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2002 Volume 18 Issue 5
2002, 18(05): 385-388
doi: 10.3866/PKU.WHXB20020501
Abstract:
The back-propagation network based predication of brain-blood concentration ratio (BB) using 27 structurally derived descriptors was investigated. A typical biased two-layer network,including a sigmoid layer and a linear output layer, suited for arbitrary function approximation was chosen for the predication. The results show that fine-tuned back-propagation network models are very efficient for predication use.
The back-propagation network based predication of brain-blood concentration ratio (BB) using 27 structurally derived descriptors was investigated. A typical biased two-layer network,including a sigmoid layer and a linear output layer, suited for arbitrary function approximation was chosen for the predication. The results show that fine-tuned back-propagation network models are very efficient for predication use.
2002, 18(05): 389-393
doi: 10.3866/PKU.WHXB20020502
Abstract:
Two novel thenoyl Schiff base compounds(A and C) have been prepared from the reactions of thenoyltrifluoroacetone with 4aminoantipyrine. The three Schiff base compounds(A, B and C), which might be prepared from the reactions, are studied using the molecular mechanism and molecular dynamic calculation methods. The results of the molecular mechanism calculation show that the compounds A, B and C are novel tridentate Schiff base ligands. The result of the quantum chemistry calculation for the thenoyltrifluoroacetone (TTA) indicates that the two products(A and C) from the Schiff reactions are normal.
Two novel thenoyl Schiff base compounds(A and C) have been prepared from the reactions of thenoyltrifluoroacetone with 4aminoantipyrine. The three Schiff base compounds(A, B and C), which might be prepared from the reactions, are studied using the molecular mechanism and molecular dynamic calculation methods. The results of the molecular mechanism calculation show that the compounds A, B and C are novel tridentate Schiff base ligands. The result of the quantum chemistry calculation for the thenoyltrifluoroacetone (TTA) indicates that the two products(A and C) from the Schiff reactions are normal.
2002, 18(05): 394-398
doi: 10.3866/PKU.WHXB20020503
Abstract:
The structure,function and development of traditional Chinese medicine drugs information system based on networks was introduced.The approach and steps of building information system,as well as the application and expectation of this system were described in detail.This system is based on five large databases,including Chinese herb database,effective components database of Chinese herb,Chinese medical recipe database,Chinese patent medicine database and Chinese medical dietotherapy prescription database.The traditional Chinese medicine drugs information system based on networks,combined with other techniques of drug design,have become an important tool for the discovery of leading compound based on traditional Chinese drugs.
The structure,function and development of traditional Chinese medicine drugs information system based on networks was introduced.The approach and steps of building information system,as well as the application and expectation of this system were described in detail.This system is based on five large databases,including Chinese herb database,effective components database of Chinese herb,Chinese medical recipe database,Chinese patent medicine database and Chinese medical dietotherapy prescription database.The traditional Chinese medicine drugs information system based on networks,combined with other techniques of drug design,have become an important tool for the discovery of leading compound based on traditional Chinese drugs.
2002, 18(05): 399-413
doi: 10.3866/PKU.WHXB20020504
Abstract:
A series of Y3+ and Eu3+ complexes have been synthesized by taking benzoic acid,onitrobenzoic acid,mnitrobenzoic acid,pnitrobenzoic acid and 3,5dinitrobenzoic acid as ligands.Based upon the properties of the explosive decomposition of the complexes,a number of Y2O3:Eu nanocrystals have been prepared by solid state thermodecomposition.TEM,Xray diffraction analyses show that the Y2O3:Eu nanocrystallites have spherical structure,and the average size of the crystals is within 40～60 nm.Introduction of Eu3+ has little effect upon the crystal structure of the oxides.Furthermore,change in the structure of the ligands of the complexes does not affect the morphology and sizes of the final products significantly.Compared with the products from the nitro substituted benzoic acid complexes,however,the Y2O3:Eu nanocrystals obtained from benzoic acid complex aggregated severely.It is to be noted that annealing temperature has an obvious effect upon the sizes of the final products.The higher the temperature is,the larger the nanocrystals will be.Fluorescence measurements demonstrated clearly that all the Y2O3:Eu nanocrystallites luminescence similarly.But,the luminescent property of the one prepared by benzoic acid complex is the superior one.
