ferrocene/ferrocenium couple. However, for CuII and FeIII the very first one-electron reductions are metal-centred. Electronic absorption in the UV to vis range are due to π-π* transitions in the opo core, giving Hopo and [Zn(opo)2] a yellow to orange colour. The structured bands ranging from 400 to 500 for all compounds are assigned to the lowest energy π-π* transitions. They show markedly higher intensities and slight shifts for the CuII (brown) and FeIII (red) complexes and we assume admixing metal contributions (MLCT for CuII, LMCT for FeIII). For both complexes long-wavelength absorptions assignable to d-d transitions were detected. Detailed spectroelectrochemical experiments confirm both the electrochemical and the optical assignments. Hopo and the complexes [Cu(opo)2], [Zn(opo)2], and [Fe(opo)3] show antiproliferative activities against HT-29 (colon cancer) and MCF-7 (breast cancer) cell lines in the range of a few µM, comparable to cisplatin under the same conditions.

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Crystal structure of a Tb^III-Cu^II glycine-hydroxamate 15-metallacrown-5 sulfate complex.

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Dataset Information

Crystal structure of a TbIII-CuII glycine-hydroxamate 15-metallacrown-5 sulfate complex.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets

Crystal structure of a Tb^III-Cu^II glycine-hydroxamate 15-metallacrown-5 sulfate complex.