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2008 Volume 24 Issue 4
2008, 24(04):
Abstract:
2008, 24(04): 547-551
doi: 10.3866/PKU.WHXB20080401
Abstract:
Target-ligand space distributions of the molecules in Xuefu Zhuyu decoction (XFZYD), a traditional Chinese medicinal recipe, on four common cardiovascular target enzymes, which were renin, angiotensin-converting enzyme I (ACE I), 3-hydro-3-methyl glutaryl coenzyme A reductase (HMG-CoAR) and P-glycoproteins (P-gp), were studied.
Target-ligand space distributions of the molecules in Xuefu Zhuyu decoction (XFZYD), a traditional Chinese medicinal recipe, on four common cardiovascular target enzymes, which were renin, angiotensin-converting enzyme I (ACE I), 3-hydro-3-methyl glutaryl coenzyme A reductase (HMG-CoAR) and P-glycoproteins (P-gp), were studied.
2008, 24(04): 552-560
doi: 10.1016/S1872-1508(08)60021-2
Abstract:
A scheme of time-dependent density functional theory (TDDFT) combined with the single-excitation configuration interaction (CIS) approach was employed to investigate the first excited singlet state (S1) for eight salicylanilide derivatives and analogues, which have similar structural formulas. The results showed that fluorescence-emitting mechanisms of these compounds were in two distinct manners (excited-state intramolecular proton transfer (ESIPT) and twisted intramolecular charge transfer (TICT)), which agreed with the well-known experiments. For ESIPT compounds with inconspicuous charge transfer (CT) during electron transition, pure functionals without Hartree-Fock (HF) exchange energy, such as OLYP and BLYP, were suitable to calculate emitting energies. For TICT compounds with large CT during electron transition, hybrid functionals with about 37% HF exchange energy, such as mPW1B95 and MPW1K, performed well. On condition that the exchange-correlation (XC ) functionals were chosen properly according to the rules above, reliable emitting energies for salicylanilide derivatives and analogues could be obtained at the TDDFT/6-31G (d)//CIS/3-21G (d) level. The average accuracy reached about 0.2 eV. For the salicylanilides with both of proton transfer (PT) and CTreaction channels, only one channel occurred actually according to the principle of energy minimum. This actual reaction decided proper XC functionals, whereas the reaction that did not occur actually was trivial. Eight appendent compounds were calculated to prove that this successful scheme is expected to be suitable for other ESIPT and TICT compounds.
A scheme of time-dependent density functional theory (TDDFT) combined with the single-excitation configuration interaction (CIS) approach was employed to investigate the first excited singlet state (S1) for eight salicylanilide derivatives and analogues, which have similar structural formulas. The results showed that fluorescence-emitting mechanisms of these compounds were in two distinct manners (excited-state intramolecular proton transfer (ESIPT) and twisted intramolecular charge transfer (TICT)), which agreed with the well-known experiments. For ESIPT compounds with inconspicuous charge transfer (CT) during electron transition, pure functionals without Hartree-Fock (HF) exchange energy, such as OLYP and BLYP, were suitable to calculate emitting energies. For TICT compounds with large CT during electron transition, hybrid functionals with about 37% HF exchange energy, such as mPW1B95 and MPW1K, performed well. On condition that the exchange-correlation (XC ) functionals were chosen properly according to the rules above, reliable emitting energies for salicylanilide derivatives and analogues could be obtained at the TDDFT/6-31G (d)//CIS/3-21G (d) level. The average accuracy reached about 0.2 eV. For the salicylanilides with both of proton transfer (PT) and CTreaction channels, only one channel occurred actually according to the principle of energy minimum. This actual reaction decided proper XC functionals, whereas the reaction that did not occur actually was trivial. Eight appendent compounds were calculated to prove that this successful scheme is expected to be suitable for other ESIPT and TICT compounds.
2008, 24(04): 561-564
doi: 10.1016/S1872-1508(08)60022-4
Abstract:
Nanostructured cobalt molybdate catalysts supported on mesoporous silica SBA-15 with different loadings were prepared by citric acid coordination-impregnation method and characterized by XRD, TEM, and BET techniques. The characterization results showed that high loading of well-dispersed crystalline CoMoO4 may be achieved using citric acid coordination-impregnation method and the mesoporous structure of the support remained intact. The catalytic activity of these catalysts in the oxidative dehydrogenation of propane was investigated. The catalysts of nanostructured cobalt molybdate supported on mesoporous silica SBA-15 showed better catalytic performance than the corresponding bulk composite oxide and nanostructured CoMoO4 supported on SBA-15 with loading of 13%(mass fraction, w) displayed propene yield of 16.8%at 823 K.
Nanostructured cobalt molybdate catalysts supported on mesoporous silica SBA-15 with different loadings were prepared by citric acid coordination-impregnation method and characterized by XRD, TEM, and BET techniques. The characterization results showed that high loading of well-dispersed crystalline CoMoO4 may be achieved using citric acid coordination-impregnation method and the mesoporous structure of the support remained intact. The catalytic activity of these catalysts in the oxidative dehydrogenation of propane was investigated. The catalysts of nanostructured cobalt molybdate supported on mesoporous silica SBA-15 showed better catalytic performance than the corresponding bulk composite oxide and nanostructured CoMoO4 supported on SBA-15 with loading of 13%(mass fraction, w) displayed propene yield of 16.8%at 823 K.
2008, 24(04): 565-570
doi: 10.1016/S1872-1508(08)60023-6
Abstract:
We have calculated the multiphoton absorption cross-sections for three expanded porphyrin derivatives using the sum-over-states-involved tensor approach in combination with the strongly correlated multireference determinant single- and double-configuration interaction method. The calculated results showed that the two- and three-photon energies corresponding to the first peak of the multiphoton absorption spectra showed a decrease (red-shifted) with the number of inserted thiophene groups, whereas the cross sections showed a remarkable increase, particularly for three-photon absorption cross-section. However, the larger twist of the molecular plane for the expanded molecule resulted in an obvious drop in the increasing trend for three-photon absorption cross-section.
We have calculated the multiphoton absorption cross-sections for three expanded porphyrin derivatives using the sum-over-states-involved tensor approach in combination with the strongly correlated multireference determinant single- and double-configuration interaction method. The calculated results showed that the two- and three-photon energies corresponding to the first peak of the multiphoton absorption spectra showed a decrease (red-shifted) with the number of inserted thiophene groups, whereas the cross sections showed a remarkable increase, particularly for three-photon absorption cross-section. However, the larger twist of the molecular plane for the expanded molecule resulted in an obvious drop in the increasing trend for three-photon absorption cross-section.
2008, 24(04): 571-575
doi: 10.1016/S1872-1508(08)60024-8
Abstract:
Quantumwell structure filmof 6H-SiC/3C-SiC/6H-SiC was fabricated on 6H-SiC(0001) with the substrate temperature of 1350 K by solid source molecular beam epitaxy (SSMBE) through the variation of Si flux rate. The crystal polytypes and luminescent properties of the film were characterized by reflection high energy electron diffraction (RHEED) and photoluminescence (PL), respectively. The results of RHEEDindicated that the filmwas 6H-SiC/3C-SiC/6H-SiC with the quantum well structure. The results of PL excited by He-Gd laser at room temperature showed that there were intense emissions in the range of 480-600 nm, which could not be observed from the substrate. The fitting peaks were consistent with the results calculated from the model of quantum well structure, which showed that such intense emissions were probably fromthe quantumwells with different widths.
