Halogen substituted β-amino acids, D,L-3-amino-3-(4-fluoro)phenylpropionic acid(D,L-HL1, 1) and D,L-3-amino-3-(4-bromo)phenylpropionic acid(D,L-HL2, 2), as well as their Cu(Ⅱ) coordination complexes[Cu(L1)2(CH3OH)2]·2CH3OH(3) and[Cu(L2)2(CH3OH)2]·2CH3OH(4) were investigated and their single crystal structures were discussed in details. Supramolecular helical chains were found in β-amino acids 1 and 2 while there was no helix in their coordination complexes 3 and 4. The formation of supramolecular helixes could be due to the hydrogen bonds between terminal-NH3+ and adjacent-COO- in β-amino acids 1 and 2. While, this kind of hydrogen bonds could not be observed in their Cu(Ⅱ) coordination complexes 3 and 4, in which central-symmetrical dimers could be formed via coplanar coordinated bonds(N-Cu-O) between-NH2 and-COO-.
Three Cd(Ⅱ) metal-organic complexes, namely[Cd(phen)2Cl2](1),[Cd(phen)Cl2](2) and[Cd(phen)(cam)]·H2O(3)(phen=1,10-phenanthroline, H2cam=camphoric acid), were hydrothermally synthesized using Cd2+, phen and H2cam as raw materials under different conditions of pH values, reaction temperatures or reactant ratios. The prepared complexes were structurally characterized by means of single-crystal X-ray diffraction, and the results show that complex 1 is a 2D supramolecular complex, which consists of[Cd(phen)2Cl2] mononuclear subunits, while complex 2 shows a 1D chain structure, in which Cd(Ⅱ) ions are connected by chloride(Cl-) bridges, with phen hanging on both sides of the chain. No cam anions have been observed in the structures of complexes 1 and 2. In complex 3, cam connects Cd(Ⅱ) ions to construct a 2D network, in which phen acts as terminal ligands. The adjacent 1D chains for complex 2 and the adjacent 2D layers for complex 3 are further linked by hydrogen bonding interactions or π-π intermolecular interactions to form 3D supramolecular networks, respectively. The effects of reaction conditions on the assembly and structures of the complexes have been discussed. The fluorescent and photocatalytic properties of complexes 1-3 and the fluorescent sensing behaviors of complexes 2 and 3 have also been investigated.
In this paper, a facile synthetic approach to prepare CdTe quantum dots(QDs) with high luminescence via a one-pot microwave irradiation reaction route using 3-mercaptopropionic acid(MPA) as both a sodium tellurite reducer and a capping molecule was described, and the mechanism of the formation of CdTe QDs was elucidated. In this approach, CdTe QDs with six different emission wavelengths of 553, 567, 577, 595, 608 and 615 nm were obtained via changing the refluxing time and the quantum yields(QY) of these QDs were 40.6%, 55.3%, 63.6%, 43.4%, 37.4% and 29.7%, respectively. The characterization results of X-ray powder diffraction(XRD) and transmission electron microscopy(TEM) indicate that the obtained QDs have a pure cubic zinc blended structure with a spherical shape. No toxic gases were released during the preparation process, indicating that the method is relatively fast, cheap and environmentally friendly.
In this work, a novel fluorescent chemosensor combining multiple photoinduced electron transfer(PET) processes for the detection of Ag+ ion was synthesized. The PET processes were derived from the lone electron pair of the selenium donors and the tertiary nitrogen atom of the coumarin fluorophore, which have not yet been used in the fluorescent chemosensor designed for Ag+ ion. Interestingly, the chemosensors showed fluorescent responses to Ag+ ion with a fluorescence enhancement factor of 3-5-fold by blocking the intramolecular PET quenching pathways. Furthermore, the probe exhibited high selectivity and sensitivity for Ag+ ion over other relevant species with detection limit down to 10 nmol/L level. The chemosensors also showed excellent performances in analyzing natural water samples. The chemosensors developed herein represent a new strategy for the PET fluorescent chemosensor design for the detection of Ag+ ion.
A series of novel chalcone derivatives was designed and synthesized via a suitable synthetic strategy in good yields using commercially available 2-amino-4-nitrophenol as an initiator. The structures of the target compounds were confirmed by means of 1H NMR, 13C NMR and high-resolution mass spectrometry(HRMS). And the ability of the target compounds to inhibit influenza viruses was evaluated. These compounds showed moderate inhibitory activity against influenza A(H9N2 and H5N1) viruses. Within this series, compounds S14 and S15 with good potency(IC50=40.3-51.5μmol/L) could be used as lead compounds in the future.
