Miren Karmele Urtiaga

Biological activity of complexes derived from pyridine-2-carbaldehyde thiosemicarbazone: Structure of [Co(C7H7N4S)2][NCS]

Biological studies on [Fe(L)2](NO3).0.5H2O (1), [Fe(L)2][PF6] (2), [Co(L)2](NCS) (3), [Ni(HL)2]Cl2.3H2O (4) and Cu(L)(NO3) (5), where HL=C7H8N4S, pyridine-2-carbaldehyde thiosemicarbazone, have been carried out. The crystal structure of compound 3 has been solved. It consists of discrete monomeric cationic entities containing cobalt(III) ions in a distorted octahedral environment. The metal ion is bonded to one sulfur and two nitrogen atoms of each thiosemicarbazone molecule. The thiocyanate molecules act as counterions. The copper(II) and iron(III) complexes react with reduced glutathione and 2-mercaptoethanol. The reaction of compound 1 with the above thiols causes the reduction of the metal ion and bis(thiosemicarbazonato)iron(II) species are obtained. The redox activity, and in particular the reaction with cell thiols, seems to be related to the cytotoxicity of these complexes against Friend erithroleukemia cells and melanoma B16F10 cells.

Topological description of a 3D self-catenated nickel hybrid vanadate Ni(bpe)(VO3)2. Thermal stability, spectroscopic and magnetic properties

The three-dimensional Ni(bpe)(VO3)2 hybrid compound, where bpe is 1,2-di(4-pyridyl)ethene, (C12H10N2), has been synthesized using mild hydrothermal conditions under autogeneous pressure at 140 °C during five days, obtaining green emerald prismatic single-crystals suitable for X-ray structure determination. The compound crystallizes in the orthorhombic system, space groupPbcn, with a = 14.9066(5), b = 7.6269(2) and c = 26.9624(10) A, Z = 8, and R1 = 0.0373 for 4149 observed reflections. Single-crystal X-ray diffraction reveals that the crystal structure is composed of a 3D self-catenated 10-connected uninodal net constructed from 36-hxl like {NiV2O6} inorganic sheets linked through bpe ligands. The thermal evolution of the crystal parameters shows three different tendencies during the heating process: (i) initial contraction, (ii) thermal expansion, (iii) structural collapse due to the thermal instability of the organic ligand. The IR spectrum shows the vibrational modes of the bpe organic molecules and those of the (VO4)3− tetrahedral oxoanions. Diffuse reflectance electronic absorption spectroscopy shows the characteristic bands of the Ni(II) d8-high spin cation in slightly distorted octahedral geometry. From the positions of the bands in the electronic spectrum the Dq (940 cm−1) and Racah, B (930 cm−1) and C (3350 cm−1), parameters have been calculated. Magnetic measurements indicate the existence of antiferromagnetic interactions between the Ni(II) centres of the dinuclear units, with a value of the J/k = −59.4, with g = 2.076.

Four nodal self-catenated [{Ni8(Bpy)16}V24O68]·8.5(H2O), combining three dimensional metal–organic and inorganic frameworks

The chiral three dimensional crystal structure of [{Ni8(Bpy)16}V24O68]·8.5(H2O) is the first example of a hybrid vanadate combining a three dimensional metal–organic subnet with a three dimensional inorganic framework. The metal–organic framework consists of 3D + 2D polycatenation of a 3D “cds” like net and two 2D “sql” layers. The vanadium oxide subunit is a complex chain constructed from V5O15 cycles linked through a single tetrahedron. The vanadate chains are located in the channels of the metal–organic framework, and corner linked to the nickel metal centres giving rise to an unprecedented four nodal self-catenated framework. Moreover, as far as we as concerned, this is the first vanadate in which the V5O15 cycles has been isolated in the solid state. The crystallization water molecules are partially encapsulated between the organic ligands and the inorganic framework. The loss of crystallization water molecules gives rise to a contraction of the 0.6% of the unit cell volume. The IR spectrum shows the characteristic bands of the vanadium oxide subunit, and the bpy ligand. The BET measurement gives rise to a type III profile, (3.7 cm2 g−1), suggesting weak adsorbate-adsorbent interactions. The thermal evolution of the magnetic susceptibility is attributed to the zero-field splitting for eight non interacting Ni(II) cations.

