Conventional quantum dots inherently carry the risk of cytotoxicity. Considering the biomedical limitations, an amino acid and vitamin were utilized to prepare highly luminescent carbon dots. Ascorbic acid and lysine were used to synthesize water soluble carbon dots which are highly biocompatible as both reactants and essential nutrients.
Prickly carbonated hydroxyapatite(CHAp) spheres were obtained via a facile template-free self-assembly method with Na2HPO4 and self-made cubic CaCO3 as reactants. X-ray diffraction results of the product revealed CHAp with high crystallinity could be successfully prepared in a short reaction time. A nucleation mechanism was proposed according to the results of characterizing the resultant powders and analyzing the growth process. It shows that the self-made CaCO3 particles play an important role in the template-free synthesis of prickly spheres.
Three small organic molecular co-crystal compounds (C3N6H6)·(C6H10O4)·H2O(1), C3H8N2O(3) and (H4btec)2·(4,4'-bipy)(4)(H4btec=1,2,4,5-benzenetetracarboxylic acid, 4,4'-bipy=4,4'-bipyridine) and one coordination supramolecular compound [Mn(C2O4)(H2O)2]·C6H11NO2(2) were synthesized by hydrothermal reaction. They were characterized by elemental analysis, infrared(IR) spectroscopy and single crystal X-ray diffraction(XRD). Structural analyses reveal that these 2D or 3D supramolecular networks of the compounds were formed by C―H···O, N―H···O, N―H···N, O―H···O and O―H···N hydrogen bonds. Therein, the functional groups of ―COOH, ―NH2 and ―OH play important roles in constructing supramolecular architectures.
Two new compounds, [Ni2(L1)(Py)6]Py·CH3OH(1) and [Ni3(L2)2(Py)4]·2DMF(2)(H4L1=N,N'-bisalicyl- bisthiocarbamide; H3L2=3-hydroxyl-2-naphthalene thiosemicarbazide; Py=pyridine; DMF=dimethyl fumarate), based upon two thiosemicarbazone ligands have been obtained and characterized by elemental analysis, Fourier transform infrared(FTIR) and X-ray diffraction(XRD). Compound 1 possesses a binuclear cluster, in which the bisalicylbisthiocarbamide acts as a hexadentate bridge. Compound 2 exhibits a linear trinuclear cluster with the triply-deprotonated ligand acting as pentadentate bridge. C―H···O, C―H···π and C―H···S weak interactions further link these molecules to form interesting supramolecular networks.
A new chemosensor based on a Schiff base has been designed and synthesized. Its sensing behavior toward various metal ions was investigated by fluorescence and UV-Vis spectroscopic methods. The fluorescence of the sensor was quenched and the color rapidly changed from canary yellow to brown after the addition of Cu2+, while no changes occurred after the addition of other metal ions, which contributes to the detection of Cu2+ with naked eyes. The fluorescence quantum yield of the ligand was calculated to be 0.52. The corresponding detection limit of Cu2+ was 5.721×10-7 mol/L, and the 1:1 binding mode of the sensor with Cu2+ was revealed by Job's plot.
We have developed a rapid, simple and label-free colorimetric method for the identification of target DNA. It is based on loop-mediated isothermal amplification(LAMP). Plain gold nanoparticles(AuNPs) are used to indicate the occurrence of LAMP. The amplified product is mixed with AuNPs in an optimized ratio, at which the deoxyribonucleotides(dNTPs) bind to the AuNPs via ligand-metal interactions and thus enhance AuNPs stability. If a target DNA is amplified, the dramatic reduction of the dNTPs leads to the aggregation of AuNPs and a color change from red to blue. The success of the method strongly depends on the ionic strength of the solution and the initial concentration of dNTPs. Unlike other methods for the identification of isothermal products, this method is simple and can be readily applied on site where instrumentation is inadequate or even lacking.
