Antonio Galdámez

Intercalation of polyaniline in the layered materials mps3, m = Mn, Cd

Abstract The intercalation compounds (Polyaniline) 1.08 Mn 0.86 PS 3 and (Polyaniline) 0.57 Cd 0.73 PS 3 have been synthesized by the ion-exchange procedure. These compounds constitute a new family of intercalates in MPS 3 (M = Mn, Cd) host layer, with Polyaniline as guest species. They have been characterized by powder X-ray diffraction (XRD), Fourier transform infrared (FTIR), differential thermal analysis (DTA), thermogravimetric analysis (TGA), and electrical conductivity measurements. Both intercalation compounds show values of electrical conductivity (σ i ) of about 10 −7 Ω −1 cm −1 at 298 K and photoconductivity at temperatures from 296 to 343 K.

N-METHYL-1H- INDOLE-2-CARBOXAMIDE FROM THE MARINE FUNGUS CLADOSPORIUM CLADOSPORIOIDES

The crystal structure of N-methyl-1H- indole-2-carboxamide C10H10N2O was determined by single crystal X-ray diffraction. The structure can be described as consisting of an indole group and as substituent, linked at C2, the N-methylcarboxamide group. The molecular structure is essentially planar. The crystal packing results in N-H ------ O hydrogen bonds which join the molecules into centrosymmetric dimeric rings. The knowledge of the crystal structure allows a complete assignment of the 1H and 13C-NMR spectra. The N-methyl-lH- indole-2-carboxamide is the first indole derivative isolated from marine fungus.

Insertion of In(III) and Ga(III) into MPS3 (M = Mn, Cd) layered materials

Abstract In 0.20 Mn 0.70 PS 3 , Ga 0.28 Cd 0.58 PS 3 and In 0.33 Cd 0.50 PS 3 compounds were synthesized by insertion of trivalent cations (In 3+ and Ga 3+ ) into MPS 3 (M = Mn, Cd). The insertion process requires the previous intercalation of K + ions into these matrices, giving rise to new materials belonging to the MPS 3 family. Such compounds were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) microprobe, differential thermal and thermogravimetric analyses (DTA/TGA), magnetic susceptibility measurements, and electrochemical impedance spectroscopy. It is inferred that the trivalent cations were incorporated, rather than intercalated, into the intralamellar region, i.e., the cations were located in the interlamellar space, following the typical topotactic ion-exchange processes of the monovalent cations. Clement and Michowicz reported a similar case for Ni 2+ insertion into MnPS 3 in 1984.

CRYSTAL STRUCTURE OF (1R,5S)-9-NITRO- 1,2,3,4,5,6-HEXAHYDRO-1,5-METHANOPYRIDO[1,2-a][1,5] DIAZOCIN-8-ONE (9-NITROCYTISINE), C11H13O3N3

The title compound (1, trivial name: 9 (or 3)-nitrocytisine) crystallizes with two independent molecules in the asymmetric unit. In its structure two rings form a bispidine framework that is fused to a 3-nitro-2-pyridone group. The half-normal probability plot reveals that the two molecules do not show any significant geometrical differences, except in conformations of the nitro-group, which is involved in intermolecular interactions. The crystal packing structure of the title compound is described in terms of three-dimensional supramolecular arrays built up from chains of N-H-O (nitro-group), hydrogen bonds and weak intermolecular C- H … O=C interactions, with graph-set descriptors C22(6) and C22(JQ) motifs, which together result in R44(26) rings motifs. These chains are additionally stabilized by intermolecular NO2…π interactions.

Highly stereoselective and catalyst-free synthesis of annulated tetrahydropyridines by intramolecular imino-Diels–Alder reaction under microwave irradiation in water

A microwave-assisted method for the synthesis of tetracyclic tetrahydropyridines via an intramolecular imino-Diels–Alder reaction in water is reported. The reaction proceeds under catalyst-free conditions and shows excellent stereoselectivity.

Synthesis of coumarin derivatives as fluorescent probes for membrane and cell dynamics studies.

Three coumarin-derived fluorescent probes, 3-acetyl-7-[(6-bromohexyl)oxy]-2H-chromen-2-one (FM1), 7-[(6-bromohexyl)oxy]-4-methyl-2H-chromen-2-one (FM2) and ethyl 2-{7-[(6-bromohexyl)oxy]-2-oxo-2H-chromen-4-yl}acetate (FM3), are described, with their photophysical constants. The compounds were tested in preliminary studies employing epifluorescence microscopy demonstrating that they allow the imaging of human neuroblastoma SH-SY5Y cell membranes. The structure of FM3 was confirmed by X-ray crystallographic analysis. Molecular dynamics (MD) simulations were used to characterize the localization and interactions of the studied compounds with a lipid bilayer model of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC).