Structural and spectroscopic studies on the [Cu(C14H15N3)(NCS)2] complex. Stereochemistry of several five-coordinate copper(II) complexes with tridentate ligands

Abstract The title compound of formula [Cu(C14H15N3)(NCS)2] [where C14H15N3 is N-(2′-(6-methyl)pyridyl)methylene-2-(2′-pyridyl)ethylamine] has been synthesized and its crystal structure determined by X-ray diffraction. It shows isolated monomeric molecules with a near-trigonal bypyramidal geometry around the CuII ion, which is coordinated to three nitrogen atoms of the tridentate ligand and two nitrogens belonging to the isothiocyanato groups. Reflectance and ESR spectra are consistent with this structure. The stereochemistries of several [Cu(tridentate ligand)(unidentate ligand)2 five-coordinate complexes are discussed.

Coordination and crystallization molecules: their interactions affecting the dimensionality of metalloporphyrinic SCFs.

Synthetic metalloporphyrin complexes are often used as analogues of natural systems, and they can be used for the preparation of new Solid Coordination Frameworks (SCFs). In this work, a series of six metalloporphyrinic compounds constructed from different meso substituted metalloporphyrins (phenyl, carboxyphenyl and sulfonatophenyl) have been structurally characterized by means of single crystal X-ray diffraction, IR spectroscopy and elemental analysis. The compounds were classified considering the dimensionality of the crystal array, referred just to coordination bonds, into 0D, 1D and 2D compounds. This way, the structural features and relationships of those crystal structures were analyzed, in order to extract conclusions not only about the dimensionality of the networks but also about possible applications of the as-obtained compounds, focusing the interest on the interactions of coordination and crystallization molecules. These interactions provide the coordination bonds and the cohesion forces which produce SCFs with different dimensionalities.

Reversible phase transformation of a pyridyl ketone based coordination polymer

[1] S. Natarajan, S. Mandal, Angew. Chem. Int. Ed. 2008, 47, 4798-9828. [2] T. Berrocal, J.L. Mesa, J.L. Pizarro, B. Bazán, M. Iglesias, A.T. Aguayo, M.I. Arriortua, T. Rojo, Chem. Commun. 2008, 4738-4740; T. Berrocal, J.L. Mesa, J.L. Pizarro, B. Bazán, M. Iglesias, J.L. Vilas, T. Rojo, M:I. Arriortua, Dalton Trans., 2010, 39, 834-846. [3] T. Berrocal, J.L. Mesa, J.L. Pizarro, L. Lezama, B. Bazán, M.I. Arriortua, T. Rojo, J. Solid State Chem. 2008, 181, 884-894; [4] T. Berrocal, E.S. Larrea, M. Iglesias, M.I. Arriortua, J. Mol. Catal. A:Chem. 2011, 335, 176-182.

Self-assembly of metallated TPP porphyrin by external dipyridyl ligands

Supramolecular entities based on self-assembly of metalloporphyrins are paradigmatic examples of the great efficiency of the nanodevices used by natural systems in photosynthesis, oxygen transport, electron transfer and catalysis [1]. Therefore, they constitute reference models for the development of new materials that make these, and other yet unexplored, functions. While metalloporphyrin biosystems operate in solution, the preparation of materials based on these macrocycles moves the problem to the solid state synthesis. Thus, obtaining supramolecular entities may be approached by different strategies of synthetic design. One of them consists on the use of external dipyridyl ligands to assemble the metallated porphyrin units. In this aspect, the range of compounds that can be used is endless. In this context, our research group is working with different combinations of organic ligands and metalloporphyrins, and the work herein presented corresponds to the compound [FeTPP(bipy)] (TPP=meso-tetraphenylporphyrin and bipy=4,4 ́bipyridine), obtained by solvothermal synthesis. The crystal structure of [FeTPP(bipy)] consists of 1D chains of alternating FeTPP and bipy molecules bonded to the axial positions of the coordination sphere. These chains are sustained by π-π stacking between the phenyl rings at about 5 Å. So far, very few compounds with TPP and bipy have been described, of which only one [2] is really a 1D coordination polymer, being all others isolated dimers. It is also remarkable that, as far as we know, this is the first structure with these ligands based on Fe, one of the most important metals in porphyrin biosystems.

Crystal Structures of Methyl and Ethyl N-(2,3-Dimethoxybenzyl)-N-(p-toluenesulfonyl)-2-phenylglycinates

The crystal structures of methyl and ethyl N-(2,3-dimethoxybenzyl)-N-(p-toluenesulfonyl)-2-phenyl-glycinates 4a and 4b respectively, have been determined by X-ray diffraction analysis. The presence of different alkyl ester groups in both molecules does not affect the geometry retaining a synclinal conformation for the N atom and the O atom of the C=O group [N-C17-C18-O5 38.1(5)° for 4a and 33.3(4)° for 4b].