RESUMEN
Cr2O3 nanoparticles were prepared by solution combustion synthesis (SCS) with chromium nitrate as the precursor and glycine as the fuel. Commercial Cr2O3 and Cr2O3 prepared by a precipitation method were also included for comparison. The morphology, structure, acidity and particle size of fresh and spent Cr2O3 catalysts were investigated by techniques such as XRD, SEM, TEM, BET and NH3-TPD. In addition, catalytic performance was evaluated for the dehydrofluorination of 1,1,1,3,3-pentafluoropropane (CF3CH2CHF2, HFC-245fa) to 1,3,3,3-tetra-fluoropropene (CF3CH=CHF, HFO-1234ze). The catalytic reaction rate of Cr2O3 prepared by SCS method is as high as 6 mmol/h/g, which is about 1.5 times and 2 times higher than that of precipitated Cr2O3 and commercial Cr2O3, respectively. The selectivity to HFO-1234ze for all the catalysts maintains at about 80%. Compared with commercial and precipitated Cr2O3, Cr2O3-SCS prepared by SCS possesses higher specific surface area and acid amount. Furthermore, significant change in the crystal size of Cr2O3 prepared by SCS after reaction was not detected, indicating high resistance to sintering.
Asunto(s)
Compuestos de Cromo/síntesis química , Fluorocarburos/química , Hidrocarburos Fluorados/química , Nanopartículas/química , Catálisis , Halogenación , Concentración de Iones de Hidrógeno , Oxidación-Reducción , Tamaño de la Partícula , Soluciones , Propiedades de SuperficieRESUMEN
Recently, several studies on the effects of a compound named "chromium malate," with the proposed formula "Cr2malate3·xH2O" where x = 3.5 or 5, on the health of healthy and diabetic rats have appeared. However, the compound is poorly characterized, and knowing the identity of this material could be important in the interpretation of the previous and of future studies on the effects of this compound in animals. Consequently, the synthesis, characterization, and identity of this material were explored. A combination of spectroscopic, magnetic, and elemental analyses and mass spectral studies reveal that the compound is probably a polymer, not a discrete molecule, and does not have the composition previously reported. The repeating unit of the polymer possesses an antiferromagnetically coupled trinuclear Cr(III) core. The current study suggests that previous reports on chromium malate and its effects in animals must be viewed with caution.
Asunto(s)
Compuestos de Cromo/análisis , Malatos/análisis , Compuestos de Cromo/síntesis química , Malatos/síntesis química , Espectrometría de Masa por Ionización de Electrospray , EspectrofotometríaRESUMEN
The complex formation between Cr(III) and morin was carried out in methanol and confirmed by analytical characterization using UV-Vis, IR, (1)H NMR, and TG-DTA. UV-Vis shows significant bathochromic shift in benzoyl upon coordination as well as IR well illustrates the peak shift of C=O group and formation of a O-Cr(III) bond. Likewise, (1)H NMR studies clarify that Cr(III) metal ion replaces the 5OH proton hence; 5-hydroxy-4-keto site is employed by morin in chelation to form six-membered stable ring system out of three available chelating sites. In addition, TG-DTA denotes the presence of coordinated and crystalline water molecules. The melting point of the complex was found to be 389 °C by DSC. In addition, Cr(III)-morin complex was found to be a more potent antioxidant than morin as evaluated by DPPH⢠and FRAP methods.
