A comprehensive study of the K
2
Mn(SO
4
)
2
(H
2
O)
2
double salt crystal with a kröhnkite-type framework is presented. Structural, morphological, thermal, vibrational, and optical properties have ...been explored and discussed. Moreover, calculations based on the density-functional perturbation theory were performed to accurately analyze inter- and intra-molecular vibrational modes, presenting 111 optical phonon modes in the spectral region of 50–3650 cm
−1
. The X-ray diffraction studies confirmed that the K
2
Mn(SO
4
)
2
(H
2
O)
2
system crystallizes in triclinic symmetry with
P
1
¯
(
C
i
1
) space group. In addition, the crystal was thermally stable from 300 K up to near 360 K and has an optical band gap of 5.78 eV, typical of insulating material. Nevertheless, when optically excited at 3.1 eV (at 400 nm),
i
.
e
., resonantly with the
6
A
1g
(S) →
4
A
1g
(G),
4
E
g
(G) electronic transition of Mn
2+
ion, a dual-emission was detected: green–yellow (≈ 562 nm) and orange (≈ 598 nm—more intense emission), both corresponding to
4
T
1g
(G) →
6
A
1g
(S) de-excitation. The dual behavior is due to the two different Mn
2+
luminescent species occupying slightly distorted octahedral (orange emission) and tetrahedral (green–yellow emission) sites. From the optical spectrum and Tanabe-Sugano diagram, the crystal-field strength and the Racah interelectronic-repulsion parameters were also estimated. The findings suggest that changes in the Mn coordination number (four- and six-fold) and in the crystalline field, the latter either by adequate doping or by the growth of mixed crystals, could lead to a tuning of the wavelength of the emitted light (from green to deep red).
Graphical abstract
We evaluated the antimicrobial activity and some mechanisms used by subinhibitory and inhibitory concentrations of the essential oil, obtained from leaves of Plectranthus amboinicus, against a ...standard strain of Klebsiella pneumoniae and 5 multiresistant clinical isolates of the bacteria. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), the rate of kill and the pH sensitivity of the essential oil were determined by microdilution tests performed in 96-well plates. Subinhibitory and inhibitory concentrations of the essential oil were tested in order to check its action on K. pneumoniae membrane permeability, capsule expression, urease activity and cell morphology. The MIC and MBC of the essential oil were 0.09±0.01%. A complete inhibition of the bacterial growth was observed after 2h of incubation with twice the MIC of the essential oil. A better MIC was found when neutral or alkaline pH broth was used. Alteration in membrane permeability was found by the increase of crystal violet uptake when the bacteria were incubated with twice the MIC levels of the essential oil. The urease activity could be prevented when all the subinhibitory concentrations were tested in comparison to the untreated group (p<0.001). Alteration of the bacterial morphology besides inhibition of the capsule expression was verified by atomic force microscopy, and Anthony's stain method, respectively. Our data allow us to conclude that the essential oil of P. amboinicus can be a good candidate for future research.
The synthesis of a new tetrabromobacteriochlorin BCBr4 is reported having the 3,4-dibromo-1H-pyrrole-2-carbaldehyde (10) as the major precursor. The BCBr4 was successfully employed in Pd ...cross-coupling reactions with methyl acrylate, phenyl acetylene and 4-ethynylanisole. In all three cases, the desired tetra-coupled products were obtained in good to excellent yields, and present a significant red shift in the UV-Vis bands above 800 nm. DFT and TD-DFT theoretical analyses of the NIR bacteriochlorin chromophores were performed in order to evaluate the effect of β substitution on their electronic structures.
•Dispersed metal nanoparticles synthesized by functionalization of complex on SBA-15.•The growth of Ru, Cu, Zn or Co nanocrystals oxides onto SBA-15 was observed.•Solids highly actives for ...1-hydroxyacetone production.•RuO2 or Co3O4 on SBA-15 achieved best results due to the sites strengths in limiting their deactivation by sintering.
Metal oxides nanoparticles dispersed on SBA-15 were synthesized by functionalization of metalloporphyrins onto modified SBA-15, for confining the growth of Ru, Cu, Zn or Co oxides nanocrystals. The composites were evaluated in the dehydration of glycerol at 250°C and 1atm. Among the solids studied, best results were achieved for RuSBA-15 and CoSBA-15 due to the resistance shown by nanoparticles to sintering. On the other hand, ZnSBA-15 and CuSBA-15, which possessed a lesser basic strength, led to parallel reaction instead of the dehydration of glycerol, by forming heavy compounds; this resulted in the catalysts deactivation by coking.
•HAP with low copper contents showed elevated selectivity to 1-hydroxyacetone.•HAPs possessing cobalt were selective to 1-hydroxyacetone and light products.•Mesoporous HAPs had the characteristic ...hydroxyapatite and monetite phases independently of the cobalt contents.•Increased copper contents resulted in the libethenite phase formation.
Calcium hydroxyapatites (HAP) containing cobalt or copper were synthesized and catalytically evaluated in the dehydration of glycerol for valuable chemical intermediates production. The solids were characterized by chemical analysis, X-ray diffraction (XRD), Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM-EDS), acid-base measurements, Raman spectroscopy and nitrogen adsorption–desorption isotherms. Cobalt-containing HAPs had the characteristic hydroxyapatite (Ca10−x(HPO4)(PO4)6−x(OH)2−xx(H2O)x) and monetite Ca(HPO4) phases, independently of the cobalt contents, being mesoporous materials. This was proven to be due to Ca2+ ions replaced by Co2+ ones in HAP structure; since the cobalt amount increased, a dispersion of nanosized cobalt species was suggested. Copper-containing hydroxyapatites showed the HAP and monetite phases. Increased copper contents provided the ionic exchange of Ca2+ by Cu2+ and resulted in the libethenite (Cu2(OH)(PO4)) phase formation as well as the deposition of CuO on solid surface. These solids possessing distinct morphologies had micro and mesopores and preserved the HAP and monetite phases, even increasing the copper content. The catalytic evaluation in the dehydration of glycerol was dependent on the content of the metals as well as the nature of the active phase. Generally, copper-containing samples were more active than those possessing cobalt, probably due to the either stable libethenite phase presence or great acidity of the formers. The catalytic performance of the solids with low copper contents showed the elevated selectivity to 1-hydroxyacetone and products from its dimerization–cyclysation reactions whereas samples possessing cobalt were selective to 1-hydroxyacetone and light products.
Power transformers are essential components in electrical energy distribution. One of their most important parts is the insulation system, consisting of Kraft paper immersed in insulating oil. ...Interfacial tension and color are major parameters used for assessing oil quality and the system׳s degradation. This work proposes the use of near infrared (NIR), molecular fluorescence, and 1H nuclear magnetic resonance (NMR) spectroscopy methods combined with chemometric multivariate calibration methods (Partial Least Squares – PLS) to predict interfacial tension and color in insulating mineral oil samples. Interfacial tension and color were also determined using tensiometry and colorimetry as standard reference methods, respectively. The best PLS model was obtained when NIR, fluorescence, and NMR data were combined (data fusion), demonstrating synergy among them. An optimal PLS model was calculated using the selected group of variables according to their importance on PLS projections (VIP). The root mean square errors of prediction (RMSEP) values of 2.9mNm−1 and 0.3 were estimated for interfacial tension and color, respectively. Mean relative standard deviations of 1.5% for interfacial tension and 6% for color were registered, meeting quality control requirements set by electrical energy companies. The methods proposed in this work are rapid and simple, showing great advantages over traditional approaches, which are slow and environmentally unfriendly due to chemical waste generation.
Display omitted
•NIR, Fluorescence, and 1H NMR spectra of 100 insulating mineral oil samples were obtained.•NMR PLS model results are similar to the NIR models for color prediction.•Data fusion combined with PLS provided the lowest prediction error for interfacial tension.•Fluorescence was the best individual technique for predicting the interfacial tension.
Globally, plant‐derived medicines have been playing an increasing and relevant role in the treatment of several diseases, thus fostering the search for new bioactive substances. Among the various ...families of plants studied, those of the Combretum genus can be highlighted since they are widely used in folk medicine for the treatment of hepatitis, malaria, respiratory infections, cancer, skin hemorrhage, and anxiety. Phytochemical studies carried out on species of the Combretum genus demonstrated the presence of several classes of bioactive chemical compounds, including the triterpene 3β,6β,16β‐trihydroxilup‐20(29)‐ene (CLF‐1). In this perspective, the objective of this review was to gather all pharmacological activities attributed to the CLF‐1 triterpene, highlighting its importance for the pharmaceutical industry. The research was performed in scientific databases such as PubMed, SciELO, LILACS, SciFinder and Science Direct. The literature indicates a great pharmacological potential of CLF‐1, evidencing its antioxidant, anti‐inflammatory, antiviral, antiparasitic, antinociceptive, healing, and antibacterial action, antinociceptive and antitumor effect. Therefore, based on the different research above, it is plausible to consider CLF‐1, obtained from different parts of the C. leprosum plant, as a molecule with biotechnological potential that may contribute to the development of new drugs and, consequently, in the treatment of various human pathologies.
The use of visible light as a means of promoting chemical transformations offers a more sustainable and efficient alternative to traditional methods in organic synthesis. This reaction mode ...represents an important tool for the discovery of new reactivities that can be applied in the synthesis of relevant compounds. Herein we present significant and selected examples of the last ten years’ publications (2012–2022) of organic synthesis methods that use visible light as a promoter in photoarylation reactions without the need for additional photocatalysts. We highlight the main advances, including the formation of EDA complexes, photolysis and self-triggered reactions as main strategies for radical formation and radical initiation steps through visible light. Furthermore, we discuss the relevance of these methods in the production of valuable organic compounds, such as pharmaceuticals, industrial chemicals and building blocks, and their respective reaction mechanisms.
Abstract
Heparin has already been found in a variety of animal tissues but only few of them became effective sources for production of pharmaceutical preparations. Here, we correlate ...physical-chemical features and anticoagulant activities of structurally similar heparins employed in the past (from bovine lung, HBL), in the present (from porcine intestine, HPI) and in development for future use (from ovine intestine, HOI). Although they indeed have similar composition, our physical-chemical analyses with different chromatography and spectrometric techniques show that both HOI and HBL have molecular size notably lower than HPI and that the proportions of some of their minor saccharide components can vary substantially. Measurements of anticoagulant activities with anti-FIIa and anti-FXa assays confirmed that HPI and HOI have potency similar each other but significantly higher than HBL. Such a lower activity of HBL has been attributed to its reduced molecular size. Considering that HOI also has reduced molecular size, we find that its increased anticoagulant potency might result from an improved affinity to antithrombin (three times higher than HBL) promoted by the high content of
N
,3,6-trisulfated glucosamine units, which in turn are directly involved in the heparin-antithrombin binding. Therefore, the anticoagulant activity of different heparins is driven by a balance between different physical-chemical components, especially molecular size and fine-tuning composition. Although such minor but relevant chemical differences reinforce the concept that heparins from different animal sources should indeed be considered as distinct drugs, HOI could be approved for interchangeable use with the gold standard HPI and as a suitable start material for producing new LMWHs.
Crude glycerin is a byproduct of the biodiesel industry and has been widely used in ruminant diets as a source of energy, usually in place of corn, primarily during periods of drought in tropical ...regions. The objective of this study was to evaluate the effect of including levels of the crude glycerin of low purity (0, 6, 12 and 18%) replacing corn in the diets of goats on the carcass characteristics, tissue composition, meat cuts yield and physicochemical parameters of meat. Forty males castrated without defined racial pattern goats an initial average weight of 19.70 ± 2.30 kg were slaughtered after 86 days. Diets content 0 and 6% crude glycerin promoted similar responses to the analyzed variables, except for pH and breast weight. No differences were observed to total digestible nutrients, slaughter body weight, commercial cut yield leg tissue composition and physicochemical parameters of meat. Crude glycerin can be included up to 12% without losses on carcass weight and meat cuts, leg composition, and meat quality. The inclusion of crude glycerin containing 63.06% glycerol and 45.57% lipids could be effective in partial replacement of corn in diets for confined goats in tropical areas.
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