A new molecularly imprinted solid-phase extraction(MISPE) monolithic cartridge was synthesized, and MISPE-DLLME(DLLME=dispersive liquid-liquid microextraction) was developed for purification of astaxanthin in shrimp waste. The eluent(methanol) from MISPE was used as the dispersive solvent in subsequent DLLME for further purifying and enriching the analyte prior to high-performance liquid chromatography(HPLC) analysis. The mobile phase was methanol-acetonitrile-water-dichloromethane(85:5:5:5, volume ratio), flow rate was 0.7 mL/min and UV wavelength was 476 nm. Under optimal conditions, good linearity was obtained in a range of 0.2―200.0 μg/mL(r2=0.9998) with a limit of detection(LOD) of 0.08 μg/mL, and the extraction recoveries at three spiked levels ranged from 88.3%―92.5% with a relative standard deviation(RSD) less than 4.3%. Moreover, the mean contents of astaxanthin in the three batches of shrimp waste were 95.9, 85.4 and 77.2 μg/g, respectively. This method combining the advantages of MISPE and DLLME results in high selectivity and low cost, which was applied to determining the astaxanthin level in shrimp waste samples.
The microwave hydrolysis and derivatization coupled with capillary electrophoresis detection were developed for the separation and determination of the amino acids in Panax notoginseng.The experimental conditions for the microwave hydrolysis and derivatization were examined and optimized. Several parameters of capillary electrophoresis, such as pH value of background electrolyte, borate concentration and applied voltage were optimized. Under the selected conditions, 11 amino acids were completely separated. The real sample was analyzed and the results were satisfactory. Compared with that of conventional heat hydrolysis and derivatization, the analytical time of this method was significantly shortened.
An investigation of the EtOAc-soluble fraction from the aerial parts of Artemisia frigida Willd.(A. frigida) led to the isolation of three new flavonoid glycosides together with three known compounds. Their structures were elucidated by spectral experiments. At the same time, high-performance liquid chromatographic(HPLC) method was used for the simultaneous determination of the six flavonoid glycosides from the aerial parts of A. frigida. The separation by gradient elution was performed on a Hypersil ODS-2 column(250 mm×4.6 mm, 5 μm) at 30 ℃ with acetonitrile and water as the mobile phase, and monitored by absorbance at 276 nm. The parameters of linearity, precision, accuracy and specificity of the method were evaluated. The recovery of the method is 96.50%―98.01%, and linearity(r>0.9992) was obtained for all the flavonoid glycosides. A high degree of specificity as well as repeatability and reproducibility(relative standard deviation values less than 2.0%) were also achieved. This assay was applied to the determination of six flavonoid glycosides in ten samples. The results indicate that the developed assay method was rapid, accurate, reliable and could be readily utilized as a quantitative analysis method for A. frigida.
At present, heavy metal pollution has become a major environmental problem, influencing the survival of human and other creatures. Developing heavy metal ion adsorbents, which are environment friendly, of low cost and good performance is one of the effective means to solve heavy metal pollution. Rich low-grade diatomite mineral, as raw material, was modified with calcium carbonate to improve the adsorption properties of diatomite for heavy metal ions. The effects of dosage(m), pH, adsorbing time(t), temperature(T) and concentration of adsorbent(c) on the removal rate of heavy metal ions(Cu2+, Pb2+, Zn2+ and Cd2+) were studied. The results show that under the suitable conditions, T=15 ℃, c=1.5 mmol/L, m=10 g/L, t=60 min, in a weak acid environment, the removal effect of the four kinds of metal ions by modified diatomite is the best.
A series of novel N-[(1-aryl-3-phenyl-pyrazol-4-yl)methylene]-2-(halo-o-hydroxyphenyl)hydrazide derivatives was synthesized and the antibacterial activity of each of them was evaluated. The supposed reaction mechanism of acquiring compounds 3a—3d is that catalytic activity is enhanced by the electron-donating groups of the first phenyl ring while decreased by electron-withdrawing groups of that ring. The result of preliminary bioassay shows that the lowest minimal inhibitory concentration(MIC) of the title compounds against Escherichia coli is 2 μg/mL. MIC values against Monilia albican and Staphlococcus aureus are as low as 4 μg/mL. They will be a series of potential antibacterial compounds against fungi and gram-negative bacteria.