2002, 18(05): 404-408
doi: 10.3866/PKU.WHXB20020505
Abstract:
It is found that Ply adsorbed roughed silver electrode,it is easy to immobilize MP11 with the electrostatic interaction and to prepare the MP11/Ply/Ag modified electrode.The preparation method of the modified electrode is simple.In addition,the modified electrode obtained shows the high and stable electrocatalytic activity for O2 reduction.It is also found that when the sixth coordination of heme in MP11 is replaced with other coordination species with stronger coordination ability,such as imidazole,its formal redox potential shifts to the negative direction and the electrocatalytic activity for O2 reduction is reduced.
It is found that Ply adsorbed roughed silver electrode,it is easy to immobilize MP11 with the electrostatic interaction and to prepare the MP11/Ply/Ag modified electrode.The preparation method of the modified electrode is simple.In addition,the modified electrode obtained shows the high and stable electrocatalytic activity for O2 reduction.It is also found that when the sixth coordination of heme in MP11 is replaced with other coordination species with stronger coordination ability,such as imidazole,its formal redox potential shifts to the negative direction and the electrocatalytic activity for O2 reduction is reduced.
2002, 18(05): 409-413
doi: 10.3866/PKU.WHXB20020506
Abstract:
An efficient method for purification of singlewalled carbon nanotubes (SWNTs) synthesized by chemical vapor deposition (CVD) has been developed.Sample purity is characterized with SEM,TEM,Raman,and TGA.The results indicate that the support and catalyst are easily removed by an acid treatment and the amorphous carbon can be separated from the SWNTS by dispersion in surfactant solution using ultrasonic agitation,and extracted completely by using reflux of the SWNTs in dilute nitric acid or oxidation of the SWNTs in the air.
An efficient method for purification of singlewalled carbon nanotubes (SWNTs) synthesized by chemical vapor deposition (CVD) has been developed.Sample purity is characterized with SEM,TEM,Raman,and TGA.The results indicate that the support and catalyst are easily removed by an acid treatment and the amorphous carbon can be separated from the SWNTS by dispersion in surfactant solution using ultrasonic agitation,and extracted completely by using reflux of the SWNTs in dilute nitric acid or oxidation of the SWNTs in the air.
2002, 18(05): 414-419
doi: 10.3866/PKU.WHXB20020507
Abstract:
The mediumrange structure order(MRSO) of liquid Al80Fe20 alloy and the evolution of microstructure of the system during the rapid cooling are analyzed by MD simulation. It is found that there exists a prepeak in the smallQ domain of structure factor for all of them, which is considered to be indicative of MRSO in the system. In the equilibrium state(1450 K), the results of simulation are further proofed by that of Xray diffraction experiment. With temperature decreasing, the height of prepeak is increasing gradually, which shows that the size of atomic clusters is getting bigger. By means of pair analysis technique and bond orientational order, we find that there exist a number of icosahedral shortrange units in the system. The minus chemical shortrange order(CSRO) parameter α indicates that there is much stronger CSRO in the liquid system. The second peak of SAlFe(Q)splits much more sharply than those of SAlAl(Q) and SFeFe(Q) at 400 K in FZ partial structure factor, which indicates that the orbit hybridization between Al and Fe atoms plays a more important pole than Al and Fe atoms solely in the ability of forming amorphous. In BT partial structure factor, there is a first peak at 17.5 nm－1 in SCC(Q), indicative of CSRO. And this position is just where a prepeak appearing in the total structure factor. So we think that it is the CSRO that result in the MRSO in the system.
