A novel heterometallic-organic framework(HMOF), namely [ZnBa(1,3-BDC)2(DMA)2] n(1)(DMA=N,Ndimethylacetamide), was synthesized by means of solvothermal method from isophthalic acid(1,3-BDC) ligand and relevant metal salts as raw materials. The single-crystal X-ray diffraction analysis result demonstrates that compound 1 is a three-dimensional(3D) framework including heterometallic tetranuclear [Zn2Ba2(COO)8] clusters as building subunits, which could be simplified into an eight-connected body-centered cubic(bcu) topological net. At room temperature, compound 1 displays strong blue luminescence in solid state. Furthermore, the quantum yield and luminescent lifetime of compound 1 were also measured.
Exploring the native defects of zeolites is highly important for understanding the properties of zeolites, such as catalysis and optics. Here, ITQ-16 films were prepared via the secondary growth method in the presence of Ge atoms. Various intrinsic defects of ITQ-16 films were fully studied through photoluminescence and FTIR characterizations. It was found that both the as-synthesized and calcined ITQ-16 films displayed multicolor photoluminescence including ultraviolet, blue, green and red emissions by exciting upon appropriate wavelengths. The results indicate that Si―OH and non-bridging oxygen hole centers(NBOHCs) are responsible for the origin of green and red emissions at 540―800 nm, while according to a variety of emission bands of calcined ITQ-16 film, blue emission bands at around 446 and 462 nm are attributed to peroxy free radicals(≡SiO2), ultraviolet emissions ranging from 250 nm to 450 nm are suggested originating from a singlet-to-triplet transition of two-fold-coordinated Si and Ge, respectively.
Three different dimensional Ni(II) coordination polymers, [Ni(3-pna)(HIP)(H2O)3]·H2O(1), [Ni(3-pna)· (1,3,5-HBTC)](2) and [Ni2(H2O)(3-pna)2(1,4-CHDC)2]4(3)(3-pna=3-pyridylnicotinamide, H2HIP=5-hydroxyisophthalic acid, 1,3,5-H3BTC=1,3,5-benzenetricarboxylic acid, 1,4-H2CHDC=1,4-cyclohexanedicarboxylic acid), were synthesized under hydrothermal conditions and characterized by means of infrared spectra(IR), thermal gravimetric (TG) analyses, powder X-ray diffraction(PXRD) and single-crystal X-ray diffraction. Complex 1 has a structure of 1D single-stranded chain, which is further stretched by hydrogen-bond interactions to form a 2D supramolecular sheet. Complex 2 shows a 2D network, which is stretched to 3D supramolecular frameworks through hydrogen-bond interactions. Complex 3 reveals a 3D skeleton with a (3,3,6,6)-connected {3·72}{32·4}{33·42·5·73·85·9}{33·45·52·72·82·9} topology. The effects of different polycarboxylates on the ultimate architectures of the complexes 1—3 were discussed. Furthermore, the fluorescent and photocatalytic properties of the title complexes were also investigated.
Molecularly imprinted membrane-zinc porphyrin-mathacrylate(MIM-Zn-MAA), a dual read-out sensor based on a molecularly imprinted membrane, was developed to recognize and detect dimethyl methylphosphonate (DMMP) as an intermediate molecule of organophosphorus pesticides. The membranes were prepared via thermal polymerization of two functional monomers(zinc porphyrin and mathacrylate) on the surface of a glass slide functionalized with ethylene glycol dimethacrylate and azobisisobutyronitrile. The morphology of the as-synthesized MIM-Zn-MAA was determined with scanning electronic microscopy. The composite membranes exhibited macrovoid morphologies, which were affected by the functional monomers. These membranes were selectively adsorbed onto the template molecule and displayed higher adsorbing capacity toward DMMP compared with their structural analogs. Changes in the fluorescent spectra were qualitatively and quantitatively monitored via fluorescence photometry. Difference maps were also obtained using colorimetry before and after the reaction between MIM-Zn-MAA and DMMP at various concentrations. The maps showed a wide linear range varying from 0.1 µmol/L to 10 mmol/L with a low detection limit of 0.1 µmol/L. These preliminary results demonstrate that the as-fabricated dual read-out sensor displays good sensitivity and selectivity toward DMMP, indicaing its considerable potential in DMMP detection in real applications.
