Yasmi Reyes-Ortega

A Modified Procedure for the Preparation of Linear Polyamines

Abstract An efficient method has been developed for obtaining linear polydentate free amines with high purity and yield than the route currently available.

The triclinic polymorph of di­bromo[(–)-sparteine-κ2N,N′]­zinc(II)

The title compound, [ZnBr 2 (C 15 H 26 N 2 )], when synthesized starting from Zn 0 , is obtained in two polymorphic forms, one belonging to space group P2 1 2 1 2 1 and one to P1. The present contribution deals with the triclinic phase, which is isostructural with the orthorhombic form but presents a larger metal-metal intermolecular separation; the Zn...Zn distance is 7.4715 (6) A for the triclinic polymorph as opposed to 6.534 A for the orthorhombic polymorph.

Spectroscopic studies of novel porphyrin-copper(II) and zinc(II) complexes that share the pinch-porphyrin family structure of iron(III) complex models of peroxidases

Six novel pinch-porphyrin complexes [(picdien)(protoporphyrinate dimethyl ester)]copper(II) (7), [(picdien)(mesoporphyrinate dimethyl ester)]copper(II) (8) and [(picdien)(deuteroporphyrinate dimethyl ester)]copper(II) (9), [(picdien)(protoporphyrinate dimethyl ester)]zinc(II) (13), [(picdien)(mesoporphyrinate dimethyl ester)]zinc(II) (14) and [(picdien)(deuteroporphyrinate dimethyl ester)]zinc(II) (15), were prepared from the corresponding free copper(II)-porphyrins (4–6), and zinc(II)-porphyrins (10–12) and picdien (N-(3H-imidazol-4-ylmethyl)-N′-{2-[(3H-imidazol-4-ylmethyl)-amino]-ethyl}-ethane-2,3-diamine). Spectroscopic studies show that complexes (7–9) and (13–15) have the pinch-porphyrin type structure previously found in iron(III) complex models of peroxidases. Complexes (7–9), were characterized by u.v.–vis., m.c.d., and e.s.r. spectroscopy. E.s.r. spectra of the copper parent compounds (4–6) at ca. 10−2–10−4 M concentrations were typical of copper(II)-dimers. The addition of the picdien ligand broke up the dimers as detected by e.s.r. Compounds (7–9) are predominantly monomeric at ca. 10−3 M concentration. The presence of picdien in (7–9) distorts the porphyrin internal portion of the plane so as to make these four internal nitrogen atoms, coordinated to copper(II), e.s.r.-distinguishable. MO and ligand field theories were used to characterize and to evaluate the directional covalence parameters of compounds (7–9). A non-fully axial, out-of-the-porphyrin-plane bonding was found for (7–9), similar to the bonding of the pinch-porphyrins-iron(III). However the in-plane distortion produced by the presence of the picdien ligand on copper(II) is significantly larger than in pinch-porphyrin-iron(III). The n.m.r. data show that the porphyrin-zinc(II) is the less strained and has the weakest bonded structure. The coordination number of the pinch-porphyrin with iron(III), copper(II) and zinc(II), is in all cases six.

Determinación del potencial bioquímico de metano (PBM) de residuos de frutas y verduras en hogares

In this work we studied the decomposition of organic matter of food kitchen wastes (substrate) by sewage sludge (inoculum) from a wastewater treatment plant, through theprocess of anaerobic digestion (AD) in order to obtain biogas and to determinethe biochemical methane potential (BMP) at the end of this process. The tests were performed with substrate:inoculum ratios 1:2 and 1:3, in terms of volatile solids (VS). The most important parameters that influence AD were VS, total solids (TS), chemical oxigen demand (COD) and pH. They were measured in the course of the process in mesophilic conditions (35 °C) and retention times of 15 days. The biogas obtained was purified by removing H 2 S and NH 3 with NaOH and H 2 SO 4 traps. For experiments with inoculum and substrate, 1.235 L of biogas with 80.15 % CH 4 were recovered and for tests without substrate, 0.720 L of biogas with 90.47 % of CH 4 were gathered. The quantification of this gas was performed by gas chromatography. The results agree with biogas production and organic load decrease, expressed as COD. For experiments S:I, the BMP values obtained were 124.82 and 127.89 mL CH 4 /g VS, for 1:3 and 103.39 and 116.27 mL CH 4 /g VS for 1:2.