A series of hydrazine and oxadiazole analogs of Sorafenib was designed, synthesized and characterized by proton nuclear magnetic resonance(1H NMR) spectrometry and high resolution mass spectrometry(HRMS). The antiproliferative activities of these compounds against human colorectal carcinoma(HCT-116) and human breast cancer (MDA-MB-231) tumor cell lines were evaluated in vitro by MTT method[MTT=3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide]. The bioassay results suggest that most of the synthesized compounds have antitumor potential to HCT-116 cell line compared with MDA-MB-231 cell line. Compounds 8a,8b,8d, 8e,9f and 9j competitive with Sorafenib demonstrated antiproliferative activities on HCT-116 cell line.
Four coumarin glycosides(1―4) and four coumarin triazoylglycosides(5―8) were synthesized by phase transfer catalytic glycosylation and copper-catalyzed azide-alkyne cycloaddition(CuAAC) respectively from 4-methyl-7-hydroxyl coumarin(4-methylumbelliferone). The structures were characterized by 1H NMR, MS or IR. The fluorescent properties of the coumarin glycosides and triazoylglycosides were studied in different solvents and compared to those of 4-methyl-7-hydroxyl coumarin.
A series of new sulfonylureas incorporating 1,2,4-triazolinone moiety was synthesized, which were further bio-assayed for the herbicidal activity against four herbs, representative of monocotyledons and dicotyledons. Some of them exhibited high potency to inhibit the growth of dicotyledons(Bassica napus and Amaranthus retroflexus) in the pot experiment. Compounds 9a and 9b also displayed an excellent herbicidal activity against Bassica napus at a concentration of 15 g/hectare, which were comparable with commercial triasulfuron.
Triazolo-fused 3',4'-cyclic nucleoside 4'-spiro nucleoside analogues were synthesized by an intramolecular 1,3-dipolar cycloaddition of 4'-azido nucleoside derived azido-alkynes in a regio- and stereo-specific manner. The thymine nucleoside base in these target compounds was transformed into the corresponding 5-methyl cytosine component. The synthesized compounds were examined in an MAGI(multinuclear-activation galactosidase indicator) assay for exploring the anti-HIV activity and in a H9 T(human T lymphocytes H9) assay for measuring the cell toxicity.
A series of novel cis-nitenpyram analogues bearing acyloxy segments anchored on the tetrahydropyrimidine ring was designed and synthesized. Preliminary bioassays indicate that all the nitenpyram analogues 3a―3n exhibit good insecticidal activities against Nilaparvata lugens and Aphis medicaginis at 100 mg/L, while analogue 3k affords the best activity in vitro and the lethal concentration 50(LC50) values(0.187, 0.214 mg/L) are close to that of nitenpyram. The structure activity relationships(SARs) suggest that their insecticidal potency is influenced by the species of acyloxy segments. The docking results reveal that analogue 3k forms stronger hydrogen-bonding with the nAChR, which explain the structure activity relationships(SARs) observed in vitro and imply that the strategies of our designed nitenpyram analogues are feasible.
A new phenylpropanoid glycoside, named cambodianin F(1), together with three known compounds, 1-O-β-D-glucopyranosyl-2-hydroxy-4-allylbenzene(2), 1-O-(6-O-α-L-rhamnopyranosyl-β-D-glucopyranosyl)-2-hydroxy-4-allylbenzene(3) and 1,2-di-O-β-D-glucopyranosyl-4-allylbenzene(4) was isolated from the dragon's blood of Dracaena cambodiana. The new compound was elucidated by HR-ESI-MS and spectroscopic techniques(UV, IR, 1D and 2D NMR).
A library of novel 3-aryl isoindolinone derivatives with aromatic amino acid derivative fragments was designed and synthesized. Two synthetic routes were employed to construct 3-aryl isoindolinone ring system for different amino acid derivatives.
