Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 1.643
Filtrar
1.
Chemosphere ; 255: 126848, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388255

RESUMO

Insensitive high explosives are increasingly being used to replace more sensitive formulations, however large quantities of environmentally hazardous wastewater are generated from loading, assembling and packing processes. Currently, there is limited literature regarding the treatment of wastewater contaminated with these hazardous insensitive high explosive materials such as 1,3,5-trinitroperhydro- 1,3,5-triazine (RDX), 2,4-dinitoranisole (DNAN) and 3-nitro-1,2,4-triazol-5-one (NTO). The preferred method of explosive wastewater treatment is adsorption by activated carbon, usually through treatment columns or fluidised beds that are simple to operate and cost effective. The aim of this research was to assess whether commercially available activated carbons would be suitable and economically viable to treat explosive wastewater containing RDX, DNAN and NTO. Bottle point tests were used to determine adsorption capacity and adsorption kinetics for the individual insensitive high explosives with three different activated carbons. Equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherms to determine the mechanisms of adsorption. Six hour bottle point tests for a mixture of the three insensitive high explosive constituents were used to consider possible preferential adsorption. As expected, RDX and DNAN were adsorbed at concentrations up to 40 mg.L-1 and 150 mg.L-1 respectively by the activated carbons tested, demonstrating the viability of treatment by adsorption. However, at the high concentrations of NTO expected in wastewater (1400 mg.L-1) activated carbons were rapidly saturated, suggesting that treatment of NTO contaminated wastewater would require prohibitively large quantities of activated carbon compared to RDX and DNAN.


Assuntos
Anisóis/química , Carvão Vegetal/química , Nitrocompostos/química , Triazinas/química , Triazóis/química , Adsorção , Substâncias Explosivas , Cinética , Modelos Químicos , Águas Residuárias
2.
Chemosphere ; 254: 126820, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32320832

RESUMO

In this study, water treatment residuals (WTRs), a safe and valuable by-product containing iron, was used as a precursor for preparing effective activator (HWTRs) of peroxymonosulfate (PMS) for imidacloprid (IMD) degradation by hydrothermal treatment. Several affecting parameters on IMD degradation including PMS concentration, HWTRs dosage, initial pH and water matrix were discussed. The results of degradation experiments demonstrated that within the reaction time of 4 h, 97.64% of IMD could be removed with 0.5 g L-1 HWTRs and 1.5 mM PMS, and the acidic conditions were favorable for IMD degradation. Both sulfate radicals (SO4•-) and hydroxyl radicals (·OH) were generated to attack the target pollutant IMD, and ·OH was the dominating radical in the HWTRs/PMS system, which was confirmed by the results of radicals scavenging experiments, electron spin-resonance spectroscopy (ESR) tests and quantitative analysis. What's more, X-ray photoelectron (XPS) spectroscopy was used to further verify the activation mechanism. Consequently, the activation by Fe(II) on the surface of HWTRs might dominate the reaction was confirmed. In addition, the possible degradation pathways of IMD were proposed on the basis of the degradation intermediates identified by LC-MS. This study offers an innovative idea for modifying raw WTRs to prepare efficient catalysts to activate PMS under relatively mild conditions.


Assuntos
Água Potável/química , Neonicotinoides/química , Nitrocompostos/química , Peróxidos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Catálise , Água Potável/análise , Radical Hidroxila , Ferro/análise , Sulfatos
3.
Science ; 367(6484): 1372-1376, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32193327

RESUMO

The structural and functional complexity of multicellular biological systems, such as the brain, are beyond the reach of human design or assembly capabilities. Cells in living organisms may be recruited to construct synthetic materials or structures if treated as anatomically defined compartments for specific chemistry, harnessing biology for the assembly of complex functional structures. By integrating engineered-enzyme targeting and polymer chemistry, we genetically instructed specific living neurons to guide chemical synthesis of electrically functional (conductive or insulating) polymers at the plasma membrane. Electrophysiological and behavioral analyses confirmed that rationally designed, genetically targeted assembly of functional polymers not only preserved neuronal viability but also achieved remodeling of membrane properties and modulated cell type-specific behaviors in freely moving animals. This approach may enable the creation of diverse, complex, and functional structures and materials within living systems.


