Síntesis y caracterización de dos nuevos cristales multicomponentes derivados de la 2,5-dihidroxi-1,4- benzoquinona con posibles aplicaciones electromagnéticas

En este trabajo se reporta la síntesis y caracterización de dos nuevos cristales multicomponentes derivados de la 2,5-dihidroxi-1,4-benzoquinona (H₂DHB) con bases nitrogenadas tales como el 1,4-diazabiciclo-[2.2.2]-octano (DABCO) y piridina (py). Los compuestos se obtuvieron a través de las técnicas de molienda y cristalización por evaporación lenta del disolvente. La caracterización por difracción de rayos-X de polvos y de monocristal permitió concluir que se obtuvieron 2 nuevas fases cristalinas con posibles aplicaciones electromagnéticas: DHB1, el cual cristalizó en un sistema cristalino monoclínico cuya unidad asimétrica está constituida de una media-molécula de H2DHB, una de DABCO y dos de agua, para formar el compuesto [HDABCO+]₂(DHB₂-).4H₂O; DHB2, cristalizó en un sistema cristalino triclínico y con unidad asimétrica compuesta por una molécula de H₂DHB y una de piridina, para formar el compuesto [Hpy+](HDHB-). Estos nuevos productos también se caracterizaron por espectroscopía IR.In this work we report the synthesis and characterization of two new multicomponent crystals derived from 2,5-dihydroxy-1,4-benzoquinone (H2DHB) with nitrogenous bases such as 1,4-diazabicyclo-[2.2.2]-octane (DABCO) and pyridine (py). Both compounds were obtained through the techniques of grinding and crystallization by slow evaporation of the solvent. Powder and single-crystal Xray diffraction characterization allowed us to conclude that two new crystalline phases with possible electromagnetic applications were obtained: DHB1, which crystallized in a monoclinic system whose asymmetric unit consists of one-half of H₂DHB, one DABCO and two lattice water molecules, affording a new compound with formula [HDABCO+]₂(DHB₂-).4H₂O; DHB2 crystallized in a triclinic system with an asymmetric unit composed of one H2DHB molecule and one pyridine molecule, to form the new compound [HPy+](HDHB-). These new products were also characterized by IR spectroscopy

Síntesis y caracterización de dos cocristales derivados del ácido gálico y metilxantinas con posibles aplicaciones farmacéuticas

En este trabajo se presenta el estudio de dos cocristales derivados del ácido gálico y metilxantinas (teobromina y teofilina) que fueron preparados y caracterizados por difracción de rayos X de polvos y de monocristal, espectroscopía IR y mediciones TGA/DSC. Este estudio contempló aplicar dos metodologías de síntesis: cristalización por evaporación y slurry. Los estudios de difracción de rayos X de monocristal nos revelaron que obtuvimos dos cristales moleculares con posibles aplicaciones farmacéuticas: GA1 (teobromina/ácido gálico/H₂O) que cristalizó en un sistema monoclínico y grupo espacial C2/c y GA2 (teofilina/ácido gálico) que cristalizó en un sistema triclínico con grupo espacial P-1. La síntesis de estos compuestos fue fácilmente reproducible por el método de slurry.This paper presents the study of two cocrystals derived from gallic acid and methylxanthines (theobromine and theophylline) that were prepared and characterized by single-crystal and powder X-ray diffraction, IR spectroscopy and TGA/DSC measurements. This study contemplated applying two synthesis methodologies: crystallization by evaporation and from the slurry. The single crystal X-ray crystallographic study revealed that we obtained two molecular crystals with possible pharmaceutical applications: GA1 (theobromine/gallic acid/H₂O) that crystallized in a monoclinic system and space group C2/c and GA2 (theophylline/gallic acid) which crystallized in a triclinic system with space group P-1. The synthesis of these compounds was easily reproducible by the slurry method

Cristales moleculares derivados del ácido gálico y pirimidinas con posibles aplicaciones farmacéuticas

El siguiente trabajo presenta el estudio de dos nuevos cristales moleculares derivados del ácido gálico y pirimidinas (timina y citosina). Los compuestos obtenidos se caracterizaron por difracción de rayos X de polvos y de monocristal, espectroscopía IR y mediciones TGA/DSC. La síntesis de los cristales moleculares se experimentó por medio de cristalización por evaporación del disolvente y por slurry. Los estudios de difracción de rayos X de monocristal nos revelaron que obtuvimos dos nuevos cristales moleculares con posibles aplicaciones farmacéuticas: PY1 (timina/ácido gálico/H2O) que cristalizó en un sistema monoclínico y grupo espacial P21/c y PY2 (citosina/ácido gálico) que cristalizó en un sistema monoclínico con grupo espacial P21. La síntesis del compuesto PY2 fue fácilmente reproducible por el método de slurry.This paper presents the study of two new molecular crystals derived from gallic acid and pyrimidines (thymine and cytosine). The compounds obtained were characterized by single-crystal and powder X-ray diffraction, IR spectroscopy and TGA/DSC measurements. The synthesis of molecular crystals was realized by crystallization by evaporation of the solvent and by slurry. The single crystal X-ray crystallographic study revealed that we obtained two new molecular crystals with possible pharmaceutical applications: PY1 (thymine/gallic acid/H2O) that crystallized in a monoclinic system and space group P21/c and PY2 (cytosine/gallic acid) which crystallized in a monoclinic system with space group P21. The synthesis of the compound PY2 was easily reproducible by the slurry method

Synthesis and characterization of AN/EGDMA-based adsorbents for phenol adsorption

"In this work, acrylonitrile (AN)/ethylene glycol dimethacrylate (EGDMA) cross-linked polymeric adsorbents were synthesized by the suspension polymerization method. The adsorbents were prepared varying the EGDMA cross-linker ratio from 100 to 60%. It was found that the swelling factor and the specific surface area changed inversely with the crosslinking degree. In addition, the thermal characterization indicated that polymers stability increased as the crosslinking degree decreased. The polymers were tested as phenol adsorbents and it was found that the higher uptake level was reached when the acrylonitrile concentration increased in the polymer. Adsorption isotherm was determined fitting the Langmuir model, indicating a homogeneous surface of the adsorbents. Moreover, the kinetic studies indicated that the rate controlling step corresponded to the intraparticle diffusion since adsorption is promoted when the adsorbent is swollen"

Phenolic resin-commercial graphite disk preparation: Effect of the resin amount and the thermal treatment on the structural, morphological and mechanical properties

"In this work, macroporous discs were prepared using synthesized phenolic resin (PR) and commercial graphite mixtures (15–40 weight percent). The structure of the PR resin was confirmed by Proton Nuclear Magnetic Resonance and Gas Chromatography Coupled to Mass Spectrometry while the curing temperature was determined by Fourier Transform Infrared Spectroscopy. Also, the surface homogeneity and the structural analysis of the prepared disks were examined by means of scanning electron microscopy and X-ray powder diffraction analysis, respectively. According to the micrographs it was observed that as the PR amount increased disks’ porosity decreased giving rise to homogeneous and smooth surfaces which was explained in terms of the X-ray diffraction analysis that proved that graphite average crystal size (ACS) values decreased progressively with PR amount. Furthermore, it was demonstrated that the mechanical resistance could be tuned with the PR amount and the thermal treatment since as both increased the disks’ hardness augmented"