Bis{μ-2,2′-[(3-aza­pentane-1,5-di­yl)bis­(nitrilo­methyl­idyne)]diphenolato}dicopper(II) dimethyl sulfoxide disolvate

The title compound, [Cu2(C18H19N3O2)2]·2C2H6OS or [Cu2(SalenN3H)2]·2DMSO, where SalenN3H is the multidentate Schiff base 2,2′-[(3-azapentane-1,5-diyl)bis(nitrilomethylidyne)]diphenolate dianion and DMSO is dimethyl sulfoxide, is a solvated dinuclear CuII complex. The neutral complex is built from two Cu(SalenN3H) units related by an inversion center. All heteroatoms in the Schiff bases coordinate the CuII ions, which display highly distorted trigonal bipyramidal geometries. The solvent molecules are located in the structural voids of the complex and are disordered over two positions with occupancies of 0.642 (15) and 0.358 (15). The previously characterized acetone disolvate of the same complex presents identical molecular and crystal structures, and crystallizes with cell parameters very close to those of the DMSO disolvate reported here.

Novel synthesis of new 1,2,4‐trithioles by reductive coupling of benzoyldithioacetic acid derivatives mediated by Sml2

1,2,4-trithioles 2a–e are readily obtained in good yields by dimerization of benzoyldithioacetic acid derivatives using samarium diiodide as a promotor under very mild conditions. The structures of compounds 2a–e were determined by IR, 1H, and 13C NMR spectroscopies using heteronuclear multiple bond correlation, heteronuclear multiple quantum correlation, and nuclear Overhauser enhancement spectroscopy experiments, mass spectrometry, and, in the case of 2a, the structure was confirmed by single-crystal X-ray diffraction studies.

Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate

The synthesis of 3,5-lutidine N-oxide dehydrate, 1, was achieved in the synthesis route of 2-amino-pyridine-3,5-dicarboxylic acid. Ochiai first used the methodology for non-substituted pyridines in 1957 in a 12 h process, but no X-ray suitable crystals were obtained. The substituted ring used in the methodology presented here clearly influenced the addition of water molecules into the asymmetric unit, which confers a different nucleophilic strength in 1. The X-ray suitable crystal compound 1 was possible due to the stabilization of the negative charge in the oxygen by the presence of two water molecules where the hydrogen atoms donate positive charge into the ring; such water molecules serve well to construct a supramolecular interaction. The hydrated molecules may be possible for the alkaline system that is reached by adjusting the pH to 10. Importantly, the double methyl substituted ring and a reaction time of 5 h, makes it a more versatile method and with wider chemical applications for future ring insertions.

Synthesis of a One-Dimensional Coordination Polymer of Nickel(II) Complex with a β-Oxodithioester Ligand

Bis-[methyl-1-hydroxy-1-cyclopentene-2-dithiocarboxylate-O,S]nickel(II) 1 was prepared starting from methyl 2-hydroxycyclopent-1-encarbodithioate ligand (CPDT) and Ni(II), and catena-[(μ2-4,4′-Bipyril)-bis-(methyl-2-hydroxy-1-cyclopentene-2-dithiocarboxylate-O,S)]nickel(ΙΙ) 2 was prepared in good yields from 1 plus 4,4′-bipyridyl (bpy) by shish-kebab methodology. The structure of 1 was confirmed by FTIR, elemental analysis, 1H NMR, UV–vis in chloroform solution and in solid, XPS, and PXRD. Compound 2 was characterized by FTIR, elemental analysis, UV–vis in chloroform solution, and in solid, XPS, PXRD, ESR, and solid state magnetization measurements. The structure of the polymer was established mostly by PXRD, ESR, and magnetization.

Crystal structure of 3,5-di­methyl­pyridine N-oxide dihydrate

In the title hydrate, water molecules and N-oxide groups of the main molecule form supramolecular chains based on R(10) ring motifs.

At last! The single-crystal X-ray structure of a naturally occurring sample of the ilmenite-type oxide FeCrO3.

A natural single crystal of the ferrimagnetic oxide FeCrO3, which was found in an opencast mine situated in the San Luis Potosí State in Mexico, has been characterized in order to elucidate some outstanding issues about the actual structure of this material. The single-crystal X-ray analysis unambiguously shows that transition metal cations are segregated in alternating layers normal to the threefold crystallographic axis, affording a structure isomorphous to that of ilmenite (FeTiO3), in the space group R3̅. The possible occurrence of cation antisite and vacancy defects is below the limit of detection available from X-ray data. Structural and magnetic results are in agreement with the coherent slow intergrowth of magnetic phases provided by the two antiferromagnetic corundum-type parent oxides Fe2O3 (hematite) and Cr2O3 (eskolaite). Our results are consistent with the most recent density functional theory (DFT) studies carried out on digital FeCrO3 [Sadat Nabi & Pentcheva (2011). Phys. Rev. B, 83, 214424], and suggest that synthetic samples of FeCrO3 might present a cation distribution different to that of the ilmenite structural type.