Assuntos
Compostos de Anilina/química , Ascorbato Peroxidases/genética , Engenharia Genética , Neurônios/fisiologia , Nitrocompostos/química , Fenilenodiaminas/química , Polímeros/química , Potenciais de Ação , Animais , Ascorbato Peroxidases/metabolismo , Caenorhabditis elegans , Membrana Celular/metabolismo , Sobrevivência Celular , Células Cultivadas , Condutividade Elétrica , Células HEK293 , Hipocampo , Humanos , Potenciais da Membrana , Camundongos , Neurônios Motores/fisiologia , Células Musculares/fisiologia , Neurônios/enzimologia , Técnicas de Patch-Clamp , Polímeros/metabolismo , Ratos , Transdução Genética
4.
Chemosphere ; 251: 126254, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32155499

RESUMO

Due to its toxicity and persistence, pesticide pollution poses a serious threat to human health and the environment. Imidacloprid or IMD is an archetypal neonicotinoid insecticide commonly used to protect a variety of crops worldwide. The present study examines the applicability of two numerical tools -- artificial neural network (ANN) and response surface methodology - Box Behnken design (RSM-BBD) -- to model and optimize oxidative IMD degradation by sodium percarbonate (SPC). The influences of SPC dose, Fe2+ catalyst dosage, and solution pH on IMD removal were evaluated. An ANN composed of an input layer with three neurons, a hidden layer with eight optimum neurons, and an output layer with one neuron was developed to map the complex non-linear process at different levels. Seventeen designed runs of different experimental conditions were derived from RSM-BBD. These experimental conditions and their response values showed to be best fitted in a reduced cubic model equation. Sensitivity analyses revealed the relative importance of the various components: Fe2+ (40.4%) > pH (31.1%) > SPC dose (28.5%). The two model were highly predictive with overall coefficients of determination and root-mean-square errors of 0.9983 and 0.31 for ANN, while 0.9996 and 0.20 for RSM-BBD. Overall, the present study established ANN and RSM-BBD as valuable and effective tools for catalytic SPC oxidation of IMD contaminants. SPC is a cleaner alternative to other oxidants for pesticide degradation as it is non-toxic, safe to handle, and produces by-products that inherently exist in the natural water matrix.


Assuntos
Carbonatos/química , Modelos Químicos , Neonicotinoides/química , Redes Neurais de Computação , Nitrocompostos/química , Catálise , Oxidantes , Oxirredução , Projetos de Pesquisa
5.
Chemistry ; 26(34): 7631-7637, 2020 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-32187755

RESUMO

Bis-sulfonamide bis-amide TAML activator [Fe{4-NO2 C6 H3 -1,2-(NCOCMe2 NSO2 )2 CHMe}]- (2) catalyzes oxidative degradation of the oxidation-resistant neonicotinoid insecticide, imidacloprid (IMI), by H2 O2 at pH 7 and 25 °C, whereas the tetrakis-amide TAML [Fe{4-NO2 C6 H3 -1,2-(NCOCMe2 NCO)2 CF2 }]- (1), previously regarded as the most catalytically active TAML, is inactive under the same conditions. At ultra-low concentrations of both imidacloprid and 2, 62 % of the insecticide was oxidized in 2 h, at which time the catalyst is inactivated; oxidation resumes on addition of a succeeding aliquot of 2. Acetate and oxamate were detected by ion chromatography, suggesting deep oxidation of imidacloprid. Explored at concentrations [2]≥[IMI], the reaction kinetics revealed unusually low kinetic order in 2 (0.164±0.006), which is observed alongside the first order in imidacloprid and an ascending hyperbolic dependence in [H2 O2 ]. Actual independence of the reaction rate on the catalyst concentration is accounted for in terms of a reversible noncovalent binding between a substrate and a catalyst, which usually results in substrate inhibition when [catalyst]≪[substrate] but explains the zero order in the catalyst when [2]>[IMI]. A plausible mechanism of the TAML-catalyzed oxidations of imidacloprid is briefly discussed. Similar zero-order catalysis is presented for the oxidation of 3-methyl-4-nitrophenol by H2 O2 , catalyzed by the TAML analogue of 1 without a NO2 -group in the aromatic ring.