The mediumrange structure order(MRSO) of liquid Al80Fe20 alloy and the evolution of microstructure of the system during the rapid cooling are analyzed by MD simulation. It is found that there exists a prepeak in the smallQ domain of structure factor for all of them, which is considered to be indicative of MRSO in the system. In the equilibrium state(1450 K), the results of simulation are further proofed by that of Xray diffraction experiment. With temperature decreasing, the height of prepeak is increasing gradually, which shows that the size of atomic clusters is getting bigger. By means of pair analysis technique and bond orientational order, we find that there exist a number of icosahedral shortrange units in the system. The minus chemical shortrange order(CSRO) parameter α indicates that there is much stronger CSRO in the liquid system. The second peak of SAlFe(Q)splits much more sharply than those of SAlAl(Q) and SFeFe(Q) at 400 K in FZ partial structure factor, which indicates that the orbit hybridization between Al and Fe atoms plays a more important pole than Al and Fe atoms solely in the ability of forming amorphous. In BT partial structure factor, there is a first peak at 17.5 nm－1 in SCC(Q), indicative of CSRO. And this position is just where a prepeak appearing in the total structure factor. So we think that it is the CSRO that result in the MRSO in the system.
2002, 18(05): 420-425
doi: 10.3866/PKU.WHXB20020508
Abstract:
The geometrical conformation of taxol has been optimized by MM3,PM3 and HF/STO3G method,respectively.An ab initio GIAO method at HF/631G level has been used to predict theoretically 1HNMR and 13CNMR chemical shifts for the conformations by three geometry optimization methods.The results show that the calculated δ 1HNMR and δ 13CNMR for the geometrical conformation optimized by HF/STO3G are the most accurate in comparison with experimentally observed data.It is inferred that,therefore,the geometrical conformation optimized by HF/STO3G must probably be approximate to the real one of taxol in d6DMSOD2O70％. From the geometrical conformation of taxol optimized by HF/STO3G,the distances between 4OAc and 3′H,4OAc and 3′Ph,4OAc and 2OCOPh are found to be 0.266 3 nm,0.310 4 nm and 0.370 7 nm,respectively.These distances are within the effective acting distances producing nuclear overhauser effect (NOE),which theoretically supports Williams′ view that there is a NOE effect in taxol molecule,and Velde′s view that there is a hydrophobic cluster formed by 4OAc,3′Ph and 2OCOPh in taxol molecule.
The geometrical conformation of taxol has been optimized by MM3,PM3 and HF/STO3G method,respectively.An ab initio GIAO method at HF/631G level has been used to predict theoretically 1HNMR and 13CNMR chemical shifts for the conformations by three geometry optimization methods.The results show that the calculated δ 1HNMR and δ 13CNMR for the geometrical conformation optimized by HF/STO3G are the most accurate in comparison with experimentally observed data.It is inferred that,therefore,the geometrical conformation optimized by HF/STO3G must probably be approximate to the real one of taxol in d6DMSOD2O70％. From the geometrical conformation of taxol optimized by HF/STO3G,the distances between 4OAc and 3′H,4OAc and 3′Ph,4OAc and 2OCOPh are found to be 0.266 3 nm,0.310 4 nm and 0.370 7 nm,respectively.These distances are within the effective acting distances producing nuclear overhauser effect (NOE),which theoretically supports Williams′ view that there is a NOE effect in taxol molecule,and Velde′s view that there is a hydrophobic cluster formed by 4OAc,3′Ph and 2OCOPh in taxol molecule.