A fast, non-destructive and eco-friendly method was developed to simultaneously determine the oil and water contents of soybean based on low field nuclear magnetic resonance(LF-NMR) relaxometry combined with chemometrics, such as partial least squares regression(PLSR). The Carr-Purcell-Meiboom-Gill(CPMG) magnetization decay data of ten soybean samples were acquired by LF-NMR and directly applied to the PLSR analysis. Calibration models were established via PLSR with full cross-validation based on the reference values obtained by the Soxhlet extraction method for measuring oil and oven-drying method for measuring water. The results indicate that the calibration models are satisfactory for both oil and water determinations; the root mean squared errors of cross-validation(RMSECV) for oil and water are 0.2285% and 0.0178%, respectively. Furthermore, the oil and water contents in unknown soybean samples were predicted by the PLSR models and the results were compared with the reference values. The relative errors of the predicted oil and water contents were in ranges of 1.25%―4.96% and 0.44%―2.49%, respectively. These results demonstrate that the combination of LF-NMR relaxometry with chemometrics shows great potential for the simultaneous determination of contents of oil and water in soybean with high accuracy.
A novel high selective and sensitive fluorescence probe termed gatifloxacin was discovered based on fluorescence “on-off” phenomenon in the presence of Se(IV). In the Tris-HCl/acetonitrile(3:7, volume ratio, Tris-HCl 0.05 mol/L, pH=7.3) system, the fluorescence intensity of gatifloxacin was linearly decreased with the concentration increase of Se(IV) in a range of 1.0×10–5―5.0×10–5 mol/L with a correlation coefficient of 0.9979(R 2=0.9958) and in a range of 5.0×10–5―1.0×10–4 mol/L with a correlation coefficient of 0.9973(R 2=0.9946). The detection limit of Se(IV) was 1.70×10–6 mol/L.
A new fluorescent probe for the detection of Hg2+ was designed and synthesized via attaching N-methylisatin to rhodamine B hydrazide through an imine linkage. In an ethanol-Tris buffer medium, the addition of Hg2+ caused a strong orange fluorescence and a visual color change from colorless to pink. Other coexisting metal ions did not interfere with the detection of Hg2+. The research on the detection of Hg2+ in natural water suggested the possibility of practical applications in environment monitoring. Based on ESI-MS analysis, the Hg2+-sensing mechanism was proposed.
Haze weather frequently occurs in many cities in China. Polycyclic aromatic hydrocarbons(PAHs) in fine particulate matter(PM2.5) can adversely affect the environment and human health. In this paper, PM2.5 samples were collected at nine sites in a city in northeastern China from September 2013 to October 2014. Sixteen USEPA(US Evironment Protection Agency) priority PAHs in PM2.5 were analyzed to determine their spatial and temporal distribution characteristics. The source apportionment of PAHs was conducted with the Positive Matrix Factorization(PMF) model. The results indicate that the concentrations of total PAHs(T-PAHs) in PM2.5 are within the range of 0.26 to 72.48 ng/m3. The seasonal variation of T-PAHs is winter>spring>autumn>summer, and the space distribution of PAHs is JZP>DP>BFH>LP> EESA>IPT>CP>HZMC>JYP. In all types of PAHs, three-ring and five-ring PAHs are significantly prominent(62%) in the heating period due to petrogenic sources and traffic emissions. Middle- and high-ring PAHs in the non-heating period are caused by coal combustion and vehicle exhaust, which accounts for 77% of the total emissions. The source apportionment results obtained by the diagnostic ratio of PAHs reflect that coal burning, traffic and other sources have a distinct influence on PAH emissions in this city. Six factors are defined by PMF v5.0, namely, coke oven emissions(7.7%), biomass burning(44.3%), petrogenic sources(10.7%), coal combustion(10.4%), gasoline engine emissions(16.7%), and diesel engine emissions(10.3%). The results indicate that the PAHs in PM2.5 in the city are primarily caused by combustion processes and vehicle exhaust.