Assuntos
Complexos de Coordenação/química , Ferro/química , Neonicotinoides/química , Nitrocompostos/química , Sulfonamidas/química , Amidas/química , Catálise , Cinética , Oxirredução , Praguicidas
6.
Ecotoxicol Environ Saf ; 191: 110234, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-32006869

RESUMO

Imidacloprid is a widely used neonicotinoid insecticide worldwide, and has attracted great concerns due to its potential threat to human and environment. Much effort was thus spent on developing the effective way for removing imidacloprid from water, but might also produce various degradation products with unknown risks. The hypothesis was then proposed that permanganate oxidation was probably the appropriate tool for eliminating imidacloprid and its toxicity through selective oxidation of specific groups. To that end, we studied the kinetics of permanganate/imidacloprid reaction by considering the effects of pH (5.0-9.0), temperature (15-35 °C), ionization strength (0.05-0.20 M), typical anions (Cl-, Br-, I-) and humic acid. Based on the identified products from mass spectrometer, the main reaction pathway was found to be the hydroxylation of C-H bond at imidazole ring, leading to the decreased toxicity evaluated by ECOSAR program. Our results demonstrate that permanganate oxidation should be a very promising technique for controlling imidacloprid contamination by effective detoxification through highly selective partial oxidation. Moreover, this study has also paved the way toward applying permanganate oxidation for in situ chemical remediation of imidacloprid, though the corresponding standards need to be established in advance.


Assuntos
Inseticidas/análise , Compostos de Manganês/química , Neonicotinoides/análise , Nitrocompostos/análise , Óxidos/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Substâncias Húmicas/análise , Inseticidas/química , Cinética , Modelos Teóricos , Neonicotinoides/química , Nitrocompostos/química , Oxirredução , Poluentes Químicos da Água/química
7.
J Agric Food Chem ; 68(8): 2329-2339, 2020 Feb 26.
Artigo em Inglês | MEDLINE | ID: mdl-32011126

RESUMO

The heavy application of neonicotinoid insecticides in agricultural production has burdened the environment. In the present study, interactions of two neonicotinoid insecticides imidacloprid and thiamethoxam with dissolved organic matter (DOM) were investigated by spectroscopic techniques, molecular modeling, and density functional theory (DFT) calculations. The static mechanism of imidacloprid and thiamethoxam quenching the endogenous fluorescence of DOM was assessed through time-resolved analyses. During the binding process, a protein-like substance binds imidacloprid and thiamethoxam later than a humic-like substance, as analyzed by two-dimensional correlation spectroscopy, but more strongly than the humic-like substance, as suggested by molecular modeling and DFT calculations. The conformational changes of DOM are attributed to imidacloprid and thiamethoxam, as assessed with three-dimensional spectra. Fourier transform infrared spectroscopy indicated that DOM binds imidacloprid and thiamethoxam by hydroxyl, aliphatic C-H, amide I, and carboxyl to form stable DOM-imidacloprid and DOM-thiamethoxam complexes. Understanding the changes in the structural conformation of humic-like and protein-like substances with imidacloprid and thiamethoxam helps further understand the fate of the neonicotinoids in the environment.


Assuntos
Inseticidas/química , Neonicotinoides/química , Nitrocompostos/química , Compostos Orgânicos/química , Tiametoxam/química , Teoria da Densidade Funcional , Interações Medicamentosas , Modelos Moleculares , Espectroscopia de Infravermelho com Transformada de Fourier
8.
Carbohydr Polym ; 230: 115603, 2020 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-31887950

RESUMO

Invisible high-security anticounterfeiting inks were developed by surface-modification of functionalized latex nanoparticles with spiropyran derivatives, which display both photochromism and fluorescence upon UV irradiation at the same time. The functionalized latex nanoparticles show different spherical, doughnut-like, and red blood cell-like morphologies depending on concentration and type of its functional groups. Microscopic investigation of the impregnated cellulosic papers with latex nanoparticles display that epoxy-functionalized spherical latex nanoparticles have considerable packing and stability on the surface of the cellulosic substrate by formation of hydrogen bonding. Epoxy-functionalized latex nanoparticles containing spiropyran were used for preparation of high-security photochromic/fluorescent anticounterfeiting inks for print-marking of different cellulosic security documents such as certificate, money, and passport with different marks. The printed marks and finger-prints on the cellulosic security documents display photochromism and red fluorescence emission upon UV irradiation with high intensity and brightness.


