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1.
Toxicol Ind Health ; 38(10): 665-674, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36062628

RESUMO

Accumulating evidence has shown that bisphenol A (BPA) affects not only the growth and development of reproductive tissues but also disrupts meiosis. Meiotic disturbances lead to the formation of aneuploid gametes, resulting in the inability to conceive, pregnancy loss, and developmental disabilities in offspring. In recent years, increasing health concerns led manufacturers to seek BPA alternatives. In response, BPA analogs have been prepared and investigated in a variety of toxicity-related studies. Despite hopes that these analogs would prove less harmful than BPA, published data show that these alternatives continue to pose a significant risk to human health. In this study, we synthesized two less investigated BPA analogs with cyclic side chains, bisphenol Y (BPY) and bisphenol Z (BPZ), and evaluated their reprotoxic potential using Caenorhabditis elegans. C. elegans were cultured on nematode growth medium plates containing a 1 mM concentration of the dimethyl sulfoxide-dissolved bisphenols. The uptake of the chemicals was via two major routes: ingestion and cuticle diffusion. Following exposure, we evaluated fertilized egg count, germline apoptosis, and embryonic lethality-three parameters previously shown to reliably predict the reprotoxic potential of bisphenols in mammals. Our results indicated that both BPY and BPZ had a significant impact on fertility, resulting in increased germline apoptosis and a reduced number of progeny, without affecting the embryonic viability. After comparison with commercially relevant BPA and bisphenol S, our findings imply that BPA analogs with cyclic side chains, BPY and BPZ, adversely affect meiotic fidelity, resulting in diminished reproductive capacity.


Assuntos
Caenorhabditis elegans , Dimetil Sulfóxido , Animais , Compostos Benzidrílicos/toxicidade , Caenorhabditis elegans/fisiologia , Cicloexanos , Feminino , Humanos , Mamíferos , Fenóis , Gravidez
2.
J Am Chem Soc ; 144(37): 16755-16760, 2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36085555

RESUMO

The toxicity, corrosiveness, and volatility of elemental bromine presents challenges for its safe storage and transportation. Purification from other halogens is also difficult. Here, we report an easy-to-prepare calix[4]pyrrole-based azo-bridged porous organic polymer (C4P-POP) that supports efficient bromine capture. C4P-POP was found to capture bromine as a vapor and from a cyclohexane source phase with maximum uptake capacities of 3.6 and 3.4 g·g-1, respectively. Flow-through adsorption experiments revealed that C4P-POP removes 80% of the bromine from a 4.0 mM cyclohexane solution at a flow rate of 45 mL·h-1. C4P-POP also allowed the selective capture of bromine from a 1:1 mixture of bromine and iodine in cyclohexane.


Assuntos
Bromo , Iodo , Cicloexanos , Halogênios , Polímeros , Porosidade , Pirróis
3.
Chem Rev ; 122(18): 14954-14986, 2022 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-36112746

RESUMO

Due to their solution processability and unique photoelectric characteristics, perovskite solar cells (PSCs) have shown considerable promise in the area of renewable energy. Although their power conversion efficiency (PCE) has risen from 3.8% to 25.7% in only a few years, their short lifetime and high material prices continue to be key roadblocks to commercial viability. Charge transporting materials (CTMs), such as hole/electron transporting materials, are critical components in PSCs because they not only govern hole or electron extraction and transporting from the perovskite layer to the electrodes but also protect the perovskite from direct contact with the ambient environment. CTMs are split into two types: inorganic CTMs (ICTMs) and organic CTMs (OCTMs). Because of their inexpensive prices, well-adjusted energy levels, and low temperature solution-processed features, OCTMs have been more frequently explored and employed than ICTMs. Various forms of OCTMs with more straightforward synthetic pathways and better performance have been thoroughly researched. Recent achievements in the development of OCTMs will be discussed and evaluated on a molecular level in this study, which will include a systematic categorization of OCTMs based on molecular functionalization techniques. In order to achieve highly efficient and stable PSCs, we will present insights on the structure-property relationship in the design of OCTMs as well as device stability. We hope that this analysis will serve as a comprehensive reference to molecular design guidelines for various types of OCTMs, spurring greater research toward designing highly efficient and OCTMs for stable PSCs.