Quantumwell structure filmof 6H-SiC/3C-SiC/6H-SiC was fabricated on 6H-SiC(0001) with the substrate temperature of 1350 K by solid source molecular beam epitaxy (SSMBE) through the variation of Si flux rate. The crystal polytypes and luminescent properties of the film were characterized by reflection high energy electron diffraction (RHEED) and photoluminescence (PL), respectively. The results of RHEEDindicated that the filmwas 6H-SiC/3C-SiC/6H-SiC with the quantum well structure. The results of PL excited by He-Gd laser at room temperature showed that there were intense emissions in the range of 480-600 nm, which could not be observed from the substrate. The fitting peaks were consistent with the results calculated from the model of quantum well structure, which showed that such intense emissions were probably fromthe quantumwells with different widths.
2008, 24(04): 576-580
doi: 10.1016/S1872-1508(08)60025-X
Abstract:
5-Aminotetrazole trinitrophloroglucinolate ((ATZ) TNPG) was prepared and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray diffraction analysis and it belonged to orthorhombic systemand Pbca space group with a=0.6624(2) nm, b=1.7933(4) nm, c=2.3117(5) nm, V=2.7458(9) nm3, Z=4, and Dc=1.849 g·cm-3. The molecular formula was confirmed to be (ATZ)TNPG·2H2O. 5-Aminotetrazole cation (ATZ+) and trinitrophloroglucinol anion (TNPG-) were linked into 2-Dlayers along b-axis and c-axis by hydrogen bonds. Then the layers were linked along a-axis by hydrogen bonds between the water molecules belonging to different layers. The thermal decomposition mechanism of the compound was studied by differential scanning calorimetry (DSC), thermogravimetry-thermogravimetric analysis (TG-DTG), and Fourier transform-infrared (FT-IR) spectroscopy techniques. Under nitrogen atmosphere with a heating rate of 10 ℃·min-1, the compound experienced one endothermic process with peak temperature of 76 ℃ and one exothermal process with peak temperature of 203 ℃. The former was confirmed to be a dehydrate process. The latter was the decomposition of TNPG- and ATZ+ in the compound. The exothermic enthalpy change of this process was -212.10 kJ·mol-1. The kinetic parameter calculation from Kissinger’s method were, E=132.1 kJ·mol-1, ln (A/s-1)=12.54 with r=0.9990, and the calculation results from Ozawa-Doyle’s method were, E=133.1 kJ·mol-1 with r=0.9992.
5-Aminotetrazole trinitrophloroglucinolate ((ATZ) TNPG) was prepared and characterized by elemental analysis and FT-IR spectroscopy. The crystal structure was determined by X-ray diffraction analysis and it belonged to orthorhombic systemand Pbca space group with a=0.6624(2) nm, b=1.7933(4) nm, c=2.3117(5) nm, V=2.7458(9) nm3, Z=4, and Dc=1.849 g·cm-3. The molecular formula was confirmed to be (ATZ)TNPG·2H2O. 5-Aminotetrazole cation (ATZ+) and trinitrophloroglucinol anion (TNPG-) were linked into 2-Dlayers along b-axis and c-axis by hydrogen bonds. Then the layers were linked along a-axis by hydrogen bonds between the water molecules belonging to different layers. The thermal decomposition mechanism of the compound was studied by differential scanning calorimetry (DSC), thermogravimetry-thermogravimetric analysis (TG-DTG), and Fourier transform-infrared (FT-IR) spectroscopy techniques. Under nitrogen atmosphere with a heating rate of 10 ℃·min-1, the compound experienced one endothermic process with peak temperature of 76 ℃ and one exothermal process with peak temperature of 203 ℃. The former was confirmed to be a dehydrate process. The latter was the decomposition of TNPG- and ATZ+ in the compound. The exothermic enthalpy change of this process was -212.10 kJ·mol-1. The kinetic parameter calculation from Kissinger’s method were, E=132.1 kJ·mol-1, ln (A/s-1)=12.54 with r=0.9990, and the calculation results from Ozawa-Doyle’s method were, E=133.1 kJ·mol-1 with r=0.9992.
2008, 24(04): 581-586
doi: 10.3866/PKU.WHXB20080407
Abstract:
Octanethiolate self-assembled monolayer-protected ld nanoparticles (C8AuNPs) were synthesized using a two-phase protocol. Au/γ-Al2O3 catalysts for low-temperature oxidation of CO were prepared by depositing C8AuNPs in hexane colloidal solution on γ-Al2O3 using“step-by-step soakage”method and by carrying out vacuum dryness and thermal treatment. For the as-prepared C8AuNPs/γ-Al2O3 catalysts, the majority of the ld nanoparticles deposited on the support was in a narrow size range of 2-3 nm. Even after 600 h of reaction, the ld particles were still in the size range of 2-4 nm. The vacuum dryness temperature affected significantly on the particle size, which increased with raising the vacuum dryness temperature. It was found from the evaluation results of catalytic performances that the 2.5%(mass fraction, w) Au/γ-Al2O3 completely converted CO to CO2 at -19 ℃ and maintained the catalytic activity at nearly 100% CO conversion for at least 900 h at 15 ℃, and the 4.0% (w) Au/γ-Al2O3 maintained the catalytic activity at nearly 100% conversion of CO for at least 2000 h in the presence of the reaction gas containing H2O at 15 ℃. Evidently, the catalyst had higher activity, od long-termstability and strong anti-moisture performance. The effect of possible factors on the catalytic activity of Au/γ-Al2O3 was studied based on the above results.
Octanethiolate self-assembled monolayer-protected ld nanoparticles (C8AuNPs) were synthesized using a two-phase protocol. Au/γ-Al2O3 catalysts for low-temperature oxidation of CO were prepared by depositing C8AuNPs in hexane colloidal solution on γ-Al2O3 using“step-by-step soakage”method and by carrying out vacuum dryness and thermal treatment. For the as-prepared C8AuNPs/γ-Al2O3 catalysts, the majority of the ld nanoparticles deposited on the support was in a narrow size range of 2-3 nm. Even after 600 h of reaction, the ld particles were still in the size range of 2-4 nm. The vacuum dryness temperature affected significantly on the particle size, which increased with raising the vacuum dryness temperature. It was found from the evaluation results of catalytic performances that the 2.5%(mass fraction, w) Au/γ-Al2O3 completely converted CO to CO2 at -19 ℃ and maintained the catalytic activity at nearly 100% CO conversion for at least 900 h at 15 ℃, and the 4.0% (w) Au/γ-Al2O3 maintained the catalytic activity at nearly 100% conversion of CO for at least 2000 h in the presence of the reaction gas containing H2O at 15 ℃. Evidently, the catalyst had higher activity, od long-termstability and strong anti-moisture performance. The effect of possible factors on the catalytic activity of Au/γ-Al2O3 was studied based on the above results.