Assuntos
Celulose/química , Nanopartículas/química , Papel/normas , Impressão/métodos , Polímeros Responsivos a Estímulos/química , Benzopiranos/química , Fluorescência , Ligação de Hidrogênio , Indóis/química , Tinta , Látex/química , Nitrocompostos/química
9.
Chemistry ; 26(32): 7219-7225, 2020 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31984562

RESUMO

Lack of new antibiotics and increasing antimicrobial resistance are among the main concerns of healthcare communities nowadays, and these concerns necessitate the search for novel antibacterial agents. Recently, we discovered the cystobactamids-a novel natural class of antibiotics with broad-spectrum antibacterial activity. In this work, we describe 1) a concise total synthesis of cystobactamid 507, 2) the identification of the bioactive conformation using noncovalently bonded rigid analogues, and 3) the first structure-activity relationship (SAR) study for cystobactamid 507 leading to new analogues with high metabolic stability, superior topoisomerase IIA inhibition, antibacterial activity and, importantly, stability toward the resistant factor AlbD. Deeper insight into the mode of action revealed that the cystobactamids employ DNA minor-groove binding as part of the drug-target interaction without showing significant intercalation. By designing a new analogue of cystobactamid 919-2, we finally demonstrated that these findings could be further exploited to obtain more potent hexapeptides against Gram-negative bacteria.


Assuntos
Antibacterianos/síntese química , Asparagina/análogos & derivados , Bactérias Gram-Negativas/efeitos dos fármacos , Nitrocompostos/química , Antibacterianos/química , Antibacterianos/farmacologia , Asparagina/química , Asparagina/farmacologia , Bactérias Gram-Negativas/química , Testes de Sensibilidade Microbiana , Conformação Molecular , Nitrocompostos/farmacologia , Relação Estrutura-Atividade
10.
Eur J Med Chem ; 186: 111829, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31757526

RESUMO

The implication of DNA methylation in cancer is today clearly established. Despite that nucleoside analogues are currently used for leukaemia treatment, their low stability in physiological conditions and their lack of selectivity arise the need for the identification of non-nucleoside DNA methyltransferase inhibitors. Here, we describe the synthesis and pharmacological characterisation of a novel class of DNA methyltransferase inhibitors: the 3-halo-3-nitroflavanones. We showed that 3-bromo-3-nitroflavanones 3b and 4a have a micromolar DNMT inhibition and an increased potency in a cell reporter model. Interestingly they are significantly more stable than the reference compounds and induce a low cytotoxicity, supporting them as new candidates for the development of non-cytotoxic cell-reprogramming epi-drugs for anticancer treatment.


Assuntos
Antineoplásicos/farmacologia , DNA (Citosina-5-)-Metiltransferases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Flavanonas/farmacologia , Nitrocompostos/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , DNA (Citosina-5-)-Metiltransferases/metabolismo , Metilação de DNA/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Flavanonas/química , Células HCT116 , Humanos , Estrutura Molecular , Nitrocompostos/síntese química , Nitrocompostos/química , Relação Estrutura-Atividade
11.
Chemosphere ; 240: 124958, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726587

RESUMO

Degradation of insensitive munitions (IMs) by ultraviolet (UV) light has become a topic of concern following observations that some UV-degradation products have increased toxicity relative to parent compounds in aquatic organisms. The present investigation focused on the Army's IM formulation, IMX-101, which is composed of three IM constituents: 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), and nitroguanidine (NQ). The IM constituents and IMX-101 were irradiated in a UV photo-reactor and then administered to Daphnia pulex in acute (48 h) exposures comparing toxicities relative to the parent materials. UV-degradation of DNAN had little effect on mortality whereas mortality for UV-degraded NTO and NQ (and associated degradation products) increased by factors of 40.3 and 1240, respectively, making UV-degraded NQ the principle driver of toxicity when IMX-101 is UV-degraded. Toxicity investigations for specific products formed during UV-degradation of NQ, confirmed greater toxicity than the parent NQ for degradation products including guanidine, nitrite, ammonia, nitrosoguanidine, and cyanide. Summation of the individual toxic units for the complete set of individually measured UV-degradation products identified for NQ only accounted for 25% of the overall toxicity measured in the exposures to the UV-degraded NQ product mixture. From these toxic unit calculations, nitrite followed by CN- were the principal degradation products contributing to toxicity. Given the underestimation of toxicity using the sum toxic units for the individually measured UV-degradation products of NQ, we conclude that: (1) other unidentified NQ degradation products contributed principally to toxicity and/or (2) synergistic toxicological interactions occurred among the NQ degradation product mixture that exacerbated toxicity.