Assuntos
Energia Solar , Compostos de Cálcio , Cicloexanos , Mesilatos , Óxidos , Titânio
4.
Int J Mol Sci ; 23(17)2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36077100

RESUMO

The enantioselective preparation of the two isomers of 4-hydroxy-2-cyclohexanone derivatives 1a,b was achieved, starting from a common cyclohexenone, through asymmetric transfer hydrogenation (ATH) reactions using bifunctional ruthenium catalysts. From these versatile intermediates, a stereoselective route to a cytosine analogue built on a bicyclo [4.1.0]heptane scaffold is described. Nucleoside kinase activity assays with this cyclopropyl-fused cyclohexane nucleoside, together with other related nucleosides (2a-e), were performed, showing that thymine- and guanine- containing compounds have affinity for herpes simplex virus Type 1 (HSV-1) thymidine kinase (TK) but not for human cytosolic TK-1, thus pointing to their selectivity for herpetic TKs but not cellular TKs.


Assuntos
Herpesvirus Humano 1 , Nucleosídeos , Antivirais , Cicloexanos , Humanos , Timidina Quinase
5.
Org Lett ; 24(37): 6789-6793, 2022 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-36094854

RESUMO

Epicoccanes A-D (1-4) are four novel metabolites of an endophytic fungus Epicoccum nigrum. Their distinct unprecedented structures are hypothesized as oxidative dimers of pyrogallol analogues. Compounds 1 and 2 possess a novel spirobicyclo[3.2.1]octane-6,1'-cyclopentane or -cyclohexane core skeleton. Compound 3 is of a unique cage-like pentacyclic system, which unusually contained three continuous spiro-carbons. Compound 4 is a highly rearranged dimer with five contiguous chiral centers. The absolute structures of 1 and 2 were deduced by electronic circular dichroism (ECD) calculations, and those of 3 and 4 were determined by X-ray crystallography. Compounds 1 and 4 showed potential antiliver fibrosis activity.


Assuntos
Ascomicetos , Pirogalol , Ascomicetos/química , Cicloexanos , Ciclopentanos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Octanos , Estresse Oxidativo
6.
J Am Chem Soc ; 144(38): 17604-17610, 2022 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-36102900

RESUMO

Chloride oxidation has tremendous utility in the burgeoning field of chlorine-mediated C-H activation, yet it remains a challenging process to initiate with light because of the exceedingly positive one-electron reduction potential, E° (Cl•/-), beyond most common transition-metal photooxidants. Herein, two photocatalytic chloride oxidation pathways that involve either one- or consecutive two-photon excitation of N-phenylphenothiazine (PTH) are presented. The one-photon pathway generates PTH•+ by oxidative quenching that subsequently disproportionates to yield PTH2+ that oxidizes chloride; this pathway is also accessed by the electrochemical oxidation of PTH. The two-photon pathway, which proceeded through the radical cation excited state, 2PTH•+*, was of particular interest as this super-photooxidant was capable of directly oxidizing chloride to chlorine atoms. Laser flash photolysis revealed that the photooxidation by the doublet excited state proceeded on a subnanosecond timescale through a static quenching mechanism with an ion-pairing equilibrium constant of 0.36 M-1. The PTH photoredox chemistry was quantified spectroscopically on nanosecond and longer time scales, and chloride oxidation chemistry was revealed by reactivity studies with model organic substrates. One- and two-photon excitation of PTH enabled chlorination of unactivated C(sp3)-H bonds of organic compounds such as cyclohexane with substantial yield enhancement observed from inclusion of the second excitation wavelength. This study provides new mechanistic insights into chloride oxidation catalyzed by an inexpensive and commercially available organic photooxidant.


