The present study reports a novel strategy to fabricate nanocrystal-assembled hierarchical MOR zeolites. This is the first demonstration of hierarchical MOR without preferential growth along the c-axis, which facilita...The present study reports a novel strategy to fabricate nanocrystal-assembled hierarchical MOR zeolites. This is the first demonstration of hierarchical MOR without preferential growth along the c-axis, which facilitates mass transfer in the 12-membered ring channels of MOR zeolite for the conversions involving bulky molecules. The facile method involves the combined use of tetraethylammonium hydroxide (TEAOH) and commercial surfactants, in which TEAOH is essential for the construction of nanocrystal assemblies. The surfactant serves as a crystal growth-inhibiting agent to further inhibit nanocrystalline particle growth, resulting in enhanced mesoporosity. The hierarchical MOR assembled particles, constructed of 20-50-nm crystallites, exhibit superior catalytic properties in the alkylation of benzene with benzyl alcohol compared with the control sample, as the hierarchical MOR possesses a larger external surface area and longer c-axis dimension. More importantly, the material shows improved activity and stability in the dimethyl ether carbonylation to methyl acetate reaction, which is a novel route to produce ethanol from syngas.展开更多
Bismuth oxybromide(BiOBr) with a hierarchical microcube morphology was successfully synthesized via microwave-assisted ionothermal self-assembly method. The as-obtained BiOBr was composed of regular multi-layered na...Bismuth oxybromide(BiOBr) with a hierarchical microcube morphology was successfully synthesized via microwave-assisted ionothermal self-assembly method. The as-obtained BiOBr was composed of regular multi-layered nanosheets, which were formed by selective adsorption of ionic liquids on the Br-terminated surface, followed by the formation of hydrogen bond-co-π-π stacking.The synthesized BiOBr exhibited high activity, excellent stability, and superior mineralization ability in the photocatalytic degradation of organic dyes under visible light owing to its enhanced light absorbance and narrow bandgap. Furthermore, photo-generated electrons were determined to be the main active species by comparison with different trapping agents used in the photocatalytic reactions.展开更多
The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is high...The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2.展开更多
This study developed a facile approach for in situ synthesis of a Ti3+ self-doped mesoporous TiO 2photocatalyst by an evaporation-induced self-assembly method using TiC l3,water,and F127 as the titanium precursor,sol...This study developed a facile approach for in situ synthesis of a Ti3+ self-doped mesoporous TiO 2photocatalyst by an evaporation-induced self-assembly method using TiC l3,water,and F127 as the titanium precursor,solvent,and soft template agent,respectively. The as-prepared samples were investigated by X-ray diffraction,N2 adsorption-desorption measurements,ultraviolet-visible diffuse reflectance spectroscopy,electron paramagnetic resonance,and transmission electron microscopy. The influence of different reaction parameters such as the dosage of F127 and calcination temperature on the photocatalytic performance of the resulting products was evaluated. The optimized product exhibited high photocatalytic activity and stability in the oxidation of nitric oxide in air and photocatalytic degradation of methylene blue. The excellent photocatalytic performance of the Ti3+ self-doped mesoporous TiO 2 photocatalyst is attributed to the cooperation between the mesoporous structure and self-doped Ti3+ enhancing light absorption and effectively suppressing the recombination of photogenerated electrons and holes.展开更多
The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission elect...The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.展开更多
The one-pot assembly reaction of a trilacunary,lone-pair-containing[B-α-SbW9O33]9.precursor with Co2+ions in an aqueous medium led to the isolation of a novel{SbO3(H2O)3}bridging,dicobalt-substituted,sandwich-type tu...The one-pot assembly reaction of a trilacunary,lone-pair-containing[B-α-SbW9O33]9.precursor with Co2+ions in an aqueous medium led to the isolation of a novel{SbO3(H2O)3}bridging,dicobalt-substituted,sandwich-type tungstoantimonate{Co2Sb2(H2O)10[B-β-SbW9O33]2}^4–(1a).This compound was structurally characterized in the solid state by single-crystal X-ray diffraction,elemental analyses,thermogravimetric analysis,and IR spectroscopy.The most remarkable feature was that 1a comprises two trilacunary[B-β-SbW9O33]9^-fragments trapping a novel,centrally symmetric,rhomb-like{Co2Sb2}belt with 10 terminal water molecules.When combined with the photosensitizer[Ru(bpy)3]^2+and the sacrificial electron acceptor S2O82.,1a exhibited efficient catalytic activity for water oxidation with a remarkable turnover number(TON)of 193,initial turnover frequency(TOFinitial)of 5.3 s^-1,O2 yield of 30.8%,and quantum yield(ФQY)of 36.2%under light-driven conditions.展开更多