ELECTRICAL BEHAVIOR OF A Cu2Fe0.4Co0.6SnS4 CERAMIC

The solid solutions Cu2Fe1-XCoXSnS4, with stannite-type structure are stable up to about 800°C. The electrical properties of the Cu2Fe0.4Co0.6SnS4 ceramic were investigated by complex impedance. The real and imaginary dielectric permittivity dependence with the temperature were measured between 10kHz and 1 MHz in temperature range 77-280K, finding that the ceramic present the characteristics behavior of a dielectric relaxation between 100 and 250 K, with a maximum at approximately 200 K. The electric permittivity found has orders of magnitude between 102 and 103. A space charge polarization mechanism is suggested to explain the observed electric relaxation.

Electrical and magnetic properties of quaternary rare earth thiophosphate: K4Sm2[PS4]2[P2S6]

O tiofosfato quaternario de metal alcalino e terra rara K4Sm2[PS4]2[P2S6] foi sintetizado pelo metodo cerâmico e caracterizado por difratometria de raios X de po (XRD), microscopia eletronica de varredura com microanalise de raios X (SEM-EDX), medidas de impedância eletroquimica e medidas magneticas. A estrutura cristalina consiste de camadas de 2∞Sm2[PS4]2[P2S6]4- separadas por cations K+. As medidas de condutividade eletrica indicam que o composto e um semicondutor com uma resistividade de 1,0 x 1011 Ω cm. O momento magnetico, obtido a partir de χ-1 versus T a baixa temperatura, e igual a 0,57 μB.

Crystal structure of potassium antimony hexathiodiphosphate, KSbP2S6

KSbP2S6, monoclinic, P1211 (No. 4), a = 6.605(1) A, b = 7.651(2) A, c = 9.754(2) A, = 92.11(3)°, V = 492.6 A, Z = 2, Rgt(F) = 0.018, wRref(F) = 0.044, T = 293 K. Source of material For the synthesis of KSbP2S6, the corresponding high purity element powders (99.99%) supplied by Aldrich were mixed in the stoichiometric amounts, sealed in evacuated quartz tubes, and heated at 1023 K for two weeks. After the reaction was completed, the sample was slowly cooled to room temperature. All manipulations were carried out under Ar atmosphere Discussion In the course of our work on chalcogen phosphates [1,2], we have preparated the quaternary antimony hexathiodiphosphate KSbP2S6. This compound is isostructural to KBiP2S6 [3]. As expected, the Sb—S bonds in KSbP2S6 are shorter that the Bi—S bonds in KBiP2S6. Also, the smaller radius of Sb results in a decreased coordination number. Thus, each Sb is coordinated by five S atoms compared with the six-coordinated Bi ions in the isostructural compound. In the title compound, each Sb ion is tri-coordinated by one ethane-like [P2S6] ligand and mono-coordinated by two [P2S6] groups forming chains, while a sixth S atom connect the Sb to a neighboring chain, through a Sb–S contact of 3.4187(9) A, to form a layer in the bc plane. The layer are separated by the K ions. The bond lengths d(Sb—S) range from 2.545(1) A to 3.1471(5) A. The compounds KMP2S6 (M = Sb, Bi) are structurally related to Na0.16Bi1.28P2S6 [4] and -KMP2Se6 [5]. Z. Kristallogr. NCS 218 (2003) 403–404 403

Development of an iron-selective antioxidant probe with protective effects on neuronal function

Iron accumulation, oxidative stress and calcium signaling dysregulation are common pathognomonic signs of several neurodegenerative diseases, including Parkinson´s and Alzheimer’s diseases, Friedreich ataxia and Huntington’s disease. Given their therapeutic potential, the identification of multifunctional compounds that suppress these damaging features is highly desirable. Here, we report the synthesis and characterization of N-(1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl)-2-(7-hydroxy-2-oxo-2H-chromen-4-yl)acetamide, named CT51, which exhibited potent free radical neutralizing activity both in vitro and in cells. CT51 bound Fe2+ with high selectivity and Fe3+ with somewhat lower affinity. Cyclic voltammetric analysis revealed irreversible binding of Fe3+ to CT51, an important finding since stopping Fe2+/Fe3+ cycling in cells should prevent hydroxyl radical production resulting from the Fenton-Haber-Weiss cycle. When added to human neuroblastoma cells, CT51 freely permeated the cell membrane and distributed to both mitochondria and cytoplasm. Intracellularly, CT51 bound iron reversibly and protected against lipid peroxidation. Treatment of primary hippocampal neurons with CT51 reduced the sustained calcium release induced by an agonist of ryanodine receptor-calcium channels. These protective properties of CT51 on cellular function highlight its possible therapeutic use in diseases with significant oxidative, iron and calcium dysregulation.