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1.
J. Health Biol. Sci. (Online) ; 10(1): 1-10, 01/jan./2022. tab, ilus, graf
Artigo em Inglês | LILACS | ID: biblio-1364028

RESUMO

Objectives: Evaluation of phenolic compounds and antioxidant activities of aqueous extracts of C. longa, P. nigrum and C. cyminum. In addition to proposing a quantum-mechanical model to evaluate the antioxidant activity. Methods: The aqueous extracts were prepared using roots of the Curcuma longa L., seeds of the Piper nigrum L. and seeds of Cuminum cyminum. The extracts were subjected to tests to detect and quantify phenolic compounds and to assess their antioxidant capacity by different methods. Furthermore, to investigate the electronic nature of the antioxidant activity of the main compounds present in these extracts, frontier molecular orbitals (FMOs) were obtained by the DFT/B3LYP/6-31G(d,p) level of theory. Results: After statistical analysis of the results, a greater number of phenolic compounds and better antioxidant activity was identified in the aqueous extracts of cumin (C. cyminum) in all three assays performed, when compared to the other extracts tested. The theoretical model based on the Pietro method is in agreement with the experimental results. Conclusion: This study has an innovative proposal with the trivial antioxidant activity combined with theoretical quantum-mechanical calculations that can serve to reduce costs and time and to predict the antioxidant activity of subsequent studies.


Objetivos: avaliar os compostos fenólicos e atividades antioxidantes dos extratos aquosos de C. longa, P. nigrum e C. cyminum bem como propor um modelo quanto-mecânico para avaliar a atividade antioxidante. Métodos: os extratos aquosos foram preparados por meio da utilização de raízes de Curcuma longa L., sementes de Piper nigrum L. e sementes de Cuminum cyminum. Os extratos foram submetidos a ensaios para detectar e quantificar compostos fenólicos e atividade antioxidante por diferentes métodos. Além disso, com objetivo de investigar a natureza eletrônica da atividade antioxidante dos principais compostos presentes nesses extratos, orbitais moleculares de fronteira (OMFs) foram obtidos pelo nível de teoria DFT/B3LYP/6-31G(d,p). Resultados: após as análises estatísticas dos resultados, a maior quantidade de compostos fenólicos com maior atividade antioxidante foi identificada no extrato aquoso do cominho (C. cyminum) em todos os ensaios realizados, quando comparados com os outros extratos testados. O modelo teórico baseado no método de Pietro está concordante com os resultados experimentais. Conclusão: este estudo possui uma proposta inovadora com a atividade antioxidante trivial combinada com cálculos quanto-mecânicos que podem servir para reduzir custos e tempo para predizer a atividade antioxidante de estudos futuros.


Assuntos
Piper nigrum , Curcuma , Compostos Fitoquímicos , Áreas de Fronteira , Compostos Fenólicos , Teoria da Densidade Funcional , Antioxidantes
2.
J Comput Chem ; 43(26): 1793-1801, 2022 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-36054551

RESUMO

In this work, various precious and non-precious metals reported in the literature as the most effective catalysts for glucose electrooxidation reaction were investigated by the density functional theory (DFT) approach in order to reveal the mechanisms taking place over the catalysts in the fuel cell. The use of a single-atom catalyst model was adopted by insertion of one Au, Cu, Ni, Pd, Pt, and Zn metal atom on the pyridinic N atoms doped graphene surface (NG). ß form of d-glucose in alkaline solution was used to determine the reaction mechanism and intermediates that formed during the reaction. DFT results showed that the desired glucono-lactone was formed on the Cu-3NG electrode in a single-step reaction pathway whereas it was produced via different two-step pathways on the Au and Pt-3NG electrodes. Although the interaction of glucose with Ni, Pd, and Zn-doped surfaces resulted in the deprotonation of the molecule, lactone product formation did not occur on these electrode surfaces. When the calculation results are evaluated in terms of energy content and product formation, it can be concluded that Cu, Pt, and especially Au doped graphene catalysts are effective for direct glucose oxidation in fuel cells reactor.