2008, 24(04): 587-594
doi: 10.3866/PKU.WHXB20080408
Abstract:
The complex potential energy surface for the reaction of·OH radical with CH3CN, including 2 intermediate complexes, 9 transition states, was theoretically probed at the CBS-QB3 level. The geometries and relative energies for various stationary points were determined. Based on the calculated CBS-QB3 potential energy surface, the possible reaction mechanism of·OH+CH3CN was proposed. The calculated results demonstrated that the formation of P1 (·CH2CN+H2O) was the dominant reaction channel. The rate constant (k1, cm3·molecule-1·s-1) of P1 was calculated by TS theory. Over the temperature range 250-3000 K, we predicted that the expression of k1 was k1(250-3000 K)=2.06×10-20T3.045exp(-780.00/T). By comparing with the obtained experimental values it was shown that the values of k1 were in od agreement with the experimental results over the temperature range 250-320 K. The calculated results indicated the formation of P1 (CH3CN+·OH) only needed a barrier of 14.2 kJ·mol-1. While the products ·CH2CN+H2O retrograded to the reactants CH3CN+·OH, an energy barrier of 111.2 kJ·mol-1 was required. These results suggested that the backward direction for the pathway of formation product P1 would be difficult in the ground electronic state.
The complex potential energy surface for the reaction of·OH radical with CH3CN, including 2 intermediate complexes, 9 transition states, was theoretically probed at the CBS-QB3 level. The geometries and relative energies for various stationary points were determined. Based on the calculated CBS-QB3 potential energy surface, the possible reaction mechanism of·OH+CH3CN was proposed. The calculated results demonstrated that the formation of P1 (·CH2CN+H2O) was the dominant reaction channel. The rate constant (k1, cm3·molecule-1·s-1) of P1 was calculated by TS theory. Over the temperature range 250-3000 K, we predicted that the expression of k1 was k1(250-3000 K)=2.06×10-20T3.045exp(-780.00/T). By comparing with the obtained experimental values it was shown that the values of k1 were in od agreement with the experimental results over the temperature range 250-320 K. The calculated results indicated the formation of P1 (CH3CN+·OH) only needed a barrier of 14.2 kJ·mol-1. While the products ·CH2CN+H2O retrograded to the reactants CH3CN+·OH, an energy barrier of 111.2 kJ·mol-1 was required. These results suggested that the backward direction for the pathway of formation product P1 would be difficult in the ground electronic state.
2008, 24(04): 595-600
doi: 10.3866/PKU.WHXB20080409
Abstract:
In an attempt to probe the influence of gasmolecule on stability of methane hydrate, geometry optimizations (by B3LYP/6-31G(d,p)) have been performed on different dodecahedral (H2O)20, CH4(H2O)20 and tetrakaidecahedral (H2O)24, CH4(H2O)24 clusters. The result suggested that the CH4(H2O)20 and CH4(H2O)24 clusters were more stable than the (H2O)20 and (H2O)24 clusters by calculating interaction energy andMulliken electron density. It also showed that the CH4 molecule was more important to the stability of methane hydrate. The calculated values of symmetric C—H stretching frequencies of methane were the same as the experimental values in the references. The crystal stability influenced by cage occupancy of hydrate was also simulated by constant-pressure and constant-temperature (NPT) molecular dynamics (MD) method. The result showed that the crystal stability was improved corresponding to the increase of the cage occupancy.
In an attempt to probe the influence of gasmolecule on stability of methane hydrate, geometry optimizations (by B3LYP/6-31G(d,p)) have been performed on different dodecahedral (H2O)20, CH4(H2O)20 and tetrakaidecahedral (H2O)24, CH4(H2O)24 clusters. The result suggested that the CH4(H2O)20 and CH4(H2O)24 clusters were more stable than the (H2O)20 and (H2O)24 clusters by calculating interaction energy andMulliken electron density. It also showed that the CH4 molecule was more important to the stability of methane hydrate. The calculated values of symmetric C—H stretching frequencies of methane were the same as the experimental values in the references. The crystal stability influenced by cage occupancy of hydrate was also simulated by constant-pressure and constant-temperature (NPT) molecular dynamics (MD) method. The result showed that the crystal stability was improved corresponding to the increase of the cage occupancy.
2008, 24(04): 601-606
doi: 10.1016/S1872-1508(08)60026-1
Abstract:
A periodical interaction model of LDHs-Cl-yH2O has been proposed. The geometry optimization and energy of the layered double hydroxides (LDHs) were calculated using CASTEP/LDAmethod at the CA-PZ level. The distribution of H2O in the interlayer and the super-molecular interaction between host layer and guest anion have been investigated by analyzing the geometric parameters, charge population, energy, and density of state (DOS ). The results showed that there was a strong super-molecular interaction between the host layer and the guest anion Cl -. In the system of LDHs-Cl-yH2O, the interlayer distance increased gradually then tended to invariableness. And in the process of hydration of LDHs-Cl, hydrogen bonding was superior to electrostatic interaction, and layer-water type hydrogen bonding was a little stronger than anion-water type hydrogen bonding between H2O and the rest of the structure. When y was 1 or 2, Cl- and the plane of water molecule were parallel to the layer; while y was 3 or 4 , distribution of Cl- and water was random. Moreover, the LDHs-Cl-yH2O would change from ionic crystal to molecular crystal with the increase of number of water molecule. The hydration of LDHs-Cl would achieve a definite saturation state.
A periodical interaction model of LDHs-Cl-yH2O has been proposed. The geometry optimization and energy of the layered double hydroxides (LDHs) were calculated using CASTEP/LDAmethod at the CA-PZ level. The distribution of H2O in the interlayer and the super-molecular interaction between host layer and guest anion have been investigated by analyzing the geometric parameters, charge population, energy, and density of state (DOS ). The results showed that there was a strong super-molecular interaction between the host layer and the guest anion Cl -. In the system of LDHs-Cl-yH2O, the interlayer distance increased gradually then tended to invariableness. And in the process of hydration of LDHs-Cl, hydrogen bonding was superior to electrostatic interaction, and layer-water type hydrogen bonding was a little stronger than anion-water type hydrogen bonding between H2O and the rest of the structure. When y was 1 or 2, Cl- and the plane of water molecule were parallel to the layer; while y was 3 or 4 , distribution of Cl- and water was random. Moreover, the LDHs-Cl-yH2O would change from ionic crystal to molecular crystal with the increase of number of water molecule. The hydration of LDHs-Cl would achieve a definite saturation state.
2008, 24(04): 607-611
doi: 10.1016/S1872-1508(08)60027-3
Abstract:
Ni-doped anatase TiO2 nanobelts (NBs) with different Ni2+ contents were simply prepared by combining ion-exchange with hydrothermal treatment. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and magnetic measurement techniques. The results showed that Ni2+ cations doped into the TiO2 lattice and no metallic nickel clusters or nanoparticles could be found. The magnetic results demonstrated that the prepared Ni-doped TiO2 samples had complex magnetic mechanism including room-temperature ferromagnetic and paramagnetic behaviors, and with the increase of Ni2+ content, the magnetization also increased under the same applied field owing to uniform distribution of Ni2+ ions in TiO2 nanobelts.
Ni-doped anatase TiO2 nanobelts (NBs) with different Ni2+ contents were simply prepared by combining ion-exchange with hydrothermal treatment. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and magnetic measurement techniques. The results showed that Ni2+ cations doped into the TiO2 lattice and no metallic nickel clusters or nanoparticles could be found. The magnetic results demonstrated that the prepared Ni-doped TiO2 samples had complex magnetic mechanism including room-temperature ferromagnetic and paramagnetic behaviors, and with the increase of Ni2+ content, the magnetization also increased under the same applied field owing to uniform distribution of Ni2+ ions in TiO2 nanobelts.
