Two isolated organic-inorganic pentavanadate-based hybrids, [H2N (CH3)2]6.34 [VV (μ3-O)4VI4V O5 (SO4)4]·(SO4)0.67·(DMF)· [HN (CH3)2]1.66 (1) and [(HN)2 (CH2)2 (CH3)4] [VV (μ3-O)4V4IVO5 (SO4)4] [H2N (CH3)2]3·(DMF)· [HN (CH3)2]0.5 (2) (DMF=N, N-dimethylformamide) have been synthesized under solvothermal conditions and structurally characterized. In compound 1, three adjacent basic units form a triangle type cluster. The symmetric double-layer exists in compound 2. The study of the third-order nonlinear optical (NLO) properties for the two compounds demonstrates that the two-photon absorption (TPA) cross-section σ values of compounds 1 and 2 are 1372 and 1228 GM, respectively, indicating that both compounds may have potential application in optical field.
Two fluorescence-enhanced probes, 4-(2, 4-dinitrophenoxy)-N-(2-hydroxyethyl)-1, 8-naphthalimide (NTE-1) and 4-(2, 4-dinitrophenoxy)-N-[4-(2, 4-dinitrophenoxy)phenyl]-1, 8-naphthalimide (NTE-2), have been designed and synthesized for detection of H2S. 4-Hydroxy-1, 8-naphthalimide as fluorophore in combination with 2, 4-dinitrophenyl ether as H2S response site constructed the fluorescence probes. The consequences showed that both NTE-1 and NTE-2 displayed large red-shift (excess 100 nm) in absorption spectra and more than 30-fold fluorescence enhancement in response to H2S. Moreover, the dual site probe, NTE-2, displayed wider linear range between fluorescence intensity and concentration of H2S (0-40 μmol/L) compared with single site probe, which can be applied to quantitative detection of high concentration of H2S. The photoinduced electron transfer (PET) response mechanism of probe was further studied by analyzing the distributions of molecular orbital. Importantly, the probes have potential practical applications in the detection of H2S.
Wood vinegar (WV) has a powerful antioxidant activity, but it is unclear which components are responsible for the antioxidant activity. In the present study, the double-column retention index qualitative method was used for the identification of the major components in five kinds of WV. And the major antioxidants of wood vinegar were accurately identified with the aid of Pearson product-moment correlation coefficients and authentic standard samples. Our results demonstrate that phenolic compounds are mainly responsible for the powerful antioxidant activity. 2, 6-Dimethoxyphenol is the most powerful antioxidant in WV. 2-Methoxyphenol and 3-methyl-1, 2-cyclopentane-dione also have an important influence on the antioxidant activity of WV. Our results suggest that the contents of 2-methoxyphenol, 2, 6-dimethoxyphenol and 3-methyl-1, 2-cyclopentanedione should act as the criteria for evaluating the antioxidant activity of WV. Our work will provide useful information for WV's application in the fields of food and medicine as antioxidants.
A new method for the synthesis of 1, 4-dihydropyridine (1, 4-DHP) calcium channel antagonists felodipine, nitrendipine and their derivatives via papain-catalyzed three-component reactions of aldehyde, methyl acetoacetate and ethyl 3-aminocrotonate was developed. Operational simplicity, mild reaction conditions and eco-friendliness are the key features of this protocol.
A facile and efficient method for the preparation of methyl ketones was developed in the reaction of alkynes and alkenes with PhIO-BF3·Et2O. The reaction features mild conditions, short time and metal-free catalyst. The possible mechanism for the formation of methyl ketones was proposed. H2O functions as both a nucleophile and an oxygen source.
A simple, efficient and green procedure for the synthesis of spiro-oxindole dihyfroquinazolinones was developed by multi-component condensation of isatoic anhydride, aniline and isatin in the presence of a novel solid acid catalyst under ultrasound irradiation. The present environmentally benign protocol offers several advantages, such as shorter reaction time, a wide range of functional group tolerance, the use of an inexpensive heterogeneous catalyst, and a high yield of products via a simple experimental and work-up procedure. The mesoporous solid acid catalyst was directly prepared from phytic acid by microwave-sulfonation method without template. The phytic acid based solid acid was fully characterized by means of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The catalyst can be recovered and reused for at least five runs without significant impact on the product yields.