Assuntos
Grafite , Catálise , Teoria da Densidade Funcional , Eletrodos , Glucose
3.
Int J Mol Sci ; 23(17)2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36077397

RESUMO

In this paper, density functional theory (DFT) was used to study the possibility of low-dimensional (2D, 1D, 0D) boron nitride nanomaterials to catalyze acetylene acetate reaction, and further explore the possible source of this catalytic activity. It is found that the catalytic activity of boron nitride nanomaterials for acetylene acetate reaction will change with the change of the geometric structure (dimension) and reaction site of the catalyst. From the geometric structure, the reaction components and the zero-dimensional BN catalyst can form chemical bonds and form complexes, while only physical adsorption occurs on the surface of the one-dimensional and two-dimensional BN catalysts. From the reaction site, the properties of different C sites on the B12N12NC-C2H2 complexes are different. Namely, a C atom connected with a B atom is more likely to have an electrophilic reaction with H+, and a C atom connected with an N atom is more likely to have a nucleophilic reaction with CH3COO-. Through the study of three kinds of BN nanomaterials with low dimensions, we found that the zero-dimensional B12N12 nanocage broke the inherent reaction inertia of BN materials and showed good catalytic activity in an acetylene acetate reaction, which is very likely to be a non-metallic catalyst for the acetylene gas-phase preparation of vinyl acetate.


Assuntos
Acetileno , Nanoestruturas , Acetatos , Acetileno/química , Compostos de Boro , Teoria da Densidade Funcional , Nanoestruturas/química
4.
Int J Mol Sci ; 23(17)2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36077404

RESUMO

Heavy charged particles induce severe damage in DNA, which is a radiobiological advantage when treating radioresistant tumors. However, these particles can also induce cancer in humans exposed to them, such as astronauts in space missions. This damage can be directly induced by the radiation or indirectly by the attack of free radicals mainly produced by water radiolysis. We previously studied the impact of a proton on a DNA base pair, using the Time Dependent-Density Functional Theory (TD-DFT). In this work, we go a step further and study the attack of the OH· radical on the Guanine nucleotide to unveil how this molecule subsequently dissociates. The OH· attack on the H1', H2', H3', and H5' atoms in the guanine was investigated using the Ehrenfest dynamics within the TD-DFT framework. In all cases, the hydrogen abstraction succeeded, and the subsequent base pair dissociation was observed. The DNA dissociates in three major fragments: the phosphate group, the deoxyribose sugar, and the nitrogenous base, with slight differences, no matter which hydrogen atom was attacked. Hydrogen abstraction occurs at about 6 fs, and the nucleotide dissociation at about 100 fs, which agrees with our previous result for the direct proton impact on the DNA. These calculations may be a reference for adjusting reactive force fields so that more complex DNA structures can be studied using classical molecular dynamics, including both direct and indirect DNA damage.


Assuntos
Nucleotídeos de Guanina , Prótons , DNA/química , Teoria da Densidade Funcional , Humanos , Hidrogênio/química
5.
J Mol Model ; 28(10): 306, 2022 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-36085333

RESUMO

The vertical excitation and emission energies of the cytosine oxo-amino form were calculated at the TD DFT level of theory with several functionals, basis sets, and solvents with different polarity (PCM). They were compared with the experimental UV absorption and fluorescence maxima, revealing that the minimal deviation of the vertical excitation energies from the of UV absorption maxima can be achieved when the hybrid functional B3LYP is applied within the calculations. Regular correlations like curves with saturation between the vertical excitation/emission energies and the dielectric constants were registered. The relaxation of the 1ππ* excited state through an ethylene-like conical intersection S0/S1 should occur through decrease of the decay rate (commented qualitatively here) with the rise of the solvent polarity.


Assuntos
Citosina , Teoria da Densidade Funcional , Fluorescência , Solventes
6.
J Mol Model ; 28(10): 297, 2022 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-36066691

RESUMO

In this study, the effect of non-covalent interactions on the para-aminosalicylic acid complex is explored using density functional theory (DFT) in the gas phase and the solution. Our findings exhibit that the achieved binding energies considerably change on going from the gas phase to the solution. Based on the obtained results, the absolute value of the binding energy of the complex in the polar solvents is lower than the non-polar ones while in the gas phase it is higher than the solution. The atoms in molecules (AIM) and the natural bond orbital (NBO) analyses are applied to estimate the topological properties and the charge transfer during complexation, respectively. The results indicate that the presence of the cation-π interaction increases the strength of the intramolecular hydrogen bond in the studied complex. Finally, the various electronic descriptors such as energy gap, hardness, softness, and electronic chemical potential are investigated to gain further insight into these interactions. According to the achieved results, the high energy gap of the complex in the water solvent indicates high chemical stability and low reactivity compared to the others. On the other hand, the most reactive as well as the softest complex belongs to the gas phase.