In this paper we present a study on the influence of the number and the thickness of silicon spacer layer on the optical properties of single-and multi-layers of self assembled Ge/Si(001) islands performed by means of...In this paper we present a study on the influence of the number and the thickness of silicon spacer layer on the optical properties of single-and multi-layers of self assembled Ge/Si(001) islands performed by means of cathodoluminescence spectroscopy,high resolution X-ray diffraction and transmission electron microscopy. In single-layer sample,we do not evidence dependence of the island no-phonon emission peak position on the silicon cap-layer thickness. In multi-layer samples having a thin(33 nm) silicon spacer layer the no-phonon emission energy value progressively blue-shifts for an increasing number of island layers. This is interpreted as an enhanced intermixing driven by the strain interaction existing between island layers. On the contrary,island emission energy position is independent on the number of layers in the sample series having a thicker spacer layer(60 nm) . These findings are consistent with the X-ray diffraction observation that islands belonging to different layers have the same composition. As a consequence we can conclude that multilayers with 60-nm spaced islands layer are more homogeneous and ordered.展开更多
The adsorption characteristics of cationic polyelectrolyte poly dimethyl diallyl ammonium chloride (PDADMAC) and anionic polyelectrolyte poly (sodium-p-styrenesulfonate) (PSS) on benzoguanamine formal- dehyde (...The adsorption characteristics of cationic polyelectrolyte poly dimethyl diallyl ammonium chloride (PDADMAC) and anionic polyelectrolyte poly (sodium-p-styrenesulfonate) (PSS) on benzoguanamine formal- dehyde (BGF) particles are investigated. The charging characteristics of BGF particles are changed and con- trolled using electrostatic self-assembly method. A variety of PE,-BGF/SiO2 composite abrasives are obtained. The as-prepared samples are analyzed by zeta potential analysis, transmission electron microscope (TEM) and thermogravimetric (TG) analysis. The composite abrasive slurries are prepared for copper polishing. The poli- shing results indicate that it is SiO2 abrasives, not only coated SiO2 abrasive on polymer particles but also free SiO2 abrasive in slurry, that offer the polishing action. The material removal rates of copper polishing are 264 nm/min, 348 nm/min and 476 nm/min using single SiO2 abrasive slurry, PE0-BGF/SiO2 mixed abrasive slur- ry and PE3-BGF/SiO2 composite abrasive slurry, respectively. The surface roughness Ra of copper wafer (with 5μm×5μm district) is decreased from 0.166 μm to 3.7 nm, 2.6 nm and 1.5 nm, and the surface peak-valley values Rrv are less than 20 nm, 14 nm and 10 nm using these kinds of slurries, respectively. Key words : chemico-mechanical polishing; polishing slurry; composite abrasives ; polyelectrolyte ; copper展开更多
Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic in...Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate (SDS) in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.展开更多
Semi-empirical AMI method was used to study 1:1 and 1:2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds in...Semi-empirical AMI method was used to study 1:1 and 1:2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds increases. The donor groups on the host and electron-withdrawing groups on the guest molecules favor hydrogen bonding interactions, and the formation of hydrogen bonding leads to electron density flow from the host to the guest molecules. Electronic spectra of these complexes were computed using INDO/SCI method. Blue-shift of the clectronic absorption spectra for the complexes, comparing that of the host, takes place, and the first peaks for different complexes changed slightly. These are in agreement with the experimcntal results. The cause of blue-shift was discussed, and the electronic transitions were assigned based on theoretical calculations. The potential curve of double proton transfer in the complex was calculated, and the transition state and activated energy relative to the N H bond were obtained.展开更多
