Pilar Amo-Ochoa

Single layers of a multifunctional laminar Cu(I,II) coordination polymer

A multifunctional bidimensional mixed-valence copper coordination polymer [Cu2Br(IN)2]n (IN = isonicotinato) has been characterized in crystal phase and isolated on graphite surface as single sheets.

Synthesis of designed conductive one-dimensional coordination polymers of Ni(II) with 6-mercaptopurine and 6-thioguanine.

Calculations performed with the goal of designing suitable electrical conductive [M(6-MP)(2)](n) (M = transition metal, 6-MP = 6-mercaptopurinato) one-dimensional coordination polymers suggested that metal ions such as Ni(II) could provide suitable materials. In this work, direct hydrothermal reactions between 6-mercaptopurine (6-MPH) and the analogous 6-thioguanine (6-ThioGH) with NiSO(4).6H(2)O yield the compounds [Ni(6-MP)(2)](n).2nH(2)O [1] and [Ni(6-ThioG)(2)](n).2nH(2)O [2]. The X-ray structures confirm that both compounds present similar structures based on one-dimensional chains in which the deprotonated nucleobases act as the bridging ligands connecting the metal ions by short distances. Electrical measurements at room temperature confirm the conductor character of both coordination polymers. The small differences found in these measurements have been rationalized with the help of density functional theory calculations. Preliminary adsorption studies on surfaces for 1 have allowed characterization of single chains on mica and graphite. The results obtained suggest the potential use of coordination polymers on nanomaterials for molecular electronics.

SYNTHESIS, CHARACTERIZATION, AND DNA MODIFICATION INDUCED BY A NOVEL PT-BERENIL COMPOUND WITH CYTOTOXIC ACTIVITY

In the present paper, we show that the reaction of the antipyranosomatid berenil drug with K2PtCl4 resulted in the synthesis of a covalent (Pt(II)-berenil compound of formula [Pt2Cl4(berenil)2]Cl4.4H2O as shown by IR, 1H, 13C, and 195Pt-NMR. The Pt-berenil compound was tested for in vitro antitumor activity against HL-60 and U-937 human leukemic cells. The results show that the LC70 values of the Pt-berenil are about two-fold lower than those of cis-DDP in both HL-60 and U-937 cell lines. Melting data of Pt-berenil:DNA and berenil:DNA complexes indicate that the platinated compound produces on a DNA secondary structure higher compaction than the berenil ligand. The mobility in agarose gels and the circular dichroism spectra of the compounds:DNA complexes revealed, moreover, that both induce drastic changes on a DNA secondary and tertiary structure. The total reflection X-ray fluorescence data showed, in additIon that DNA platination in Pt-berenil:DNA complexes occurs within minutes after addition of the drug, in contrast to what that observed in cis-DDP:DNA complexes. On the basis of these results, we propose that in Pt-berenil, the berenil ligand acts as a carrier of the active cis-P(II) centers towards DNA.

An unusual triple parallel interpenetrated 2D Cu-polymer, with a 3D triple interpenetration via H-bonding

Compound [Cu2(CN)(IN)(HIN)]n (IN = isonicotinate), based on fused chair shaped [Cu6(μ-isonicotinic)2(μ-isonicotinate)2(μ-cyanide)2] hexagons, is a rare example of a triple interpenetrated two-dimensional ligand-to-metal coordinative bonding network and simultaneously a triple interpenetrated three-dimensional hydrogen bonding network.

A way to obtain cyclopalladation of unsubstituted 2-phenylimidazole derivatives

Abstract This work shows that difficulties of obtaining cyclopalladated complexes with 2-phenylimidazole and 2-phenylbenzimidazole as ligands. The protection of the NH group in the heterocycle with an acetyl group allows the formation of several cyclopalladated complexes of both ligands. The X-ray structure of the dimeric acetate-bridge complex of N -acetyl-2-phenyl-benzimidazole is described. The subsequent displacement of the protective group affords a monomeric cyclopalladated complex of 2-phenylbenzimidazole, as well as a coordination complex of this ligand.

Reversible recrystallization process of copper and silver thioacetamide-halide coordination polymers and their basic building blocks†

Three-dimensional [CuX(TAA)]n (X = Br (1), I (2)) and bi-dimensional [AgX(TAA)]n (X = Cl (3), Br (4)) coordination polymers have been isolated by the direct synthesis from copper(I) and silver(I) halides and thioacetamide (TAA). These are multifunctional materials showing electrical conductivity (values at room temperature ranging from 7 × 10−6 to 2 × 10−9 S cm−1) and luminescence in the blue region. The unusual solubility of 1–4 in different solvents and the recrystallization process observed for 1 and 2 in acetonitrile and for 3 and 4 in pyridine have been measured. We show preliminary results of the processability of 2 on glass for the production of organized thin films. These results are very attractive for the processability of coordination polymers in materials science and nanoscience.