Assuntos
Ácido Aminossalicílico , Tuberculose , Teoria da Densidade Funcional , Humanos , Modelos Moleculares , Teoria Quântica , Solventes/química
7.
J Comput Chem ; 43(28): 1923-1935, 2022 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-36069663

RESUMO

A new set of auxiliary basis function suitable to fit the induced electron density is presented. Such set has been optimized in order to furnish accurate absorption spectra using the complex polarizability algorithm of time-dependent density functional theory (TDDFT). An automatic procedure has been set up, able, thanks to the definition of suitable descriptors, to evaluate the resemblance of the auxiliary basis-dependent calculated spectra with respect to a reference. In this way, it has been possible to reduce the size of the basis set maximizing the basis set accuracy. Thanks to the choice to employ a collection of molecules for each element, such basis has proven transferable to molecules outside the collection. The final sets are therefore much more accurate and smaller than the previously optimized ones and have been already included in the database of the last release of the AMS suite of programs. The availability of the present new set will allow to improve drastically the applicability range of the polTDDFT method with higher accuracy and less computational effort.


Assuntos
Algoritmos , Teoria da Densidade Funcional
8.
Anal Chem ; 94(38): 13243-13249, 2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36107722

RESUMO

Liposomes are emerging therapeutic formulations for site-specific delivery of chemotherapeutic drugs. The efficiency and selectivity of drug delivery by these carriers largely rely on their surface properties, shape, and size. There is a growing demand for analytical approaches that can be used for structural and morphological characterization of liposomes at the single-vesicle level. AFM-IR is a modern optical nanoscopic technique that combines the advantages of scanning probe microscopy and infrared spectroscopy. Our findings show that AFM-IR can be used to probe conformational changes in phospholipids that take place upon their assembly into liposomes. Such conclusions can be made based on the corresponding changes in intensities of the lipid vibrational bands as the molecules transition from a solid state into large unilamellar vesicles (LUVs). This spectroscopic analysis of LUV formation together with density functional theory calculations also reveals the extent to which the molecular conformation and local environment of the functional groups alter the AFM-IR spectra of phospholipids. Using melittin as a test protein, we also examined the extent to which LUVs can be used for protein internalization. We found that melittin enters LUVs nearly instantaneously, which protects it from possible structural modifications that are caused by a changing environment. This foundational work empowers AFM-IR analysis of liposomes and opens new avenues for determination of the molecular mechanisms of liposome-drug interactions.


Assuntos
Lipossomos , Fosfatidilcolinas , Teoria da Densidade Funcional , Lipossomos/química , Meliteno , Microscopia de Força Atômica , Conformação Molecular , Fosfatidilcolinas/química , Fosfatidilserinas , Fosfolipídeos/química , Espectrofotometria Infravermelho , Lipossomas Unilamelares
9.
Molecules ; 27(17)2022 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-36080281

RESUMO

In this paper, Amomi fructus (Latin) was used to explore the mechanism of ionic liquids (ILs) in improving the extraction efficiency of essential oils. Microwave assisted ionic liquid treatment followed by a hydro-distillation (MILT-HD) process for isolating Amomi fructus essential oil was optimized by multi-objective optimization. Under optimum operating conditions, the IL-assisted extraction method not only enhances extraction efficiency but also reduces energy demands and CO2 emissions. Since the hydrogen bond structure network of cellulose in the cell wall is an important reason for hindering diffusion of essential oils, the mechanism of ILs was explored by density functional theoretical (DFT) and molecular dynamics (MD) simulations. According to DFT calculations, ILs can facilitate the cleavage of cellulose chains and have strong non-covalent interactions with cellulose. Based on the MD simulations, the degree of destruction of the cellulose hydrogen bond structure was explored. According to the DFT and MD simulations, the ILs can significantly destroy cellulose structure, thereby promoting essential oil release from the plant. These results were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). This work is conducive to better understand the MILT-HD process for isolating essential oil and comprehensively understand the mechanism of ILs in the extraction process.


Assuntos
Líquidos Iônicos , Óleos Voláteis , Celulose/química , Teoria da Densidade Funcional , Líquidos Iônicos/química , Simulação de Dinâmica Molecular , Óleos Voláteis/química
10.
J Chem Phys ; 157(8): 084104, 2022 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-36049992

RESUMO

Resonance Raman spectroscopy has long been established as one of the most sensitive techniques for detection, structure characterization, and probing the excited-state dynamics of biochemical systems. However, the analysis of resonance Raman spectra is much facilitated when measurements are accompanied by Density Functional Theory (DFT) calculations that are expensive for large biomolecules. In this work, resonance Raman spectra are therefore computed with the Density Functional Tight-Binding (DFTB) method in the time-dependent excited-state gradient approximation. To test the accuracy of the tight-binding approximations, this method is first applied to typical resonance Raman benchmark molecules, such as ß-carotene, and compared to results obtained with pure and range-separated exchange-correlation functionals. We then demonstrate the efficiency of the approach by considering a computationally challenging heme variation. Overall, we find that the vibrational frequencies and excited-state properties (energies and gradients) that are needed to simulate the spectra are reasonably accurate and suitable for interpretation of experiments. We can therefore recommend DFTB as a fast computational method to interpret resonance Raman spectra.