Assuntos
Anisóis/química , Guanidinas/efeitos da radiação , Triazóis/química , Raios Ultravioleta , Animais , Anisóis/toxicidade , Daphnia/efeitos dos fármacos , Poluentes Ambientais/química , Poluentes Ambientais/toxicidade , Guanidinas/toxicidade , Mutação , Nitrocompostos/química , Nitrocompostos/toxicidade , Testes de Toxicidade , Triazóis/toxicidade
12.
Molecules ; 24(24)2019 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-31847419

RESUMO

Carbohydrates are abundant renewable resources and are a feedstock for green chemistry and sustainable synthesis of the future. Among the hexoses and the pentoses present in biomass, mannitol was selected in the present project as a valuable platform, directly available from the chiral pool, to build highly functionalized molecules. Starting from (R)-2,3-O-cyclohexylidene glyceraldehyde, which is easily prepared in a large scale from D-mannitol, an enantiopure chiral nitro alkene was prepared by reaction with nitromethane, and its reactivity studied. Organocatalytic Michael addition of dimethyl malonate, ß-keto esters, and other nucleophiles on the nitro alkene afforded high stereoselectivity and densely functionalized chiral molecules, which were further synthetically developed, leading to five-membered lactones and bicyclic lactams. Preliminary studies showed that the metal-free catalytic reaction on the chiral nitro alkene can be performed under continuous flow conditions, thus enabling the use of (micro)mesofluidic systems for the preparation of enantiomerically pure organic molecules from the chiral pool.


Assuntos
Manitol/química , Nitrocompostos/química , Catálise , Técnicas de Química Sintética , Teoria da Densidade Funcional , Ésteres , Espectroscopia de Ressonância Magnética , Manitol/análogos & derivados , Estrutura Molecular , Nitrocompostos/síntese química , Nitrocompostos/farmacologia , Estereoisomerismo
13.
Molecules ; 24(22)2019 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-31717507

RESUMO

A chiral primary amine-salicylamide is used as an organocatalyst for the enantioselective conjugate addition of α,α-disubstituted aldehydes to maleimides and nitroalkenes. The reactions are performed in deep eutectic solvents as reaction media at room temperature, leading to the corresponding adducts with enantioselectivities up to 88% (for maleimides) and 80% (for nitroalkenes). Catalyst and solvent can be recovered and reused.


Assuntos
Alcenos/química , Maleimidas/química , Nitrocompostos/química , Solventes/química , Aminas/química , Catálise , Salicilamidas/química
14.
Biomater Sci ; 7(12): 4944-4962, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31650136

RESUMO

Oligonucleotides are widely used biological materials in the fields of biomedicine, nanotechnology, and materials science. Due to the demands for the photoregulation of DNA activities, scientists are placing more and more research interest in the interactions between reversible photochromic molecules and DNAs. Photochromic molecules can work as switches for regulating the DNAs' behavior under light irradiation; meanwhile, DNAs also exert influence over the photochromic molecules. The photochromic molecules can be attached to DNAs either by covalent bonds or by noncovalent forces, which results in different regulative functions. Azobenzenes, spiropyrans, diarylethenes, and stilbene-like compounds are important photochromic molecules working as photoswitches. By summarizing their interactions with oligonucleotides, this review intends to facilitate the relevant research on oligonucleotides/photochromic molecules in the biological and medicinal fields and in materials science.