Assuntos
Cloretos , Cloro , Cátions/química , Cloretos/química , Cloro/química , Cicloexanos , Oxirredução , Fotólise
7.
Acta Crystallogr C Struct Chem ; 78(Pt 7): 398-404, 2022 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-35788504

RESUMO

The highly effective recognition and detection of metal ions and anions in water has attracted much attention with respect to environmental safety. Herein, a novel Cd-based coordination polymer, poly[[4,4'-bis(2-methylimidazol-1-yl)biphenyl]bis(cyclohexane-1,2-dicarboxylato)dicadmium(II)], [Cd2(C8H10O4)2(C20H18N4)]n or [Cd(CHADC)(4,4'-BMIBP)0.5]n, (I), has been synthesized employing cis-cyclohexane-1,2-dicarboxylic acid (H2CHADC) and 4,4'-bis(2-methyl-1H-imidazol-1-yl)biphenyl (4,4'-BMIBP). Single-crystal X-ray analysis reveals that (I) presents a 6-connected hxl two-dimensional layer based on Cd6(CHADC)6 clusters with the point symbol (36·46·53). Furthermore, (I) has been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis and fluorescence spectroscopy, and exhibits good stability and excellent photoluminescence properties. Coordination polymer (I) was chosen as a fluorescent probe to sense different target analytes and shows an obvious selective recognition response to Fe3+ cations and Cr2O72-/CrO42- anions through luminescence-quenching effects in aqueous solution. The sensing mechanism was investigated and showed that the detection mechanism was resonance energy transfer between (I) and the Fe3+, Cr2O72- and CrO42- ions.


Assuntos
Cádmio , Polímeros , Cádmio/química , Cristalografia por Raios X , Ácidos Cicloexanocarboxílicos , Cicloexanos , Compostos de Dansil , Ácidos Dicarboxílicos , Ligação de Hidrogênio , Íons , Polímeros/química , beta-Ciclodextrinas
8.
Int J Mol Sci ; 23(14)2022 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-35886881

RESUMO

Ionic liquids (ILs) are known for their unique characteristics as solvents and electrolytes. Therefore, new ILs are being developed and adapted as innovative chemical environments for different applications in which their properties need to be understood on a molecular level. Computational data-driven methods provide means for understanding of properties at molecular level, and quantitative structure-property relationships (QSPRs) provide the framework for this. This framework is commonly used to study the properties of molecules in ILs as an environment. The opposite situation where the property is considered as a function of the ionic liquid does not exist. The aim of the present study was to supplement this perspective with new knowledge and to develop QSPRs that would allow the understanding of molecular interactions in ionic liquids based on the structure of the cationic moiety. A wide range of applications in electrochemistry, separation and extraction chemistry depends on the partitioning of solutes between the ionic liquid and the surrounding environment that is characterized by the gas-ionic liquid partition coefficient. To model this property as a function of the structure of a cationic counterpart, a series of ionic liquids was selected with a common bis-(trifluoromethylsulfonyl)-imide anion, [Tf2N]-, for benzene, hexane and cyclohexane. MLR, SVR and GPR machine learning approaches were used to derive data-driven models and their performance was compared. The cross-validation coefficients of determination in the range 0.71-0.93 along with other performance statistics indicated a strong accuracy of models for all data series and machine learning methods. The analysis and interpretation of descriptors revealed that generally higher lipophilicity and dispersion interaction capability, and lower polarity in the cations induces a higher partition coefficient for benzene, hexane, cyclohexane and hydrocarbons in general. The applicability domain analysis of models concluded that there were no highly influential outliers and the models are applicable to a wide selection of cation families with variable size, polarity and aliphatic or aromatic nature.


Assuntos
Líquidos Iônicos , Benzeno , Cátions , Cicloexanos , Hexanos , Humanos , Hidrocarbonetos , Líquidos Iônicos/química , Aprendizado de Máquina
9.
Methods Enzymol ; 671: 435-470, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35878989