Assuntos
Teoria Quântica , Vibração , Simulação por Computador , Teoria da Densidade Funcional , Análise Espectral Raman
11.
J Mol Graph Model ; 117: 108314, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-36041352

RESUMO

The properties to be an active drug candidate of the complex Pt(TEEDA)Cl2, C1; Pd(TEEDA)Cl2, C2 and their hydrolysed product [Pt(TEEDA)(OH2)2]2+, C1' and [Pd(TEEDA)(OH2)2]2+, C2' were predicted by Lipinski's rule of 5 and PASS (prediction of activity spectra for substances) web tool. Their structural profile, HOMO-LUMO energy and electronic potential surface ware analysed by DFT calculation. Their TD-DFT spectra were compared with experimental UV-Vis spectra. The hydrolysis mechanisms of C1 & C2 to the diaqua form C1' and C2' were extensively investigated by DFT method in different levels of theory and using CPCM/water model and compared with recognised Pt based anticancer drugs. All the stationary states, including the transition state for the reactions were identified by the DFT calculation. The IRC calculation confirmed that the transition states are well connected and corelate with reactants and products. Interaction of the complexes with DNA & HSA was also investigated by molecular docking study.


Assuntos
Antineoplásicos , Cisplatino , Antineoplásicos/química , Cisplatino/química , DNA/química , Teoria da Densidade Funcional , Hidrólise , Simulação de Acoplamento Molecular , Água
12.
J Hazard Mater ; 440: 129738, 2022 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-35985218

RESUMO

A novel carbon nitride based self-cleaning hydrogel photocatalyst (KI-PCN gel, potassium and iodine co-doped carbon nitride confined in alginate) has been successfully constructed by a facile method. Fabricated photocatalyst showed enhanced synergistic adsorption-photocatalytic degradation property on a high concentration of methylene blue (HMB) because of enhanced carrier separation efficiency and improved light adsorption capacity of KI-PCN. As expected, the KI-PCN gel showed the highest apparent rate constant value (Kapp =0.0310 min-1), which was about 38.8 and 5.8 times as that of blank hydrogel (Kapp=0.0008 min-1) and PCN gel (Kapp=0.0053 min-1), respectively. Meanwhile, KI-PCN gel can continuously adsorb low concentration of MB (LMB), and the MB-adsorbed KI-PCN gel can self-clean under light irradiation. The bench-scale experiments simulating real river showed that KI-PCN gel can effectively and continuously remove LMB (0.1-20 ppm), indicating the possibility for the removal of contaminants in natural rivers. Furthermore, the possible degradation pathways were proposed by combining the density functional calculations (DFT) and intermediates identified by liquid chromatography-mass spectrometry (LC-MS). This work proposed a new perspective to acquire a novel self-cleaning and easily recyclable photocatalyst for treatment of wide concentration range organic wastewater as well as remediation of natural waterbody.


Assuntos
Iodo , Águas Residuárias , Alginatos , Catálise , Teoria da Densidade Funcional , Hidrogéis , Azul de Metileno , Nitrilas , Potássio , Carbonitrila de Pregnenolona , Águas Residuárias/química
13.
Org Biomol Chem ; 20(36): 7216-7220, 2022 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-36044005

RESUMO

We have found that derivatization of the trianglamine macrocycle by aliphatic aldehydes leads selectively to one of the two possible diastereomeric aminal products. X-ray analysis, NMR measurements and DFT calculations pointed to the product possessing a higher symmetry.