A series of triphenylene derivatives with six symmetric substituents was synthesized from hexabromotriphenylene. The synthesis was conducted by six-fold palladium-catalyzed Hagihara-Sonogashira cross- coupling reactions to yield the hexa-alkynyl substituted triphenylene derivatives of HTP1, HTP2, HTP3 and HTP4. The six symmetric substituents can not only endow the triphenylene the longer π-conjugated range, but also increase the solubility of the compounds. Their photophysical, electrochemical, thermal properties were investigated respectively. With the comparison of their properties, the structure-property relationships were established which demonstrated the influences of different substituents on the electronic nature and the mesomorphic phase of these disk-shaped molecules. In addition, with the scanning electron microscopy(SEM) and polarized optical microscopy(POM) characterization, the self-assembly behaviors of the compounds were also investigated.
The molecular mechanism of triple-negative breast cancer(TNBC) remains unclear, and there has been no effective targeted therapy for it. A better understanding of the mechanisms of TNBC is urgently needed to identify new therapeutic targets. In this study, eight cases of premenopausal TNBC patients were collected, and a comparative proteomic analysis of their breast cancer tissues and matched paraneoplastic ones was performed via isobaric tags for relative and absolute quantitation(iTRAQ) technology coupled with two-dimensional liquid chromatography-tandem mass spectrumetry(2D LC-MS/MS). The researches result in the identification of 1254 nonredundant proteins, of which 1243 proteins reached the strict quantitative standard. The quantitative comparison reveal that among the 214 proteins, 81 proteins significantly increased and 133 proteins decreased in TNBC tissues compared to corresponding ones in control. The Gene Ontology(GO) annotations and pathway analysis show their distributions in GO and the marked functions, as well as the closely related signal transduction pathways involved in extra cellular matrix (ECM)-receptor interaction, protein digestion and absorption, renin-angiotensin system, complement and coagulation cascades and focal adhesion. This pilot study will lay a foundation for further searching for therapeutic targets of TNBC and exploring the molecular mechanism, which can also be extended as a part of a large scale biomarker discovery plan.
In the process of cultivating Rhodobater sphaeroides R26.1, some of which turned from blue to pink due to the irradiation of a beam of leaking white light. The mutant strains were named ‘pinky' strains, which were cultivated in the red light and in the dark for a comparative study. It turned out that the strains did not grow in the dark, so they might be photosynthetic bacteria. The electronic absorption spectrum of the ‘pinky' strains was measured, which shows they contained two main photosynthetic pigments, carotenoids(Cars) and bacteriochlorophylls(BChls). And then they were extracted and analyzed. It proves that Bchls included Bchl a and Bchl a'. Nuclear magnetic resonance (NMR) spectra were exploited to determine the chemical structure of Cars. The results indicate that there were seven kinds of Cars, including lycopene, rhodopin, anhydrorhodovibrin, 3,4-dihydroanhydrorhodovibrin, 3,3,4-dihydrospirilloxanthin, 3,4,3',4'-tetrahydrospirilloxanthin and spirilloxanthin. Based on the above results, it was found that most identified Cars formed via spirilloxanthin biosynthesis pathway. The analyzed results of 16S rRNA gene show that the homology of ‘pinky' strains with Rhodopseudomonas palusteris was 99%. Rhodopseudomonas palusteris has been cultivated in our laboratory. Because of its strong vitality, it did not become extinct with so many years passing. When Rhodobater sphaeroides R26.1 was cultivated, it got rejuvenated under the appropriate conditions and caused Rhodobater sphaeroides R26.1 to be contaminated.
