Experimental and theoretical studies on the structure and spectroscopic properties of N-scorpionate complexes obtained from metallic cobalt in a one pot synthesis

Selective Cytotoxicity of Complexes with N,N,N-Donor Dipodal Ligand in Tumor Cells

The present article demonstrates selective cytotoxicity against cancer cells of the complexes [Co(L^D)₂]I₂∙CH₃OH (1), [CoL^D(NCS)₂] (2) and [VOL^D(NCS)₂]∙C₆H₅CH₃ (3) containing the dipodal tridentate ligand LD = N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine), formed in situ. All tested complexes expressed greater anticancer activities and were less toxic towards noncancerous cells than cisplatin. Cobalt complexes (1 and 2) combined high cytotoxicity with selectivity towards cancer cells and caused massive tumour cell death. The vanadium complex (3) induced apoptosis specifically in cancer cells and targeted proteins, controlling their invasive and metastatic properties. The presented experimental data and computational prediction of drug ability of coordination compounds may be helpful for designing novel and less toxic metal-based anticancer species with high specificities towards tumour cells.

Stereochemistry of coordination polyhedra vs. single ion magnetism in penta- and hexacoordinated Co(ii) complexes with tridentate rigid ligands

A tridentate ligand L (2,6-bis(1-(3,5-di-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine) was synthesized and used for the preparation of three pentacoordinated Co(ii) complexes of formula [Co(L)X₂] (where X = NCS^- for 1, X = Cl^- for 2 and X = Br^- for 3) and one ionic compound 4 ([Co(L)₂]Br₂·2CH₃OH·H₂O) containing a hexacoordinated Co(ii) centre. Static magnetic data were analysed with respect to the spin (1-3) or the Griffith-Figgis (4) Hamiltonian. Ab initio calculations enable us to identify the positive axial magnetic anisotropy parameter D accompanied by a significant degree of rhombicity in the reported complexes. Also, magneto-structural correlation was outlined for this class of compounds. Moreover, all four compounds exhibit slow relaxation of magnetisation at an applied static magnetic field with either both low- and high-frequency relaxation channels (3) or a single high-frequency relaxation process (1, 2 and 4). The interplay between the stereochemistry of coordination polyhedra, magnetic anisotropy and the relaxation processes was investigated and discussed in detail.

Scorpionate complexes of aza-18-crown-6 containing fluoronitrophenyl substituents as studied by electrospray ionization mass spectrometry

RATIONALE

Coordination of a metal cation by a nitro group is rare and the interaction between them is usually weak. Examples of complexes in which such an interaction takes place are metal complexes of cyclams containing nitrophenyl or nitrobenzyl substituents. It seemed to be interesting to check if in the complexes of the respective crown ether conjugates the interaction can also take place.

METHODS

We synthesized the respective conjugates of aza-18-crown-6, namely fluoro-substituted N-nitrophenylaza-18C6 conjugates. Their complexes with alkali and alkali earth metal cations were generated in the gas phase by electrospray ionization mass spectrometry (ESI-MS). Both collision-induced dissociation 'in-source' and collision-induced dissociation tandem mass spectrometry (ESI-CID-'in-source' and ESI-CID-MS/MS) were used to study the gas-phase stabilities of the generated complexes.

RESULTS

The gas-phase decomposition of the studied complexes indicated that the complexes formed by the conjugates containing a nitro group at the ortho position are more stable than those formed by the conjugates with a nitro group at the para position.

CONCLUSIONS

This indicates that a metal cation complexed by crown ether ring is additionally coordinated by a nitro group in the scorpionate mode. To the best of our knowledge, our finding provide the first example of a complex in which a metal cation complexed by a crown ether ring is additionally coordinated by a nitro group.

A family of complexes with N-scorpionate-type and other N-donor ligands obtained in situ from pyrazole derivative and zerovalent cobalt. Physicochemical and cytotoxicity studies

In this paper we described one pot synthetic pathways which generated in situ three complexes which contain three different ligands: N,N,N-tris(3,5-dimethylpyrazolylmethyl)amine (L¹), urotropine (L²) and 3,5-dimethylpyrazole (L³).

A new Co(II) complex of diniconazole: synthesis, crystal structure and antifungal activity

A new Co(II) complex of diniconazole, namely diaqua[(E)-(RS)-1-(2,4-dichlorophenyl)-4,4-dimethyl-2-(1H-1,2,4-triazol-1-yl-κN(4))pent-1-en-3-ol]cobalt(II) dinitrate dihydrate, [Co(C15H17Cl2N3O)3(H2O)2](NO3)2·2H2O, was synthesized and characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. Crystal structural analysis shows that the centrosymmetric Co(II) cation is coordinated by four diniconazole ligands and two water molecules, forming a six-coordinated octahedral structure. There are also two free nitrate counter-anions and two additional solvent water molecules in the structure. Intermolecular O-H...O hydrogen bonds link the complex cations into a one-dimensional chain. In addition, the antifungal activity of the complex against Botryosphaeria ribis, Gibberella nicotiancola, Botryosphaeria berengriana and Alternariasolani was studied. The results indicate that the complex shows a higher antifungal activity for Botryosphaeria ribis and Botryosphaeria berengriana than diniconazole, but a lower antifungal activity for Gibberella nicotiancola and Alternariasolani.

New oxovanadium(iv) complexes with pincer ligand obtained in situ: experimental and theoretical studies on the structure, spectroscopic properties and antitumour activity

Experimental and theoretical studies on the structure and spectroscopic properties of two complexes: [VOL¹(NCS)₂] (1) and [VOL¹(NCS)₂]·C₆H₅CH₃ (2) where L¹-N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine have been reported.