Syntheses, crystal structures, and bond valence sum analyses of lanthanide complexes with a planar pentadentate ligand

Tetraaqua[2,6-diacetylpyridine bis(semicarbazone)]samarium(III) trinitrate

The structure of tetraaqua[2,6-diacetylpyridine bis(semicarbazone)]samarium(III) trinitrate, [Sm(C11H15N7O2)(H2O)4](NO3)3, has monoclinic (P21/c) symmetry. The 2,6-diacetylpyridine (DAPSC) ligand is pentadentate. The coordination of the DAPSC ligand and four coordinated water molecules around the metal cation is best described as a distorted tricapped trigonal prism. The structure displays intermolecular hydrogen bonding. The structure is isomorphous with many other published lanthanide(III) nitrate salts with the DAPSC ligand, 2,6-diacetylpyridinebis(semicarbazone). One of the three nitrate counter-anions is disordered, which is consistent with the structures of other +3 lanthanide nitrate salts with DAPSC. Refinement of occupancies for the disordered nitrate group gave major and minor occupancies of 54.9 (14) and 45.1 (14)%, respectively.

Synthesis, characterization and crystal structures of two pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent. Anticancer properties of various metal complexes of the same ligand

In this work synthesis, characterization and crystal structures of two isothiocyanato Fe(III) complexes with 2,2'-[2,6-pyridinediylbis(ethylidyne-1-hydrazinyl-2-ylidene)]bis[N,N,N-trimethyl-2-oxoethanaminium] dichloride (H₂LCl₂) ligand, with composition [FeL(NCS)₂]SCN·2H₂O and [FeL(NCS)₂]₂[Fe(H₂O)(NCS)₅]·4H₂O, has been reported. Both iron(III) complexes possess the same pentagonal-bipyramidal complex cation, while the nature of their anions depends on mole ratio of NH₄SCN and FeCl₃·6H₂O used in reaction. Cytotoxic activity of new Fe(III) complexes, as well as of previously synthesized isothiocyanato Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand, was tested against five human cancer cell lines (HeLa, MDA-MB-453, K562, LS174 and A549) and normal cell line MRC-5. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes. The investigation of potential of these complexes to induce HeLa and K562 cell cycle perturbations was also evaluated. Mechanism of cell death mode was elucidated on the basis of morphological changes of HeLa cells as well as identification of target caspases. It was established that DNA damage could be responsible for the activity of Fe(III) and Co(II) complexes.

SYNOPSIS

Pentagonal-bipyramidal Fe(III) complexes with dihydrazone of 2,6-diacetylpyridine and Girard's T reagent have been synthesized and characterized. Cytotoxic activity of Fe(III) complexes and Co(II), Ni(II), Mn(II), Zn(II) and Cd(II) complexes with the same ligand was tested. The best activity was observed in the case of Fe(III), Co(II) and Cd(II) complexes.

Metal induced folding: synthesis and conformational analysis of the lanthanide complexes of two 44-membered hydrazone macrocycles

Six new lanthanide complexes of two 44-membered macrocycles have been prepared and characterised in solution. An analysis of the conformations of the free macrocycles and their lanthanide complexes both in solution (2D NMR) and in solid state (X-ray crystallography) demonstrate that the complexation induces changes in folding of the macrocycles.