Two novel series of sixteen aminoalkyl-substituted polymethoxychalcone derivatives 2a―2h and 3a―3h were synthesized from 2′-hydroxy-3,4,5,4′,6′-pentamethoxy chalcone(1) through extending alkoxy side chain at the 2′-position, and introducing amine hydrogen bond receptor at the end of the side chain. The structures of all the synthesized compounds were confirmed by 1H NMR, 13C NMR and MS techniques. Furthermore, all the compounds were tested for antiproliferative activities in vitro against a panel of three human cell lines(HeLa, HCC1954 and SK-OV-3) via CCK-8 assay. The results show that all the target compounds exhibit antiproliferative activities against the three human cancer cells with IC50 values of 4.62―48.21 μmol/L, except compound 2h against SK-OV-3 cells. Most of these compounds were more active when compared to the positive control cis-Platin.
A series of amino alcohol derivatives containing 1,3,4-oxadiazole moieties was synthesized with 7-bromo-2-tetralone as starting materials, 2,2-dimethyl-1,3-oxazolidine as intermediates and Strecker reaction and cyclization with POCl3 as key steps. The structures of the key intermediate and target compounds were confirmed by 1H NMR, 13C NMR and HRMS. Some compounds have resulted in the generation of highly potent sphingosine 1-phosphate receptor type 1(S1P1) agonists.
Twenty-two novel 1,3,4-thiadiazole derivatives were synthesized using different aromatic acids as starting materials, followed by cyclization, coupling and deprotection reaction. The structures of all the target compounds were identified by means of 1H nuclear magnetic resonance(NMR), 13C NMR and high resolution mass spectrometer(HRMS). Further biological evaluations were performed for chronic myelogenous leukemia cell and breast cancer cell. The results suggest that most of the target compounds exhibit potent anti-proliferative activities. Especially, compound 5b shows better antiproliferative activities against MDA-MB-231 and K562 cell lines compared with gossypol.
The photolysis results of new diferrocenyl substituted cyclopentadienone(3) show that sunlight and air play an important role in the decomposition of compound 3, and two new compounds, 2-cyclopentenone(4) and α-pyrone(5), were obtained via photolysis of compound 3. The photolysis process was investigated by 1H NMR, and a plausible mechanism for the formation of compound 5 was deduced. The cycloaddition reactions of substituted cyclopentadienones(3, 7, 9) with maleimide gave substituted imides 8, 10, 11, 12 and an unprecedented diferrocenyl substituted 1H-pyrrol-3(2H)-one derivative 13, respectively. The structures of compounds 4, 5, 8, 10, 11, 12 and 13 were confirmed by X-ray single crystal diffraction analysis technique.
In an attempt to find leading thiazole carboxanilides exhibiting fungicidal activities, we designed and synthesized a new series of 2-sulfursubstituted thiazole carboxanilides via the reaction between 2-sulfur substituted thiazole carboxylic acid chlorides and substituted aniline. The fungicidal activities of the title compounds against Rhizoctonia solani were screened and the results were remarkable. The most potent compound 8i, N-[2,6-dichloro-4-(trifluoromethyl)phenyl]-2-methylthio-4-(trifluoromethyl)thiazole-5-carboxamide, was identified. The fungicidal EC50 of compound 8i against Rhizoctonia solani was 1.28 mg/L, being comparable to that of Thifluzamide. The results indicate that compound 8i can be considered as a lead compound for further research.
An expedient and efficient method for selective methylation of catechol coumarins by working with different alkalis under appropriate reaction conditions is reported. Esculetins were selectively methylated at position 6 and position 7 in good yield using CH3I in the presence of NaH and Na2CO3, respectively. However, daphnetins showed less regioselectivity under the same reaction conditions. Furthermore, the site preference for the methylation reaction was interpreted by the density functional theory at B3LYP/6-31+G(d) level.
In this paper, a new diterpene together with seven known diterpenes was isolated from Wedelia prostrata. The chemical structure of the new compound was elucidated via 1D and 2D nuclear magnetic resonance(NMR) techniques and mass spectrometry and identified to be 3α-phenylpropionoyloxy-ent-kaur-16-en-oic acid(1). The isolated diterpenes were tested for their cytotoxicity activities via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. The results show that compounds 1, 2, 3, 4 and 6 exhibit different levels of cytotoxic activities. Especially, compound 2 shows significant cytotoxicity toward HeLa and A549 cell lines(IC50=6.14 and 8.76 μmol/L).