Asunto(s)
Antioxidantes/síntesis química , Compuestos de Cromo/síntesis química , Cromo/química , Complejos de Coordinación/síntesis química , Flavonas/síntesis química , Flavonoides/síntesis química , Antioxidantes/química , Compuestos de Cromo/química , Complejos de Coordinación/química , Flavonas/química , Flavonoides/químicaRESUMEN
Chromium is a common contaminant of soils and aquifers and constitutes a major environmental problem. In nature, chromium usually exists in the form of two oxidation states, trivalent, Cr(III), which is relatively innocuous for biota and for the aquatic environment, and hexavalent, Cr(VI) which is toxic, carcinogenic and very soluble. Accordingly, the majority of wastewater and groundwater treatment technologies, include a stage where Cr(VI) is reduced to Cr(III), in order to remove chromium from the aqueous phase and bind the element in the form of environmentally stable solid compounds. In the absence of iron the final product is typically of the form Cr(OH)3·xH2O whereas in the presence of iron the precipitate is a mixed Fe(1-x)Crx(OH)3 phase. In this study, we report on the synthesis, characterisation and stability of mixed (Fex,Cr1-x)(OH)3 hydroxides as compared to the stability of Cr(OH)3. We established that the plain Cr(III) hydroxide, abiding to the approximate molecular formula Cr(OH)3·3H2O, was crystalline, highly soluble, i.e. unstable, with a tendency to transform into the stable amorphous hydroxide Cr(OH)3(am) phase. Mixed Fe0.75Cr0.25(OH)3 hydroxides were found to be of the ferrihydrite structure, Fe(OH)3, and we correlated their solubility to that of a solid solution formed by plain ferrihydrite and the amorphous Cr(III) hydroxide. Both our experimental results and thermodynamic calculations indicated that mixed Fe(III)-Cr(III) hydroxides are more effective enhancers of groundwater quality, in comparison to the plain amorphous or crystalline Cr(III) hydroxides, the latter found to have a solubility typically higher than 50µg/l (maximum EU permitted Cr level in drinking water), while the amorphous Cr(OH)3(am) phase was within the drinking water threshold in the range 5.7Asunto(s)
Compuestos de Cromo/síntesis química
, Compuestos Férricos/síntesis química
, Contaminación del Agua/prevención & control
RESUMEN
A new series of Cr(III) macrocyclic complexes have been synthesized by template condensation of ligands 2-[4-chloro-2-(2-oxo-1,2-diphenyl-ethylideneamino)-phenylimino]-1,2-diphenyl-ethanone (ML(1)) and 2-[4-fluro-2-(2-oxo-1,2-diphenyl-ethylideneamino)-phenylimino]-1,2-diphenyl-ethanone (ML(2)) respectively, with appropriate diamines i.e. 1,2-phenylenediamine, 4- chloro 1,2-phenylenediamine and 4-fluro- 1,2-phenylenediamine in the presence of CrCl(3).6H(2)O. The ligands and their complexes have been characterized on the basis of elemental analyses, molecular weight determinations, conductance and magnetic susceptibility measurements and spectral studies including IR, ESR, electronic spectra and X-ray powder diffraction studies. On the basis of these studies, a six-coordinated octahedral geometry has been proposed for all these complexes. The newly synthesized ligands and their complexes have been screened for their antimicrobial, nematicidal and pesticidal activities. The results are indeed positive.
Asunto(s)
Antiinfecciosos/síntesis química , Antiinfecciosos/farmacología , Antinematodos/farmacología , Compuestos de Cromo/farmacología , Compuestos Macrocíclicos/síntesis química , Compuestos Macrocíclicos/farmacología , Plaguicidas/farmacología , Animales , Antibacterianos/síntesis química , Antibacterianos/química , Antibacterianos/farmacología , Antinematodos/síntesis química , Antinematodos/química , Bencimidazoles/farmacología , Carbamatos/farmacología , Técnicas de Química Sintética , Compuestos de Cromo/síntesis química , Compuestos de Cromo/química , Evaluación Preclínica de Medicamentos/métodos , Espectroscopía de Resonancia por Spin del Electrón , Ligandos , Compuestos Macrocíclicos/química , Espectroscopía de Resonancia Magnética , Pruebas de Sensibilidad Microbiana , Mariposas Nocturnas/efectos de los fármacos , Plaguicidas/síntesis química , Plaguicidas/química , Fenilendiaminas/química , Espectrofotometría Infrarroja , Estreptomicina/farmacología , Tylenchoidea/efectos de los fármacos , Difracción de Rayos XRESUMEN
The painter, Vincent van Gogh, and some of his contemporaries frequently made use of the pigment chrome yellow that is known to show a tendency toward darkening. This pigment may correspond to various chemical compounds such as PbCrO(4) and PbCr(1-x)S(x)O(4), that may each be present in various crystallographic forms with different tendencies toward degradation. Investigations by X-ray diffraction (XRD), mid-Fourier Transform infrared (FTIR), and Raman instruments (benchtop and portable) and synchrotron radiation-based micro-XRD and X-ray absorption near edge structure spectroscopy performed on oil-paint models, prepared with in-house synthesized PbCrO(4) and PbCr(1-x)S(x)O(4), permitted us to characterize the spectroscopic features of the various forms. On the basis of these results, an extended study has been carried out on historic paint tubes and on embedded paint microsamples taken from yellow-orange/pale yellow areas of 12 Van Gogh paintings, demonstrating that Van Gogh effectively made use of different chrome yellow types. This conclusion was also confirmed by in situ mid-FTIR investigations on Van Gogh's Portrait of Gauguin (Van Gogh Museum, Amsterdam).