We cloned the three androgen response elements(AREs, including AREⅠ, AREⅡ, and AREⅢ) with a core transactivation TATA element of the prostate-specific antigen(PSA) promoter into pGL2 basic vector to create an artificial pGL2/AREs-TATA reporter system, which was applied to evaluating the effects of different xeno-oestrogens[bisphenol A(BPA), 4-nonylphenol(4-NP), dichlorodiphenyl trichloroethane(DDT) or diethylstilbestrol (DES)] on androgen receptor(AR) abnormal activation to regulate PSA expression and cell proliferation. In all the three AREs, AREⅢ-TATA displayed as a major element responsive to AR-mediated DHT stimulation of PSA promoter. Therefore, pGL2/AREⅢ-TATA reporter was adopted to analyze the activation capacity of AR activated by four different xeno-oestrogens. The activation of pGL2/AREⅢ-TATA reporter by each xeno-oestrogen was analyzed in two different cell lines, one was HEK293T(Human Embryonic Kidney 293T) cell line, and the other was AR stably expressed DU145 cell line, which was produced by infecting AR with pLenti-puro-AR into the prostate cancer DU145 cells and that were scanned with puromycin and tested by AR antibody. In both the two cell lines, BPA or DES significantly induced AR-mediated transcriptional activity of AREⅢ-TATA reporter, whereas DDT or 4-nonylphenol did not. Moreover, AR-mediated cell proliferation in response to each of four xeno-oestrogens was measured in MTT assays in both HEK293T cell or AR stably expressed DU145 cell lines. BPA or DES, as an AR inducer, exhibited an enhanced effect in cell proliferation, rather than the effect of DDT or 4-NP, in both cell lines. Finally, we demonstrated that BPA or DES stimulated PSA expression and enhanced the recruitment of AR onto the PSA promoter, resulting in stronger binding to AREⅢ sites. Taken together, four xeno-oestrogens were identified to have different activities on AR. BPA and DES are demonstrated to be androgenic effectors in the regulation of PSA activation or cell proliferation.
A novel machine learning method, gene expression programming(GEP), was employed to build quatitative structure-activity relationship(QSAR) models for predicting the enhancement effect of nitroimidazole compounds on irradiation. The models were based on descriptors which were calculated from the molecular structures. Four descriptors were selected from the pool of descriptors by best multiple linear regression(BMLR) method. After that, three regression methods, multiple linear regression(MLR), support vector machine(SVM) and GEP, were used to build QSAR models. Compared to MLR and SVM, GEP produced a better model with the square of correlation coefficient(R2), 0.9203 and 0.9014, and the root mean square error(RMSE), 0.6187 and 0.6875, for training set and test set, respectively. The results show that the GEP model has better predictive ability and more reliable than the MLR and SVM models. This indicates that GEP is a promising method on relevant researches in radiation area.
A series of iron(Ⅲ) chlorophyllins was prepared from silkworm excrement crude chlorophyll extract as a raw material. Aerobic oxidation of cyclohexene by using the prepared iron(Ⅲ) chlorophyllins as biomimetic catalysts was studied under atmospheric pressure in the absence of reducing agent and solvent. The results indicate that chlorophyll iron porphyrins have better catalytic performance than the industrial-applied iron tetraphenylporphyrin and cobalt tetraphenylporphyrin, and possess a higher selectivity for 2-cyclohexen-1-one. The smaller the polarity of iron(Ⅲ) chlorophyllin's ligand is, the easier the catalytic oxidation of cyclohexene will be. Esterification products of iron(Ⅲ) chlorophyllins can catalyze the oxidation of cyclohexene better than non-esterified iron(Ⅲ) chlorophyllins, and therefore show a higher conversion of cyclohexene and a higher selectivity for 2-cyclohexen-1-one than the non-esterified ones. Among the six synthesized iron(Ⅲ) chlorophyllin catalysts, iron(Ⅲ) methyl-pyropheophorbide-a is the best biomimetic catalyst for the highest conversion of cyclohexene. The influences of catalyst's substituent, polarity and ring structure on the catalytic performance were discussed. The catalytic performance of iron(Ⅲ) chlorophyllins improves with decreasing polarity, increasing conjugated degree of porphyrin's ring or enhancing chlorophyllins' stability. Possible mechanism of cyclohexene aerobic oxidation catalyzed by iron(Ⅲ) chlorophyllins was also discussed.