Surface-plasmon(SP) modes triggered on metal nanostructures were strongly coupled to the local restricted electronmagnetic field supported by a Fabry-Perot(F-P) cavity. This hybrid system provided an ideal platform to study the interaction between SP and F-P resonators on nanoscales. However, the time-resolved transient energy transfer process is far from resolved. In this letter, we addressed this question by time-resolved femtosecond pump-probe technology and readily observed the transient energy transfer between SP and nanocavity resonant energy. The interaction resulted in the emergence of hybrid splitting mode and the oscillating dynamics between upper and lower polariton branch(the split hybrid states). Our work may provide a well comprehension of strong coupling between SP modes and F-P resonator modes, and lay some groundwork for many future photonic applications.
By employing atomistic simulations based on an empirical potential model and a self-consistent-charge density-functional tight-binding method, the collision dynamics process of an energetic carbon ion impinging on the Stone-Wales defect in a single-walled carbon nanotube was investigated. The outwardly and inwardly displacement threshold energies for the primary knock-on atom in the Stone-Wales defect were calculated to be 24.0 and 25.0 eV, respectively. The final defect configuration for each case was a 5-1DB-T(DB=dangling bond) defect formed in the front surface of the nanotube. Moreover, the minimum incident energy of the projectile prompting the primary knock-on atom displacement was predicted to be 71.0 eV, and the time evolutions of the kinetic and potential energies of the projectile and the primary knock-on atom were both plotted to analyze the energy transfer process.
Highly ordered 2D and 3D-Co3O4 catalysts were prepared using SBA-15 and KIT-6 as templates. Nano-Co3O4 catalyst was obtained by calcination of cobalt nitrate as a comparison. The BET surface area of nano- Co3O4, 2D-Co3O4 and 3D-Co3O4 catalysts was 16.2, 63.9 and 75.1 m2/g, respectively. All the catalysts were tested for the total combustion of methane and their catalytic performance was in order of 3D-Co3O4(T 90=355 °C)>2D-Co3O4 (T 90=383 °C)>nano-Co3O4(T 90=455 °C). It was also found that the order of the areal specific reaction rates for the combustion of methane follow the same order of total activity. The characterization result demonstrated that enhanced catalytic performance of methane of the 2D-Co3O4 and 3D-Co3O4 catalysts was due to their pronounced reducibility and abundant active Co3+ species which was caused by the preferential exposure of {220} crystal planes in 3D-Co3O4 and 2D-Co3O4 catalysts compared to the nano-Co3O4.
A series of guanidine salts of 4,4′-azo-1,2,4-triazol-5-one with guanidine(1), aminoguanidine(2), diaminoguanidine(3) and triaminoguanidine(4) was prepared. Compounds 2―4 were characterized by infrared(IR) spectroscopy, elemental analysis and single-crystal X-ray diffraction. Thermal decomposition processes of compounds 1―4 were investigated by differential scanning calorimetry(DSC), and all the compounds showed good thermal stability up to 190 °C. Moreover, these four guanidine salts are more unstable with the increasing number of amino groups. Thermal stability parameters(T e, 0 and T b) and thermodynamic functions(ΔS ≠, ΔH ≠ and ΔG ≠) for compounds 1―4 were calculated. The constant-volume combustion heats(Δc U) for compounds 2―4 were determined and tended to increase with the increase of the number of amino groups. The calculated standard molar enthalpy of formation(Δf H m 0) of compounds 2―4 are–541.04,–178.67 and–83.08 kJ/mol, respectively. The impact sensitivities results indicate these four energetic salts are less sensitive than 1,3,5-trinitrotriazacyccohexane(RDX) and 1,3,5,7-tetranitrotetraqza-cyclo-octane(HMX).