A bilayer model with ohmic anode contact and injection limited cathode contact has been proposed to calculate the recombination efficiency and recombination zone width of the device. The effects of the thickness of ho...A bilayer model with ohmic anode contact and injection limited cathode contact has been proposed to calculate the recombination efficiency and recombination zone width of the device. The effects of the thickness of hole transport layer and the barriers of organic/organic interface on the combination efficiency and recombination width have been discussed. It is found that: (1) When the electrons are blocked fully and the holes are not blocked significantly at the organic/organic interface, for a given Lh/L, the recombination efficiency increases with increasing the applied voltage, but at a higher applied voltage, the recombination efficiency decreases with increasing Lh/L; (2) The recombination efficiency increases with increasing applied voltage and Hh', and when applied voltage and Hh' exceed some value, the recombination efficiency appears as a plateau; (3) The recombination width decreases with increasing the applied voltage and Lh/L. This model might explain the relative experiment phenomena.展开更多
Fluorogens with aggregation-induced emission (AIE) characteristics have recently been widely applied for studying biological events, and fluorogens with “smart” properties are especially desirable. Herein, we ration...Fluorogens with aggregation-induced emission (AIE) characteristics have recently been widely applied for studying biological events, and fluorogens with “smart” properties are especially desirable. Herein, we rationally designed and synthesized a biotinylated and reduction-activatable probe (Cys(StBu)-Lys(biotin)-Lys(TPE)-CBT (1)) with AIE properties for cancer-targeted imaging. The biotinylated probe 1 can be actively uptaken by the biotin receptor-overexpressing cancer cells, and then “smartly” self-assemble into nanoparticles inside cells and turn the fluorescence “On”. Employing this “smart” strategy, we successfully applied probe 1 for cancer-targeted imaging. We envision that this biotinylated intelligent probe 1 might be further developed for cancer-targeted imaging in routine clinical studies in the near future.展开更多
We investigate tunneling electron induced luminescence from isolated single porphyrin molecules that are decoupled by striped-phase self-assembled monolayer of octanethiol from the underneath Au(111) substrate. Intr...We investigate tunneling electron induced luminescence from isolated single porphyrin molecules that are decoupled by striped-phase self-assembled monolayer of octanethiol from the underneath Au(111) substrate. Intrinsic single-molecule electroluminescence has been realized by such decoupling at both bias polarities. The photon emission intensity acquired from the molecular lobe is found stronger than that from the molecular center. These re- sults provide useful information on the understanding of electroluminescent behavior and mechanism in molecular tunnel junctions.展开更多
基金supported by the National Natural Science Foundation of China(21101150,21476228,21473182)~~
文摘The present study reports a novel strategy to fabricate nanocrystal-assembled hierarchical MOR zeolites. This is the first demonstration of hierarchical MOR without preferential growth along the c-axis, which facilitates mass transfer in the 12-membered ring channels of MOR zeolite for the conversions involving bulky molecules. The facile method involves the combined use of tetraethylammonium hydroxide (TEAOH) and commercial surfactants, in which TEAOH is essential for the construction of nanocrystal assemblies. The surfactant serves as a crystal growth-inhibiting agent to further inhibit nanocrystalline particle growth, resulting in enhanced mesoporosity. The hierarchical MOR assembled particles, constructed of 20-50-nm crystallites, exhibit superior catalytic properties in the alkylation of benzene with benzyl alcohol compared with the control sample, as the hierarchical MOR possesses a larger external surface area and longer c-axis dimension. More importantly, the material shows improved activity and stability in the dimethyl ether carbonylation to methyl acetate reaction, which is a novel route to produce ethanol from syngas.
基金supported by the National Natural Science Foundation of China(20937003,21261140333,21237003,21207091,21577092,2171101231)Shanghai Government(12230706000,11JC1409000,12YZ091,15520711300)+1 种基金Yunnan Applied Basic Research Project of Province(2013FZ109,2016FB016)Key Projects of Yunnan Provincial Department of Education(2015Z183,2016ZZX207)~~
文摘Bismuth oxybromide(BiOBr) with a hierarchical microcube morphology was successfully synthesized via microwave-assisted ionothermal self-assembly method. The as-obtained BiOBr was composed of regular multi-layered nanosheets, which were formed by selective adsorption of ionic liquids on the Br-terminated surface, followed by the formation of hydrogen bond-co-π-π stacking.The synthesized BiOBr exhibited high activity, excellent stability, and superior mineralization ability in the photocatalytic degradation of organic dyes under visible light owing to its enhanced light absorbance and narrow bandgap. Furthermore, photo-generated electrons were determined to be the main active species by comparison with different trapping agents used in the photocatalytic reactions.