A novel series of diaryl biuret derivatives containing a tetrazole moiety was designed and synthesized. All the target compounds were evaluated for their in vitro antitumor activity against HT-29, HepG2, MCF-7 and A549 cells by MTT assay. Most of them exhibited obvious antitumor activity, and four of them (4a, 4c, 4h and 7a) were superior to sorafenib in general. Among them, Compound 4h displayed more potent activity than sorafenib in all tested cancer cells. Compound 4c exhibited the most outstanding activity in inhibition of growth of HepG2 cells (IC50=0.55 μmol/L). Further, they both revealed favorable metabolic stability in in vitro assay. Compounds 4c and 4h are promising candidates for further development.
A series of Cs-modified CuO/CeO2 mixed oxide catalysts was prepared for enhancing the stable activity of N2O decomposition. It was found that Cs modification promoted the catalytic performance of CuO/CeO2 catalysts significantly. The 1%Cs-CuO/CeO2 catalyst exhibited the best activity, and the conversion of N2O reached 100% at 380℃ in the presence of 2% O2. The catalytic behaviors were investigated by means of XRD, N2 adsorption isotherms, XPS, H2-TPR (TPR:temperature-programmed reduction), CO-IR, O2-TPD (TPD:temperature-programmed desorption) and diffused reflectance infrared Fourier transform spectorscopy (DRIFTs). The results revealed that Cs modification promoted the activity and the oxygen resistance by enhancing the desorption of surface oxygen species and increasing the content of Ce3+. CO-DRIFTs revealed that Ce3+ could efficiently facilitate the regeneration of active Cu+ sites by an oxygen migration step. The possible reaction mechanism was also discussed.
Interactions among Cu (Ⅱ), doxorubicin and copper operon C (CopC) have been investigated in detail by means of fluorescence, UV-Vis, IR spectra, isothermal titration calorimetry (ITC) and molecular docking in Tris-HCl buffer (50 mmol/L, pH=7.4, 25℃). The results suggest that Cu (Ⅱ)-doxorubicin is formed in a Cu (Ⅱ) to doxorubicin molar ratio of 1:2, and the conditional stability constant, K [Cu (Ⅱ)-doxorubicin] is 1.90×109 L2/mol2, CopC and doxorubicin can form a 1:1 complex, the conditional stability constant is greater than 105 L/mol. Binding of doxorubicin causes a conformational change in CopC with the reduction of β-sheet and increase of random coil, and the stability of CopC is decreased. Cu (Ⅱ), doxorubicin and CopC can form a CopC-Cu (Ⅱ)-doxorubicin ternary complex. The formation of CopC-Cu (Ⅱ)-doxorubicin reduced greatly the reduction rate of Cu (Ⅱ) by ascorbate (Vc), i.e., the binding of doxorubicin affects the action of CopC as redox switch.
The electrochemical reaction of Bi (Ⅲ) and co-reduction behaviour of Bi (Ⅲ) and Y (Ⅲ) ions were researched in molten LiCl-KCl on a tungsten (W) electrode employing a range of electrochemical techniques. Cyclic voltammetric and square-wave voltammetric results revealed that the reduction of Bi (Ⅲ) was a one-step process, with the exchange of three electrons on a W electrode, and diffusion-controlled. The electrochemical curves showed two reduction peaks pertaining to the formation of Bi-Y alloy compounds, because of the co-reduction of Bi (Ⅲ) and Y (Ⅲ) by metallic Y deposited on the pre-deposited Bi-coated W electrode and reacting with Bi metal in molten LiCl-KCl. Furthermore, galvanostatic electrolysis was conducted using liquid Bi as cathode to extract yttrium at different current intensities, and the extractive products were analyzed by SEM, EDS and XRD. The results indicated that BiY intermetallic compound was formed in the molten LiCl-KCl-YCl3 system.
In this study, a dissipative particle dynamics mehtod was used to study the solubilization enhancing effect of platycodin towards 5 different drug components. Two factors were mainly considered, including the XlogP value of drug components and the sugar chain length of platycodin. As a result, it was found that there was an optimal drug XlogP value for the solubilization enhancing effect of platycodin, and it was different between the drug's own XlogP value and the optimal drug XlogP value of platycodin that determines the solubilization enhancing effect.