2008, 24(04): 612-618
doi: 10.3866/PKU.WHXB20080412
Abstract:
Polypyrrole (PPy) films were synthesized by potentiolstatic method froma para-toluenesulfonic sodium (p-TSNa) solution on stainless steel. Cyclic voltammetry of PPy-modified electrodes in the wide potential range from -1.6 to 0.8 V was conducted in H2SO4, Na2SO4, and NaOH solutions, respectively. The results showed that cyclic voltammogramin H2SO4 solution was featured by H+ insertion during reduction process and H+ expulsion during oxidation process. A unique peak associated to H+ reduction was first discovered. In Na2SO4 and NaOH solutions, cyclic voltammograms are featured by Na+ insertion during reduction process and Na+ expulsion during oxidation process. The data of FT-IR absorption spectra demonstrated that NaOH treatment had made extensive structure degradation, but Na2SO4 and H2SO4 treatments had not made conjugated structure changes on PPy films.
Polypyrrole (PPy) films were synthesized by potentiolstatic method froma para-toluenesulfonic sodium (p-TSNa) solution on stainless steel. Cyclic voltammetry of PPy-modified electrodes in the wide potential range from -1.6 to 0.8 V was conducted in H2SO4, Na2SO4, and NaOH solutions, respectively. The results showed that cyclic voltammogramin H2SO4 solution was featured by H+ insertion during reduction process and H+ expulsion during oxidation process. A unique peak associated to H+ reduction was first discovered. In Na2SO4 and NaOH solutions, cyclic voltammograms are featured by Na+ insertion during reduction process and Na+ expulsion during oxidation process. The data of FT-IR absorption spectra demonstrated that NaOH treatment had made extensive structure degradation, but Na2SO4 and H2SO4 treatments had not made conjugated structure changes on PPy films.
2008, 24(04): 619-624
doi: 10.1016/S1872-1508(08)60028-5
Abstract:
The ion transfer reaction of 2-benzoylpyridine-thiosemicarbazone (HL), which has antimicrobial and antifungal properties and anticancer activity, has been studied to determine its lipophilicity by cyclic voltammetry at the water/1,2-dichloroethane (1,2-DCE) interface. The physicochemical parameters such as standard partition coefficient (lgPI) and the standard Gibbs energy of transfer (⊿G0,w→otr, I ) of the protonated formof the ligand were measured as a function of pH in aqueous phase. The protonated form of the ligand exhibited reversible or quasi-reversible voltammograms at the 1,2-DCEintherangeof pH1-5. The protonationconstants of the ligand, pKa1 andpKa2,were determinedspectrophotometrically and were found to be 12.14 and 3.24, respectively. The standard Gibbs energy of transfer (⊿G0, w→otr, N ) and the partition coefficient of neutral species (lgPN) were also determined by the shake-flask method. The standard Gibbs energy of transfer of this compound across the water/1,2-DCE interface was evaluated as the quantitative measure of its lipophilicity. The difference between lgPI and lgPN was related to the degree of charge delocalization and was used to evaluate qualitatively the lipophilicity of the ligand.
The ion transfer reaction of 2-benzoylpyridine-thiosemicarbazone (HL), which has antimicrobial and antifungal properties and anticancer activity, has been studied to determine its lipophilicity by cyclic voltammetry at the water/1,2-dichloroethane (1,2-DCE) interface. The physicochemical parameters such as standard partition coefficient (lgPI) and the standard Gibbs energy of transfer (⊿G0,w→otr, I ) of the protonated formof the ligand were measured as a function of pH in aqueous phase. The protonated form of the ligand exhibited reversible or quasi-reversible voltammograms at the 1,2-DCEintherangeof pH1-5. The protonationconstants of the ligand, pKa1 andpKa2,were determinedspectrophotometrically and were found to be 12.14 and 3.24, respectively. The standard Gibbs energy of transfer (⊿G0, w→otr, N ) and the partition coefficient of neutral species (lgPN) were also determined by the shake-flask method. The standard Gibbs energy of transfer of this compound across the water/1,2-DCE interface was evaluated as the quantitative measure of its lipophilicity. The difference between lgPI and lgPN was related to the degree of charge delocalization and was used to evaluate qualitatively the lipophilicity of the ligand.
2008, 24(04): 625-632
doi: 10.1016/S1872-1508(08)60029-7
Abstract:
Effects of TritonX-100 on the properties of hemoglobin (Hb) and on the controlled release of ribavirin were studied using the methods of UV-Vis spectrum, fluorescence spectrum, zeta potential, conductivity, high-performance liquid chromatographic (HPLC), and image morphology in Hb/ribavirin/H2Osystem. With the increase of concentration of Triton X-100 in the system, the intrinsic fluorescence intensity, synchronous fluorescence intensity, fluorescence polarization, zeta potential, and morphology of Hb all changed gradually, and the ribavirin located on the Hb surface was dissociated and released out. When the concentration of Triton X-100 was higher than 1×10-5 mol·L-1, the stronger interaction of Triton X-100 with Hb was predominant. Hb was unfolded and denaturized. A little Triton X-100 can protect Hb fromthe effects of ribavirin.
Effects of TritonX-100 on the properties of hemoglobin (Hb) and on the controlled release of ribavirin were studied using the methods of UV-Vis spectrum, fluorescence spectrum, zeta potential, conductivity, high-performance liquid chromatographic (HPLC), and image morphology in Hb/ribavirin/H2Osystem. With the increase of concentration of Triton X-100 in the system, the intrinsic fluorescence intensity, synchronous fluorescence intensity, fluorescence polarization, zeta potential, and morphology of Hb all changed gradually, and the ribavirin located on the Hb surface was dissociated and released out. When the concentration of Triton X-100 was higher than 1×10-5 mol·L-1, the stronger interaction of Triton X-100 with Hb was predominant. Hb was unfolded and denaturized. A little Triton X-100 can protect Hb fromthe effects of ribavirin.
2008, 24(04): 633-638
doi: 10.3866/PKU.WHXB20080415
Abstract:
N-doped TiO2 (anatase) with high visible light photocatalytic activity was prepared by treating nanotube titanic acid (NTA) in NH3 flowat different temperatures. The crystalline structure of N-doped TiO2 determined by XRD was anatase when the treating temperature was higher than 400 ℃, however, a newphase (TiN) emerged at 700 ℃. The UV-Vis diffuse reflectance spectra (DRS) display that N-doped TiO2 has a continuous absorption at λ=400 nm. The photocatalytic activity of the N-doped TiO2 was determined by the photocatalytic oxidation of propylene under visible light irradiation. The highest photocatalytic activity was obtained for the catalyst treated at 600 ℃ in NH3 flow, which was active even under λ=500 nm, its kinetic behavior was accordant with the first order reaction formula.
N-doped TiO2 (anatase) with high visible light photocatalytic activity was prepared by treating nanotube titanic acid (NTA) in NH3 flowat different temperatures. The crystalline structure of N-doped TiO2 determined by XRD was anatase when the treating temperature was higher than 400 ℃, however, a newphase (TiN) emerged at 700 ℃. The UV-Vis diffuse reflectance spectra (DRS) display that N-doped TiO2 has a continuous absorption at λ=400 nm. The photocatalytic activity of the N-doped TiO2 was determined by the photocatalytic oxidation of propylene under visible light irradiation. The highest photocatalytic activity was obtained for the catalyst treated at 600 ℃ in NH3 flow, which was active even under λ=500 nm, its kinetic behavior was accordant with the first order reaction formula.