RESUMO

The apocarotenoid phytohormone abscisic acid (ABA) regulates several aspects of plant development and stress responses. ABA is synthesized in response to multiple stressors and indirectly activates subfamily 2 Snf1-related kinases (SnRK2s) by receptor-mediated inhibition of clade A type IIC protein phosphatases (PP2Cs), which normally repress SnRK2 activity. The binding of ABA to its receptors triggers a change in receptor conformation that directs the formation of a receptor-ligand-PP2C complex that inhibits the activity of PP2C; this core mechanism can be harnessed for phosphatase activity-based measurements of receptor activation. In this chapter, we describe general methods for determining the effects of small molecules on ABA receptor function and supplement these with methods describing the synthesis of the high-affinity ligands opabactin (OP), which activates subfamily III and II ABA receptors, and the pan-receptor antagonist antabactin (ANT), and TAMRA-ANT fluorescent derivative of ANT. We present simple methods for quantifying receptor-ligand interactions using both PP2C inhibition and fluorescence polarization (FP) assays. Controls for determining the quality of recombinant receptors are provided, which are required for both quantitative analyses and for experimental consistency. Collectively, these methods will facilitate consistent biochemical measurements of the effects of ligand binding on ABA receptor function in vitro. Although the chapter describes ABA-specific methods, they illustrate and address a common need across receptor systems-reproducible assays that enable high throughput discovery and subsequent optimization of receptor modulators.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Ácido Abscísico/metabolismo , Ácido Abscísico/farmacologia , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Benzamidas , Proteínas de Transporte/metabolismo , Cicloexanos , Regulação da Expressão Gênica de Plantas , Ligantes , Transdução de Sinais
10.
Sci Rep ; 12(1): 11834, 2022 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-35821239

RESUMO

Selenium nanoparticles (Se-NPs) has recently received great attention over owing to their superior optical properties and wide biological and biomedical applications. Herein, crystallographic and dispersed spherical Se-NPs were green synthesized using endophytic fungal strain, Penicillium crustosum EP-1. The antimicrobial, anticancer, and catalytic activities of biosynthesized Se-NPs were investigated under dark and light (using Halogen tungsten lamp, 100 Watt, λ > 420 nm, and light intensity of 2.87 W m-2) conditions. The effect of Se-NPs was dose dependent and higher activities against Gram-positive and Gram-negative bacteria as well different Candida spp. were attained in the presence of light than obtained under dark conditions. Moreover, the viabilities of two cancer cells (T47D and HepG2) were highly decreased from 95.8 ± 2.9% and 93.4 ± 3.2% in dark than those of 84.8 ± 2.9% and 46.4 ± 3.3% under light-irradiation conditions, respectively. Significant decreases in IC50 values of Se-NPs against T47D and HepG2 were obtained at 109.1 ± 3.8 and 70.4 ± 2.5 µg mL-1, respectively in dark conditions than 19.7 ± 7.2 and 4.8 ± 4.2 µg mL-1, respectively after exposure to light-irradiation. The photoluminescence activity of Se-NPs revealed methylene blue degradation efficiency of 89.1 ± 2.1% after 210 min under UV-irradiation compared to 59.7 ± 0.2% and 68.1 ± 1.03% in dark and light conditions, respectively. Moreover, superior stability and efficient MB degradation efficiency were successfully achieved for at least five cycles.


Assuntos
Anti-Infecciosos , Nanopartículas Metálicas , Selênio , Antibacterianos/química , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Cicloexanos , Fungos , Bactérias Gram-Negativas , Bactérias Gram-Positivas , Nanopartículas Metálicas/química , Penicillium , Selênio/química , Selênio/farmacologia
11.
Toxicol Sci ; 189(2): 268-286, 2022 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-35861430

RESUMO

Due to their endocrine disruption properties, phthalate plasticizers such as di(2-ethylhexyl) phthalate (DEHP) can affect the hormone-dependent development of the mammary gland. Over the past few years, DEHP has been partially replaced by 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH) which also have potential endocrine disrupting properties. The goal of the present study is to understand the impact of a gestational and lactational exposure to DEHP and DINCH on mammary gland development using Sprague Dawley rats. Both plasticizers altered the adipocytes of the mammary gland fat pad of adult progeny, as demonstrated by a decrease in their size, folding of their membrane, and modulations of the lipid profiles. DEHP treatments decreased the expression of Rxrα and Scd1 at the low and high dose, respectively, but did not affect any of the other genes studied. DINCH modulation of lipid metabolism could be observed at puberty by a decreased expression of genes implicated in triglyceride synthesis, lipid transport, and lipolysis, but by an increased expression of genes of the ß-oxidation pathway and of genes involved in lipid storage and fatty acid synthesis at adulthood, compared with control and DEHP-treated rats. A strong upregulation of different inflammatory markers was observed following DINCH exposure only. Together, our results indicate that a gestational and lactational exposure to DINCH has earlier and more significant effects on lipid homeostasis, adipogenesis, and the inflammatory state of the adult mammary gland than DEHP exposure. The long-term consequence of these effects on mammary gland health remained to be determined.