Asunto(s)
Antimonio/análisis , Cromatos/análisis , Compuestos de Cromo/análisis , Plomo/análisis , Pinturas , Titanio/análisis , Compuestos de Cromo/síntesis química , Cristalización , Espectroscopía Infrarroja por Transformada de Fourier , Espectrometría Raman , Difracción de Rayos XRESUMEN
Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept.
Asunto(s)
Compuestos de Cromo/síntesis química , Cromo/aislamiento & purificación , Residuos Industriales/prevención & control , Sulfatos/síntesis química , Curtiembre , Cromo/química , Conservación de los Recursos Naturales/métodos , Contaminación Ambiental/prevención & control , IncineraciónRESUMEN
We report eight new A(2)B-type (M(n+)) corrolate compounds (two structural studies) that include the oxo[5,15-bis(pentafluorophenyl)-10-R-corrolatochromium(V)] [R = 2-/3-thienyl (1a/2a), 3-thianaphthyl (3a)] species. The first examples of meso-A(2) (thienyl)- and Cr-A(2)B-corrole types are represented herein. Characterization includes cyclic voltammetry, electron paramagnetic resonance, 2D ((1)H and (13)C) NMR, and UV-vis spectroscopy, mass spectrometry, and elemental analysis. Compounds 1a-3a have enabled analyte binding capacity studies. [Cu(2+)...O=Cr(cor)] binding represents a new selective mode of corrole-based detection, whereas free-base A(2)B-corroles exhibited limited M(n+) selectivity. The 10-position substitution affects optical profiles in analyte titrations. A limited amount of PPh(3) O-atom uptake from [O=Cr(cor)] was also demonstrated.
Asunto(s)
Compuestos de Cromo/química , Porfirinas/química , Catálisis , Compuestos de Cromo/síntesis química , Cristalografía por Rayos X , Electroquímica , Espectroscopía de Resonancia por Spin del Electrón , Metales/química , Modelos Moleculares , Estructura Molecular , Porfirinas/síntesis química , Espectrofotometría UltravioletaRESUMEN
AlPO(4)-5 and its chromium-containing analogue, CrAPO-5, were prepared using aluminum dross in the presence of triethylamine as a structure directing agent; both Al dross powder and an extracted precipitate from Al dross in an alkali solution were used as an aluminum source. These materials were characterized by XRD, BET surface area measurement, SEM, EDX, XRF, ESR, and UV-vis spectroscopy. Their textural properties were found close to those of the corresponding reference samples prepared using pure Al(OH)(3). CrAPO-5 samples prepared from the aluminum dross were tested as a catalyst for liquid phase oxidation of tetralin using t-butyl hydroperoxide as an oxidizing agent, which showed virtually identical catalytic performances to that obtained by a reference CrAPO-5 catalyst.