文摘The solar-driven catalytic conversion of CO2 to useful chemical fuels is regarded as an environmentally friendly approach to reduce the consumption of fossil fuels and mitigate the greenhouse effect.However,it is highly intriguing and challenging to promote the selectivity and efficiency of visible-light-responsive photocatalysts that favor the adsorption of CO2 in photoreduction processes.In this work,three-dimensional hierarchical Cd0.8Zn0.2S flowers(C8Z2S-F)with ultrathin petals were successfully synthesized through an in-situ self-assembly growth process using sodium citrate as a morphology director.The flower-like Cd0.8Zn0.2S solid solution exhibited remarkable photocatalytic performance in the reduction of CO2,generating CO up to 41.4μmol g^−1 under visible-light illumination for 3 h;this was nearly three times greater than that of Cd0.8Zn0.2S nanoparticles(C8Z2S-NP)(14.7μmol g^−1).Particularly,a comparably high selectivity of 89.9%for the conversion of CO2 to CO,with a turnover number of 39.6,was obtained from the solar-driven C8Z2S-F system in the absence of any co-catalyst or sacrificial agent.Terahertz time-domain spectroscopy indicated that the introduction of flower structures enhanced the light-harvesting capacity of C8Z2S-F.The in situ diffuse reflectance infrared Fourier transform spectroscopy unveiled the existence of surface-adsorbed species and the conversion of photoreduction intermediates during the photocatalytic process.Empirical characterizations and predictions of the photocatalytic mechanism demonstrated that the flower-like Cd0.8Zn0.2S solid solution possessed desirable CO2 adsorption properties and an enhanced charge-transfer capability,thus providing a highly effective photocatalytic reduction of CO2.
基金supported by the National Natural Science Foundation of China(2147707921207090)+2 种基金the Shanghai Rising Star Program(15QA1403300)the Program for Changjiang Scholars and Innovative Research Team(IRT1269)the Specialized Research Fund for the Doctoral Program of Higher Education(20123127120009)~~
文摘This study developed a facile approach for in situ synthesis of a Ti3+ self-doped mesoporous TiO 2photocatalyst by an evaporation-induced self-assembly method using TiC l3,water,and F127 as the titanium precursor,solvent,and soft template agent,respectively. The as-prepared samples were investigated by X-ray diffraction,N2 adsorption-desorption measurements,ultraviolet-visible diffuse reflectance spectroscopy,electron paramagnetic resonance,and transmission electron microscopy. The influence of different reaction parameters such as the dosage of F127 and calcination temperature on the photocatalytic performance of the resulting products was evaluated. The optimized product exhibited high photocatalytic activity and stability in the oxidation of nitric oxide in air and photocatalytic degradation of methylene blue. The excellent photocatalytic performance of the Ti3+ self-doped mesoporous TiO 2 photocatalyst is attributed to the cooperation between the mesoporous structure and self-doped Ti3+ enhancing light absorption and effectively suppressing the recombination of photogenerated electrons and holes.
基金Projects(51102026,51272032) supported by the Program for the National Natural Science Foundation of ChinaProject(11A014) supported by the Scientific Research Fund of Hunan Provincial Education DepartmentProject supported by the Aid Program for Science and Technology Innovative Research Team in Higher Educational Instituions of Hunan Province,China
文摘The mesoporous Ti O2 has been synthesized by evaporation induced self assembly(EISA) method. The thermogravimetric/differential scanning calorimetric(TG/DSC), X-ray diffraction(XRD), high-resolution transmission electron microscopy(HR-TEM) and N2 adsorption desorption and adsorption are used to study the effects of the synthesized process condition on the microstructure of the as-synthesized mesoporous Ti O2. The photocatalytic performances of as-synthesized samples are evaluated by the degradation of the formaldehyde under ultraviolet light irradiations. The results demonstrate that the as-synthesized mesoporous Ti O2 are anatase with the uniform size about 20-40 nm. The sample is prepared using cetyltrimethyl ammonium bromide(CTAB) as the template with average pore size distribution of 8.12 nm, specific surface area of 68.47 m2/g and pore volume of 0.213 m L/g. The samples show decomposition of formaldehyde 95.8% under ultraviolet light irradiations for 90 min. These results provide a basic experimental process for preparation mesoporous Ti O2, which will posses a broad prospect in terms of the applications in improving indoor air quality.