Assuntos
Dietilexilftalato , Plastificantes , Animais , Cicloexanos , Ácidos Dicarboxílicos/toxicidade , Dietilexilftalato/toxicidade , Ésteres/toxicidade , Ácidos Graxos , Hormônios , Metabolismo dos Lipídeos , Lipídeos , Ácidos Ftálicos , Plastificantes/toxicidade , Ratos , Ratos Sprague-Dawley , Maturidade Sexual , Triglicerídeos
12.
Inorg Chem ; 61(25): 9710-9724, 2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-35696150

RESUMO

The oxidation of alkanes with m-chloroperbenzoic acid (mCPBA) catalyzed by the B12 derivative, heptamethyl cobyrinate, was investigated under several conditions. During the oxidation of cyclohexane, heptamethyl cobyrinate works as a catalyst to form cyclohexanol and cyclohexanone at a 0.67 alcohol to ketone ratio under aerobic conditions in 1 h. The reaction rate shows a first-order dependence on the [catalyst] and [mCPBA] while being independent of [cyclohexane]; Vobs = k2[catalyst][mCPBA]. The kinetic deuterium isotope effect was determined to be 1.86, suggesting that substrate hydrogen atom abstraction is not dominantly involved in the rate-determining step. By the reaction of mCPBA and heptamethyl cobyrinate at low temperature, the corresponding cobalt(III)acylperoxido complex was formed which was identified by UV-vis, IR, ESR, and ESI-MS studies. A theoretical study suggested the homolysis of the O-O bond in the acylperoxido complex to form Co(III)-oxyl (Co-O•) and the m-chlorobenzoyloxyl radical. Radical trapping experiments using N-tert-butyl-α-phenylnitrone and CCl3Br, product analysis of various alkane oxidations, and computer analysis of the free energy for radical abstraction from cyclohexane by Co(III)-oxyl suggested that both Co(III)-oxyl and the m-chlorobenzoyloxyl radical could act as hydrogen-atom transfer reactants for the cyclohexane oxidation.


Assuntos
Alcanos , Hidrogênio , Catálise , Clorobenzoatos , Cicloexanos/química
13.
Chem Commun (Camb) ; 58(57): 7968-7971, 2022 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-35758098

RESUMO

Concise and general synthesis protocols are reported to generate all-syn mono-, di- and tri-alkylated cyclohexanes where a single fluorine is located on the remaining carbons of the ring. The alkyl groups are positioned to lie equatorially and to have triaxial C-F bonds imparting polarity to these ring systems. Intermolecular electrostatic interactions in the solid-state structure of the trialkylated systems are explored and the resultant supramolecular order opens up prospects for design in soft materials.


Assuntos
Cicloexanos , Flúor , Carbono , Cicloexanos/química , Fluoretos , Flúor/química , Eletricidade Estática
14.
Anal Sci ; 38(8): 1067-1072, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35726115

RESUMO

The ion-transfer reaction at the 1,6-dichlorohexane (DCH) | water (W) interface in the presence of an organometallic cation, tetraphenylantimony (TPhSb+), in DCH was studied voltammetrically. When TPhSb+ salt with [(C4F9SO2)2N]- ion was added to the DCH-phase and the W-phase was buffered at pH < 6, a reversible cyclic voltammogram due to the simple transfer of TPhSb+ ion across the DCH | W interface was observed within the polarizable potential window. When the W-phase was buffered at pH > 7, the midpoint potential shifted to more positive potentials with increasing pH. The voltammogram could be attributed to the transfer of the OH- ion assisted by the formation of TPhSbOH, which is stable in DCH. Also, a 7reversible voltammogram due to the TPhSb+-assisted transfer of F- ion was observed at the TPhSb+ (DCH) | F- (W, unbuffered) interfacial system. The same results were achieved when TPhSb[(C4F9SO2)2N] in DCH was replaced by TPhSbOH or TPhSbF, indicating the applicability of the TPhSb+ and TPhSbOH (DCH) | OH- (W) interfacial system to a pH sensor for alkaline solution and that of the TPhSb+ and TPhSbF (DCH) | F- (W) interface to a F- ion sensor.