The assignment of the rovibrational spectra of molecule-Ne complexes is always a challenge to study van der Waals systems, since they usually exhibit behavior intermediate between free rotor and rigid rotor. In this paper, the microwave and infrared spectra of CH3F-Ne, a model system for symmetric-top-atom dimer, were firstly predicted and analyzed based on the four-dimensional ab initio intermolecular potential energy surfaces(PESs), which explicitly incorporate the v 3(C—F) stretch normal model coordinate of the CH3F monomer. Analytic three-dimensional PESs were obtained by least-squares fitting vibrationally averaged interaction energies for v 3(CH3F)=0 and 1 to the Morse/long-range(MLR) potential function for symmetry top impurity with atom model. These PESs fitting to 2340 points have root-mean-square(RMS) deviations of 0.07 cm–1, and require only 167 parameters. Based on the analytical vibrationally averaged PESs, the rovibrational energy levels were calculated by employing Lanczos algorithm, with combined radial discrete variable representation and parity-adapted angular finite basis representation. Based on the wavefunction analysis and comparison of CH3F-Ne with CH3F-He and CH3F-Ar complexes, the bound states were assigned. Spectral parameters for CH3F-Rg(Rg: rare gas, Rg=He, Ne, Ar) complexes were fitted and discussed. Temperature dependent transition intensities for CH3F-Ne were also reported and analyzed. The complete microwave and infrared spectra information for CH3F-Ne made it possible to provide important guidance for future experimental spectroscopic assignments.
The inhibition effect of three azole compounds, 2-aminobenzimidazole(ABM), 2-aminothiazole(AT) and 2-aminobenzothiazole(ABT), on the corrosion of mild steel in a 1 mol/L HCl solution was investigated by means of potentiodynamic polarization measurement, electrochemical impedance spectroscopy(EIS) and scanning electron microscopy( SEM). The correlation between inhibition efficiency and molecular structure of inhibitor was theoretically studied via quantum chemical calculations. The results show that the inhibition efficiency(η) of the inhibitors follows the order of η ABT>η AT>η ABM. Moreover, ABM, AT and ABT belong to mixed-type inhibitors. The adsorption of the inhibitors on the steel surface follows the Langmuir adsorption isotherm, with both physisorption and chemisorption.
In this work, a metal-organic framework with free standing basic groups(e. g., amino and acylamide groups) decorated in the pore wall was utilized to catalyze the CO2 cycloaddition reaction and its basic properties were tested in Knoevenagel condensation reactions. The results reveal that the metal-organic framework(MOF) material has excellent catalytic activity and high repeatability for the synthesis of chloropropene carbonate from CO2 and epichlorohydrin with no co-catalyst under mild reaction conditions, suggesting that it is a promising heterogeneous catalyst for CO2 cycloaddition reaction.
The size-controlled silica microspheres were prepared by a facile method and the growth mechanism was simply studied. The as-prepared samples were characterized by scanning electron microscopy and transmission electron microscopy. The CO2 adsorption behaviors and methane catalytic oxidation were also measured. The results show that the as-prepared silica is perfect sphere, and the particle size can be controlled by adding tartaric acid. Spherical silica and sphere/tube(rod)-shaped silica were obtained by adjusting reaction time. Silica microspheres with uniform size exhibit high capacity of CO2 adsorption, while others with wide size-distribution exhibit excellent catalytic performance, suggesting it is an effective method by regulating size to utilize its advantages selectively. Therefore, it will be an ideal strategy to develop the efficient multifunctional materials by a facile route.
We successfully synthesized four kinds of copolymers with varying molecular weights of poly(lactideco- glycolide)(PLGA) to yield methoxy-poly(ethylene glycol)-block-poly(lactide-co-glycolide)(mPEG-PLGA) nanocarriers: mPEG-PLGA(3k), mPEG-PLGA(9k), mPEG-PLGA(11k) and mPEG-PLGA(16k). An antitumor drug, 10-hydroxycamptothecin(HCPT), was encapsulated into the mPEG-PLGA nanocarrier cores by self-assembly in dialysis. The lower molecular weight nanocarriers degraded more quickly, resulting in mass loss, pH decline, and a rapid HCPT release rate in vitro. The degradation and drug release of the nanocarriers were dependent on the PLGA molecular weight. However, the larger molecular weight nanocarriers could not increase the loading content and encapsulation efficiency. Considering the antitumor effect of these nanocarriers, the mPEG-PLGA(9k) nanocarrier, which had the highest drug loading content[(7.72±0.57)%] and a relatively high encapsulation efficiency [(22.71±5.53)%], is an optimum agent for drug delivery.