Ru/Ce-Zr catalysts were prepared by impregnation of Ru on the hydrothermally synthesized Ce-Zr mixed oxide with different molar ratio of Ce/Zr. The resultant products were systematically characterized by inductively coupled plasma (ICP), X-ray diffraction (XRD), scanning electron microscopy (SEM)/energy dispersive spectrometry (EDS), H2-temperature programmed reduction (H2-TPR), NH3-temperature programmed desorption (NH3-TPD) and X-ray photoelectron spectroscopy (XPS). It was proved by H2-TPR and NH3-TPD that the introduction of Ru can improve the activity of oxygen of catalysts and the presence of Zr contributes to the increments of acid properties of catalysts. When the molar ratio of Ce-Zr was 8:4, the quantity of Ru was 0.9% (mass ratio), and the calcined temperature of catalysts was at 400℃, the removal rate of 90% for trichloroethylene (TCE) was reached at 250℃ for 5360 mg/m3 TCE and the stability of the catalysts was investigated under the condition. The results showed that the high removal rate can be maintained for at least 90 h, which is promising for industrial application.
Novel Fe3O4-decorate hierarchical porous carbon skeleton derived from maize straw (Fe3O4@MSC) was synthesized by a facile co-precipitation process and a calcination process, which was developed as a UV assisted heterogeneous Fenton-like catalyst. The as-synthesized catalysts were characterized via X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer-Emmet-Teller (BET) and vibrating sample magnetometer (VSM) at room temperature. The morphology and structure analysis revealed that the as-prepared Fe3O4@MSC retained the original pore morphology of the maize straw material. The non-uniform polyhedral Fe3O4 grew on the whole surface of the MSC, which reduced the aggragation of Fe3O4 and provided more active sites to strengthen the UV-assisted Fenton-like reaction. As a result, the tetracycline (TC) degradation efficiency after 40 min reaction and total organic carbon (TOC) removal efficiency after 2 h reaction of Fe3O4@MSC catalyzing UV-Fenton system reached 99.2% and 72.1%, respectively, which were more substantial than those of Fe3O4@MSC/H2O2 (31.5% and 2%), UV/H2O2 system (68% and 23.4%) and UV/Fe3O4/H2O2 (80% and 37.5%). The electron spin resonance (ESR) results showed that the ·OH played an important role in the catalytic reaction. A possible degradation pathway of TC was proposed on the basis of the identified intermediates. Overall, the UV assisted heterogeneous Fenton-like process in Fe3O4@MSC improved the cycle of Fe3+/Fe2+ and activated the interfacial catalytic site, which eventually realized the enhancement of degradation and mineralization to tetracycline.
Today, due to the increasingly stringent European directives concerning the use of molecules with certain toxicities towards the environment or their users, the essential oils, extracts, and molecules derived from plants exhibiting the characteristic of being biodegradable can be considered as a source of green corrosion inhibitors instead of harmful synthetic chemicals. The present work was devoted to testing the essential oil extracted from Mentha pulegium leaves (M1) as a corrosion inhibitor for C-steel in 1 mol/L HCl solution using both electrochemical techniques and gravimetric measurements for the evaluation of the inhibition efficiencies at different temperatures. The results obtained showed that the inhibition efficiency increased with an increase in M1 concentration to reach a maximum va-lue of 92.21%. We sought to determine the molecule responsible for this high efficiency, starting with the analysis of oil chemical composition by gas chromatography coupled with mass spectrometry. This analysis revealed that menthol (M2) and isomenthol (M3) were the principal constituents. In order to identify the molecule responsible for the inhibition and explain the protection mechanism involved, quantum chemical calculations and Monte Carlo simulations were used to explain the interaction of menthol, the major constituent of M1 with the Fe-surface. To practically confirm these results, we studied the action of 1 mol/L HCl on steel with and without the addition of M2 by both methods (gravimetric and electrochemical study). A very high efficiency was obtained, an efficiency of 94.90% at 10-3 mol/L, which was retained for a long exposure time, and slightly decreased in function of temperature. Finally, a good correlation between the experimental data, theoretical calculations, and SEM studies was obtained, which denied that the M1 efficiency was only a result of a synergy effect and confirmed the high efficiency of Mentha oil and its main component (menthol) as a strong ecological inhibitor of corrosion.