Asunto(s)
Compuestos de Aluminio/síntesis química , Compuestos de Cromo/síntesis química , Fosfatos/síntesis química , Catálisis , Oxidación-Reducción , Tetrahidronaftalenos/químicaRESUMEN
The reactions of either p-tert-butylcalix[4]areneH(4) [Cax(OH)(4)], 1,3-dimethoxy-p-tert-butylcalix[4]areneH(2) [Cax(OH)(2)(OMe)(2)] or p-tert-butylcalix[6]areneH(6) [Cax[6](OH)(6)] with alkali metal cations and the chromium complexes [CrCl(3)(THF)(3)] or [CrCl(2)(THF)] (THF = tetrahydrofuran) are described. In particular, the treatment of [Cax(OH)(4)] with in situ generated M[Cr(Ot-Bu)(4)] (M = Li or K) affords, after work-up, the complex {[CrCax(O)(4)(NCMe)](2)[Li(THF)](2)[Li(NCMe)](2)Cl(2)(micro(4)-O)}.2.25(MeCN) and two forms of {K(MeCN)(x)[CrCax(O)(4)(NCMe)][CrCax(OH)(O)(3)(NCMe)]}.MeCN (x = 3 or 4) , respectively. The potassium salt of [Cax(OH)(4)] reacts with [CrCl(2)(THF)] to afford a highly sensitive complex, which on exposure to air gives rise to the compound {[CrCax(O)(4)K(THF)(2)](2)H(micro-O)(H(2)O)K(THF)(H(2)O)(micro-THF)}(2).6THF , that possesses four chromium calixarene units, two sets of K(+) ions that are coordinated in two very different environments together with terminal and bridging THF ligands. The reaction of n-BuLi with [Cax(OH)(4)], followed by the addition of [CrCl(3)(THF)(3)] affords, after work-up, the complex {Cr[micro-Cax(OH)(O)(3)](NCMe)}(2).4Me(2)C[double bond, length as m-dash]O.0.5H(2)O (). Complex is also available via the hydrolysis of complex . Interaction of [Cax(OH)(2)(OMe)(2)] with NaH or n-BuLi in THF affords, following the addition of [CrCl(3)(THF)(3)], the demethylated dimer {Cr[micro-Cax(OH)(O)(3)](NCMe)}(2).4MeCN (), which is a different solvate of , or the monomeric salt {Cax(O)(2)(OMe)(2)CrCl(2)[Li(NCMe)(2)]}.2MeCN (), respectively. The reaction of 1,3-dipropoxy-p-tert-butylcalix[4]areneH(2), [Cax(OH)(2)(On-Pr)(2)], with n-BuLi followed by [CrCl(3)(THF)(3)] affords the monomeric complex [CrCl(2)Cax(O)(2)(On-Pr)(2)Li(NCMe)(2)].3MeCN (). Interaction of the mono-methoxy ligand [Cax(OH)(3)(OMe)] with n-BuLi in diethyl ether followed by addition of [CrCl(3)(THF)(3)] in THF affords, upon work-up, the complex [CrCax(OMe)(O)(3)(NCMe)](2).MeCN (). Interaction of p-tert-butylcalix[6]areneH(6) [Cax[6](OH)(6)] with Na[Cr(Ot-Bu)(4)] (formed in situ from [CrCl(3)(THF)(3)] and excess NaOt-Bu) affords the complex {CrCax[6](O)(3)(OH)(3)Na(NCMe)(2)(micro-OH)}(2).4MeCN (). Complexes - have been structurally characterised; for and , it was necessary to use synchrotron radiation. Screening of - for ethylene polymerisation using either methylaluminoxane (MAO) or dimethylaluminium chloride (DMAC) as co-catalyst afforded only very poor catalytic activities (Asunto(s)
Calixarenos/química
, Compuestos de Cromo/química
, Compuestos de Cromo/síntesis química
, Cristalografía por Rayos X
, Modelos Químicos
, Estructura Molecular
RESUMEN
We synthesized the chromium (phenylalanine)(3) [Cr(D-phe)(3)] by chelating chromium(III) with D-phenylalanine ligand in aqueous solution to improve the bioavailability of chromium, and reported that Cr(D-phe)(3) improved insulin sensitivity. AMP-activated protein kinase (AMPK) is a key mediator for glucose uptake and insulin sensitivity. To address the molecular mechanisms by which Cr(d-phe)(3) increases insulin sensitivity, we investigated whether Cr(D-phe)(3) stimulates glucose uptake via activation of AMPK signaling pathway. H9c2 myoblasts and isolated cardiomyocytes