Cadmium—1,4-cyclohexanedicarboxylato coordination polymers bearing different di-alkyl-2,2’-bipyridines: syntheses, crystal structures and photoluminescence studies

Cadmium–1,4-cyclohexanedicarboxylato coordination polymers bearing different di-alkyl-2,2′-bipyridines: syntheses, crystal structures and photoluminescence studiesFour coordination polymers have been synthesized using self-assembly solution reactions under ambient conditions, reacting Cd(II) ions with 1,4-cyclohexanedicarboxylic acid in the presence of different 2,2′-bipyridine co-ligands: {[Cd(H2O)(e,a-cis-1,4-chdc)(2,2′-bpy)]·H2O}n (1); [Cd2(H2O)2(e,a-cis-1,4-chdc)2(4,4′-dmb)2]n (2); {[Cd(e,a-cis-1,4-chdc)(5,5′-dmb)]·H2O·CH3OH}n (3) and {[Cd(e,e-trans-1,4-chdc)(4,4′-dtbb)]·CH3OH}n (4), where 1,4-chdc = 1,4-cyclohexanedicarboxylato, 2,2′-bpy = 2,2′-bipyridine, 4,4′-dmb = 4,4′-dimethyl-2,2′-bipyridine, 5,5′-dmb = 5,5′-dimethyl-2,2′-bipyridine and 4,4′-dtbb = 4,4′-di-tert-butyl-2,2′-bipyridine. Crystallographic studies show that compound 1 has a 1D structure propagating along the crystallographic b-axis; the Cd ion in 1 is six-coordinated with a distorted-octahedral coordination sphere. Compound 2 has two crystallographic different Cd ions and both are six-coordinated with a distorted-octahedral coordination sphere. Compound 3 exhibits a seven-coordinated Cd ion having a distinctive distorted-monocapped trigonal prismatic geometry. In compound 4, the Cd ion is also seven-coordinated in a distorted monocapped octahedral geometry. Compounds 2, 3 and 4 possess rhombic-shaped dinuclear units (Cd2O2) as nodes to generate larger cycles made up of four dinuclear units, a Cd4 motif, bridged by four 1,4-chdc ligands, accomplishing, thus, 2D structures. Remarkably, in compound 4 the 1,4-chdc ligand conformation changes to the equatorial, equatorial trans, unlike the other compounds where the bridging ligand conformation is the more typical equatorial, axial cis. The solid state luminescence properties of 1–4 were investigated; polymers 3 and 4 exhibited a strong blue emission (λem = 410–414 nm) compared to 1 and 2; structure-related photoluminescence is attributed to the degree of hydration of the compounds. Furthermore, Cd-polymer 3 suspended in acetone allows the fluorescence selective sensing of acetonitrile over common organic solvents such as alcohols and DMF, based on turn-on fluorescence intensity with a limit of 53 μmol L−1.CONACYT; UNA

ESTUDIO DE POLÍMEROS POROSOS SINTETIZADOS POR PLASMA

Se presenta un estudio sobre la síntesis y procesamiento por plasma para la obtención de copolímeros porosos basados en pirrol, alilamina y etilenglicol. El objetivo es determinar las condiciones de síntesis a las que se producen mayor cantidad de poros en el copolímero. Estos materiales se copolimerizaron por medio de descargas luminiscentes en un reactor tubular de vidrio a 10-1 mbar y 40- 100 W utilizando yodo como dopante

New CaO-based adsorbents prepared by solution combustion and high-energy ball-milling processes for CO2 adsorption: Textural and structural influences

New CaO-based adsorbents prepared by solution combustion and high-energy ball-milling processes for CO2 adsorption: Textural and structural influencesIn the present work, new CaO-based adsorbents were obtained by a fast solution combustion method and high-energy ball-milling process to study their CO2 capture behavior under different moderate pressure and temperature conditions. The as-prepared CaO products were characterized systematically using different analytical techniques such as X-ray diffraction, scanning electron microscopy and N2 physisorption measurements. The results showed that the CaO prepared by solution combustion and ball-milled during 2.5 h showed the maximum CO2 adsorption capacity of 9.31 mmol/g at 25 C and 1 atm mainly via chemisorption with CaCO3 formation, which was corroborated by infrared spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy studies. In general, the obtained results revealed that the synthesized CaO nanopowders from solution combustion that were treated by high-energy ball-milling enhanced their CO2 adsorption capacity due to improved structural and textural properties, and this CaO-based adsorbent can be used as a promising material for CO2 capture in post-combustion CO2 capture technologies on a large scale, under atmospheric pressure and temperature conditions

MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance

MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performanceA series ofMgO-based adsorbents were prepared through solution–combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N2 physisorptionmeasurements, and employed as potential adsorbents for CO2 adsorption. The influence of structural and textural properties of these adsorbents over the CO2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution–combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5 hr (MgO-BM2.5h), exhibited the maximum CO2adsorption capacity of 1.611 mmol/g at 25°C and 1 atm, mainly via chemisorption. The CO2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO2 adsorption–desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution–combustion and treated by ball-milling during 2.5 hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO2 capture technologies

Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutions

Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutionsRemoval potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMABr) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8 h) than materials with BODA (10 and 12 h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The qmax is greater for materials modified with BODA (0.9232 and 4.2448 mg/g) than for materials modified with HDTMA (0.6731 and 3.9121 mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process

Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutions

Influence of the chain length of surfactant in the modification of zeolites and clays. Removal of atrazine from water solutionsRemoval potentials of a surfactant modified zeolite (SMZ) and clay (SMC) for atrazine adsorption were evaluated. Materials were modified with hexadecyl trimethyl ammonium bromide (HDTMABr) and benzyl octadecyl dimethyl ammonium (BODA) chloride considering the critical micellar concentration (CMC) of each one (0.94 and 0.041 meq/L, respectively). The influence of the surfactant was analyzed in detail, particularly the formation of surfactant layers (complete or partial) connected with the length of the surfactant tail (16 and 18 methyl groups or number of carbons in the chain). Raw materials were characterized by XRD and Fourier transform infrared spectroscopy (FTIR), SMZ and SMC were analyzed by FTIR. Results obtained from kinetic adsorption experiments shown that equilibrium time is less for materials modified with HDTMA (8 h) than materials with BODA (10 and 12 h). Materials modified with the largest chain surfactant (BODA) showed more resistance to atrazine masse transference. The chemisorption was presented in the adsorption mechanisms of atrazine and adsorbent materials. Based on the results of adsorption isotherms Langmuir isotherms showed the better correlation coefficients value. The qmax is greater for materials modified with BODA (0.9232 and 4.2448 mg/g) than for materials modified with HDTMA (0.6731 and 3.9121 mg/g). Therefore, SMZ and SMC modified with the largest chain surfactant has more affinity for the pesticide. The removal process at high concentration of atrazine depends of the partition process but at lower concentration, it occurs not only by this process but also by absorption process

Dinuclear Co(II)‑Muconate Complex Displaying Distorted‑TrigonalPrismatic Geometry, 2D Supramolecular Array and Weak Antiferromagnetism

Influence of the 2D supramolecular array in the distorted trigonal prismatic geometry of a dinuclear Co(II)-muconate complex exhibiting weak antiferromagnetic exchange.Dinuclear complex [ Co2(H2O)4(dmb)2(muc)][muc] (1) (muc = muconate; dmb = 5,5′-dimethyl-2,2′-bipyridine), was obtained by self-assembly solution reaction, under ambient conditions, and it was structurally characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. The complex 1 crystallizes in the monoclinic system in the C2/c space group. Noticeably, the six-coordinated Co(II) centers display a distorted-trigonal prismatic configuration. This uncommon coordination geometry is attained due to the hydrogen bonding interactions of the crystalline structure of 1, yielding thus a 2D supramolecular array. Magnetic properties measurements reveal that metaprism 1 exhibits weak antiferromagnetic ordering with θ(C-W) = -14.4 K and an E2 = 0.032 cm− 1 accordingly to Curie–Weiss model and Rueff phenomenological approach, respectively.Universidad Autónoma del Estado de México Universidad Nacional Autónoma de Méxic

Reporte del monitoreo ambiental en el marco de la supervisión regular de la Coordinación de Hidrocarburos realizado del 17 al 20 de junio de 2014, en la empresa Vopak Perú S.A., en el distrito Callao, provincia Callao, región Callao.

Presenta el reporte del monitoreo ambiental de efluente y suelo en el marco de la supervisión regular de la Coordinación de Hidrocarburos, realizado en las instalaciones de la empresa Vopak Perú S. A., ubicada en el distrito Callao, provincia Callao, región Callao, del 17 al 20 de junio de 2014. Se aplicó para el monitoreo de efluentes el "Protocolo de Monitoreo de la Calidad en Agua", en concordancia con el Decreto Supremo No 046-93-EM "Reglamento para la Protección Ambiental en las Actividades de Hidrocarburos". Esta ficha no incluye los resultados analíticos del monitoreo ambiental. Contiene los siguientes anexos: copia de certificado de calibración de equipo, copia de cadena de custodia con sello de recepción del laboratorio, registro fotográfico y mapa de ubicación de puntos de monitoreo

Biogenic Silver Nanoparticles as Sensors of Cu2+ and Pb2+ in Aqueous Solutions

Biogenic Silver Nanoparticles as Sensors of Cu2+ and Pb2+ in Aqueous SolutionsSilver nanoparticles (Ag-NPs) were bio-synthesized using Camellia sinensis (green tea) aqueous extract. Nanoparticles prepared with 10-3 M AgNO3 solution, using 3mL of green tea extract and at 60˚C, have spherical shape with a mean diameter of 7nm. The formation of the nanoparticles was confirmed by UV-Vis spectrophotometry through studies of the surface plasmon resonance (SPR). The morphology, size and crystalline structure of the Ag-NPs were determined using high definition transmission electron microscopy (TEM). Moreover, these green synthesized Ag-NPs were found to exhibit good sensing properties towards Cu2+ and Pb2+ ions in aqueous solutions. This metal ions-sensing ability of the biogenic Ag-NPs was monitored by UV-Vis spectrophotometry (SPR analyses) and fluorescence spectroscopy

Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM

Se describe brevemente el origen del Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM (CCIQS). Se presentan principalmente las actividades científicas que se desarrollan en este centro relacionadas con la nanociencia y la nanotecnología (NyN), y a los investigadores responsables de las mismas. Además, se relata de manera sucinta la importancia de la formación de recursos humanos a través de los programas de licenciatura y posgrado de la Facultad de Química de la UAEM