Luminescent Thermochromism of 2D Coordination Polymers Based on Copper(I) Halides with 4‐Hydroxythiophenol

Solvothermal reactions between copper(I) halides and 4-mercaptophenol give rise to the formation of three coordination polymers with general formula [Cu3 X(HT)2 ]n (X=Cl, 1; Br, 2; and I, 3). The structures of these coordination polymers have been determined by X-ray diffraction at both room- and low temperature (110 K), showing a general shortening in Cu-S, Cu-X and Cu-Cu bond lengths at low temperatures. 1 and 2 are isostructural, consisting of layers in which the halogen ligands act as μ3 -bridges joining two Cu1 and one Cu2 atoms whereas in 3 the iodine ligands is as μ4 -mode but the layers are quasi-isostructural with 1 or 2. These compounds show a reversible thermochromic luminescence, with strong orange emission for 1 and 2, but weaker for 3 at room temperature, whereas upon cooling at 77 K 1 and 2 show stronger yellow emission, and 3 displays stronger green emission. DFT calculations have been used to rationalize these observations. These results suggest a high potential for this novel and promising stimuli-responsive materials.

Electrical Bistability around Room Temperature in an Unprecedented One-Dimensional Coordination Magnetic Polymer

The synthesis, crystal structure, and physical properties of an unprecedented one-dimensional (1D) coordination polymer containing [Fe2(S2C6H2Cl2)4](2-) entities bridged by dicationic [K2(μ-H2O)2(THF)4](2+) units are described. The magnetic properties show that the title compound presents pairwise Fe-Fe antiferromagnetic interactions that can be well reproduced with a S = 1/2 dimer model with an exchange coupling, J = -23 cm(-1). The electrical conductivity measurements show that the title compound is a semiconductor with an activation energy of about 290 meV and two different transitions, both with large hysteresis of about 60 and 30 K at 260-320 K and 350-380 K, respectively. These two transitions are assumed to be due to slight structural changes in the cation-anion interactions. Differential Scanning Calorimetry confirms the presence of both transitions. This compound represents the first sample of a coordination polymer showing electrical bistability.

Electrical Conductivity and Strong Luminescence in Copper Iodide Double Chains with Isonicotinato Derivatives.

Direct reactions between CuI and isonicotinic acid (HIN) or the corresponding esters, ethyl isonicotinate (EtIN) or methyl isonicotinate (MeIN), give rise to the formation of the coordination polymers [CuI(L)]n with L=EtIN (1), MeIN (2) and HIN (3). Polymers 1-3 show similar structures based on a CuI double chain in which ethyl-, methyl isonicotinate or isonicotinic acid are coordinated as terminal ligands. Albeit, their supramolecular architecture differs considerably, affecting the distances and angles of the central CuI double chains and thereby their physical properties. Hence, the photoluminescence shows remarkable differences; 1 and 2 show a strong yellow emission, whereas 3 displays a weak emission; and 1 and 2 are semiconductors with moderate room temperature conductivities, whereas 3 has increased electrical conductivity up to 3×10(-3)  S cm(-1) . Additionally, 1 and 2 present an irreversible transition to a highly conducting phase with a conductivity almost 4 orders of magnitude higher and a quasi-metallic behaviour. Thermogravimetric analysis (TGA) coupled to a mass spectrometer and magnetic measurements point to a partial thermally induced oxidation of the carboxylate groups of the ligands with Cu(I) to Cu(0) reduction. DFT calculations have been carried out to rationalise these observations.

Strong luminescent copper(I) halide coordination polymers and dinuclear complexes with thioacetamide and N,N′-donor ligands

Direct reactions between copper(I) halides, thioacetamide (TAA) and 4,4′-bipyridine (4,4′-bpy) or pyrazine (pyz) in MeCN led to the formation of mixed ligand compounds [Cu2Cl2(TAA)2(4,4′-bpy)]n (1), [Cu2X2(TAA)4(4,4′-bpy)]·(4,4′-bpy) (X = Cl (2), Br (3) and I (4)) and [Cu2Cl2(TAA)2(pyz)]n (5), and the binuclear complex [Cu2I2(TAA)4] (6). The formation of these compounds strongly depends on both the ratio of the reactants and the halide. The structures of these compounds have been determined by X-ray diffraction showing interesting intermolecular interactions based on hydrogen bonding. The physical properties of these compounds show that 1–5 are strongly luminescent with red emission (500–750 nm) at room temperature in the solid state, while compound 1 behaves as a semiconductor and 5 as an insulator.