With the oxidation treatment, eighteen compounds were separated from 20(S)-ginsenoside Rg2, Rh1, protopanaxatriol(PPT) and their 20(R)-epimers in total and cytotoxicity of most of them was evaluated against three human cancer cell lines HeLa, A549 and MCF-7 by 3-(4,5-dimetylthiazol-z-yl)-2,5-diphenyltetrazolium bromide(MTT) assay. Their structures were confirmed by means of nuclear magnetic resonance(NMR) and mass spectrometry and the results were compared with those of previous literature. In this study, we systematically semisynthesized all four ocotillol type saponins, i.e., (20S, 24S), (20S, 24R), (20R, 24S) and (20R, 24R). All the configurations at C20 kept the same with their starting materials. Meanwhile a pair of C24 epimers was generated in terms of ocotillol type saponins. In addition, seven compounds(4-8, 13 and 14) were reported firstly. The cytotoxic results distinguished the ocotillol type products(6, 7, 13 and 14) from 20(R)-PPT and 20(R)-ginsenoside Rh1, which possessed better cytotoxicities than their correspondents from 20(S)-epimers against HeLa cells, and the carbonyl group at C3 can improve the cytotoxi-city, which helped us to gain deeper insight into Ocotillol type saponins.
Anthranilic diamides are one of the most important classes of modern agrochemical insecticides. To discover new structures with higher activity, lower toxicity and lower residue, a series of novel anthranilic diamides containing dihydroisoxazoline and isoxazole was designed and synthesized. Their structures were characterized by means of melting points, proton nuclear magnetic resonance(1H NMR), 13C NMR and high resolution mass spec-trometry(HRMS). According to the bioassay data, it was found that some of the title compounds exhibit moderate insecticidal activity and good antifungal activity. In particularly, compound 15b with a concentration of 50 mg/L shows a lethality rate of 60.0% against Mythimna separata Walker and a lethality rate of 50.0% against Culex pipiens pallens with a concentration of 1mg/L. Moreover, compound 15b showed good antifungal activities(58.8%, 77.1%, 70.7%, 55.3%, 60.7%, 65.4%) when against all the tested fungi(Cercospora arachidicola Hori, Physalospora piricola, Rhizoctonia cerealis, Bipolaris maydis, Watermelon anthracnose, Fusarium moniliforme). The effects of compounds 14h, 14j and 15b on the concentration of intracellular calcium ion([Ca2+]i) in the central neurons of Mythimna separate Walker were well investigated via calcium imaging technique. The results demonstrate that the novel compounds can elevate the calcium concentration in the neurons, denoting that some new structures are potential modulators of the insect ryanodine receptor(RyR).
A series of novel thiazole Schiff base derivatives containing benzo[d][1,3]dioxole moiety was designed, synthesized and screened for their fungicidal activities. The preliminary results demonstrated that compounds 6p, 6q and 6r possessed potent activities against Phytophthora infestans, Pyricularia oryzae and Septoria tritici in vitro. Compounds 6d and 6r exhibited remarkable activities against Botrytis cinerea(whole plant) and Phytophthora infestans(leaf disk) respectively in vivo, which were identified as the most promising candidates for further study and could be used as possible lead compounds for developing new fungicides.
This study details Ni-catalyzed cross coupling of aryl Grignard reagents with aryl halides in toluene, a nonpolar solvent with a high boiling point. The reaction was applied for the synthesis of various biaryls in good yields without the introduction of a large steric ligand. The Kumada-Tamao-Corriu(KTC) reaction in toluene was then successfully modified to proceed under neat conditions for the efficient syntheses of symmetrical biaryls, particularly in large-scale preparations. Unactivated aryl chlorides show higher reactivity than aryl bromides, particularly under neat conditions. Mechanistic investigations suggest a radical procedure for the catalytic cycle, and the origin of the radical intermediates being aryl halides.
A convenient and efficient method was developed for the synthesis of naphtho[2,1-b]furans via 4-dimethylaminopyridine(DMAP)-catalyzed cascade reaction of 2-hydroxy-1-naphthaldehydes and α-halogenated ketones in moderate to good yields in the presence of Na2CO3 at 80℃ for 6 h. The mechanism for this process was briefly discussed with a tentative catalytic cycle proposed. Moreover, this method features organocatalysts and high step-economy, which makes it practical and attractive.