Mesoporous scaffold structures have played great roles in halide perovskite solar cells (PSCs), due to the excellent photovoltaic performance and commercial perspective of mesoporous PSCs. Here, we reported a mixed-phase TiO2 mesoporous film as an efficient electron transport layer (ETL) for mesoporous perovskite solar cells. Due to the improved crystal phase, film thickness and nanoparticle size of TiO2 layer, which were controlled by varying the one-step hydrothermal reaction time and annealing time, the PSCs exhibited an outstanding short circuit photocurrent density of 25.27 mA/cm2, and a maximum power conversion efficiency (PCE) of 19.87%. It is found that the ultra-high Jsc attributes to the excellent film quality, light capturing and excellent electron transport ability of mixed-phase TiO2 mesoporous film. The results indicate that mix-phase mesoporous metal oxide films could be a promising candidate for producing effective ETLs and high efficiency PSCs.
The chain length effect of four chiral aliphatic alcohols, (S)-2-butanol, (S)-2-pentanol, (S)-2-hexanol and (S)-2-heptanol, on their specific optical rotations (OR) was studied experimentally and theoretically via quantum theory. Many conformations of each chiral alcohol exist as conformer pairs in solution. The OR sum from these pairs of conformers has much smaller contributions to OR values than that contributed by the most stable conformation. These four alcohols' OR values were also investigated using the matrix model, which employs each substituent's comprehensive mass, radii, electronegativity and symmetry number as the elements in the matrix. These are all particle properties. This matrix determinant is proportional to its OR values within a closely related structural series of chiral compounds. The experimental OR values and the matrix determinants of these four alcohols were compared with the predicted OR values obtained from quantum theory wave functions. The ORs predicted by the matrix method, which is based on particle function statistics, agreed with the results from quantum theory. The agreement between OR predictions by the matrix method and DFT calculations illustrates the wave-particle duality of polarized light that is operating in these predictions.
Chlorophenols are known as persistent organic pollutants. Therefore, research on the removal of chlorophenols has attracted widespread attention. Herein, the photocatalytic degradation of 4-chlorophenol by Gd-doped β-Bi2O3 under visible light irradiation was studied. The results showed that Gd-doped β-Bi2O3 materials are efficient catalysts for the photocatalytic degradation of chlorophenols, and 2% (atomic fraction) Gd-doped β-Bi2O3 exhibits the highest photocatalytic activity for 4-chlorophenol degradation, because doping an appropriate amount of Gd3+ ions can effectively reduce the recombination rate of the photogenerated e-/h+ pairs and then enhance the photocatalytic performance. When the reaction was carried out at 25℃ for 6 h using the 2% Gd-doped β-Bi2O3 micro/nano materials of 200 mg and at air flow rate of 40 mL/min, the degradation rate of 4-chlorophenol reached 92.3%. Additionally, based on the analysis of the products, it was speculated that the dominant photocatalytic degradation mechanism of 4-chlorophenol by Gd-doped β-Bi2O3 under visible light irradiation is an oxidative process involving an attack by the hydroxyl radical.
Copper-cobalt bimetallic oxides-doped alumina hollow spheres (CuCo/AHS) were fabricated through the sacrificial carbonaceous template strategy. The dependence of the physicochemical properties and morphologies of CuCo/AHS on the composition of copper and cobalt in CuxCoy/AHS (x/y=9/1, 7/3, 5/5, and 3/7) was characterized by means of X-ray powder diffraction, nitrogen physisorption, atomic adsorption spectroscopy, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. Among these catalysts, Cu7Co3/AHS catalyst exhibited perfect hollow sphere structure, thin wall, and big pore size. The calcined catalysts were examined for the epoxidation of styrene with tert-butyl hydroperoxide as oxidant. Compared with the monometallic counterparts (Cu/AHS and Co/AHS) and other CuxCoy/AHS catalysts, Cu7Co3/AHS catalyst showed higher performance, yielding a styrene conversion of 64.6% with 93.0% selectivity toward styrene oxide. In addition, the strong interaction of Cu2+ or Co2+ with AHS ensured good stability after four consecutive reactions.
The carbon nanotubes supported palladium (Pd/CNT) nanocatalysts were modified by cerium oxides/hydroxides and their catalytic performances for methanol oxidation were evaluated. Electrochemical measurements indicate that the introduction of cerium remarkably improves the catalytic activity of Pd/CNT catalysts towards methanol oxidation. X-Ray photoelectron spectra results reveal an interaction between palladium and cerium oxides. It is also observed that cerium-modified catalysts have excellent poison resistances, which is attributed to the poison-removal ability of cerium oxides/hydroxides. The highly oxidized cerium oxides/hydroxides have a strong ability to inhibit the accumulation of carbonaceous intermediates on the active sites of Pd catalysts.
