A Novel Synthesis of 2-Amino-2-deoxy-D-gluconic Acid and Its Complexation with Cu（Ⅱ） in Alkaline Medium

A novel synthesis of the functional carbohydrate 2-amino-2-deoxy-D-gluconic acid was introduced and itscomplex formation with Cu(Ⅱ)was investigated to obtain the stability constant for its further applications to thefood and pharmaceutical industries.The equilibrium was investigated by spectrophotometric measurements andprocessed by dual-series linear regression method.Results:the yield of 2-amino-2-deoxy-D-gluconic acid is 70%.The complexation molar ratio is 1:2,the molar apsorptivity of the complex is 39.906 L·mol~(-1)·cm~(-1) at 630 nm,and the stability constant β_n is 6.24×10~5.     

Novel Perchlorate and Sulphate Salts of 2-Aminonicotinic Acid: Synthesis,Characterization, Thermal Studies and Hirshfeld Surface Analysis

Since 2-aminonicotinic acid is a zwitterionic molecule,the salt or co-crystal strategy was used for the precipitation under identical conditions and obtained two novel salts: salt 1 with 2:1:2 stoichiometry of 2-aminonicotinic acid:perchloric acid:H_2O and salt 2 with 2:1:3 stoichiometry of 2-aminonicotinic acid:sulfuric acid:H_2O. Their crystal structures were characterized by single-crystal X-ray diffraction,differential scanning calorimetry(DSC) and thermogravimetric analyses(TGA). The structure determination shows that two salts are both primarily stabilized by the strong N–H···O hydrogen bonding interaction between 2-aminonicotinic acid and its corresponding acids. Constituents of the salt-crystalline phase were also investigated in terms of Hirshfeld surfaces. In the crystal lattice,a three-dimensional hydrogen-bonded network is observed,including the formation of a two-dimensional molecular scaffolding motif. Hirshfeld surfaces and fingerprint plots of two salts show that the structures are stabilized by H···H,O–H···O and C–O···π intermolecular interactions.     

Novel Efficient Light-Emitting Polyfluorene Derivatives Modified by Electron-Deficient Moieties with Nonlinear Structure

Two novel fluorene-based copolymers (PFSD and PFMD) containing squaric acid or maleimide unit in the main chain were synthesized in good yields by Suzuki coupling reaction. The resulting polymers possess excellent thermal stability, high electron affinity and high photolurninescence (PL) quantum yields. They can fluoresce in yellow-light range due to either the charge transfer between a fluorene segment and an electron-deficient containing squaric acid/maleimide segment of the polymers or the Forrster energy transfer between different polymer chains.The results from PL measurements of the isothermally heated polymer thin films show that the commonly observed aggregate excimer formation in polyfluorenes is very effectively suppressed in these two polymers due to the nonlinear structures of maleimide and squaric acid moieties. Double-layer polymer light-emitting diodes (PLED) were fabricated using the resulting polymers as the emitting layers and Ba or Mg：Ag(V：V=10：1) as cathodes.All the devices show bright yellow emission (562-579nm) with different maximum external quantum efficiencies (0.006%-1.13%). Compared with the other devices, indium-tin oxide (ITO)/polyethylenedioxythiophene (PEDOT):polystyrene sulfonic acid (PSS)/PFMD/Mg:Ag has the higher maximum external quantum efficiency of 1.13% at 564cd/m^2 with a bias of 8.4V.     

N-Heterocyclic carbene-catalyzed [4+2] cyclization of a-chloroaldehydes and aurones: Highly enantioselective synthesis of benzofuran-fused dihydropyran-2-ones

The chiral N-heterocyclic carbene-catalyzed [4 + 2] annulation of a-chloroaldehydes and aurones was developed, giving the corresponding benzofuran–fused dihydropyranones in good to high yields with good diastereoselectivities and excellent enantioselectivities. The catalytic cycle features with the generation of enolate from chloroaldehdye and its following [4 + 2] cycloaddtion with aurones.     

HYPERBRANCHED CONJUGATIVE MACROMOLECULES CONSTRUCTED FROM TRIPLE-BOND BUILDING BLOCKS

Polycyclotrimerization and polycoupling of acetylenic monomers respectively furnish hyperbranched polyarylenes and polyynes with high molecular weights(up to 1×10~6)in high yields(up to 99.9%).The polymers possess low intrinsic viscosities and high thermal stabilities,losing little of their weights when heated to＞400℃.Upon pyrolysis at＞800℃,the polymers graphitize with high char yields(up to 86%).Hyperbranched polyarylenes efficiently emit deep-blue to blue-green lights with fluorescence quantum yields up to 98% and strongly attenuate intense laser pulses with optical power-limiting performances superior to that of C_(60),a well-known optical lirniter.Poly(alkenephenylenes),poly(aroylarylenes)and polyynes are readily cross-linkable by UV irradiation,serving as excellent photoresist materials for the generation of patterns with nanometer resolution.Thin films of hyperbranched polyynes exhibit very high refractive indexes(n up to 1.86).The internal and terminal acetylene moieties of the polyynes readily form complexes with cobalt carbonyls,which can be transformed into soft ferromagnetic ceramics with high magnetic susceptibilities(M_s up to ca.118 emu/g)and near-zero magnetic losses.     

Novel triphenylamine-based two-photon absorption dyes including benzophenone parts

New two-photon absorption dyes including benzophenone parts,p-N,N-diphenylamino-p'-phenacylstilbene(C1),4,4-di-(4- benzoylstyrene)yltriphenylamine(C2) and 4,4',4-tri(4-benzoylstyrene)yltriphenylamine(C3),were synthesized and characterized by ~1H NMR and elemental analysis.The ratio of the molar extinction coefficients of compounds was approximately equal to the ratio of the branch amount of the compounds,namely,C1:C2:C3 was 1:2:3.Extremely high fluorescence quantum yields were detected for these compound...     

The tuning of pore structures and acidity for Zn/Al layered double hydroxides:The application on selective hydrodesulfurization for FCC gasoline

Co–Mo catalysts applied on the hydrodesulfurization(HDS) for FCC gasoline were prepared with Zn–Al layered double hydroxides(LDHs) to improve their performances,and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn–Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH-,CO2-,Al3+,and Zn2+. The neutralization p H is a main factor to affect the pore structures and acidity of Zn–Al/LDHs,and a series of Zn–Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas(SBET) and acidities,three Co Mo/LDHs catalysts were prepared,and their HDS performances were compared with traditional Co Mo/Al2O3 catalysts. The results indicated that catalysts prepared with high SBETpossessed high HDS activity,and Br?nsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than Co Mo/Al2O3,and could restrain the reactions of re-combination between olefin and H2 S which could be due to the existence of Br?nsted acid sites.     

Lewis Acid Modulation in a Amido-functional Diarylethene and Its Hypsochromism Effect

A photochromic diarylethene,1,2-bis(2-methyl-5-(4-N,N-dimethylaminophenyl)thien-3-yl)perfluorocyclopen-tene in proton-donating media was studied.The ammonium salt came into being in the presence of acetic acidfollowing localization of lone pair electrons of the amino group.The maximum absorption of the salt had a 36 nmhypsochromic shift,and its molar extinction coefficient increased to 3.494×10~4 L·mol~(-1)·cm~(-1).The conjugationaland delocalizational energy levels were calculated by Gaussian 98,and its hypsochromic shift mechanism was alsodiscussed.     

Photochemical reaction of azobenzene in solvent-swollen Nafion membranes

The photochemical reactions of azobenzene (AB) incorporated into different solvent-swollen Nafion membranes were investigated. The location of azobenzene in water-swollen Nafion membranes was different from that in methanol-swollen Nafion membranes, which was responsible for the different photochemical reactions of AB. In methanol-swollen Nafion membranes only trans-cis isomerization took place, while in water-swollen Nafion membranes photochemical cyclization of AB occurred after rapid trons-cis isomerization. The relation between the relative quantum yields and the light intensity showed that the cyclization was a two-photo process. The numbers of AB molecules per cluster (nAB /cluster) in Nafion membranes with different AB concentrations and different water contents were calculated. Under the experimental condition two competitive photocyclization mechanisms were suggested by nAB /cluster in Nafion membranes, relative quantum yields of the cyclization, and the change of the ratio of benzidine to benz     

DIRECT DETERMINATION OF NEODYMIUM AND ERBIUM IN RARE EARTH MIXTURE BY DERIVATIVE SPECTROPHOTOMETRY

The absorption spectra of 4f electron transitions of the complexes of neodymium and erbium with 8-hydroxyquinoline-5-sulphonic acid in the presence of diethylamine and ethanol have been measured by normal and third-derivative spectrophotometry. Their molar absorptivities are 70.7 l.mol~(-1).cm~(-1) for Nd and 62.5 l.mol~(-1).cm~(-1) for Er. They are 7.6 times and 14.9 times greater than those of corresponding chlorides, respectively. Use of the third-derivative spectra both eliminates the interference of Ce(Ⅳ) and increases the sensitivity for Nd and Er. Beer,s Law was obeyed from 0-10 ug/ml of Nd and Er. The method has been applied to the determination of neodymium and erbium in rare earth mixtures.     

Truxene-based Conjugated Microporous Polymers via Different Synthetic Methods

Four truxene-based conjugated microporous polymers(Tr-CMPs)were prepared via different synthetic methods and their structure-property relationships were studied.The polymer networks have high Brunauer-Emmett-Teller(BET)specific surface areas ranging from 554 m^2·g^–1to 1024 m^2·g^–1.Pore sizes of the CMPs with different linkers are mainly located between 0.60 and 1.96 nm.Among all the Tr-CMPs,TrCMP4 has the highest BET surface area of 1024 m^2·g^–1and exhibits the highest H2 uptake of 0.88 wt%.Tr-CMP2 prepared by Suzuki-Miyaura coupling reaction has the highest photoluminescence quantum yields(PLQYs)of 13.06% and CO2 uptake of 6.25 wt%.     

CARBAZOLE-CONTAINING HYPERBRANCHED POLY（ARYLENEETHYNYLENE）S： SYNTHESIS, CHARACTERIZATION, AND PROPERTIES

New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields(up to 87%)by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)_2 in THF.The structures and properties of the polymers are characterized and evaluated by IR,NMR, TGA,UV,photoluminescence,and cyclic voltammetry analyses.All the polymers are soluble in common organic solvents and show outstanding thermal stability(≥430℃).They graphitize in high yields(up to 79%)when pyrolyzed at 800℃. Upon photoexcitation,the polymers emit a strong deep blue light of ca.400 nm with quantum yields larger than 60%.     

In situ monitoring of coordination copolymerization of butadiene and isoprene via ATR-FTIR spectroscopy

<正>FTIR spectroscopy in combination with a diamond tipped attenuated total reflectance(ATR) immersion probe was utilized to study in situ the copolymerization of butadiene(Bd) and isoprene(Ip) with neodymium-based catalyst in hexane. The relationship between the signal intensity of monomer and its concentration was investigated.The kinetic study of copolymerization of Bd and Ip was further conducted,and the monomer reactivity ratios were determined via in situ ATR FTIR.The signal band at 1010 cm~(-1) was assigned to wagging vibration of Bd and its intensity was proportional to Bd concentration([Bd]) in the range of 0.46-3.88 mol·L~(-1).The signal bands at 890 and 989 cm~(-1) were assigned to wagging vibration of Ip and the signal intensity was also proportional to Ip concentration([Ip]) in the range of 0.08-4.73 mol·L~(-1) at 890 cm~(-1) and 0.08-7.49 mol·L~(-1) at 989 cm~(-1),respectively.Thus the signal band at 1010 cm~(-1) was chosen to monitor Bd concentration and bands at 989 and 890 cm~(-1) to monitor Ip concentration during the copolymerization,respectively.It was demonstrated that the conversions of Bd and Ip calculated from FTIR data agreed very well with those obtained gravimetrically.The polymerization rates were first order with respect to both[Bd]and[Ip],respectively at different polymerization temperatures.The apparent propagation activation energy for Bd and Ip could be determined to be 54.4 kJ·mol~(-1) and 57.7 kJ·mol~(-1),respectively.The monomer reactivity ratios were calculated to be 1.08 for Bd(r_(Bd)) and 0.48 for IP(r_(Ip)) based on FTIR data.The Bd-Ip copolymer products with random sequence could be obtained with only one glass transition temperature.     

Synthesis and Primary Research on Antitumor Activity of Three New Panaxadiol Fatty Acid Esters

For making use of Ginseng resources that exhibit an antitumor activity and for finding new anticancer drugs,three new fatty acid ester compounds: 3β-acetoxy panaxadiol ( Ⅰ ), 3β-palmitic acid aceloxy panaxadiol ( Ⅱ ), and 3β-octadecanoic acid aceloxy panaxadiol( Ⅰ , Ⅱ , and Ⅲ ) were synthesized with panaxadiol, diacetyl oxide, palmityl chloride and stearyl chloride, and their structures were determined via MS, 13C NMR, IR, TLC, and so on. The molar yields of the three compounds are 75.14%, 79. 08%, and 72. 57%, respectively. Meanwhile, the antitumor activity of the three new panaxadiol fatty acid ester derivatives and panaxadiol was compared by using the method of MTT. Tumor cell used was Vero cell line. Positive control was 5-FU, blank was an RPMI1640 culture medium, negative control was an RPMI1640 culture medium and the solvent for drugs to be tested. Compound Ⅰ has the strongest antitumor activity followed by panaxadiol; compounds Ⅱ and Ⅲ have similar and weakest antitumor activities.Furthermore, the antitumor activities of the panaxadiol fatty acid ester derivatives show positive correlation with the concentration of the test group, but show no relationship with the molecular weight of fatty acid. The methods that are used to synthesize the three compounds with high yields and strong antitumor activities are simple and show a great potential for meeting the needs of industrial manufacture of these drugs.     

Assemblies and Properties of Asymmetric Supercapacitors Based on WO3/Carbon Cloth北大核心CSCD

The demand for a new generation of flexible, portable, and high-capacity power sources increases rapidly with the development of advanced wearable electronic devices. One dimensional (1D) nanowires structures have been demonstrated as one of the most ideal electrode materials in energy storage systems due to their advantages in both micorstructures and their high surface areas. Here we report a simple process for large-scale fabrication of self-standing composite film electrodes composed of WO3nanorods on carbon cloth. In order to improve the energy density of supercapacitor, we assembled an asymmetric supercapacitor using WO3nanorods and activated carbon cloth as positive and negative electrodes, respectively. The scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to characterize the morphology and structure of the electrode materials, respectively. In addition, cyclic voltammetry (CV), galvanostatic charge-diacharge (GCD) test, and electrochemical impedance spectroscopy (EIS) were employed to study the electrode materials in a three-electrode system. It was found that the WO3nanorods exhibited attractive electrochemical performance as well as remarkable flexibility with the high areal capacitance of 3347 mF·cm-2at 5 mA·cm-2. In addition, to improve the electrochemical performance of activated carbon cloth by introducing function groups onto its surface for producing pseudocapacitance and increasing surface area by electrochemically oxidizing CC in the mixed acid solution, it was also shown the high areal capacitance of 1160 mF·cm-2at 7 mA·cm-2. This method was simpler and more effective compared with the previous strategies for activating carbon materials. The as-fabricated asymmetric supercapacitor based on WO3/carbon cloth exhibited high areal capacitance of 58.96 F·cm-2at 61.9 mA·cm-2, high energy density of 20.36 mWh·cm-2at 0.48 W·cm-2with the operation voltage window expanding to 0 ~ 1.6 V, and excellent lifespan after 3000 cycles. This work opens up a novel, low-cost route to design advanced integrated-array and high performance electrode materials for portable supercapacitor application on a large scale. © Journal of Electrochemistry 2018.     

Dielectric investigations on how Mg salt is dispersed in and released from polylactic acid

Composite biomaterials made of biodegradable polylactic acid （PLA） and bioactive magnesium （Mg） salt are developed for orthopaedic implants or metal implant coatings. The releasing of Mg salt into the biological environment benefits the bone growth, while with the releasing of Mg salt and degradation of PLA there forms a porous scaffold for tissue engineering. The size and morphology of the salt and voids are adjustable with such preparation conditions as salt content, pH of casting solution, and the solidification rate, so that we can control the salt releasing and degradation rate of PLA. Dielectric spectroscopy is used to investigate the dispersive structures of Mg salt and voids in the polymer matrix and to monitor the in situ releasing of Mg salts in the simulated body fluid （SBF）. The current study provides us with an orthopedic biomaterial with controllable multi-phase structures, and a tool to investigate the in vivo behaviors of biomaterials.     

Mild and Efficient Catalytic Protocol for Tetrahydropyranylation of Alcohols Using Acidic Keggin and Wells‐Dawson Structures

A simple, mild and effective procedure is reported to the generation of 2-tetrahydropyranyl acetals from alcohols. Keggin and Wells-Dawson heteropolyoxometalates were used as catalysts at ambient temperature in acetone as solvent with good yields and high selectivities in a short reaction time. Different reaction parameters affecting efficiency of the protocol were also studied. The use of these acid catalysts allows replacing the usual soluble inorganic acids, contributing to waste reduction.     

柠檬酸用量对碳纳米管制备的影响

Carbon nanotubes (CNTs) were prepared by chemical vapor catalytic deposition using the catalyst prepared by citric acid complexometry. The effect of the dosage of citric acid on the CNTs yield and morphologywas studied. The transmission electron microscopy and X-ray diffraction were used to characterize CNTs morphology and crystal structures of the catalysts, respectively. The results show that the dosage of citric acid can greatly affect the CNTs yield and morphology: the CNTs have a high yield about 1 345.8% (1 h) at a 2∶1 molar ratio of citric acid and metal ion, and the obtained CNTs diameter is relatively narrow distributed (25～30 nm); when themolar ratio of citric acidto metal ion is 3∶1, the CNTs yield is about 407.2% (1 h), and the obtained CNTs diameter is relatively wide distributed (25～50 nm), moreover, the CNTs is more rough than that obtained with 2∶1 molar ratio of citric acid to metal ion.     

A series of stable,metastable and unstable salts of Imatinib with improved solubility

Pharmaceutical salt formation is the most preferred and effective method to enhance the physicochemical properties of APIs. The aim of the study was to design and synthesize a series of new salts to improve the solubility of Imatinib(IM). Two stable salts with malonic acid(S1) and citric acid(S5), one metastable salt with fumaric acid(S2), two unstable salts with citric acid(S3, S4) were obtained for the first time.Single crystal and powder X-ray diffraction, Fourier transform infrared, differen...     

Influence of Gd doping on the absolute quantum efficiency and lifetime of EuxGd1-x（TTA）3phens

Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.