2002, 18(05): 426-431
doi: 10.3866/PKU.WHXB20020509
Abstract:
Catalytic generation of hydrogen by partial oxidation of ethanol over a series of NiFe catalysts has been studied.The catalytic performances have been investigated over various O2/C2H5OH molar ratio at 473～573 K.These NiFe catalysts showed high performances for the partial oxidation of ethanol to hydrogen and Ni50Fe50 catalyst had the best activity when reaction temperature was between 548K and 573 K.The optimum reaction conditions for Ni50Fe50 catalyst are O2/C2H5OH =1.0、T=573 K.The fresh and used catalysts were characterized by XRD and XPS.The XRD patterns showed the main components of the active catalysts are the spinaltype structure of magnetite and FeNi3 alloy(see Fig.4).The decrease in the selectivity for hydrogen of the catalyst may be resulted from the conversion of FeNi3 alloy phase in the catalyst during long term reaction(see Fig.5).XPS results confirmed that the phase of the bulk catalyst is mainly FeNi3 alloy and that of the surface catalyst is mainly magnetite (see Fig 6).
Catalytic generation of hydrogen by partial oxidation of ethanol over a series of NiFe catalysts has been studied.The catalytic performances have been investigated over various O2/C2H5OH molar ratio at 473～573 K.These NiFe catalysts showed high performances for the partial oxidation of ethanol to hydrogen and Ni50Fe50 catalyst had the best activity when reaction temperature was between 548K and 573 K.The optimum reaction conditions for Ni50Fe50 catalyst are O2/C2H5OH =1.0、T=573 K.The fresh and used catalysts were characterized by XRD and XPS.The XRD patterns showed the main components of the active catalysts are the spinaltype structure of magnetite and FeNi3 alloy(see Fig.4).The decrease in the selectivity for hydrogen of the catalyst may be resulted from the conversion of FeNi3 alloy phase in the catalyst during long term reaction(see Fig.5).XPS results confirmed that the phase of the bulk catalyst is mainly FeNi3 alloy and that of the surface catalyst is mainly magnetite (see Fig 6).
2002, 18(05): 432-436
doi: 10.3866/PKU.WHXB20020510
Abstract:
The catalytic reduction desulfuration on cobalt oxide was investigated using UBIQEP method.It was found that the reaction followed the Redox mechanism in the reduction process of SO2 with CO at low temperature.First,the carbon monoxide reacted with lattice oxygen and produced oxygen vacancy on the surface.Then,the SO2 was reduced on the vacancy of oxygen anion.At high temperature,however,there was intermediate COS.Therefore,the reaction followed both the Redox mechanism and the COS intermediate mechanism.The intermediate product,SO,is much unstable which can be reduced by CO rapidly and can be oxidized by surface oxygen species.The COS can inhibit the surface oxygen species that can influence the reaction.
The catalytic reduction desulfuration on cobalt oxide was investigated using UBIQEP method.It was found that the reaction followed the Redox mechanism in the reduction process of SO2 with CO at low temperature.First,the carbon monoxide reacted with lattice oxygen and produced oxygen vacancy on the surface.Then,the SO2 was reduced on the vacancy of oxygen anion.At high temperature,however,there was intermediate COS.Therefore,the reaction followed both the Redox mechanism and the COS intermediate mechanism.The intermediate product,SO,is much unstable which can be reduced by CO rapidly and can be oxidized by surface oxygen species.The COS can inhibit the surface oxygen species that can influence the reaction.
2002, 18(05): 437-440
doi: 10.3866/PKU.WHXB20020511
Abstract:
The adsorption of hexene（C6H12）on Ru() surface has been studied by the polarized angleresolved ultraviolet photoemission spectroscope (ARUPS) and Xray photoemission spectroscope (XPS). The results show that the hexene absorbs in a molecular state on the Ru() surface below 200 K,the molecular orbits of πCC,σCC and πCH were found at 7.5,9.4 and 11.1 eV respectively.The results of the polarized ARUPS show that the σCC orbit is symmetry about a mirror plane along <> azimuth but the πCC orbit is antisymmetry about a mirror plane.The results suggest that the hexene molecule lies in a plane along <> azimuth.With warming the substrate to 200 K the πCH molecular orbit increases 0.2 eV in binding energy,and the C 1s core level decreases 0.3 eV in binding energy,the results suggest that dehydrogenated of hexene occurs at 200 K.