Better understanding of the relationship between the substrate preference and structural module of esterases is helpful to novel enzyme development. For this purpose, two chimeric esterases AAM7 and PAR, constructed via domain swapping between two ancient thermophilic esterases, were investigated on their molecular simulation(including homology modeling, substrates docking and substrate binding affinity validation) and enzymatic assay(specific activities and activation energies calculating). Our results indicate that the factors contributing to the substrate preference of many enzymes especially the broad-specificity enzymes like esterases are multiple and complicated, the substrate binding domains or binding pockets are important but not the only factor for substrate preference.
Traditional researches on metal corrosion under salt solutions deposit conditions are usually carried out by visual, electron microscopic observations and simple electrochemical measurement via a traditional one-piece electrode. These techniques have difficulties in measuring localized corrosion that frequently occur in inhomogeneous media. This paper reports the results from the experiments using specially shaped coupons and a relatively new method of measuring heterogeneous electrochemical processes, namely, the wire beam electrode(WBE). Preliminary results from copper and aluminum corrosion in highly concentrated sodium chloride solutions with and without solid deposits show that the method is useful in simulating and studying corrosion especially localized corrosion in pipelines.
Compression isotherm for stearic acid was obtained by means of molecular dynamic simulation and compared to experimentally measured values for the Langmuir monolayers. Compared to the previous simulation, the present simulation has provided a method to reproduce the compression of the monolayer. The result is consistent with other experimental results. By analyzing the alkyl tails, the configuration of stearic acid molecules during the compression process was studied and a uniform monolayer was obtained after compression. Stearic acid molecules were observed to form fine organized monolayer from completely random structure. Hexatic order of the arrangement has been identified for the distribution of stearic acid molecules in the monolayer. At the end of the compression, the stearic acid molecules were tightly packed in the gap of two other molecules. At last, the hydrogen bonds in the system were analyzed. The main hydrogen bonds were from stearic acid-water interaction and their intensities constantly decreased with the decreased of surface area per molecule. The weak hydrogen bond interaction between stearic acid molecules may be the reason of easy collapse.
A mechanism about the origin of the selectivities for the cleavage of dioxolane five-membered rings on pyranoside rings was suggested. Quantum chemical studies were performed to testify the rationality of the mechanism. It is thus suggested that the selectivities should be dependent on the differences of the free energy at the transition states when the five-membered ring cleaves. Natural bond orbital(NBO) analysis was further made to assess the influence of stereoelectronic effects on the selectivities.
Three kinds of crystal phase BiPO4(HP, LTBP, and HTBP) were selectively synthesized by controlling the preparation conditions. Structures of the three samples are all constructed by PO4 and BiO8 polyhedra but with different geometric structures. Detailed characterization was carried out by X-ray diffraction(XRD), scanning eletron microscopy(SEM) and Raman, UV-Vis, and luminescence spectrometries. Three samples exhibit huge distinctions in their photoluminescence(PL) lifetime: 0.68, 162 and 160 μs for HP, LTBP, and HTBP, respectively. More interesting, an outstanding photocatalytic activity is observed for as-prepared LTBP nanorod, which shows even higher activity for the degradation of MB solution than P25. In addition, experiments were carried out to clarify the role of hydroxyl (·OH) and superoxide radicals(O2·) played in photocatalytic process and it was found O2· was the main active species in BiPO4 photocatalysts. Further comparison of structural and photocatalytic properties of the three samples finds that structure distortion is contributed to their property difference. A correlation was found between photocatalytic performance and the distortion of BiO8 dodecahedra. The internal field generated by the distortion of BiO8 dodecahedra was believed advantageous for the separation of electron and hole, which was in favor of the improvement of photocatalytic activity. This correlation may help to design other photocatalysts with high activity.