The reaction of β,β-dicyanostyrene derivatives(1) with 1,3-dibromo-5,5-dimethylhydantoin(DBDMH) was systematicly studied. The reaction could generate different products when promoted by different mild bases. When the reaction was promoted by NaOAc(100%, molar ratio to compound 1), β,β-dicyanostyrene derivatives could be directly converted into corresponding α,β-dehydroamino derivatives in good to excellent yields in one-pot. When the reaction was promoted by K3PO4(80%, molar ratio to compound 1), the corresponding α,β-dehydroamino and double-α,β-dehydroamino compounds were simultaneously obtained and the total conversion of β,β-dicyanostyrene derivatives was up to 90% or higher.
With the help of first-principles molecular dynamics calculations, we obtained the atomic picture of amorphous AlSb(a-AlSb) for phase-change memory application. Generally, a-AlSb shows sp3 bonding network, which is the intrinsic characteristic for its good thermal stability. Significant wrong(homogenous) Al-Al bonds can also be observed from the pair correlation function. This hints the amorphous phase may consist of Al cluster and Sb-rich Al-Sb alloy. Recent experiment has observed the Sb-rich region of AlSb alloy can be switched to crystal, on the basis of which, combined with our calculations, we thus propose that on the one hand such a Sb-rich region in a-AlSb can retain the rapid crystallization like pure Sb solid and on the other hand some Al atoms play the important role of stabilizing Sb rich network with sp3 bonding. The present study offers a microscopic view to understand the phase change mechanism of AlSb alloy for information storage device.
Hollow tube-like activated carbon(HTAC) was fabricated by a simple and efficient carbonization method with cotton as carbon precursor activated by KOH without any template. The activation time from 0 to 90 min showed no significant effect on the micro-morphology, but greatly influenced the specific surface area and electrochemical performance. In the end, it was found that the sample activated for 60 min(HTAC-60) has a higher specific surface area of 2600 m2/g, a larger pore volume of 1.52 cm3/g and a greater specific capacitance of 483 F/g at a current density of 0.2 A/g in 1 mol/L H2SO4. Moreover, the sample HTAC-60 shows excellent cycle stability(only 12.2% loss after 5000 cycles) and a high energy density of 67.1 or 37.2 W·h·kg-1 at a power density of 200 or 1000 W/kg, respectively, operated in a voltage range of 0-1.0 V in 1 mol/L H2SO4. The results indicate that cotton can potentially be used as a raw material for producing low cost and high performance activated carbon electrode materials for electric double layer capacitor.
In order to utilize the brine resources in China, the solid-liquid equilibria in quaternary system Li+, K+//SO42-, B4O72--H2O at 288 K was studied by the isothermal solution equilibrium method. Solubilities and densities of solutions were determined experimentally. According to the experimental data, the equilibrium phase diagrams, density-composition diagram and corresponding water content diagram of the quaternary system were plotted. Double salt KLiSO4 was found in the reciprocal quaternary system Li+, K+//SO42-, B4O72--H2O at 288 K. The quaternary system has three invariant points, seven univariant curves and five fields of crystallization. The five crystallization regions correspond to Li2B4O7·3H2O, Li2SO4·H2O, K2B4O7·4H2O, K2SO4 and KLiSO4, respectively. The crystallization field of salt Li2B4O7·3H2O is the largest, whereas that of Li2SO4·H2O is the smallest. The experimental results show that Li2SO4·H2O has a strong salting-out effect on other salts.
A novel spherical cellulose adsorbent with amide and sulphinate groups was used for a first reduction of trichloroacetic acid(TCAA) and a subsequent adsorption of generated species, haloacetic acids. The removal mechanism involved TCAA reduction by sulphinate groups and the adsorption of the haloacetic acids through electrostatic interaction with amide group. Investigation of product formation and subsequent disappearance reveals that the reduction reactions proceed via sequential hydrogenolysis, and transform to acetate ultimately. Adsorption of haloacetic acids was ascertained by low chloride mass balances(89.3%) and carbon mass balances(75.1%) in solution. The pseudo-first-order rate constant for TCAA degradation was (0.93±0.12) h-1. Batch experiments were conducted to investigate the effect of pH value on the reduction and adsorption process. The results show that the reduction of TCAA by sulphinate groups requires higher pH values while the electrostatic attraction of haloacetic acids by amino group is favorable in more acidic media.