The adsorption of hexene（C6H12）on Ru() surface has been studied by the polarized angleresolved ultraviolet photoemission spectroscope (ARUPS) and Xray photoemission spectroscope (XPS). The results show that the hexene absorbs in a molecular state on the Ru() surface below 200 K,the molecular orbits of πCC,σCC and πCH were found at 7.5,9.4 and 11.1 eV respectively.The results of the polarized ARUPS show that the σCC orbit is symmetry about a mirror plane along <> azimuth but the πCC orbit is antisymmetry about a mirror plane.The results suggest that the hexene molecule lies in a plane along <> azimuth.With warming the substrate to 200 K the πCH molecular orbit increases 0.2 eV in binding energy,and the C 1s core level decreases 0.3 eV in binding energy,the results suggest that dehydrogenated of hexene occurs at 200 K.
2002, 18(05): 441-445
doi: 10.3866/PKU.WHXB20020512
Abstract:
The thermal pressure coefficients and internal pressures of ethanol＋nhexane liquid mixtures have been measured at different temperatures and compositions.These experimental data are corrected with modified van der Waals model proposed in our previous work.From the parameter of this model B/A2 ,a formula describing the relationship between the dissociation degree of selfassociation and the composition of ethanol in the mixture is obtained.Based on this formula,a model is designed for the mixing of alcohols and hydrocarbons and the equation which can be satisfactorily used to describe the variation of excess enthalpies with the composition are established.It can clearly display the contributions of the physical and chemical action to the excess enthalpies.
The thermal pressure coefficients and internal pressures of ethanol＋nhexane liquid mixtures have been measured at different temperatures and compositions.These experimental data are corrected with modified van der Waals model proposed in our previous work.From the parameter of this model B/A2 ,a formula describing the relationship between the dissociation degree of selfassociation and the composition of ethanol in the mixture is obtained.Based on this formula,a model is designed for the mixing of alcohols and hydrocarbons and the equation which can be satisfactorily used to describe the variation of excess enthalpies with the composition are established.It can clearly display the contributions of the physical and chemical action to the excess enthalpies.
2002, 18(05): 446-450
doi: 10.3866/PKU.WHXB20020513
Abstract:
Using ab initio molecular orbital theory,the hydrogen abstraction reaction CH2O＋O[3P]→CHO＋OH has been studied.The geometries of the reactants,transition state and products have been optimized at the QCISD/6311G[d,p] level.The forward and reverse reaction potential barriers are 38.86 kJ•mol－1 and 67.23 kJ•mol－1 respectively at the QCISD(t,full)/6311G[d,p]//QCISD/6311G[d,p].By analyzing the changes of the generalized normalmode vibrational frequencies along the IRC,we found that the C－H bond breaking and the O－H bond forming took place as a concerted process.And there is a reactive vibrational normalmode which leads to the process of reaction from reactants to products.At the temperature range of 1 300～2 270 K,the forward and reverse reaction rate constants obtained by using the improved canonical variational transition state theory (ICVT),are consistent with the experimental values.
Using ab initio molecular orbital theory,the hydrogen abstraction reaction CH2O＋O[3P]→CHO＋OH has been studied.The geometries of the reactants,transition state and products have been optimized at the QCISD/6311G[d,p] level.The forward and reverse reaction potential barriers are 38.86 kJ•mol－1 and 67.23 kJ•mol－1 respectively at the QCISD(t,full)/6311G[d,p]//QCISD/6311G[d,p].By analyzing the changes of the generalized normalmode vibrational frequencies along the IRC,we found that the C－H bond breaking and the O－H bond forming took place as a concerted process.And there is a reactive vibrational normalmode which leads to the process of reaction from reactants to products.At the temperature range of 1 300～2 270 K,the forward and reverse reaction rate constants obtained by using the improved canonical variational transition state theory (ICVT),are consistent with the experimental values.
2002, 18(05): 451-454
doi: 10.3866/PKU.WHXB20020514
Abstract:
The TiO2/organic composite thin film was prepared using supermolecular selfassembly method on glass substrate. The structure of the thin film was characterized by FTIR, UVVis, XRD and TEM techniques. The results indicated that the thin film was composed of alternative orderly appeared organic and inorganic layers. The distance between organic layer and inorganic layer was 4.20 nm before polymerization and 3.91 nm after polymerization, respectively. The inorganic layers were composed of TiO2 nanoparticles.
The TiO2/organic composite thin film was prepared using supermolecular selfassembly method on glass substrate. The structure of the thin film was characterized by FTIR, UVVis, XRD and TEM techniques. The results indicated that the thin film was composed of alternative orderly appeared organic and inorganic layers. The distance between organic layer and inorganic layer was 4.20 nm before polymerization and 3.91 nm after polymerization, respectively. The inorganic layers were composed of TiO2 nanoparticles.
2002, 18(05): 455-458
doi: 10.3866/PKU.WHXB20020515
Abstract:
Influence of different surfactants，such as anionic sodium dodecylsulfate(SDS)，cationic cetyltrimethylammonium bromide(CTAB), and nonionic octylphenylpoly(ethylene glycol)(OP)upon water solution viscosity(η) of the hydrophobicallymodified watersoluble amphoteric cellulosic graft copolymer(CGAO) of carboxymethyl cellulose(CMC) grafted with acrylamide(AM) and (methacryloxyethyl)dimethyloctylammonium bromide(ADMOAB) has been investigated. It was found that the maximum(ηmax) of solution viscosity of CGAO was obtained in the neighborhood of the critical micelle concentration of SDS and OP at 10 s－1 of shear rate and 25 ℃. ηmax in the presence of SDS was much larger than that in the presence of OP； and the higher the content of ADMOAB of hydrophobe in CGAO, the larger ηmax was. In the case of CTAB, η continuously decreased with the increment of CTAB concentration. However, for nonhydrophobicallymodified graft copolymer(CGA) of CMC with AM, its η reduced with the increasing concentration of SDS or CTAB, but η was almost independent of OP. And the hydrophobic association between surfactants and CGAO was demonstrated by the retention time measured through gel permeation chromatography.
Influence of different surfactants，such as anionic sodium dodecylsulfate(SDS)，cationic cetyltrimethylammonium bromide(CTAB), and nonionic octylphenylpoly(ethylene glycol)(OP)upon water solution viscosity(η) of the hydrophobicallymodified watersoluble amphoteric cellulosic graft copolymer(CGAO) of carboxymethyl cellulose(CMC) grafted with acrylamide(AM) and (methacryloxyethyl)dimethyloctylammonium bromide(ADMOAB) has been investigated. It was found that the maximum(ηmax) of solution viscosity of CGAO was obtained in the neighborhood of the critical micelle concentration of SDS and OP at 10 s－1 of shear rate and 25 ℃. ηmax in the presence of SDS was much larger than that in the presence of OP； and the higher the content of ADMOAB of hydrophobe in CGAO, the larger ηmax was. In the case of CTAB, η continuously decreased with the increment of CTAB concentration. However, for nonhydrophobicallymodified graft copolymer(CGA) of CMC with AM, its η reduced with the increasing concentration of SDS or CTAB, but η was almost independent of OP. And the hydrophobic association between surfactants and CGAO was demonstrated by the retention time measured through gel permeation chromatography.
2002, 18(05): 459-462
doi: 10.3866/PKU.WHXB20020516
Abstract:
The catalytic performance of carbon nanotubessupported nickel catalyst for the hydrogenation of Chlorophyll at normal temperature and pressure was studied.The catalyst was characterized by TEM and FTIR. The results showed that preoxidation of carbon nanotubes by boiling nitric acid could create functional groups, such as －OH and －COOH, and enhanced the dispersion of Ni, thus leading to a rise in catalytic activity. Activity test also showed that the catalyst with 7％ Ni loading is the most effective in the hydrogenation reaction.