Assuntos
Substâncias Luminescentes/química , Oligonucleotídeos/química , Compostos Azo/química , Benzopiranos/química , Indóis/química , Estrutura Molecular , Nitrocompostos/química
15.
Ecotoxicol Environ Saf ; 186: 109822, 2019 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-31634658

RESUMO

Nitroaromatic compounds (NACs) are an important type of environmental organic pollutants. However, it is lack of sufficient information relating to their potential adverse effects on human health and the environment due to the limited resources. Thus, using in silico technologies to assess their potential hazardous effects is urgent and promising. In this study, quantitative structure activity relationship (QSAR) and classification models were constructed using a set of NACs based on their mutagenicity against Salmonella typhimurium TA100 strain. For QSAR studies, DRAGON descriptors together with quantum chemistry descriptors were calculated for characterizing the detailed molecular information. Based on genetic algorithm (GA) and multiple linear regression (MLR) analyses, we screened descriptors and developed QSAR models. For classification studies, seven machine learning methods along with six molecular fingerprints were applied to develop qualitative classification models. The goodness of fitting, reliability, robustness and predictive performance of all developed models were measured by rigorous statistical validation criteria, then the best QSAR and classification models were chosen. Moreover, the QSAR models with quantum chemistry descriptors were compared to that without quantum chemistry descriptors and previously reported models. Notably, we also obtained some specific molecular properties or privileged substructures responsible for the high mutagenicity of NACs. Overall, the developed QSAR and classification models can be utilized as potential tools for rapidly predicting the mutagenicity of new or untested NACs for environmental hazard assessment and regulatory purposes, and may provide insights into the in vivo toxicity mechanisms of NACs and related compounds.


Assuntos
Poluentes Ambientais , Hidrocarbonetos Aromáticos , Mutagênicos , Nitrocompostos , Algoritmos , Simulação por Computador , Poluentes Ambientais/química , Poluentes Ambientais/toxicidade , Hidrocarbonetos Aromáticos/química , Hidrocarbonetos Aromáticos/toxicidade , Aprendizado de Máquina , Mutagênicos/química , Mutagênicos/toxicidade , Nitrocompostos/química , Nitrocompostos/toxicidade , Relação Quantitativa Estrutura-Atividade , Reprodutibilidade dos Testes , Salmonella typhimurium/efeitos dos fármacos , Salmonella typhimurium/genética
16.
J Agric Food Chem ; 67(43): 12105-12116, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31600056

RESUMO

Sublethal exposure to neonicotinoids affects honey bee olfaction, but few studies have investigated the sublethal effects of the enantioselective neonicotinoid dinotefuran on honey bee olfaction. This study assessed the sublethal olfactory toxicity of dinotefuran enantiomers to honey bees. Compared to R-dinotefuran, S-dinotefuran had higher acute oral toxicity, sucrose sensitivity effects, octopamine concentrations, lower learning ability, and memory effects on honey bees. High-throughput circular RNA sequencing of the honey bee brain revealed that R-dinotefuran caused more gene regulatory changes than S-dinotefuran. Gene ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses demonstrated that the SERCA, Kca, and Maxik genes may be related to the enantioselective effects of dinotefuran isomers on honey bee olfaction. These results indicated that the current ecotoxicological safety knowledge about chiral dinotefuran effects on honey bees should be amended.


Assuntos
Abelhas/efeitos dos fármacos , Guanidinas/toxicidade , Inseticidas/química , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Animais , Abelhas/fisiologia , Guanidinas/química , Neonicotinoides/química , Nitrocompostos/química , Olfato/efeitos dos fármacos , Estereoisomerismo
17.
J Mol Model ; 25(9): 298, 2019 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-31482374

RESUMO

A series of nitro-imidazole derivatives were designed by replacing hydrogen atoms on imidazole ring with nitro group one by one. In order to investigate the thermodynamic stability, heat of formation (HOF), and bond dissociation energy (BDE) are calculated at the B3PW91/6-311+G(d,p) level. In order to investigate the impact sensitivity and detonation property, the drop height (H50), free space per molecule in crystal lattice (ΔV), detonation velocity (D), and detonation pressure (P) are calculated by using the empirical Kamlet-Jacobs (K-J) equation. The results show that the thermal stabilities of title molecules are determined by whether nitro group is associated to 1-position or not and accompanied with the steric hindrance between nitro groups and the charge population on the carbon atoms of imidazole ring. The excellent impact sensitivity and detonation performance of title molecules are also evaluated. On the consideration both of stability and detonation characters, 2,4,5-trinitro-1H-imidazole (D = 8.98 km/s, P = 36.70 GPa) is screened out as the potential high-energy-density molecule for further research.