2008, 24(04): 639-645
doi: 10.3866/PKU.WHXB20080416
Abstract:
B3LYP/aug-cc-pvDZ level of theory was applied to study the geometries, bond dissociation energies, and energetic material properties of s-triazine derivatives in which hydrogen atoms of s-triazine have been substituted by —CN, —NO2, —NH2, —N3, —N2H, —NHNH2, —N4H, and —N4H3 groups. Compared with the parent molecules unsubstituted, derivatives substituted by —CN and —NH2 groups result in higher bond dissociation energies, whereas the others lead to lower ones. The studies indicated that the higher formation heats of compounds substituent groups possess, the higher ones of derivatives. The normalized formation heats of these derivatives substituted by —CN, —N3, and —N4H are 71.9, 78.7, and 82.6 kJ, which are higher than that of triazido-s-triazine (70.2 kJ) reported. For derivatives substituted by —N4H, —N3, —N4H3, —N2H, and —CN groups, formation heats calculated lie in the range of 863.1 -1735.2 kJ·mol -1, but derivatives substituted by —N4H and —N4H3 show low dissociation energies and relatively low stability.
B3LYP/aug-cc-pvDZ level of theory was applied to study the geometries, bond dissociation energies, and energetic material properties of s-triazine derivatives in which hydrogen atoms of s-triazine have been substituted by —CN, —NO2, —NH2, —N3, —N2H, —NHNH2, —N4H, and —N4H3 groups. Compared with the parent molecules unsubstituted, derivatives substituted by —CN and —NH2 groups result in higher bond dissociation energies, whereas the others lead to lower ones. The studies indicated that the higher formation heats of compounds substituent groups possess, the higher ones of derivatives. The normalized formation heats of these derivatives substituted by —CN, —N3, and —N4H are 71.9, 78.7, and 82.6 kJ, which are higher than that of triazido-s-triazine (70.2 kJ) reported. For derivatives substituted by —N4H, —N3, —N4H3, —N2H, and —CN groups, formation heats calculated lie in the range of 863.1 -1735.2 kJ·mol -1, but derivatives substituted by —N4H and —N4H3 show low dissociation energies and relatively low stability.
2008, 24(04): 646-652
doi: 10.3866/PKU.WHXB20080417
Abstract:
A method of preparing poly(acrylamide-co-methacrylic acid)-tungsten-silver (P(AM-co-MAA)-W-Ag) composite microspheres with core-shell structures by a copolymer microgel template was described. P(AM-co-MAA)-W composite microspheres were fabricated by centrifugal deposition of tungsten powder on the surface of the polymer template. After absorbing a layer of poly(vinylpyrrolidone) (PVP) on the template of P(AM-co-MAA)-W microspheres and fully immersing them in the AgNO3 aqueous solution, P(AM-co-MAA)-W-Ag composite microspheres were prepared slowly by introducing ammonia gas in the reverse suspension system. It was demonstrated that varying the concentrations of PVP and AgNO3 could modulate the deposition amount of silver on the surface of microspheres. Furthermore, the elementary mechanism of the formation of silver was proposed. The PVP acts both as a stabilizing agent and a reducing agent for the deposition of metal Ag particles.
A method of preparing poly(acrylamide-co-methacrylic acid)-tungsten-silver (P(AM-co-MAA)-W-Ag) composite microspheres with core-shell structures by a copolymer microgel template was described. P(AM-co-MAA)-W composite microspheres were fabricated by centrifugal deposition of tungsten powder on the surface of the polymer template. After absorbing a layer of poly(vinylpyrrolidone) (PVP) on the template of P(AM-co-MAA)-W microspheres and fully immersing them in the AgNO3 aqueous solution, P(AM-co-MAA)-W-Ag composite microspheres were prepared slowly by introducing ammonia gas in the reverse suspension system. It was demonstrated that varying the concentrations of PVP and AgNO3 could modulate the deposition amount of silver on the surface of microspheres. Furthermore, the elementary mechanism of the formation of silver was proposed. The PVP acts both as a stabilizing agent and a reducing agent for the deposition of metal Ag particles.
2008, 24(04): 653-658
doi: 10.3866/PKU.WHXB20080418
Abstract:
The optimized structures and binding energies of a series of C6H5—H…X hydrogen-bonded complexes involving H2O, HCOH, NH3, CH2NH and HCN as proton acceptors were determined at B3LYP/6-311+G(3df, 2p) level. The calculated results showed that the binding energies of C6H5—H…X complexes were dependent on the nature of the proton-accepting groups. The contributions of π-bond, double-bond, triple-bond to the hydrogen bonds, and the
interaction energies between lone-pair electrons and the C—H antibond were discussed in detail by natural population analysis (NPA) and natural bond orbital analysis (NBO).
The optimized structures and binding energies of a series of C6H5—H…X hydrogen-bonded complexes involving H2O, HCOH, NH3, CH2NH and HCN as proton acceptors were determined at B3LYP/6-311+G(3df, 2p) level. The calculated results showed that the binding energies of C6H5—H…X complexes were dependent on the nature of the proton-accepting groups. The contributions of π-bond, double-bond, triple-bond to the hydrogen bonds, and the
interaction energies between lone-pair electrons and the C—H antibond were discussed in detail by natural population analysis (NPA) and natural bond orbital analysis (NBO).
2008, 24(04): 659-664
doi: 10.3866/PKU.WHXB20080419
Abstract:
The frequency response (FR) technique were applied to study adsorption mechanism of ethene on parent mordenite and the mordenite modified by CuO and Cs+. The FR spectra of ethene on parent mordenite and modified mordenite were recorded and analyzed at temperature of 252 and 273 K and in the pressure range of 26.6-3990 Pa. The results showed that adsorption of ethene was the rate controlling step and there were two parallel adsorption processes in ethene/parent mordenite system. Those two processes were attributed to adsorption process of ethene on proton acid sites (low frequency adsorption) and on sodium cation sites (high frequency adsorption), and the numbers of sites available for adsorption of ethene were 0.692 and 0.828 mmol·g-1, respectively. The number of adsorption sites in low frequency adsorption was increased by the introduction of CuO, which was located among the proton acid sites and covered the sodium cation sites in high frequency adsorption. Chemical adsorption was the main sorption process in mordenite channels modified by CuO. The number of adsorption sites in high frequency adsorption was increased by the introduction of Cs+, which counteracted proton acid sites in low frequency adsorption. Physical adsorption was the main sorption process in mordenite channels modified by Cs+. The effective mass fraction of CuO for modification was 5%. The ethene adsorption processes on zeolites can be studied in detail by combining the FR spectra, isotherms, and Langmuir model.
The frequency response (FR) technique were applied to study adsorption mechanism of ethene on parent mordenite and the mordenite modified by CuO and Cs+. The FR spectra of ethene on parent mordenite and modified mordenite were recorded and analyzed at temperature of 252 and 273 K and in the pressure range of 26.6-3990 Pa. The results showed that adsorption of ethene was the rate controlling step and there were two parallel adsorption processes in ethene/parent mordenite system. Those two processes were attributed to adsorption process of ethene on proton acid sites (low frequency adsorption) and on sodium cation sites (high frequency adsorption), and the numbers of sites available for adsorption of ethene were 0.692 and 0.828 mmol·g-1, respectively. The number of adsorption sites in low frequency adsorption was increased by the introduction of CuO, which was located among the proton acid sites and covered the sodium cation sites in high frequency adsorption. Chemical adsorption was the main sorption process in mordenite channels modified by CuO. The number of adsorption sites in high frequency adsorption was increased by the introduction of Cs+, which counteracted proton acid sites in low frequency adsorption. Physical adsorption was the main sorption process in mordenite channels modified by Cs+. The effective mass fraction of CuO for modification was 5%. The ethene adsorption processes on zeolites can be studied in detail by combining the FR spectra, isotherms, and Langmuir model.