were treated with Cr(D-phe)(3) (25microM). Western blotting was used for signaling determination. The glucose uptake was determined by 2-deoxy-D-glucose-(3)H accumulation. HPLC measured concentrations of AMP. The mitochondrial membrane potential (Deltapsi) was detected by JC-1 fluorescence assay. Cr(D-phe)(3) stimulated the phosphorylation of alpha catalytic subunit of AMPK at Thr(172), as well the downstream targets of AMPK, acetyl-CoA carboxylase (ACC, Ser(212)) and eNOS (Ser(1177)). Moreover, Cr(D-phe)(3) significantly stimulated glucose uptake in both H9c2 cells and cardiomyocytes. AMPK inhibitor compound C (10microM) dramatically inhibited the glucose uptake stimulated by Cr(D-phe)(3), while it did not affect insulin stimulation of glucose uptake. Furthermore, in vivo studies showed that Cr(D-phe)(3) also activated cardiac AMPK signaling pathway. The increase of cardiac AMP concentration and the decrease of mitochondrial membrane potential (Deltapsi) may contribute to the activation of AMPK induced by Cr(D-phe)(3). Cr(D-phe)(3) is a novel compound that activates AMPK signaling pathway, which contributes to the regulation of glucose transport during stress conditions that may be associated the role of AMPK in increasing insulin sensitivity.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Compuestos de Cromo/farmacología , Glucosa/metabolismo , Compuestos Organometálicos/farmacología , Fenilalanina/análogos & derivados , Animales , Transporte Biológico Activo/efectos de los fármacos , Transporte Biológico Activo/fisiología , Línea Celular , Compuestos de Cromo/síntesis química , Activación Enzimática/efectos de los fármacos , Activación Enzimática/fisiología , Resistencia a la Insulina/fisiología , Ratones , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Compuestos Organometálicos/síntesis química , Fenilalanina/síntesis química , Fenilalanina/farmacología , Ratas , Transducción de Señal/efectos de los fármacos , Transducción de Señal/fisiologíaRESUMEN
A hydrogen reduction and activated sintering process was proposed to prepare chromic oxide green pigment. Through ICP, XRD, SEM, FT-IR, UV, and CIE-L*a*b* colorimetric analysis, key factors and mechanism that influenced preparation of chromic oxide green pigment were studied. The results revealed that lower hydrogen reduction temperature, suitable addition of Al and Ba, were beneficial to obtaining the high quality chromic oxide green pigment. Typically, when the hydrogen reduction temperature was kept at 450-500 degrees C, physicochemical properties and color performance of the prepared chromic oxide green pigment doped with about 0.1-0.2 wt % Al and 0.2-0.5 wt % Ba conformed to commercial pigment standards. Additionally, characteristics of the green process were discussed. About 90 wt % KOH was reused directly and about 90 wt % Cr(VI) was conversed to Cr(III) directly from potassium chromate to chromic oxide green pigment. Integrating the proprietary green metallurgical process from chromite ore to potassium chromate of this laboratory, more than 99 wt % Cr(VI) could be conversed to Cr(III) compounds and about 99 wt % KOH could be recycled to use. The whole green process, ranging from chromite ore to chromic oxide green pigment, eventually not only provided the possibility for producing the high quality chromic oxide green pigment, but could reach comprehensive utilization of resources, inner recycle of KOH, and zero emission of Cr(VI).
Asunto(s)
Química Inorgánica/métodos , Compuestos de Cromo/síntesis química , Colorantes/síntesis química , Rastreo Diferencial de Calorimetría , Compuestos de Cromo/química , Colorantes/química , Electrones , Hidrógeno/química , Microscopía Electrónica de Rastreo , Oxidación-Reducción , Espectrofotometría Ultravioleta , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Difracción de Rayos XRESUMEN
Chromium (Cr) is a cytotoxic metal that can be associated with a variety of types of DNA damage, including Cr-DNA adducts and strand breaks. Prior studies with purified human cytochrome b(5) and NADPH:P450 reductase in reconstituted proteoliposomes (PLs) demonstrated rapid reduction of Cr(VI) (hexavalent chromium, as CrO(4)(2-), and the generation of Cr(V), superoxide (O(2)(*-)), and hydroxyl radical (HO(*)). Studies reported here examined the potential for the species produced by this system to interact with DNA. Strand breaks of purified plasmid DNA increased over time aerobically, but were not observed in the absence of O(2). Cr(V) is formed under both conditions, so the breaks are not mediated directly by Cr(V). The aerobic strand breaks were significantly prevented by catalase and EtOH, but not by the metal chelator diethylenetriaminepentaacetic acid (DTPA), suggesting that they are largely due to HO(*) from Cr-mediated redox cycling. EPR was used to assess the formation of Cr-DNA complexes. Following a 10-min incubation of PLs, CrO(4)(2-), and plasmid DNA, intense EPR signals at g=5.7 and g=5.0 were observed. These signals are attributed to specific Cr(III) complexes with large zero field splitting (ZFS). Without DNA, the signals in the g=5 region were weak. The large ZFS signals were not seen, when Cr(III)Cl(3) was incubated with DNA, suggesting that the Cr(III)-DNA interactions are different when generated by the PLs. After 24 h, a broad signal at g=2 is attributed to Cr(III) complexes with a small ZFS. This g=2 signal was observed without DNA, but it was different from that seen with plasmid. It is concluded that EPR can detect specific Cr(III) complexes that depend on the presence of plasmid DNA and the manner in which the Cr(III) is formed.
Asunto(s)
Compuestos de Cromo/química , Citocromos b5/química , Roturas del ADN de Doble Cadena , Proteolípidos/química , Compuestos de Cromo/síntesis química , ADN Bacteriano/química , Escherichia coli/química , Humanos , Radical Hidroxilo/síntesis química , Radical Hidroxilo/química , NADPH-Ferrihemoproteína Reductasa/química , Oxidación-Reducción , Superóxidos/síntesis química , Superóxidos/química , Factores de TiempoRESUMEN
We investigated the influence of a substituent and a Lewis base on boron upon the thermodynamic stability of metal complexes of borane-Lewis base adducts, [M(CO)5(eta1-BH(2)R.L)] (M=Cr, W) and [CpMn(CO)2(eta1-BH2R.L)], where R=Cl, I, m-C6H4F, Ph, H, Me, Et; L=PMe3, PPh3, NMe3, quinuclidine. In these compounds, the stability of the metal-borane linkage was enhanced by increasing the electron-releasing ability of the substituent on boron. A stronger base L additionally stabilized the complexes. The strength of the borane-metal interaction is thus mainly ascribed to the electron donation from the BH sigma orbital to metal rather than the back-donation into the BH sigma* orbital. This result supports the bonding model for the B-H-M linkage in the borane complexes suggested by MO calculations, where the borane-to-metal electron donation is predominant while the metal back-donation into the BH sigma* orbital is negligible. Such a stability trend of the borane complexes makes a sharp contrast to that of many silane and dihydrogen complexes.
Asunto(s)
Aminas/química , Boranos/química , Boro/química , Monóxido de Carbono/química , Compuestos de Cromo/química , Hidrógeno/química , Fosfinas/química , Boranos/síntesis química , Compuestos de Cromo/síntesis química , Concentración de Iones de Hidrógeno , Espectroscopía de Resonancia Magnética , Compuestos de Manganeso/síntesis química , Compuestos de Manganeso/química , Modelos Moleculares , Conformación Molecular , Protones , Temperatura , TermodinámicaRESUMEN
Two chromium(III) complexes of glucosaminic acid were synthesized by neutralization and exchange reaction. The formation of 1 : 1 and 2 : 3 (Cr : glucosaminate) complexes was confirmed by elemental analyses and spectroscopic studies. The effect of the complexes on decreasing blood sugar was investigated on type-2 diabetes model rats induced by tetraoxypyrimidine. The results indicated that the effect on decreasing blood sugar was comparable to that of picolinate chromium complex (Cr(pic)(3)) currently used world wide.