Assuntos
Substâncias Explosivas/química , Hidrogênio/química , Nitrocompostos/química , Nitroimidazóis/química , Substâncias Explosivas/síntese química , Nitroimidazóis/síntese química , Teoria Quântica , Relação Estrutura-Atividade , Temperatura , Termodinâmica
18.
ACS Appl Mater Interfaces ; 11(41): 38226-38231, 2019 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-31529963

RESUMO

Near-infrared (NIR) microlasers play a significant role in telecommunication and biomedical tissue imaging. However, it remains a big challenge to realize NIR microlasers because of the difficulty in preparing highly efficient NIR luminescent materials and perfect optical resonators. Here, we propose a molecular design strategy to creatively realize the first spiropyrane (SP)-based NIR microlasers with low threshold from self-assembled microsphercial caps. The tetraphenylethylene (TPE) moiety with a highly twisted conformation provides a large free volume to facilitate the photoisomerization process of SP and enhance NIR emission of merocyanine in the solid state. Moreover, self-assembled TPE-SP microsphercial caps simultaneously serve as gain media and resonant microcavities, providing optical gain and feedback for NIR laser oscillations with a low threshold (3.68 µJ/cm2). These results are beneficial for deeply understanding the SP microstructures-lasing emission characteristic relationship and provide a useful guideline for the rational molecular design of NIR microlasers with special functionalities.


Assuntos
Benzopiranos/química , Indóis/química , Lasers , Microesferas , Nitrocompostos/química
19.
Analyst ; 144(20): 6041-6047, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31508616

RESUMO

In the present study, four copper-based metal-organic frameworks were facilely prepared to study the effects of the substituent groups of the ligand on the enzyme-like properties of these frameworks. It was found that all of them were capable of catalyzing the reaction between 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2; this demonstrated their enzyme-like properties. Moreover, the enzyme-like catalytic properties of all the Cu-MOFs obtained herein were studied in detail. Interestingly, the results indicate that the four Cu-MOFs should be addressed as different enzyme mimics although the chemical structures of their ligands are quite similar. Among these four MOFs, the Cu-MOF with the -NO2 group (Cu-MOF (ii)) exhibits highest catalytic activity at neutral pH, which would be beneficial for its application in real biological samples. Moreover, its catalytic activity should be ascribed to the generation of oxygen induced by Cu-MOF (ii)-catalyzed H2O2 decomposition; this accordingly indicates that this MOF should be called a catalase mimic. Under optimized conditions, the Cu-MOF (ii) was applied to develop a (GSH) colorimetric assay for glutathione (GSH). In addition, GSH detection in serum was performed, and satisfactory results were obtained. Therefore, a simple, sensitive and selective colorimetric assay based on the MOF catalase mimic for the detection of GSH was developed.


Assuntos
Materiais Biomiméticos/química , Técnicas Biossensoriais/métodos , Catalase/química , Cobre/química , Glutationa/sangue , Estruturas Metalorgânicas/química , Nitrocompostos/química , Catálise , Humanos
20.
Chemistry ; 25(58): 13436-13443, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31453653

RESUMO

Studying noncanonical intermolecular interactions between a ligand and a protein constitutes an emerging research field. Identifying synthetically accessible molecular fragments that can engage in intermolecular interactions is a key objective in this area. Here, it is shown that so-called "π-hole interactions" are present between the nitro moiety in nitro aromatic ligands and lone pairs within protein structures (water and protein carbonyls and sulfurs). Ample structural evidence was found in a PDB analysis and computations reveal interaction energies of about -5 kcal mol-1 for ligand-protein π-hole interactions. Several examples are highlighted for which a π-hole interaction is implicated in the superior binding affinity or inhibition of a nitro aromatic ligand versus a similar non-nitro analogue. The discovery that π-hole interactions with nitro aromatics are significant within protein structures parallels the finding that halogen bonds are biologically relevant. This has implications for the interpretation of ligand-protein complexation phenomena, for example, involving the more than 50 approved drugs that contain a nitro aromatic moiety.


Assuntos
Simulação por Computador , Modelos Moleculares , Nitrocompostos/química , Proteínas/química , Sequência de Aminoácidos , Bases de Dados de Proteínas , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Estrutura Molecular , Ligação Proteica , Relação Estrutura-Atividade , Termodinâmica , Água
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA