A unique nanocomposite of CeO_(2)nanoparticles and Ce-doped manganese oxide nanofibers having a crystalline cryptomelane-type octahedral molecular sieve(KMn_(8)O_(16)·nH_(2)O,abbreviated as OMS-2)structure(denote...A unique nanocomposite of CeO_(2)nanoparticles and Ce-doped manganese oxide nanofibers having a crystalline cryptomelane-type octahedral molecular sieve(KMn_(8)O_(16)·nH_(2)O,abbreviated as OMS-2)structure(denoted CeO_(2)-CeOMS-2)was prepared by the reaction of Ce(NO_(3))3 and KMnO_(4)at 90°C.CeO_(2)-CeOMS-2 shows extremely high photothermocatalytic activity,very low selectivity for acetaldehyde(an unfavorable byproduct),and excellent durability for ethyl acetate removal under UV-visible-infrared(UV-vis-IR)irradiation.In striking contrast,pure CeO_(2),pure OMS-2,and TiO_(2)(P25)showed much lower photothermocatalytic activities and higher selectivities for acetaldehyde.The CO_(2)production rate within the first five minutes(r CO2)of reaction with CeO_(2)-CeOMS-2 was as high as 1102.5μmol g-1 min-1,which is 137,17,and 30-times higher than those of pure CeO_(2),pure OMS-2,and TiO_(2)(P25),respectively.CeO_(2)-CeOMS-2 also shows good photothermocatalytic activity under vis-IR(λ>420 or 560 nm)irradiation.Further,even under vis-IR(λ>830 nm)irradiation,efficient photothermocatalytic activity was achieved.In addition,the catalytic activity of CeO_(2)-CeOMS-2 is far superior to those of pure CeO_(2)and OMS-2,which is attributed to the fact that Ce doping significantly improves the lattice oxygen activity of OMS-2.The high photothermocatalytic activity of CeO_(2)-CeOMS-2 arises from the synergy between the photocatalytic effect of the CeO_(2)nanoparticles and light-driven thermocatalysis of the Ce-doped OMS-2.The novel photoactivation of Ce-doped OMS-2,which is unlike that of conventional photocatalysis on semiconductor photocatalysts,further promotes the catalytic activity because the surface oxygen activity of Ce-doped OMS-2 is promoted upon UV-vis-IR or vis-IR(λ>560 nm)irradiation.展开更多
A new method for the determination of baicalin with HPLC-CL was developed. The method was based on the chemiluminescence reaction between KMnO4 and baicalin sensitized from HCHO. The linear range was 3.7?0-6~9.8?0-5...A new method for the determination of baicalin with HPLC-CL was developed. The method was based on the chemiluminescence reaction between KMnO4 and baicalin sensitized from HCHO. The linear range was 3.7?0-6~9.8?0-5 mol/L with detection limit of 1.7?0-6 mol/L and the relative standard deviation was 2.5 % (Cs=6.6?0-5 mol/L, n=5). The method has been applied to the determination of baicalin in oral administration, injection, Scutellariae radix and granules with good results.展开更多
A trinudear Mn（II） coordination complex Mna （HEDTA）2-10H20 （EDTA=ethylene diamine tetraacetic acid） 1 has been synthesized and characterized by X-ray crystal structure determination. In addition, IR spectrum, th...A trinudear Mn（II） coordination complex Mna （HEDTA）2-10H20 （EDTA=ethylene diamine tetraacetic acid） 1 has been synthesized and characterized by X-ray crystal structure determination. In addition, IR spectrum, thermogravimetric analysis, electron paramagnetic resonance （EPR） spectra and magnetic susceptibility of this complex are discussed. X-ray determination indicates that six- and seven-coordinate modes between Mn（Yl） and H4EDTA exist alternately in 1. Furthermore, detailed discussion of magnetic ordering in tile temperature range of 2-300 K reveals the antiferromagnetic interactions in the complex.展开更多
Despite of considerable efforts on the MnO2-based catalytic combustion,the different structural and component requirements of MnO2 for gas-phase selective oxidation and complete oxidation largely remain unknown.By com...Despite of considerable efforts on the MnO2-based catalytic combustion,the different structural and component requirements of MnO2 for gas-phase selective oxidation and complete oxidation largely remain unknown.By comparing four types of MnO2 with different crystal structures(α,β,γandδ),γ-MnO2 was found to be the most efficient catalyst for both aerobic selective oxidation of ethanol and CO oxidation.The structural effect ofγ-MnO2 was further investigated by doping metal ions into the framework and by comparing the catalytic performance in the gas-phase aerobic oxidation of CO and ethanol.Among ten M-γ-MnO2 catalysts,Zn-γ-MnO2 showed the lowest temperature(160°C)for achieving 90%CO conversion.The CO oxidation activity of the M-γ-MnO2 catalysts was found to be more relevant to the surface acidity-basicity than the reducibility.In contrast,surface reducibility has been demonstrated to be more crucial in the gas-phase ethanol oxidation.Cu-γ-MnO2 with higher reducibility and more oxygen vacancies of Mn^2+/Mn^3+species exhibited higher catalytic activity in the selective ethanol oxidation.Cu-γ-MnO2 achieved the highest acetaldehyde yield(75%)and space-time-yield(5.4 g gcat^-1 h^-1)at 200°C,which are even comparable to the results obtained by the state-of-the-art silver and gold-containing catalysts.Characterization results and kinetic studies further suggest that the CO oxidation follows the lattice oxygen-based Mars-van Krevelen mechanism,whereas both surface lattice oxygen and adsorbed oxygen species involve in the ethanol activation.展开更多
The polystyrene supported phenylalanine Schiff base complex of Mn（Ⅱ） （PS-Sal-Phe-Mn ） was prepared with chloromethylated styrene polymer heads, 2 L-phenylalanine and manganese （Ⅱ） acetate tetrahyrate., The pol...The polystyrene supported phenylalanine Schiff base complex of Mn（Ⅱ） （PS-Sal-Phe-Mn ） was prepared with chloromethylated styrene polymer heads, 2 L-phenylalanine and manganese （Ⅱ） acetate tetrahyrate., The polymeric ligand and the complex were characterized by FT.IR,, small area X-ray photoelectron spectroscopy （XPS）, and ICP-AES. in the presence of the manganese complex, cyclohexene （1） was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2.cyclohexen-l-ol （2）, 2-cyclohexen-l-one （3）and 2-cyclohexen-1-hydroperoxide （4）, which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-l-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.展开更多
ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and...ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and diethyl ketone by the one-step synthesis method over this catalyst were studied,and meanwhile,the impact of the catalyst preparation conditions and the reaction conditions on catalyst performance was also investigated.It was observed that under the conditions when Ni loading was 25%,calcination temperature was 400℃ and reduction temperature was 410℃,this catalyst had good catalytic performance on the reaction.The suitable reaction conditions were achieved:reaction temperature was 400℃;reaction at atmospheric pressure;liquid hourly space velocity of raw material of 0.5 h 1 ;and the molar ratio of(methanol)/(methyl ethyl ketone)/(water) was equal to 1/1/1.Under such conditions,the conversion of methyl ethyl ketone could achieve 41.7%,and the overall selectivity of methyl isopropyl ketone and diethyl ketone could achieve 83.3%,which was comparable to the conversion of 38.1% and the selectivity of 82.2% achieved by using palladium as the active material.The good stability made this catalyst have good prospects for industrial application.展开更多
The reaction behaviors of the title complexes have been studied in thesystem of dinitrogen gas by means of in situ IR. It has been found that some activefragments created at some stage of the thermal decomposition pro...The reaction behaviors of the title complexes have been studied in thesystem of dinitrogen gas by means of in situ IR. It has been found that some activefragments created at some stage of the thermal decomposition process of the complexes.enable.the acetic acid both obtained from the ligand of the complexes and introducedfrom outside to convert to acetone by decarboxylation. Their optimum reaction temperatures are of 240~270℃ for [Fe2MnO(O2CCH3),(H2O)3], 290~320 C for [Fe3Q(O2CCH3)6(H2O)3], 300~330℃ for [Fe2CoO(O2CCH3),(H2O)3] and 320~ 350℃for [Fe2NiO(O2CCH3)6(H2O)3], indicating the lowering sequence of the activity of active species. At the same time it has been shown that this activity may come from thejoined contributions of both the coordinating capability of the hetero-metals in the complexes and their structural factors. On the basis of the TGA, DTA and EI-MS data,the composition of the active fragments has been tentatively inferred as [Fe2MnO(O2CCH3)3-2].展开更多
The effect of tumor-targeted photodynamic therapy（PDT） was improved by designing nanotheranostics to promote oxygenation in a tumor microenvironment（TME）wherein hypoxia, acidosis, and the elevated levels of H2O2 a...The effect of tumor-targeted photodynamic therapy（PDT） was improved by designing nanotheranostics to promote oxygenation in a tumor microenvironment（TME）wherein hypoxia, acidosis, and the elevated levels of H2O2 are three main characteristics. In this study, a carbon dot（CD）PDT agent recently developed by our group was firstly applied as reducing agent to react with potassium permanganate for fabricating CDs/manganese dioxide（CDs/MnO2） composites,which were in turn modified with polyethylene glycol（PEG） to form water-soluble CDs/MnO2-PEG nanohybrids. In a normal physiological environment, the as-prepared nanohybrids exhibited quenched fluorescence, weak singlet oxygen generation, and low magnetic resonance imaging（MRI） signal.However, given the high sensitivity of MnO2 to the TME, the CDs/MnO2-PEG nanohybrids changed from an ＂off＂ to an＂on＂ state with synchronously enhanced fluorescence, singlet oxygen generation, and MRI signal in the TME. In vitro and in vivo analyses have revealed that CDs/MnO2-PEG nanohybrids could be applied as TME-driven, turn-on nanotheranostics for the MR/fluorescence bimodal imaging-guided PDT of cancer.Moreover, complete clearance of CDs/MnO2-PEG nanohybrids from the body of mice was observed, indicating their low long-term toxicity and good biocompatibility. This work offers a new nanotheranostic candidate for modulating the unfavorable TME, particularly for the targeted PDT of cancer through precise positioning and oxygen generation.展开更多
文摘A unique nanocomposite of CeO_(2)nanoparticles and Ce-doped manganese oxide nanofibers having a crystalline cryptomelane-type octahedral molecular sieve(KMn_(8)O_(16)·nH_(2)O,abbreviated as OMS-2)structure(denoted CeO_(2)-CeOMS-2)was prepared by the reaction of Ce(NO_(3))3 and KMnO_(4)at 90°C.CeO_(2)-CeOMS-2 shows extremely high photothermocatalytic activity,very low selectivity for acetaldehyde(an unfavorable byproduct),and excellent durability for ethyl acetate removal under UV-visible-infrared(UV-vis-IR)irradiation.In striking contrast,pure CeO_(2),pure OMS-2,and TiO_(2)(P25)showed much lower photothermocatalytic activities and higher selectivities for acetaldehyde.The CO_(2)production rate within the first five minutes(r CO2)of reaction with CeO_(2)-CeOMS-2 was as high as 1102.5μmol g-1 min-1,which is 137,17,and 30-times higher than those of pure CeO_(2),pure OMS-2,and TiO_(2)(P25),respectively.CeO_(2)-CeOMS-2 also shows good photothermocatalytic activity under vis-IR(λ>420 or 560 nm)irradiation.Further,even under vis-IR(λ>830 nm)irradiation,efficient photothermocatalytic activity was achieved.In addition,the catalytic activity of CeO_(2)-CeOMS-2 is far superior to those of pure CeO_(2)and OMS-2,which is attributed to the fact that Ce doping significantly improves the lattice oxygen activity of OMS-2.The high photothermocatalytic activity of CeO_(2)-CeOMS-2 arises from the synergy between the photocatalytic effect of the CeO_(2)nanoparticles and light-driven thermocatalysis of the Ce-doped OMS-2.The novel photoactivation of Ce-doped OMS-2,which is unlike that of conventional photocatalysis on semiconductor photocatalysts,further promotes the catalytic activity because the surface oxygen activity of Ce-doped OMS-2 is promoted upon UV-vis-IR or vis-IR(λ>560 nm)irradiation.
文摘A new method for the determination of baicalin with HPLC-CL was developed. The method was based on the chemiluminescence reaction between KMnO4 and baicalin sensitized from HCHO. The linear range was 3.7?0-6~9.8?0-5 mol/L with detection limit of 1.7?0-6 mol/L and the relative standard deviation was 2.5 % (Cs=6.6?0-5 mol/L, n=5). The method has been applied to the determination of baicalin in oral administration, injection, Scutellariae radix and granules with good results.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.20490210,10574047)the Doctor Foundation of China(Grant No.20030487003)
文摘A trinudear Mn（II） coordination complex Mna （HEDTA）2-10H20 （EDTA=ethylene diamine tetraacetic acid） 1 has been synthesized and characterized by X-ray crystal structure determination. In addition, IR spectrum, thermogravimetric analysis, electron paramagnetic resonance （EPR） spectra and magnetic susceptibility of this complex are discussed. X-ray determination indicates that six- and seven-coordinate modes between Mn（Yl） and H4EDTA exist alternately in 1. Furthermore, detailed discussion of magnetic ordering in tile temperature range of 2-300 K reveals the antiferromagnetic interactions in the complex.
文摘Despite of considerable efforts on the MnO2-based catalytic combustion,the different structural and component requirements of MnO2 for gas-phase selective oxidation and complete oxidation largely remain unknown.By comparing four types of MnO2 with different crystal structures(α,β,γandδ),γ-MnO2 was found to be the most efficient catalyst for both aerobic selective oxidation of ethanol and CO oxidation.The structural effect ofγ-MnO2 was further investigated by doping metal ions into the framework and by comparing the catalytic performance in the gas-phase aerobic oxidation of CO and ethanol.Among ten M-γ-MnO2 catalysts,Zn-γ-MnO2 showed the lowest temperature(160°C)for achieving 90%CO conversion.The CO oxidation activity of the M-γ-MnO2 catalysts was found to be more relevant to the surface acidity-basicity than the reducibility.In contrast,surface reducibility has been demonstrated to be more crucial in the gas-phase ethanol oxidation.Cu-γ-MnO2 with higher reducibility and more oxygen vacancies of Mn^2+/Mn^3+species exhibited higher catalytic activity in the selective ethanol oxidation.Cu-γ-MnO2 achieved the highest acetaldehyde yield(75%)and space-time-yield(5.4 g gcat^-1 h^-1)at 200°C,which are even comparable to the results obtained by the state-of-the-art silver and gold-containing catalysts.Characterization results and kinetic studies further suggest that the CO oxidation follows the lattice oxygen-based Mars-van Krevelen mechanism,whereas both surface lattice oxygen and adsorbed oxygen species involve in the ethanol activation.
文摘The polystyrene supported phenylalanine Schiff base complex of Mn（Ⅱ） （PS-Sal-Phe-Mn ） was prepared with chloromethylated styrene polymer heads, 2 L-phenylalanine and manganese （Ⅱ） acetate tetrahyrate., The polymeric ligand and the complex were characterized by FT.IR,, small area X-ray photoelectron spectroscopy （XPS）, and ICP-AES. in the presence of the manganese complex, cyclohexene （1） was effectively oxidized by molecular oxygen without reductant. The major products of the reaction were 2.cyclohexen-l-ol （2）, 2-cyclohexen-l-one （3）and 2-cyclohexen-1-hydroperoxide （4）, which was different with typical oxidation of cyclohexene. The influence of reaction temperature and additive for oxidation had been studied. The selectivity of 2-cyclohexen-l-hydroperoxide varied with reaction time and different additives. The mechanism of cyclohexene oxidation had also been discussed.
基金Supported by the National Science and Technology Support Program Project (2006BAE03B06)
文摘ZrO2-MnO2-ZnO supports were prepared by the co-precipitation method,and then Ni-Na/ZrO2-MnO2-ZnO catalysts were prepared by the impregnation method.In this paper,the reactions to synthesize methyl isopropyl ketone and diethyl ketone by the one-step synthesis method over this catalyst were studied,and meanwhile,the impact of the catalyst preparation conditions and the reaction conditions on catalyst performance was also investigated.It was observed that under the conditions when Ni loading was 25%,calcination temperature was 400℃ and reduction temperature was 410℃,this catalyst had good catalytic performance on the reaction.The suitable reaction conditions were achieved:reaction temperature was 400℃;reaction at atmospheric pressure;liquid hourly space velocity of raw material of 0.5 h 1 ;and the molar ratio of(methanol)/(methyl ethyl ketone)/(water) was equal to 1/1/1.Under such conditions,the conversion of methyl ethyl ketone could achieve 41.7%,and the overall selectivity of methyl isopropyl ketone and diethyl ketone could achieve 83.3%,which was comparable to the conversion of 38.1% and the selectivity of 82.2% achieved by using palladium as the active material.The good stability made this catalyst have good prospects for industrial application.
文摘The reaction behaviors of the title complexes have been studied in thesystem of dinitrogen gas by means of in situ IR. It has been found that some activefragments created at some stage of the thermal decomposition process of the complexes.enable.the acetic acid both obtained from the ligand of the complexes and introducedfrom outside to convert to acetone by decarboxylation. Their optimum reaction temperatures are of 240~270℃ for [Fe2MnO(O2CCH3),(H2O)3], 290~320 C for [Fe3Q(O2CCH3)6(H2O)3], 300~330℃ for [Fe2CoO(O2CCH3),(H2O)3] and 320~ 350℃for [Fe2NiO(O2CCH3)6(H2O)3], indicating the lowering sequence of the activity of active species. At the same time it has been shown that this activity may come from thejoined contributions of both the coordinating capability of the hetero-metals in the complexes and their structural factors. On the basis of the TGA, DTA and EI-MS data,the composition of the active fragments has been tentatively inferred as [Fe2MnO(O2CCH3)3-2].
基金supported by the National Natural Science Foundation of China (51472252 and 51572269)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17000000)
文摘The effect of tumor-targeted photodynamic therapy（PDT） was improved by designing nanotheranostics to promote oxygenation in a tumor microenvironment（TME）wherein hypoxia, acidosis, and the elevated levels of H2O2 are three main characteristics. In this study, a carbon dot（CD）PDT agent recently developed by our group was firstly applied as reducing agent to react with potassium permanganate for fabricating CDs/manganese dioxide（CDs/MnO2） composites,which were in turn modified with polyethylene glycol（PEG） to form water-soluble CDs/MnO2-PEG nanohybrids. In a normal physiological environment, the as-prepared nanohybrids exhibited quenched fluorescence, weak singlet oxygen generation, and low magnetic resonance imaging（MRI） signal.However, given the high sensitivity of MnO2 to the TME, the CDs/MnO2-PEG nanohybrids changed from an ＂off＂ to an＂on＂ state with synchronously enhanced fluorescence, singlet oxygen generation, and MRI signal in the TME. In vitro and in vivo analyses have revealed that CDs/MnO2-PEG nanohybrids could be applied as TME-driven, turn-on nanotheranostics for the MR/fluorescence bimodal imaging-guided PDT of cancer.Moreover, complete clearance of CDs/MnO2-PEG nanohybrids from the body of mice was observed, indicating their low long-term toxicity and good biocompatibility. This work offers a new nanotheranostic candidate for modulating the unfavorable TME, particularly for the targeted PDT of cancer through precise positioning and oxygen generation.