基金financially supported by the National Natural Science Foundation of China(21773096)the Fundamental Research Funds for the Central Universities(lzujbky-2018-k08)the Natural Science Foundation of Gansu Province(17JR5RA186)~~
文摘The one-pot assembly reaction of a trilacunary,lone-pair-containing[B-α-SbW9O33]9.precursor with Co2+ions in an aqueous medium led to the isolation of a novel{SbO3(H2O)3}bridging,dicobalt-substituted,sandwich-type tungstoantimonate{Co2Sb2(H2O)10[B-β-SbW9O33]2}^4–(1a).This compound was structurally characterized in the solid state by single-crystal X-ray diffraction,elemental analyses,thermogravimetric analysis,and IR spectroscopy.The most remarkable feature was that 1a comprises two trilacunary[B-β-SbW9O33]9^-fragments trapping a novel,centrally symmetric,rhomb-like{Co2Sb2}belt with 10 terminal water molecules.When combined with the photosensitizer[Ru(bpy)3]^2+and the sacrificial electron acceptor S2O82.,1a exhibited efficient catalytic activity for water oxidation with a remarkable turnover number(TON)of 193,initial turnover frequency(TOFinitial)of 5.3 s^-1,O2 yield of 30.8%,and quantum yield(ФQY)of 36.2%under light-driven conditions.
文摘In this paper we present a study on the influence of the number and the thickness of silicon spacer layer on the optical properties of single-and multi-layers of self assembled Ge/Si(001) islands performed by means of cathodoluminescence spectroscopy,high resolution X-ray diffraction and transmission electron microscopy. In single-layer sample,we do not evidence dependence of the island no-phonon emission peak position on the silicon cap-layer thickness. In multi-layer samples having a thin(33 nm) silicon spacer layer the no-phonon emission energy value progressively blue-shifts for an increasing number of island layers. This is interpreted as an enhanced intermixing driven by the strain interaction existing between island layers. On the contrary,island emission energy position is independent on the number of layers in the sample series having a thicker spacer layer(60 nm) . These findings are consistent with the X-ray diffraction observation that islands belonging to different layers have the same composition. As a consequence we can conclude that multilayers with 60-nm spaced islands layer are more homogeneous and ordered.
基金Natural Science Foundation of Zhejiang Province(No.Z1080625)
文摘The adsorption characteristics of cationic polyelectrolyte poly dimethyl diallyl ammonium chloride (PDADMAC) and anionic polyelectrolyte poly (sodium-p-styrenesulfonate) (PSS) on benzoguanamine formal- dehyde (BGF) particles are investigated. The charging characteristics of BGF particles are changed and con- trolled using electrostatic self-assembly method. A variety of PE,-BGF/SiO2 composite abrasives are obtained. The as-prepared samples are analyzed by zeta potential analysis, transmission electron microscope (TEM) and thermogravimetric (TG) analysis. The composite abrasive slurries are prepared for copper polishing. The poli- shing results indicate that it is SiO2 abrasives, not only coated SiO2 abrasive on polymer particles but also free SiO2 abrasive in slurry, that offer the polishing action. The material removal rates of copper polishing are 264 nm/min, 348 nm/min and 476 nm/min using single SiO2 abrasive slurry, PE0-BGF/SiO2 mixed abrasive slur- ry and PE3-BGF/SiO2 composite abrasive slurry, respectively. The surface roughness Ra of copper wafer (with 5μm×5μm district) is decreased from 0.166 μm to 3.7 nm, 2.6 nm and 1.5 nm, and the surface peak-valley values Rrv are less than 20 nm, 14 nm and 10 nm using these kinds of slurries, respectively. Key words : chemico-mechanical polishing; polishing slurry; composite abrasives ; polyelectrolyte ; copper
基金This work is supported by the National Natural Science Foundation of China (No.21473171 and No.21573208), the Pundamental Research Funds for the Central Universities (No.JB160508), and the Huashan Mountain Scholar Program.