2008, 24(04): 665-669
doi: 10.3866/PKU.WHXB20080420
Abstract:
The electrochemical behavior of aluminium in LiNO3-KNO3 molten salt electrolyte was studied by means of cyclic voltammetry and potentiostatic electrolysis. It was shown that the electrochemical reduction of Li+ at the aluminium electrode was followed by the diffusion of the nascent Li atom formed at the electrode surface into aluminiummatrix; and the β-phase and γ-phase Li-Al alloys were formed by alloying of Li atomwith Al; the electrode process was controlled by the diffusion of Li atom into Al matrix. The cyclic voltammetric experiments showed that both reductive peak current and oxidative peak current increased firstly with the increase of cycles, and then reached to a constant value after certain cycles. This indicated that the aluminium electrode had od electrochemical stability in the LiNO3-KNO3 molten salt electrolyte.
The electrochemical behavior of aluminium in LiNO3-KNO3 molten salt electrolyte was studied by means of cyclic voltammetry and potentiostatic electrolysis. It was shown that the electrochemical reduction of Li+ at the aluminium electrode was followed by the diffusion of the nascent Li atom formed at the electrode surface into aluminiummatrix; and the β-phase and γ-phase Li-Al alloys were formed by alloying of Li atomwith Al; the electrode process was controlled by the diffusion of Li atom into Al matrix. The cyclic voltammetric experiments showed that both reductive peak current and oxidative peak current increased firstly with the increase of cycles, and then reached to a constant value after certain cycles. This indicated that the aluminium electrode had od electrochemical stability in the LiNO3-KNO3 molten salt electrolyte.
2008, 24(04): 670-674
doi: 10.3866/PKU.WHXB20080421
Abstract:
The equilibrium geometries, vibrational frequencies, atomization energies, adiabatic electron separations, adiabatic detachment energies (EAD), and adiabatic ionization potentials of the low-lying electronic states for the NaP4 clusters and its ions were investigated employing the DFT method, and then compared with the photoelectron spectra. According to the computed results, the reasonable assignments for the photoelectron spectra of NaP-4 were suggested.
The equilibrium geometries, vibrational frequencies, atomization energies, adiabatic electron separations, adiabatic detachment energies (EAD), and adiabatic ionization potentials of the low-lying electronic states for the NaP4 clusters and its ions were investigated employing the DFT method, and then compared with the photoelectron spectra. According to the computed results, the reasonable assignments for the photoelectron spectra of NaP-4 were suggested.
2008, 24(04): 675-680
doi: 10.3866/PKU.WHXB20080422
Abstract:
The thermal behavior of maceral particles was investigated using the micro heating stage. The phenomena of devolatilization and semicoke contraction on pyrolysis of the particles were observed directly in the micro-picture taken online. The curve of the particle area which changed with increasing the temperature was obtained by means of image analysis on the micro-picture. The results of the above processes showed that three stages were involved in the process of semicoke contraction: slow contraction stage, transitional contraction stage, and rapid contraction stage. The values of the apparent activation energy, pre-exponential factor, and reaction rate constant might increase in the three stages as a result of different features shown by the chemical bond breakage types, its bond energy as well as the free radical pieces, and condensation reaction in each stage. In terms of semicoke contraction, the reaction rate constant of vitrinite was bigger than that of inertinite; the reaction rate constants of ShenDong coal and its macerals with lower metamorphic grade were bigger than those of PingShuo coal and its corresponding macerals, namely, the former had better semicoke contraction reactivity.
The thermal behavior of maceral particles was investigated using the micro heating stage. The phenomena of devolatilization and semicoke contraction on pyrolysis of the particles were observed directly in the micro-picture taken online. The curve of the particle area which changed with increasing the temperature was obtained by means of image analysis on the micro-picture. The results of the above processes showed that three stages were involved in the process of semicoke contraction: slow contraction stage, transitional contraction stage, and rapid contraction stage. The values of the apparent activation energy, pre-exponential factor, and reaction rate constant might increase in the three stages as a result of different features shown by the chemical bond breakage types, its bond energy as well as the free radical pieces, and condensation reaction in each stage. In terms of semicoke contraction, the reaction rate constant of vitrinite was bigger than that of inertinite; the reaction rate constants of ShenDong coal and its macerals with lower metamorphic grade were bigger than those of PingShuo coal and its corresponding macerals, namely, the former had better semicoke contraction reactivity.
2008, 24(04): 681-685
doi: 10.3866/PKU.WHXB20080423
Abstract:
Mesoporous SnO2 was synthesized using a cationic surfactant cetytrimethylammonium bromide (CTAB) as template and tin chloride (SnCl4·5H2O) as inorganic precursor. The product was examined with X-ray diffraction (XRD), N2-adsorption/desorption isotherms (BET), and transmission electron microscopy (TEM). Electrochemical properties of the mesoporous SnO2 were measured as anode of lithium-ion battery. The results showed that a certain amount of ammonium was critical for fabricating of ordered mesoporous structure. OH - ions served as structure director, helping Sn(ClxBry )2- unit to assemble into liquid crystal and form the ordered mesoporous structure. Electrochemical measurements showed od capacity retaining ability in 40 cycles. Large irreversible capacity loss can be attributed to trapping of Li+ ion in the pores.
Mesoporous SnO2 was synthesized using a cationic surfactant cetytrimethylammonium bromide (CTAB) as template and tin chloride (SnCl4·5H2O) as inorganic precursor. The product was examined with X-ray diffraction (XRD), N2-adsorption/desorption isotherms (BET), and transmission electron microscopy (TEM). Electrochemical properties of the mesoporous SnO2 were measured as anode of lithium-ion battery. The results showed that a certain amount of ammonium was critical for fabricating of ordered mesoporous structure. OH - ions served as structure director, helping Sn(ClxBry )2- unit to assemble into liquid crystal and form the ordered mesoporous structure. Electrochemical measurements showed od capacity retaining ability in 40 cycles. Large irreversible capacity loss can be attributed to trapping of Li+ ion in the pores.
2008, 24(04): 686-690
doi: 10.3866/PKU.WHXB20080424
Abstract:
The electronic structures, formation enthalpies, and reaction enthalpies of Li-Al-H system complex were investigated using plane-wave pseudo-potential method based on density functional theory. Calculated cell parameters were in agreement with experiment. The interaction between Al and H atoms was strong covalent bond and the interaction between Li andHatoms was strong ionic bond in both LiAlH4 and Li3AlH6. The calculated reaction enthalpies for reactions (1) LiAlH4→1/3Li3AlH6+2/3Al+H2, (2) 1/3Li3AlH6→LiH+1/3Al+1/2H2, and (3) LiH+Al→LiAl+1/2H2 were 14.3, 14.9, and 50.9 kJ·mol-1 at 298 K, respectively, which were in agreement with experiment results.
The electronic structures, formation enthalpies, and reaction enthalpies of Li-Al-H system complex were investigated using plane-wave pseudo-potential method based on density functional theory. Calculated cell parameters were in agreement with experiment. The interaction between Al and H atoms was strong covalent bond and the interaction between Li andHatoms was strong ionic bond in both LiAlH4 and Li3AlH6. The calculated reaction enthalpies for reactions (1) LiAlH4→1/3Li3AlH6+2/3Al+H2, (2) 1/3Li3AlH6→LiH+1/3Al+1/2H2, and (3) LiH+Al→LiAl+1/2H2 were 14.3, 14.9, and 50.9 kJ·mol-1 at 298 K, respectively, which were in agreement with experiment results.