A cobalt nanoparticles-attached indium tin oxide(CoNPs/ITO) electrode was applied to the immobilization of hemoglobin(Hb) and an Hb modified CoNPs/ITO electrode(Hb/CoNPs/ITO) was prepared. The direct electron transfer of Hb was shown by the well-behaved voltammetric responses for Hb/CoNPs/ITO electrode and the effects of scan rate and pH value were observed. Based on the catalytic activity of Hb immobilized on the CoNPs/ITO electrode toward the reduction of H2O2, a mediator-free H2O2 sensor was developed. A linear relationship existed between the catalytic current and the H2O2 concentration in a range of 1.0―100.0 μmol/L with a detection limit (S/N=3) of 0.2 μmol/L.
The partial least squares(PLS) method was employed to establish a quantitative ion characteristics-activity relationship(QICAR) model for metal ion toxicity(EC50 of 15 metal ions). The ion characteristics included AN(the atomic number), ΔIP(the change in ionization potential, eV), Xm(the electronegativity, eV), AW(the atomic weight), Xm2r(the covalent index), ΔE0(the absolute difference between electrochemical potential of the ion and that of its first stable reduced state, eV),|lgKOH|(the absolute value of the lg of the first hydrolysis constant), AR(the atomic radius, nm), AR/AW(the ratio between atomic radius and atomic weight) and σp(the softness index) selected based on relative correlation analysis. The simulated and tested(with the other four metals) efficiency coefficients of the model are 0.88 and 0.96, respectively. The information revealed from the QICAR model indicates that the value of the metal ion toxicity was positively correlated with variables AN, ΔIP, Xm, AW and Xm2r; negatively correlated with variables ΔE0, |lgKOH|, AR/AW, AR and σp, and ion characteristics ΔE0, Xm, σp and Xm2r were found to contribute more to the toxicity of metal ions via the accurate analysis method provided by PLS. The model could be used to predict the toxicity of the target metals and preliminary to assess combined pollution and environmental risk for heavy metals in the environments.
A new ruthenium complex containing bidentate xanthate ligands was synthesized in a good yield. This complex was characterized by elemental analysis, proton nuclear magnetic resonance(1H NMR), Fourier transform infrared(FTIR) and UV-Vis spectroscopies. The cyclic voltammetry of the complex revealed one quasi-redox wave centered at Ru(Ⅲ)/ Ru(Ⅱ) couple, indicating its catalytic potential. So the preparation of a glass carbon electrode modified with ruthenium xanthate complex and its electrocatalytic activity toward the oxidation of tryptophan(Trp) were also studied. The experimental results show that the modified electrode had excellent electrocatalytic activity for the oxidation of tryptophan. Moreover, under the optimized conditions, the oxidation peak current was proportional to tryptophan concentration in a range of 2.5×10-7 to 5.0×10-5 mol/L with a correlation coefficient of 0.9928 and a detection limit of 8.3×10-8 mol/L(S/N=3). Using the proposed method, tryptophan was successfully determined in pharmaceutical samples with standard addition method.
A large number of the isomers of neutral and ionic Snn(n=2—15) clusters have been designed and optimized at the level of MP2/LANL2DZ with the aid of the Gaussian 09 software package. The most stable geometric structures of ionic(cationic and anionic) Sn clusters have been compared with the corresponding neutral geometries. Most structures of Snn+ and Snn are similar to each other except for the structures of those with n=5, 11 and 15; while the anions Snn- are almost different from Snn clusters with n=9—15 except for Sn12- and Sn14-. The electronic properties have been calculated, including binding energy, second difference in energy, HOMO-LUMO gaps, ionization potentials, and electron affinities.
With density functional theory(DFT) method, the optimization of molecular configurations and the calculation of frontier molecular orbitals were achieved for triphenylamine(TPA)-based dye-sensitized solar cell materials at the B3LYP/6-31G(d, p) level. Time-dependent density functional theory(TD-DFT) was applied to calculating the probability of the transition from the ground state to the excited state. And UV-Vis absorption spectra were derived with Franck-Condon approximation. The conjugation length, substitution groups and spatial effects show a slight influence on the dihedral angle of the TPA group. The increase of conjugation length may cause a smaller energy gap as well as a higher highest occupied molecular orbital(HOMO) and a lower lowest unoccupied molecular orbital (LUMO). The introduction of methoxyl group and TPA group could lower the energy gap while the HOMO and LUMO were elevated in energy.