文摘Molecular self-assembly is extremely important in many fields, but the characterization of their corresponding intermolecular interactions is still lacking. The C-H stretching Raman band can reflect the hydrophobic interactions during the self-assembly process of sodium dodecyl sulfate (SDS) in aqueous solutions. However, the Raman spectra in this region are seriously overlapped by the OH stretching band of water. In this work, vertically polarized Raman spectra were used to improve the detection sensitivity of spectra of C-H region for the first time. The spectral results showed that the first critical micelle concentration and the second critical micelle concentration of SDS in water were 8.5 and 69 mmol/L, respectively, which were consistent with the results given by surface tension measurements. Because of the high sensitivity of vertically polarized Raman spectra, the critical micelle concentration of SDS in a relatively high concentration of salt solution could be obtained in our experiment. The two critical concentrations of SDS in 100 mmol/L NaCl solution were recorded to be 1.8 and 16.5 mmol/L, respectively. Through comparing the spectra and surface tension of SDS in water and in NaCl solution, the self-assembly process in bulk phase and at interface were discussed. The interactions among salt ions, SDS and water molecules were also analyzed. These results demonstrated the vertically polarized Raman spectra could be employed to study the self-assembly process of SDS in water.
文摘Semi-empirical AMI method was used to study 1:1 and 1:2 hydrogen bond complexes formed with perylene dianhydride and pyridine derivatives. The weak interaction energy become bigger as the number of hydrogen bonds increases. The donor groups on the host and electron-withdrawing groups on the guest molecules favor hydrogen bonding interactions, and the formation of hydrogen bonding leads to electron density flow from the host to the guest molecules. Electronic spectra of these complexes were computed using INDO/SCI method. Blue-shift of the clectronic absorption spectra for the complexes, comparing that of the host, takes place, and the first peaks for different complexes changed slightly. These are in agreement with the experimcntal results. The cause of blue-shift was discussed, and the electronic transitions were assigned based on theoretical calculations. The potential curve of double proton transfer in the complex was calculated, and the transition state and activated energy relative to the N H bond were obtained.
基金Excellent Youth Foundation of Hunan Province(03JJY1008) Science Foundation for Post-doctorate of China(2004035083)
文摘A bilayer model with ohmic anode contact and injection limited cathode contact has been proposed to calculate the recombination efficiency and recombination zone width of the device. The effects of the thickness of hole transport layer and the barriers of organic/organic interface on the combination efficiency and recombination width have been discussed. It is found that: (1) When the electrons are blocked fully and the holes are not blocked significantly at the organic/organic interface, for a given Lh/L, the recombination efficiency increases with increasing the applied voltage, but at a higher applied voltage, the recombination efficiency decreases with increasing Lh/L; (2) The recombination efficiency increases with increasing applied voltage and Hh', and when applied voltage and Hh' exceed some value, the recombination efficiency appears as a plateau; (3) The recombination width decreases with increasing the applied voltage and Lh/L. This model might explain the relative experiment phenomena.
基金supported by Anhui Scientific and Technological Project(No.1704a0802164)the Natural Science Foundation of the Anhui Higher Education Institutions of China(No.KJ2018A0192)
文摘Fluorogens with aggregation-induced emission (AIE) characteristics have recently been widely applied for studying biological events, and fluorogens with “smart” properties are especially desirable. Herein, we rationally designed and synthesized a biotinylated and reduction-activatable probe (Cys(StBu)-Lys(biotin)-Lys(TPE)-CBT (1)) with AIE properties for cancer-targeted imaging. The biotinylated probe 1 can be actively uptaken by the biotin receptor-overexpressing cancer cells, and then “smartly” self-assemble into nanoparticles inside cells and turn the fluorescence “On”. Employing this “smart” strategy, we successfully applied probe 1 for cancer-targeted imaging. We envision that this biotinylated intelligent probe 1 might be further developed for cancer-targeted imaging in routine clinical studies in the near future.
文摘We investigate tunneling electron induced luminescence from isolated single porphyrin molecules that are decoupled by striped-phase self-assembled monolayer of octanethiol from the underneath Au(111) substrate. Intrinsic single-molecule electroluminescence has been realized by such decoupling at both bias polarities. The photon emission intensity acquired from the molecular lobe is found stronger than that from the molecular center. These re- sults provide useful information on the understanding of electroluminescent behavior and mechanism in molecular tunnel junctions.