A pyrolyzed ash containing about 50% carbon, named silicon carbon black (SiCB), was prepared by the anoxic pyrolysis of rice husk. Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), transmission electron microscopy (TEM) and universal material testing machine were used to analyze the stress-strain relationship, Mullins effect and static viscoelastic properties of SiCB-filled vulcanized natural rubber (NR), and SiCB was compared with a commercially available semi-reinforcing furnace (SRF) carbon black. The results show that the vulcanized natural rubber filled with SiCB had similar reinforcing properties to those of that filled with traditional SRF, but obvious differences between them exist in stress-strain properties and stress softening resistance. We tried to discuss the related phenomena with the aid of the modified two-layer theory. And it is successfully predicted and verified that SiCB has good compression resistance and obvious stress relaxation advantages in compression stress relaxation.
The effects of replacement on the optical properties of diketopyrrolopyrrole (DPP)-based polymers were discussed through replacing the thieno [3, 2-b]thiophene units by thiophene units. It is easy to see that the role of replacement would lead to blue shift of steady-state absorption spectrum when thieno [3, 2-b]thiophene units is replaced by thiophene units. Meanwhile, the transient absorption data indicate that the role of replacement would not change the relaxation mechanism of polymer, but is able to adjust the photo-excitation relaxation rate of polymer. Their intensity-dependent dynamic curves show that the exciton-exciton annihilation (EEA) would participate in the relaxation process when the polymer is in the aggregation. Through comparing the EEA data between the polymers, it is found that the role of replacement would change the spatial distribution of exciton.
A series of comb-shaped poly (arylene ether sulfone)s containing pendant 2-methyl-3-alkylimidazolium group (ImPAES-Cx, x=1, 6, 10) was prepared and characterized as novel anion exchange membranes. These ImPAES-Cx membranes were obtained by benzylic bromination and imidazolium functionalization. The characteristic nano-phase separation structure was formed in membranes with longer alkyl side chains, as confirmed by small-angle X-ray scattering. The nano-phase separation structures endowed ImPAES-Cx membranes with improved ionic conductivity, dimensional stability (at least 60% decrease water uptake and swelling ratio at 60℃) and mechanical properties, together with excellent alkaline stability. Especially, ImPAES-C6 membranes possessed enhanced hydroxide conductivity and chemical stability simultaneously. These results suggest that it is a feasible strategy to introduce appropriate length of alkyl side chains into anion exchange membranes (AEMs) to improve the performance.
Amorphous poly (9, 9-di-n-octyl-2, 7-fluorene) (PFO) thin films were characterized in situ via thermal annealing based on grazing incidence X-ray diffraction (GIXRD) profiles, UV-visible absorption spectrophotometry, and Fourier transform infrared spectroscopy (FTIR). The results of GIXRD indicated that the amorphous phase transformed into a crystalline phase when the annealing temperature was higher than 80℃. Different outcomes were elicited for the intensities and d-spacings of the diffraction peaks below and above 80℃, which were attributed to the formation of the k-phase. The mechanism of phase transition was revealed by in situ UV-visible absorption and FTIR spectra, whereby the rearrangement of the side chains was dominant and the movement of the main chains was minimal, even when the annealing temperature was lower than 80℃. In contrast, the rearrangement of the main chains was dominant when the temperature was higher than 80℃.
Pt/Fe3O4-DIB-DETA-CNS (PFDDC) nanocomposite (DIB=2, 4-dihydroxybenzaldehyde; DETA=diethylene-triamine; CNS=carbon nanosphere) was synthesized by dispersing Pt nanoparticles on magnetic carbon nanospheres. The structure, morphology and composition of the nanocomposite were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). In addition, the nanocomposite showed superior peroxidase-like activity towards 3, 3', 5, 5'-tetramethylbenzidine (TMB) with a visual color change in the presence of hydrogen peroxide (H2O2). Therefore, the PFDDC nanocomposite provides a sensing platform for the colorimetric detection of H2O2 with high sensitivity and selectivity. Furthermore, the nanocomposite can be conveniently preserved and separated. These features enable the nanocomposite to colorimetrically detect H2O2 for potential pharmaceutical, environmental and industrial applications.