Assuntos
Fluoretos , Água , Ânions , Cicloexanos , Eletroquímica/métodos
15.
Molecules ; 27(12)2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35744961

RESUMO

This work presents the first report on the phytochemical investigation of Harpephyllum caffrum Bernh. gum exudate. A known cardanol, 3-heptadec-12'-Z-enyl phenol (1) and three new alk(en)ylhydroxycyclohexanes, namely, (1R,3R)-1,3-dihydroxy-3-[heptadec-12'(Z)-enyl]cyclohexane (2) (1S,2S,3S,4S,5R)-1,2,3,4,5-pentahydroxy-5-[octadec-13'(Z)-enyl]cyclohexane (3) and (1R,2S,4R)-1,2,4-trihydroxy-4-[heptadec-12'(Z)-enyl]cyclohexane (4) were isolated from the gum. The structures of the compounds were determined by extensive 1D and 2D NMR spectroscopy and HR-ESI-MS data. The ethanolic extract of the gum was found to be the most potent tyrosinase inhibitor with IC50 of 11.32 µg/mL while compounds 2 and 3, with IC50 values of 24.90 and 26.99 µg/mL, respectively, were found to be potential anti-tyrosinase candidates from the gum. Gum exudate may be a potential source for non-destructive harvesting of selective pharmacologically active compounds from plants. The results also provide evidence that H. caffrum gum may find application in cosmetics as a potential anti-tyrosinase agent.


Assuntos
Anacardiaceae , Monofenol Mono-Oxigenase , Cicloexanos , Exsudatos e Transudatos , Estrutura Molecular , Extratos Vegetais/química , Extratos Vegetais/farmacologia
16.
Sci Rep ; 12(1): 11016, 2022 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-35773322

RESUMO

In the current study, a simple dry coating method was utilized to fabricate a super-hydrophobic super-magnetic powder (ZS@BIF) for oily water purification using zinc stearate (ZS) and banded iron formation (BIF). The produced composite was fully characterized as a magnetic sorbent for oily water treatment. The results of X-ray diffraction diffractometer (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS) and particle size analysis revealed the fabrication of homogenous hydrophobic-magnetic composite particles with core-shell structure. Contact angle and magnetic susceptibility results showed that 4 (BIF): 1 (Zs) was the ideal coverage ratio to render the core material superhydrophobic and preserve its ferromagnetic nature. The capability of the fabricated composite to sorb. n-butyl acetate, kerosene, and cyclohexane from oil-water system was evaluated. ZS@BIF composite showed a higher affinity to adsorb cyclohexane than n-butyl acetate and kerosene with a maximum adsorption capacity of about 22 g g-1 and 99.9% removal efficiency. Moreover, about 95% of the adsorbed oils could be successfully recovered (desorbed) by rotary evaporator and the regenerated ZS@BIF composite showed high recyclability over ten repeated cycles.


Assuntos
Ferro , Purificação da Água , Adsorção , Cicloexanos , Interações Hidrofóbicas e Hidrofílicas , Querosene , Fenômenos Magnéticos , Óleos , Purificação da Água/métodos
18.
Langmuir ; 38(19): 6191-6200, 2022 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-35508911