Assuntos
Aldeídos , Teoria da Densidade Funcional , Espectroscopia de Ressonância Magnética
14.
Int J Mol Sci ; 23(15)2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35955684

RESUMO

Pharmaceutical cocrystals can offer another advanced strategy for drug preparation and development and can facilitate improvements to the physicochemical properties of active pharmaceutical ingredients (APIs) without altering their chemical structures and corresponding pharmacological activities. Therefore, cocrystals show a great deal of potential in the development and research of drugs. In this work, pharmaceutical cocrystals of ethenzamide (ETZ) with 2,6-dihydroxybenzoic acid (26DHBA), 2,4-dihydroxybenzoic acid (24DHBA) and gallic acid (GA) were synthesized by the solvent evaporation method. In order to gain a deeper understanding of the structural changes after ETZ cocrystallization, terahertz time domain spectroscopy (THz-TDS) and Raman spectroscopy were used to characterize the single starting samples, corresponding physical mixtures and the cocrystals. In addition, the possible molecular structures of ETZ-GA, ETZ-26DHBA and ETZ-24DHBA cocrystals were optimized by density functional theory (DFT). The results of THz and Raman spectra with the DFT simulations for the three cocrystals revealed that the ETZ-GA cocrystal formed an O-H∙∙∙O hydrogen bond between the -OH of GA and oxygen of the amide group of the ETZ molecule, and it was also found that ETZ formed a dimer through a supramolecular amide-amide homosynthon; meanwhile, the ETZ-26DHBA cocrystal was formed by a powerful supramolecular acid-amide heterosynthon, and the ETZ-24DHBA cocrystal formed the O-H∙∙∙O hydrogen bond between the 4-hydroxy group of 24DHBA and oxygen of the amide group of the ETZ molecule. It could be seen that in the molecular structure analysis of the three cocrystals, the position and number of hydroxyl groups in the coformers play an essential role in guiding the formation of specific supramolecular synthons.


Assuntos
Amidas , Oxigênio , Cristalização , Teoria da Densidade Funcional , Estrutura Molecular , Preparações Farmacêuticas , Salicilamidas
15.
Int J Mol Sci ; 23(15)2022 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-35955897

RESUMO

In this study, we report the synthesis of a new organic-inorganic molecular salt of the clinically used antifungal drug fluconazole, (H2Fluconazole).SnCl6.2H2O. By detailed investigation and analysis of its structural properties, we show that the structure represents a 0D structure built of alternating organic and inorganic zig-zag layers along the crystallographic c-axis and the primary supramolecular synthons in this salt are hydrogen bonding, F···π and halogen bonding interactions. Magnetic measurements reveal the co-existence of weak ferromagnetic behavior at low magnetic field and large diamagnetic contributions, indicating that the synthesized material behaves mainly as a diamagnetic material, with very low magnetic susceptibility and with a band gap energy of 3.6 eV, and the salt is suitable for semiconducting applications. Extensive theoretical study is performed to explain the acceptor donor reactivity of this compound and to predict the Cl-substitution effect by F, Br and I. The energy gap, frontier molecular orbitals (FMOs) and the different chemical reactivity descriptors were evaluated at a high theoretical level. Calculations show that Cl substitution by Br and I generates compounds with more important antioxidant ability and the intramolecular charge transfer linked to the inorganic anion.


Assuntos
Fluconazol , Halogênios , Benchmarking , Teoria da Densidade Funcional , Halogênios/química , Ligação de Hidrogênio
16.
J Mol Model ; 28(9): 278, 2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-36028595

RESUMO

A combination of high open-circuit voltage (Voc) and short-circuit current density (Jsc) typically creates effective organic solar cells (OSCs). To enhance the open-circuit voltage, we have designed three new fullerene-free acceptor molecules with elongated π-conjugation in the end-capped units. Y-series-based newly designed molecules (CPSS-4F, CPSS-4Cl, CPSS-4CN) exhibited a narrow energy bandgap with high electron mobility. Red shift in the absorption spectrum with high intensities is also noted for designed molecules. Low binding and excitation energies of designed molecules favor easy excitation of exciton in the excited state. Further, CPSS-4F, CPSS-4Cl, and CPSS-4CN exhibited better open-circuit voltage with favorable molecular orbitals contributions. Transition density analysis (TDM) was also performed to locate the total transitions in the designed molecules. Outcomes of all analyses suggested that designed molecules are effective contributors to the active layer of organic solar cells.