2008, 24(04): 691-694
doi: 10.3866/PKU.WHXB20080425
Abstract:
The effect of cationic surfactant, dodecyltrimethyl ammonium bromide (DTAB), on oxygen reduction reaction was studied by rotating vitreous carbon disk electrode. The results showed that the catalytic activity of vitreous carbon electrode on oxygen reduction reaction could be improved significantly by DTAB. From the analyses on the relation between the current of oxygen reduction and rotating speed of the electrode and the Tafel relation between kinetic current and potential, it was found that DTAB promoted the transfer coefficient of charge transfer step for oxygen reduction reaction on vitreous carbon electrode, thus improved the kinetics of oxygen reduction reaction.
The effect of cationic surfactant, dodecyltrimethyl ammonium bromide (DTAB), on oxygen reduction reaction was studied by rotating vitreous carbon disk electrode. The results showed that the catalytic activity of vitreous carbon electrode on oxygen reduction reaction could be improved significantly by DTAB. From the analyses on the relation between the current of oxygen reduction and rotating speed of the electrode and the Tafel relation between kinetic current and potential, it was found that DTAB promoted the transfer coefficient of charge transfer step for oxygen reduction reaction on vitreous carbon electrode, thus improved the kinetics of oxygen reduction reaction.
2008, 24(04): 695-699
doi: 10.3866/PKU.WHXB20080426
Abstract:
Ba0.6Sr0.4TiO3:Re (BST:Re) thin films were synthesized by ion beam sputtering deposition. M (100) and Si(100) substrates were used for different measure requirements. The as-deposited multilayer films were transformed into polycrystalline films after two-step anealling-diffusion at lower temperature and crystallization at higher temperature. The dielectric constants of BST:Re/M (Re=Er, Eu, Pr/Al) samples were determined by a scanning tip microwave near-field microscopy. The results indicated that the dopings of appropriate amount of rare earth ions improved the dielectric constants, where the optimal doping concentratrations of Er3+ and Eu3+ ions were around 4.5% and 5.7%(atom fraction), respectively. The samples co-doped with Pr3+ and Al3+ t an optimum performance under 4-8 of Al/Pr molar ratio. We also investigated the photoluminescence properties of BST:Re/Si (Re=Er, Eu) samples. The luminescent quenching concentrations of Er3+ and Eu3+ ions doped in BST thin films were 4.20% and 8.95% (atom fraction), respectively.
Ba0.6Sr0.4TiO3:Re (BST:Re) thin films were synthesized by ion beam sputtering deposition. M (100) and Si(100) substrates were used for different measure requirements. The as-deposited multilayer films were transformed into polycrystalline films after two-step anealling-diffusion at lower temperature and crystallization at higher temperature. The dielectric constants of BST:Re/M (Re=Er, Eu, Pr/Al) samples were determined by a scanning tip microwave near-field microscopy. The results indicated that the dopings of appropriate amount of rare earth ions improved the dielectric constants, where the optimal doping concentratrations of Er3+ and Eu3+ ions were around 4.5% and 5.7%(atom fraction), respectively. The samples co-doped with Pr3+ and Al3+ t an optimum performance under 4-8 of Al/Pr molar ratio. We also investigated the photoluminescence properties of BST:Re/Si (Re=Er, Eu) samples. The luminescent quenching concentrations of Er3+ and Eu3+ ions doped in BST thin films were 4.20% and 8.95% (atom fraction), respectively.
2008, 24(04): 700-704
doi: 10.3866/PKU.WHXB20080427
Abstract:
Based on 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H--pyran (DCJTB) acting as dopant and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) acting as hole-blocking layer, the EL spectra of two kinds of organic light-emitting diodes (OLEDs) ITO/NPB/BCP/Alq3:DCJTB/Alq3/Al (structure A) and ITO/NPB/BCP/Alq3/Alq3:DCJTB/Alq3/Al (structure B) were investigated. Our experimental data showed that the relative emission intensity of green light was low in the EL spectra of devices with structure A, and it was hard to enhance the relative emission intensity of green light by only increasing the thickness of Alq3 layer. On the other hand, the thin layer of Alq3 inserted between BCP layer and dopant layer (Alq3:DCJTB) had a tremendous impact on the relative emission intensity of green light for devices with structure B, and a strong green light emission could be obtained by inserting an ultrathin layer of Alq3. Further, by optimizing the device structure, a stable white OLED ITO/NPB(50 nm)/BCP(3 nm)/Alq3(3 nm)/Alq3:DCJTB(1%(w))(5 nm)/Alq3(7 nm)/Al was obtained with ultrathin organic layers of BCP, Alq3 and Alq3:DCJTB. The CIE of the device almost kept at (0.33, 0.37) with increasing the applied voltages (14-18 V), and its luminance reached 11521 cd·m-2 at the current density of 432 mA·cm-2.
Based on 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H--pyran (DCJTB) acting as dopant and 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) acting as hole-blocking layer, the EL spectra of two kinds of organic light-emitting diodes (OLEDs) ITO/NPB/BCP/Alq3:DCJTB/Alq3/Al (structure A) and ITO/NPB/BCP/Alq3/Alq3:DCJTB/Alq3/Al (structure B) were investigated. Our experimental data showed that the relative emission intensity of green light was low in the EL spectra of devices with structure A, and it was hard to enhance the relative emission intensity of green light by only increasing the thickness of Alq3 layer. On the other hand, the thin layer of Alq3 inserted between BCP layer and dopant layer (Alq3:DCJTB) had a tremendous impact on the relative emission intensity of green light for devices with structure B, and a strong green light emission could be obtained by inserting an ultrathin layer of Alq3. Further, by optimizing the device structure, a stable white OLED ITO/NPB(50 nm)/BCP(3 nm)/Alq3(3 nm)/Alq3:DCJTB(1%(w))(5 nm)/Alq3(7 nm)/Al was obtained with ultrathin organic layers of BCP, Alq3 and Alq3:DCJTB. The CIE of the device almost kept at (0.33, 0.37) with increasing the applied voltages (14-18 V), and its luminance reached 11521 cd·m-2 at the current density of 432 mA·cm-2.
2008, 24(04): 705-708
doi: 10.3866/PKU.WHXB20080428
Abstract:
Henry’s lawconstants (HLC) of volatile aromatic compounds were determined using a dynamics approach by coupling a stripping cell directly to a homemade proton transfer reaction mass spectrometry (PTR-MS). The intensity of C6H6H+ ion dependence on liquid height of benzene solution was explored in order to ensure the equilibrium of aromatic compound components between the gas-bubbles and water. The HLC of benzene measured at 25 ℃ is in agreement with the reported value in literature, showing that this method is valid. HLC values were presented for benzene, toluene, ethylbenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dimethylbenzene, 1,3-dimethylbenzene, 1,4-dimethylbenzene, and 1,2,4-trimethylbenzene. Compared to the conventional techniques, the dynamics extraction combination with PTR-MS is simple, fast, and less prone to artifacts in the HLC measurement.