Comb-like polyethylene(PE) was prepared via anionic polymerization combined with “graft-onto” process. The polybutadiene(PB) backbone underwent hydroxylation at 1,2-vinyl groups to obtain a controlled number of hydro- xyl groups along the main chain. After the translation of hydroxyl groups to tosyl groups, a nucleophilic substitution by living anionic PB chains was achieved. The comb PE was finally obtained by the hydrogenation of the obtained unsaturated comb polymer. Since the living anionic polymerization was used to prepare the backbones and the branch chains, molecular weight to molecular weight distribution(Mw/Mn<1.5) can be well-controlled in the final comb polymer, including the average number and length of branches.
Two non-fullerene small molecules, BT-C6 and BT-C12, based on the vinylene-linked benzothiadiazole- thiophene(BT) moiety flanked with 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)malononitrile have been synthesized and characterized by solution/thin film UV-Vis absorption, photoluminescence(PL), and cyclic voltammetry(CV) measurements. The two molecules show intense absorption bands in a wide range from 300 nm to 700 nm and low optical bandgaps for BT-C6(1.60 eV) and for BT-C12(1.67 eV). The lowest unoccupied molecular orbital(LUMO) levels of both the molecules are relatively higher than that of [6,6]-phenyl C61 butyric acid methyl ester(PCBM), promising high open circuit voltage(Voc) for photovoltaic application. Bulk heterojunction(BHJ) solar cells with poly(3-hexylthiophene) (P3HT) as the electron donor and the two molecules as the acceptors were fabricated. Under 100 mW/cm2 AM 1.5 G illumination, the devices based on P3HT:BT-C6(1:1, mass ratio) show a power conversion efficiency(PCE) of 0.67%, a short-circuit current(Jsc) of 1.63 mA/cm2, an open circuit voltage(Voc) of 0.74 V, and a fill factor(FF) of 0.56.
The submicron chromium dioxide(CrO2) thin film was fabricated on a poly-crystal titania(TiO2) film using Si wafers as substrates by atmospheric pressure chemical vapor deposition(CVD) method. X-Ray diffraction patterns show that the CrO2 films were pure rutile structure. Scanning electron microscopy(SEM) images indicate that the CrO2 films consisted of submicron grains with a grain size of 250―750 nm. The magnetic researches reveal that the magnetic easy axis is parallel to the films, and at room temperature, the CrO2 films show linear magnetoresistance.
A novel amphiphilic β-cyclodextrin/poly(L-aspartate)(β-CD-PASP) copolymer was prepared by ring- opening polymerization of polysuccinimide(PSI). This copolymer bears β-CD units along the macromolecular chain and the structure was characterized by infrared(IR) and proton nuclear magnetic resonance(1H NMR). The molecular weight of the copolymer was determined by gel permeation chromatography(GPC). The copolymer micelle were prepared by direct dissolution method. The critical micelle concentration(CMC) of the copolymer micelle was mea- sured by flourescence technique with pyrene as probe. The size distribution of micelle was characterized on a dynamic laser light scattering particle size analyzer and its shape was observed by transmission electron microscopy(TEM). The results show that the copolymer could self-assemble into micelle with a low CMC, and the effective diameter of the micelle was 116.3 nm. The methotrexate(MTX)-loaded micelle were prepared and the drug loading content(DLC) was 22.86%. The MTX-loaded copolymer exhibited a better water-solubility than the free drug.
Hollow polypyrrole nanospheres were successfully prepared in a Span80/PEG400/H2O(PEG=polyethy-lene glycol) niosome system. The formation and morphology of the nanospheres vary with the concentrations of pyrrole monomer, salt and Span80. The shell thickness of the nanospheres increases gradually with monomer content. NaCl can promote the formation of the nanospheres. The formation mechanism of the nanospheres was discussed.