A kind of water-stable phosphotungstic acid/polyvinyl alcohol(PW12/PVA) fiber was prepared by thermal or chemical crosslinking treatments with the help of electrospinning, and silver nanoparticles(NPs) modified fibrous precursor was successfully obtained by photoreduced method. The nanocomposites were characterized by transformation infrared spectroscopy(FTIR), UV-Vis diffuse reflection spectroscopy(DRS), field environmental scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM) and X-ray photoelectron spectroscopy(XPS). The results indicate that the sizes of silver NPs are about 20 or 40 nm on thermally or glutaraldehyde(GA) vapor crosslinked PW12/PVA fiber, respectively. As a photocatalyst, PW12/PVA fiber possesses high surface area to volume ratio, stable recyclability, and efficient transportation of electrons under visible light. The nanohybrids exhibit excellent photocatalytic activity for the degradation of Rhodamin B than PW12/PVA nanofiber.
Single-handed helical and C-shaped 3-aminophenol-formaldehyde resin nanotubes were prepared via a supramolecular templating approach. The chiral templates and 3-aminophenol were initially organized into helical nanoribbons, followed by the adsorption of formaldehyde onto the surfaces of the helical nanoribbons. Subsequent to polymerization and further thermosetting of the resin oligomers, 3-aminophenol-formaldehyde resin nanotubes were obtained after removing the templates. When low amounts of 3-aminophenol were added, straight C-shaped 3-aminophenol-formaldehyde resin nanotubes were obtained. Increasing the amount of added 3-aminophenol led to the formation of single-handed helical nanotubes instead. When the single-handed helical resin nanotubes were carbonized at 900 °C under Ar, single-handed helical carbonaceous nanotubes were obtained. Raman spectrum indicates that this carbon is predominantly amorphous. Circular dichroism spectra illustrate that both the helical resin nanotubes and the carbonaceous nanotubes exhibit optical activity. This work indicates that the added amount and the edge-adsorption mode of the precursors on the templates determine the final morphology and chirality of the products.
Polyorganosiloxane foam(SIF) nanocomposites reinforced with vinyl-modified montmorillonite(Mt-V) and hydroxyl-modified montmorillonite(Mt-OH) were prepared through cross-linking and foaming. The effects of modified Mt on the density, pore morphology, and thermal and compressive properties of the prepared polyorganosiloxane foams were investigated. The structure of the polyorganosiloxane foam was studied by solid-state nuclear magnetic resonance analysis. Clay dispersion in polyorganosiloxane nanocomposites and pore morphology were investigated by X-ray diffraction and scanning electron microscopy analyses. The thermal and mechanical properties of the prepared materials were also evaluated by differential scanning calorimeter, thermogravimetric analysis, thermal diffusivity and compressive strength. The results show that Mt-V exhibits improved cell structure, thermal insulation, and crush compressive than Mt-OH. The addition of modified Mt reduces the density, cell size, and thermal conductivity but increases the high-temperature resistance and compressive strength of the nanocomposite. The amount of the residues of SIF/Mt-OH nanocomposites increases by 9% compared with that of the pure SIF. Furthermore, SIF/Mt-V decreases the thermal conductivity to 0.014 W/mK and the cell size to 98 μm. Those properties give the material potential application value in the aerospace and construction industry.
A roadblock for supramolecular hydrogels is their poor mechanical properties. Herein, to enhance the mechanical strength of supramolecular hydrogels, agarose(AG) was incorporated into the low molecular weight hydrogelator( G1). The results of scanning electron microscopy(SEM), circular dichroism(CD) and Fourier transform infrared spectroscopy(FTIR) prove that G1 gelators can self-assemble into cross-linked network together with AG. The mechanical properties of the gels are characterized by a rotary rheometer and the mechanical properties of the hybrid hydrogels(Hgel) can be significantly improved and may be further tuned by changing the ratio of the two components. For example, the elastic modulus of Hgel II[m(G1):m(AG)=7:3] is about 2 times higher than that of G1 hydrogel. The results demonstrate that the mechanical property of hybrid supramolecular hydrogels can be adjusted through the formation of a cross-linked network.