Asunto(s)
Glucemia/metabolismo , Compuestos de Cromo/farmacología , Glucosamina/análogos & derivados , Aloxano/toxicidad , Animales , Compuestos de Cromo/síntesis química , Compuestos de Cromo/química , Diabetes Mellitus Experimental/sangre , Diabetes Mellitus Experimental/inducido químicamente , Diabetes Mellitus Experimental/tratamiento farmacológico , Modelos Animales de Enfermedad , Glucosamina/síntesis química , Glucosamina/química , Glucosamina/farmacología , Masculino , Ácidos Picolínicos/síntesis química , Ácidos Picolínicos/química , Ácidos Picolínicos/farmacología , RatasRESUMEN
The reaction of [Cr(urea)(6)]Cl(3).3H(2)O with H(2)salen (H(2)salen=N,N(')-ethylenebis(salicylaldimine) in water-methanol mixture (40:60v/v) under reflux yielded the complex bis[N-(2-aminoethyl)salicylaldiminato]chromium(III) chloride monohydrate, [Cr(aesaldmn)(2)]Cl.H(2)O. The complex was characterized by elemental analysis, molar conductance, magnetic susceptibility, spectroscopic (UV-vis and IR) data and X-ray diffraction studies. The new ligand, N-(2-aminoethyl)salicylaldimine, Haesaldmn, possibly resulted from the hydrolytic cleavage of one end of the H(2)salen ligand during reflux. Binding of this chromium(III) complex to CT DNA has been studied using UV-vis spectroscopy with an apparent binding constant of 2.68 x 10(3)M(-1). It shows that the binding mode is electrostatic while the emission of ethidium bromide to CT DNA in the absence and in the presence of the complex show that it binds DNA with partial intercalation.
Asunto(s)
Compuestos de Cromo/química , ADN/química , Compuestos Organometálicos/química , Compuestos de Cromo/síntesis química , Cristalografía , Desnaturalización de Ácido Nucleico , Compuestos Organometálicos/síntesis química , Espectrofotometría Infrarroja , Espectrofotometría Ultravioleta , Electricidad Estática , Difracción de Rayos XRESUMEN
Mesoporous chromium oxide (Cr2O3) nanocrystals were first synthesized by the thermal decomposition reaction of Cr(NO3)3.9H2O using citric acid monohydrate (CA) as the mesoporous template agent. The texture and chemistry of chromium oxide nanocrystals were characterized by N2 adsorption-desorption isotherms, FTIR, X-ray diffraction (XRD), UV-vis, and thermoanalytical methods. It was shown that the hydrate water and CA are the crucial factors in influencing the formation of mesoporous Cr2O3 nanocrystals in the mixture system. The decomposition of CA results in the formation of a mesoporous structure with wormlike pores. The hydrate water of the mixture provides surface hydroxyls that act as binders, making the nanocrystals aggregate. The pore structures and phases of chromium oxide are affected by the ratio of precursor-to-CA, thermal temperature, and time.
Asunto(s)
Compuestos de Cromo/química , Compuestos de Cromo/síntesis química , Nanoestructuras/química , Temperatura , Tamaño de la Partícula , Sensibilidad y Especificidad , Espectrofotometría Ultravioleta/métodos , Espectroscopía Infrarroja por Transformada de Fourier/métodos , Propiedades de Superficie , Difracción de Rayos XRESUMEN
Two Anderson-type heteropolyanion-supported copper phenanthroline complexes, [Al(OH)6Mo6O18[Cu(phen)(H2O)2]2]1+ (1c) and [Al(OH)6Mo6O18[Cu(phen)(H2O)Cl]2]1- (1a) complement their charges in one of the title compounds [Al(OH)6Mo6O18[Cu(phen)(H2O)2]2][Al(OH)6Mo6O18[Cu(phen)(H2O)Cl]2].5H2O [1c][1a].5 H2O 1. Similar charge complementarity exists in the chromium analogue, [Cr(OH)6Mo6O18[Cu(phen)(H2O)2]2][Cr(OH)6Mo6O18[Cu(phen)(H2O)Cl]2].5 H2O [2c][2a].5 H2O 2. The chloride coordination to copper centers of 1a and 2a makes the charge difference. In both compounds, the geometries around copper centers are distorted square pyramidal and those around aluminum/chromium centers are distorted octahedral. Three lattice waters, from the formation of intermolecular O-H.....O hydrogen bonds, have been shown to self-assemble into an "acyclic water trimer" in the crystals of both 1 and 2. The title compounds have been synthesized in a simple one pot aqueous wet-synthesis consisting of aluminum/chromium chloride, sodium molybdate, copper nitrate, phenanthroline, and hydrochloric acid, and characterized by elemental analyses, EDAX, IR, diffuse reflectance, EPR, TGA, and single-crystal X-ray diffraction. Both compounds crystallize in the triclinic space group P. Crystal data for 1: a = 10.7618(6), b = 15.0238(8), c = 15.6648(8) angstroms, alpha = 65.4570(10), beta = 83.4420(10), gamma = 71.3230(10), V = 2182.1(2) angstroms3. Crystal data for 2: a = 10.8867(5), b = 15.2504(7), c = 15.7022(7) angstroms, alpha = 64.9850(10), beta = 83.0430(10), gamma = 71.1570(10), V = 2235.47(18) angstroms3. In the electronic reflectance spectra, compounds 1 and 2 exhibit a broad d-d band at approximately 700 nm, which is a considerable shift with respect to the value of 650-660 nm for a square-pyramidal [Cu(phen)2L] complex, indicating the coordination of [M(OH)6Mo6O18]3- POM anions (as a ligand) to the monophenanthroline copper complexes to form POM-supported copper complexes 1c, 1a, 2c, and 2a. The ESR spectrum of compound 1 shows a typical axial signal for a Cu2+ (d9) system, and that of compound 2, containing both chromium(III) and copper(II) ions, may reveal a zero-field-splitting of the central Cr3+ ion of the Anderson anion, [Cr(OH)6Mo6O18]3-, with an intense peak for the Cu2+ ion.
Asunto(s)
Química Inorgánica/métodos , Metales/química , Modelos Moleculares , Cloruro de Aluminio , Compuestos de Aluminio/síntesis química , Compuestos de Aluminio/química , Cloruros/síntesis química , Cloruros/química , Compuestos de Cromo/síntesis química , Compuestos de Cromo/química , Cobre/química , Cristalografía por Rayos X/métodos , Espectroscopía de Resonancia por Spin del Electrón , Ácido Clorhídrico/química , Estructura Molecular , Molibdeno/química , Fenantrolinas/química , AguaRESUMEN
The divalent metal ion sorption (Cu(2+), Cd(2+), Ni(2+), and Pb(2+)) on chromium phosphate (CrPO(4)) was studied as a function of pH, temperature, and concentration of metal ions. The sorption of metal ions is observed to increase with the increase in pH, temperature, and concentration of metal ions in solution. The mechanism of sorption is found to be the exchange of the hydrolyzed metal cations with the protons from solid at high temperature. The sorption at low temperature is found to be accompanied by the precipitation of the corresponding metal phosphates such as Pb(3)(PO(4))(2).
Asunto(s)
Compuestos de Cromo/química , Metales Pesados/química , Fosfatos/química , Adsorción , Compuestos de Cromo/síntesis química , Concentración de Iones de Hidrógeno , Fosfatos/síntesis química , Potenciometría , Sensibilidad y Especificidad , Propiedades de Superficie , Temperatura , VolumetríaRESUMEN
We discuss two complexes of Cr(4+) for their possible utility as models for Cr toxicity studies. They are Cr(dien)(O2)2(.)H2O (dien = diethylenetriamine) and Cr(NH3)3(O2)2, which have been recently characterized by x-ray diffraction and magnetic techniques. We present their optical and infrared absorption spectra as quick aids in their identification procedure. We also summarize the general properties of some well-characterized Cr(5+) compounds. All of these compounds are water soluble with the Cr(5+) samples being fairly stable in basic solutions. They can all be prepared as pure crystals with a shelf life of over 2 years when stored in a refrigerator.