Pendent drop method was adopted to measure the surface tension of dimethyl sulfoxide(DMSO)/water mixtures. A new pendent drop apparatus was built up and checked with water, and a good agreement of our data with literature could be found. With the new apparatus, the surface tensions of nine DMSO/water mixtures with mass fractions of water from 0.1 to 0.9 were investigated in a temperature range of 298-338 K. The expanded uncertainty for surface tension measurement was estimated to be 0.5% at a confidence level of 95%(k=2) in the whole temperature range. A thermodynamic-based relation was used to predict the surface properties of DMSO/water mixtures. Based on the relation and Gibbs adsorption theory, a prediction model was proposed for the calculation of surface relative excess and the thickness of the surface molecule layer.
Silver nanoparticles(Ag NPs) were prepared by dealloying Mg-Ag alloy precursor. The obtained Ag NPs have an average ligament size of (50±10) nm. Electrocatalytic activity of Ag NPs towards oxygen reduction reaction(ORR) in 0.1 mol/L NaOH solution was assessed via cyclic voltammetry(CV), rotating ring disk elec-trode(RRDE) techniques, and electrochemical impedance spectroscopy(EIS). The electrochemical active area for the ORR was evaluated by means of the charge of the underpotential deposition(UPD) of lead(Pb) on Ag NPs. The CV results indicate that Ag NPs have a higher current density and more positive onset potential than the bulk Ag electrode. RRDE was employed to determine kinetic parameters for O2 reduction. Ag NPs exhibit a higher kinetic current density of 25.84 mA/cm2 and a rate constant of 5.45×10-2 cm/s at -0.35 V vs. Hg/HgO. The number of electrons(n) involved in ORR is close to 4. Further, EIS data show significantly low charge transfer resistances on the Ag NPs electrode. The results indicate that the prepared Ag NPs have a high activity and are promising catalyst for ORR in alkaline solution.
Pyridinium ionic liquids(ILs, 1-ethyl acetate pyridinium hexfluorophosphate[EAPy][PF6] and 1-ethyl acetate-3-methyl pyridinium hexfluorophosphate[EAMPy][PF6]), were synthesized by a two-step process involving introduction of one ethyl acetate group and anion metathesis. Colorless single crystals of the two ILs were initially obtained using the solvent-evaporation method in mixed solvents. Single-crystal X-ray diffraction was used to determine the crystal structures.[EAPy][PF6] crystallizes in the monoclinic space group C2/c with a=2.2748(16) nm, b=0.6204(4) nm, c=1.8552(12) nm and Z=8, whereas[EAMPy][PF6] crystallizes in the orthorhombic space group P212121 with a=0.7126(17) nm, b=1.2792(3) nm, c=1.5327(3) nm and Z=4. The structure of[EAPy][PF6] contains double zigzag chains formed by alternately pairing large organic cations with the octahedral anions of[P1F6]- or[P2F6]-. The[P1F6]- and[P2F6]- anions occupy respectively two distinct crystallographic sites in crystal packing models. The structure of[EAMPy][PF6] includes ladder-type chains constructed through pairing pyridinium cations with inorganic anions of[PF6]-. The[PF6]- anion in[EAMPy][PF6] shows a distorted octahedron structure and is sandwiched by ethyl acetate groups in crystallographic stacking. This study reveals the influence of chemical mo-dification involving the methyl group(CH3) onto crystallographic structure of pyridinium ILs. Thermal analysis indicates that the difficult crystallization of the two ILs is related to the low void filling of ion pairs in crystal structure, leading to relatively low melting point and evident supercooling during the cooling process. Additionally, the experimental results indicate that the two ILs have electrochemical activity. The ethyl acetate group also allows downward shifting of electrochemical windows to less negative positions and the ionic conductivities of the two ILs follow an Arrhenius-type behavior.
The density functional theory(DFT) was used to investigate the adsorptions of carbon dioxide(CO2) on kaolinite surfaces and the influences of Na+ and H2O on the adsorption. Both cluster and periodic models of kaolinite were considered. The calculated results indicate that stable complexes can be formed between adsorbed CO2 and the surfaces of kaolinite in the presence or absence of sodium cation and water molecule. The Al-O octahedral surface has a larger adsorption affinity for CO2 than the Si-O tetrahedral surface of kaolinite because the hydroxyl groups of kaolinite Al-O surface present more activity than the basal O atoms of the Si-O tetrahedral surface in the inter-molecular interactions. The existence of exchangeable sodium cations exerts the significant effect on the adsorption of CO2 with the dramatic increase of the adsorption energy, while the presence of water molecule decreases the adsorption strength insignificantly. The calculated Gibbs free energies of the adsorption reveal that the adsorptions of CO2 on all the investigated kaolinite surfaces are feasible thermodynamically in the gas phase. Surface free energy was calculated to provide the predictions of the surface stability as a function of temperature.