Assuntos
Fulerenos , Energia Solar , Teoria da Densidade Funcional , Elétrons , Estrutura Molecular
17.
Int J Mol Sci ; 23(16)2022 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-36012292

RESUMO

Hydrogen-bond (H-bond) energies in 310-helices of short alanine peptides were systematically examined by precise DFT calculations with the negative fragmentation approach (NFA), a modified method based on the molecular tailoring approach. The contribution of each H-bond was evaluated in detail from the 310-helical conformation of total energies (whole helical model, WH3-10 model), and the results were compared with the property of H-bond in α-helix from our previous study. The H-bond energies of the WH3-10 model exhibited tendencies different from those exhibited by the α-helix in that they depended on the helical position of the relevant H-bond pair. H-bond pairs adjacent to the terminal H-bond pairs were observed to be strongly destabilized. The analysis of electronic structures indicated that structural characteristics cause the destabilization of the H-bond in 310-helices. We also found that the longer the helix length, the more stable the H-bond in the terminal pairs of the WH3-10 model, suggesting the action of H-bond cooperativity.


Assuntos
Peptídeos , Teoria da Densidade Funcional , Ligação de Hidrogênio , Modelos Moleculares , Peptídeos/química , Conformação Proteica em alfa-Hélice
18.
Molecules ; 27(16)2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-36014326

RESUMO

Under the DFT calculations, two-dimensional (2D) GeSi, SnSi, and SnGe monolayers, considered as the structural analogues of famous graphene, are confirmed to be dynamically, mechanically and thermodynamically stable, and all of them can also possess good conductivity. Furthermore, we systematically investigate their electrocatalytic activities in overall water splitting. The SnSi monolayer can show good HER catalytic activity, while the SnGe monolayer can display remarkable OER catalytic activity. In particular, the GeSi monolayer can even exhibit excellent bifunctional HER/OER electrocatalytic activities. In addition, applying the biaxial strain or doping heteroatoms (especially P atom) can be regarded as the effective strategies to further improve the HER activities of these three 2D monolayers. The doped GeSi and SnSi systems can usually exhibit higher HER activity than the doped SnGe systems. The correlative catalytic mechanisms are also analyzed. This work could open up a new avenue for the development of non-noble-metal-based HER/OER electrocatalysts.


Assuntos
Grafite , Catálise , Teoria da Densidade Funcional , Condutividade Elétrica , Grafite/química , Modelos Teóricos
19.
Anal Methods ; 14(35): 3405-3415, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35983903

RESUMO

In this work, an isoxazolyl-azo pyrimidine optical chemosensor (PICS) was efficiently synthesized and applied for naked-eye detection of Ag+ ions in solution. The chemical formula of the PICS was recognized by UV-vis, FTIR and NMR analyses. The detection ability of PICS toward various ions was assessed. The results revealed the excellent selectivity and sensitivity of the chemosensor PICS to Ag+ ions in aqueous DMSO solutions. The PICS displayed an obvious color change from yellow to dark red in the presence of silver ions. The PICS could efficiently detect Ag+ ions over a wide pH range of 6-11, which makes it suitable for detection of Ag+ under physiological conditions. PICS also binds Ag+ ions to form a 1 : 1 stoichiometry complex (PICS-Ag+), resulting in a bathochromic shift in the absorption maximum from 372 to 410 nm. The detection limit of the probe PICS towards Ag+ was calculated to be 1.78 µM. Furthermore, the probe PICS shows excellent detection performance in the solid state, and PICS-based test strips were fabricated and applied as efficient Ag+ test kits for detection of silver ions in water samples. In addition, the sensing mechanism of PICS-Ag+ was completely evaluated using the density functional theory (DFT) calculations. Results indicated that the calculated energy gap between the HOMO and LUMO (3.41 eV) of PICS-Ag is lower than that of the free PICS (3.57 eV). This suggests that a red shift occurred upon addition of the Ag+ ion to PICS.


Assuntos
Colorimetria , Prata , Colorimetria/métodos , Teoria da Densidade Funcional , Dimetil Sulfóxido/química , Íons , Espectroscopia de Ressonância Magnética , Pirimidinas , Prata/análise , Prata/química , Água/química
20.
Dalton Trans ; 51(33): 12436-12441, 2022 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-35943556

RESUMO

The HBED chelator is used to stabilize small and hard metal ions such as Fe3+, Ti4+, Ga3+ and Al3+ in both medicine and industry. While the coordination of hexadentate HBED4- is known in the case of Fe3+, Ti4+ and Ga3+, it is unknown in the case of the small Al3+ ion since its corresponding complex has never been fully characterized. Thus, in this work the coordination pattern in a newly synthesized aluminum HBED-based complex ([Al-HBED-NN]-Na+) was determined using 2D NMR in conjunction with DFT calculations.


Assuntos
Alumínio , Quelantes , Alumínio/química , Quelantes/química , Teoria da Densidade Funcional , Íons/química , Espectroscopia de Ressonância Magnética
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