RESUMO

Hydrophobins, a new class of potential protein emulsifiers, have been extensively employed in the food, pharmaceutical, and chemical industries. However, the knowledge of the underlying molecular mechanism of protein adsorption at the oil-water interface remains elusive. In this study, all-atom molecular dynamics simulations were performed to probe the adsorption orientation and conformation change of class II hydrophobin HFBI at the cyclohexane-water interface. It was proposed that a hydrophobic dipole of the protein could be used to quantitatively predict the orientation of the adsorbed HFBI. Simulation results revealed that HFBI adsorbed at the interface with the patch-up orientation toward the oil phase, regardless of its initial orientations. HFBI's secondary structure was maintained to be intact in the course of simulations despite relatively significant variations in the tertiary structure observed, which could well preserve the bioactivity of HFBI. From the energy analysis, the driving force for interface adsorption was primarily determined by van der Waals interactions between HFBI and cyclohexane. Further analysis indicated that the adsorption orientation and conformation of HFBI at the oil-water interface were typically regulated by the hydrophobic patch and some key residues. This study provides some insights into the orientation, conformation, and adsorption mechanism of proteins at the oil-water interface and theoretical guidelines for the design and development of novel biological emulsifiers involved in the food, pharmaceutical, and chemical industries.


Assuntos
Proteínas Fúngicas , Simulação de Dinâmica Molecular , Adsorção , Cicloexanos , Proteínas Fúngicas/química , Interações Hidrofóbicas e Hidrofílicas , Óleos/química , Conformação Proteica , Propriedades de Superfície , Água/química
19.
Molecules ; 27(10)2022 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-35630625

RESUMO

Nickel oxide powder was prepared by simple calcination of nickel nitrate hexahydrate at 500 °C for 5 h and used as a catalyst for the oxidation of cyclohexane to produce the cyclohexanone and cyclohexanol-KA oil. Molecular oxygen (O2), hydrogen peroxide (H2O2), t-butyl hydrogen peroxide (TBHP) and meta-chloroperoxybenzoic acid (m-CPBA) were evaluated as oxidizing agents under different conditions. m-CPBA exhibited higher catalytic activity compared to other oxidants. Using 1.5 equivalent of m-CPBA as an oxygen donor agent for 24 h at 70 °C, in acetonitrile as a solvent, NiO powder showed exceptional catalytic activity for the oxidation of cyclohexane to produce KA oil. Compared to different catalytic systems reported in the literature, for the first time, about 85% of cyclohexane was converted to products, with 99% KA oil selectivity, including around 87% and 13% selectivity toward cyclohexanone and cyclohexanol, respectively. The reusability of NiO catalyst was also investigated. During four successive cycles, the conversion of cyclohexane and the selectivity toward cyclohexanone were decreased progressively to 63% and 60%, respectively, while the selectivity toward cyclohexanol was increased gradually to 40%.


Assuntos
Cicloexanonas , Peróxido de Hidrogênio , Cicloexanos , Cicloexanóis , Níquel , Oxidantes , Oxigênio , Pós
20.
Molecules ; 27(10)2022 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-35630726

RESUMO

Spiro-substituted nitroxyl biradicals are widely used as reagents for dynamic nuclear polarization (DNP), which is especially important for biopolymer research. The main criterion for their applicability as polarizing agents is the value of the spin-spin exchange interaction parameter (J), which can vary considerably when different couplers are employed that link the radical moieties. This paper describes a study on biradicals, with a ferrocene-1,1'-diyl-substituted 1,3-diazetidine-2,4-diimine coupler, that have never been used before as DNP agents. We observed a substantial difference in the temperature dependence between Electron Paramagnetic Resonance (EPR) spectra of biradicals carrying either methyl or spirocyclohexane substituents and explain the difference using Density Functional Theory (DFT) calculation results. It was shown that the replacement of methyl groups by spirocycles near the N-O group leads to an increase in the contribution of conformers having J ≈ 0. The DNP gain observed for the biradicals with methyl substituents is three times higher than that for the spiro-substituted nitroxyl biradicals and is inversely proportional to the contribution of biradicals manifesting the negligible exchange interaction. The effects of nucleophiles and substituents in the nitroxide biradicals on the ring-opening reaction of 1,3-diazetidine and the influence of the ring opening on the exchange interaction were also investigated. It was found that in contrast to the methyl-substituted nitroxide biradical (where we observed the ring-opening reaction upon the addition of amines), the ring opening does not occur in the spiro-substituted biradical owing to a steric barrier created by the bulky cyclohexyl substituents.


Assuntos
Cicloexanos , Óxidos de Nitrogênio , Espectroscopia de Ressonância de Spin Eletrônica
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