Monodisperse emulsion copolymer was synthesized by semi-continuous core-shell emulsion polymerization of styrene, butyl acrylate and γ-methacryloxypropyl trimethoxy silane(KH570). The emulsion particles size and its polydispersion were measured by dynamic light scattering(DLS). The properties of emulsion copolymer were characterized by differential scanning calorimetry(DSC), thermogravimetric analysis(TGA) and measurement of contact angle. The particle morphology was observed under a transmission electron microscope(TEM) and atomic force microscopy(AFM). The results indicate that emulsion nanoparticles containing silicon possess core-shell structures and narrow polydispersity(PDI≤0.08). The thermal stability and hydrophobicity of emulsion copolymer were improved with KH570 introduced into the system.
Epoxy resin was used to modify polybutylene terephthalate(PBT) and glycidyl methacrylate functionalized methyl methacrylate-butadiene(MB-g-GMA) blend. Results show that MB-g-GMA dispersed in PBT matrix uniformly and PBT/MB-g-GMA/epoxy blends reveal good compatibility. However, the added epoxy resin restricted the mobility of PBT macromolecular chains during the growth process of the crystal, which reduced the final crystallinity of PBT. The PBT/MB-g-GMA blend containing 1%(mass fraction) epoxy resin exhibited good mechanical properties. For example, the notched impact strength of the PBT/MB-g-GMA blend with 1%(mass fraction) epoxy resin was about 2 times that of PBT/MB-g-GMA blend. Sanning electron microscope(SEM) results show that the shear yielding of the PBT matrix and the cavitations of rubber particles were the major toughening mechanisms. The chemical reaction between PBT and epoxy resin induced the high complex viscosity and storage modulus of PBT/MB-g-GMA blend.
A magnetic nanoparticles-loaded polymeric nanocarrier was developed. Amphiphilic copolymer, methoxy polyethylene glycol-poly(D,L-lactide-co-glycolide)(MPEG-PLGA) could self-assemble to form nanomicelle with the help of emulsion-solvent evaporation technique. This nanocarrier with core-shell structure was loaded with magnetic iron oxide nanoparticles(IONPs) and anticancer drug paclitaxel(PTX). The hydrodynamic diameter of IONPs-PTX-loaded nanocarrier showed an average size of 110 nm with a polydispersity index(PDI) of 0.136, and its zeta potential was (-4.76±0.36) mV. The drug-loading content and encapsulation efficiency were 4.47% and 31.28%, respectively. In vitro drug release experiment was performed and a sustained release profile was observed. 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide(MTT) assay indicated that IONPs-PTX-loaded nanocarrier showed comparable cytotoxicity with free paclitaxel. When an external magnetic field was applied, the nanocarrier significantly localized at the target area, demonstrating that the nanocarrier could be used for potential magnetic targeted drug delivery.
A layered aluminoborophosphate(LABP-DDA) was hydrothermally synthesized using dodecylamine as a structure-directing agent, and was added into polyamide 66(PA66) to obtain nanocomposites, PA66/LABP-DDA, via melt intercalation method. The characterization results of transmission electron microscopy(TEM) and small angle X-ray scattering (SAXS) indicate that LABP-DDA has been successfully exfoliated into nano-layers of PA66 matrix. The unstable γ phase of PA66 was found in the composites with the help of X-ray diffraction(XRD) and differential scanning calorimetry(DSC). The heterogeneous nucleation effect of LABP-DDA resulted in an increasement of about 10℃ in melting temperature and an increasement of about 7% in crystallinity when compared with those of neat PA66. The introduction of LABP-DDA did not significantly affect the toughness and strength of PA66. The results of flammability test indicate that LABP-DDA possesses positive synergistic flame retarding effect in the presence of melamine polyphosphate(MPP) and the 77%PA66/(23-x)%MPP/x%LABP-DDA(x=1, 2) samples in thickness of 1.6 mm reached from Fail to V-1 rating based on UL94, compared with 77%PA66/23%MPP.