Henry’s lawconstants (HLC) of volatile aromatic compounds were determined using a dynamics approach by coupling a stripping cell directly to a homemade proton transfer reaction mass spectrometry (PTR-MS). The intensity of C6H6H+ ion dependence on liquid height of benzene solution was explored in order to ensure the equilibrium of aromatic compound components between the gas-bubbles and water. The HLC of benzene measured at 25 ℃ is in agreement with the reported value in literature, showing that this method is valid. HLC values were presented for benzene, toluene, ethylbenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2-dimethylbenzene, 1,3-dimethylbenzene, 1,4-dimethylbenzene, and 1,2,4-trimethylbenzene. Compared to the conventional techniques, the dynamics extraction combination with PTR-MS is simple, fast, and less prone to artifacts in the HLC measurement.
2008, 24(04): 709-714
doi: 10.3866/PKU.WHXB20080429
Abstract:
With p-N,N-dimethylaminobenzonitrile (DMABN) as probe, the variations of the intensity of its second fluorescence emission (Ia) and the corresponding characteristic wave-length (λa) with the surfactant (dodecyltrimethyl-ammonium bromide C12TABr, quaternary ammonium Gemini surfactant C12-3-C12·2Br and sodium dodecylsulfate SDS) concentration (c) in NaBr-containing or n-C4H9OH-containing aqueous solution were measured by a Hitachi F4500 fluorescence spectrophotometer. The results showed that the break point on the Ia-c curve and the minimum of the derivative variation corresponding to the λa-c curve agreed well with the critical micelle concentration (cmc) of the surfactant. This extends the range of DMABN as probe to measure the cmc of surfactant.
With p-N,N-dimethylaminobenzonitrile (DMABN) as probe, the variations of the intensity of its second fluorescence emission (Ia) and the corresponding characteristic wave-length (λa) with the surfactant (dodecyltrimethyl-ammonium bromide C12TABr, quaternary ammonium Gemini surfactant C12-3-C12·2Br and sodium dodecylsulfate SDS) concentration (c) in NaBr-containing or n-C4H9OH-containing aqueous solution were measured by a Hitachi F4500 fluorescence spectrophotometer. The results showed that the break point on the Ia-c curve and the minimum of the derivative variation corresponding to the λa-c curve agreed well with the critical micelle concentration (cmc) of the surfactant. This extends the range of DMABN as probe to measure the cmc of surfactant.
2008, 24(04): 715-719
doi: 10.3866/PKU.WHXB20080430
Abstract:
The interaction between malachite green (MG) and bovine serum albumin (BSA) was investigated via fluorescence and ultraviolet-visible absorption spectra in buffer solutions at different temperatures. The experimental results showed that static quenching was involved in addingMGin BSAsolution. The binding constants (KA) were 7.69×104 L·mol-1 (10 ℃), 5.31×104 L·mol-1 (20 ℃), and 4.85×104 L·mol-1 (37 ℃), respectively, and they reacted at a molar ratio of 1:1. The energy transfer efficiency E was 0.1635 and the binding distance r was 2.30 nm between MG and BSA according to Forster non-radiative energy transfer mechanism. The interaction between MG and BSA was driven mainly by hydrogen bonds and Vander Waals force according to thermodynamic parameters.
The interaction between malachite green (MG) and bovine serum albumin (BSA) was investigated via fluorescence and ultraviolet-visible absorption spectra in buffer solutions at different temperatures. The experimental results showed that static quenching was involved in addingMGin BSAsolution. The binding constants (KA) were 7.69×104 L·mol-1 (10 ℃), 5.31×104 L·mol-1 (20 ℃), and 4.85×104 L·mol-1 (37 ℃), respectively, and they reacted at a molar ratio of 1:1. The energy transfer efficiency E was 0.1635 and the binding distance r was 2.30 nm between MG and BSA according to Forster non-radiative energy transfer mechanism. The interaction between MG and BSA was driven mainly by hydrogen bonds and Vander Waals force according to thermodynamic parameters.
2008, 24(04): 720-724
doi: 10.3866/PKU.WHXB20080431
Abstract:
The insertion reactions of the germylenoid H2C=GeLiCl with RH(R=F, OH, NH2) were studied using the DFT B3LYP and QCISD methods. The geometries of the stationary points on the potential energy surfaces of the reactions were optimized at the B3LYP/6-311+G(d,p) level. The calculated results indicated that the mechanisms of the insertion reactions of H2C=GeLiCl with HF, H2O, and NH3 were identical to each other. The QCISD/6-311++ G(d,p)//B3LYP/6-311+G(d,p) calculated potential energy barriers of the three reactions were 173.53, 194.48, and 209.05 kJ·mol-1, and the reaction energies for the three reactions were 60.18, 72.93, and 75.34 kJ·mol-1, respectively. Under the same situation, the insertion reactions should occur easily in the following order: H—F>H—OH>H—NH2.
The insertion reactions of the germylenoid H2C=GeLiCl with RH(R=F, OH, NH2) were studied using the DFT B3LYP and QCISD methods. The geometries of the stationary points on the potential energy surfaces of the reactions were optimized at the B3LYP/6-311+G(d,p) level. The calculated results indicated that the mechanisms of the insertion reactions of H2C=GeLiCl with HF, H2O, and NH3 were identical to each other. The QCISD/6-311++ G(d,p)//B3LYP/6-311+G(d,p) calculated potential energy barriers of the three reactions were 173.53, 194.48, and 209.05 kJ·mol-1, and the reaction energies for the three reactions were 60.18, 72.93, and 75.34 kJ·mol-1, respectively. Under the same situation, the insertion reactions should occur easily in the following order: H—F>H—OH>H—NH2.
2008, 24(04): 725-728
doi: 10.3866/PKU.WHXB20080432
Abstract:
Water-soluble CdTe quantum dots (GdTe-Qs) were prepared using mercaptocarboxylic acid as stabilizer, and effects of pH and amino acids on fluorescence of CdTe-QDs were investigated. The results revealed that the fluorescence of the CdTe-QDs varied with the change of pH, and the alanine and serine could quench the fluorescence while cysteine enhanced the fluorescence.
Water-soluble CdTe quantum dots (GdTe-Qs) were prepared using mercaptocarboxylic acid as stabilizer, and effects of pH and amino acids on fluorescence of CdTe-QDs were investigated. The results revealed that the fluorescence of the CdTe-QDs varied with the change of pH, and the alanine and serine could quench the fluorescence while cysteine enhanced the fluorescence.
2008, 24(04): 729-736
doi: 10.3866/PKU.WHXB20080433
Abstract:
The diversity of thermal decomposition behavior of host in a host-guest supermolecule was described in detail. The concept of a survived host was given. A survived host means the product of a host-guest supermolecule losing its guest after heated. It served as a powerful evidence for the weak intermolecular interaction between host and guest in inclusion phenomenon. Focused on survived cyclodextrin (survived CD), the present work carefully compared the differences of thermal decomposition behavior among free CD, complexed CD, and survived CD, an dpointed out an important conceptual error which had occurred in some papers due to a lack of appreciation of the relationship between survived CD and complexed CD.
The diversity of thermal decomposition behavior of host in a host-guest supermolecule was described in detail. The concept of a survived host was given. A survived host means the product of a host-guest supermolecule losing its guest after heated. It served as a powerful evidence for the weak intermolecular interaction between host and guest in inclusion phenomenon. Focused on survived cyclodextrin (survived CD), the present work carefully compared the differences of thermal decomposition behavior among free CD, complexed CD, and survived CD, an dpointed out an important conceptual error which had occurred in some papers due to a lack of appreciation of the relationship between survived CD and complexed CD.