The catalytic performance of carbon nanotubessupported nickel catalyst for the hydrogenation of Chlorophyll at normal temperature and pressure was studied.The catalyst was characterized by TEM and FTIR. The results showed that preoxidation of carbon nanotubes by boiling nitric acid could create functional groups, such as －OH and －COOH, and enhanced the dispersion of Ni, thus leading to a rise in catalytic activity. Activity test also showed that the catalyst with 7％ Ni loading is the most effective in the hydrogenation reaction.
2002, 18(05): 463-467
doi: 10.3866/PKU.WHXB20020517
Abstract:
Mixed micellization of quaternary ammonium dimeric surfactants, C12sC12•2Br(s=2,3,4,6), and a nonionic surfactant C12E10 or C12E23 in aqueous solution have been investigated using conductivity measurement. The results show that C12sC12•2Br and C12E10 or C12E23 form mixed micelles. The values of the total critical micelle concentration lie always among and , which are the critical micelle concentrations for individual surfactant 1 and surfactant 2, respectively. Addition of a few nonionic surfactant, for example α2=0.1, the molar fraction of C12E10 or C12E23 in the mixed micelle exceeds 0.35. With further increasing the concentration of the nonionic surfactant in solution, the main component in the mixed micelles becomes gradually C12E10 or C12E23.
Mixed micellization of quaternary ammonium dimeric surfactants, C12sC12•2Br(s=2,3,4,6), and a nonionic surfactant C12E10 or C12E23 in aqueous solution have been investigated using conductivity measurement. The results show that C12sC12•2Br and C12E10 or C12E23 form mixed micelles. The values of the total critical micelle concentration lie always among and , which are the critical micelle concentrations for individual surfactant 1 and surfactant 2, respectively. Addition of a few nonionic surfactant, for example α2=0.1, the molar fraction of C12E10 or C12E23 in the mixed micelle exceeds 0.35. With further increasing the concentration of the nonionic surfactant in solution, the main component in the mixed micelles becomes gradually C12E10 or C12E23.
2002, 18(05): 468-472
doi: 10.3866/PKU.WHXB20020518
Abstract:
A series of [(nC4H9)4N][EuxM1－x (TTA)4](M=La, Sm,Gd, Tb) dopedcomplexes were synthesized. The results of FTIR and XRD spectroscopies indicated that the structures of the doped complexes are as same as that of pure complexes [(nC4H9)4N][Ln(TTA)4](Ln=Eu, La, Sm, Gd, Tb). It is found that the luminescent intensity of the dopedcomplexes did not have a linear relation with amount of Eu3＋. Addition of La3＋, Gd3＋ and Tb3＋ increased the luminescence of Eu3＋ in varying degrees, and addition of Sm3＋ decreased the luminescence of Eu3＋. The possible intermolecular energy transfer mechanism by triplet states of ligands was discussed.
A series of [(nC4H9)4N][EuxM1－x (TTA)4](M=La, Sm,Gd, Tb) dopedcomplexes were synthesized. The results of FTIR and XRD spectroscopies indicated that the structures of the doped complexes are as same as that of pure complexes [(nC4H9)4N][Ln(TTA)4](Ln=Eu, La, Sm, Gd, Tb). It is found that the luminescent intensity of the dopedcomplexes did not have a linear relation with amount of Eu3＋. Addition of La3＋, Gd3＋ and Tb3＋ increased the luminescence of Eu3＋ in varying degrees, and addition of Sm3＋ decreased the luminescence of Eu3＋. The possible intermolecular energy transfer mechanism by triplet states of ligands was discussed.
2002, 18(05): 473-476
doi: 10.3866/PKU.WHXB20020519
Abstract:
Nanosized porous TiO2 films supported on nickel are prepared by solgel process. The STM morphology of the nanosized TiO2 films has been given. It is known by STM, that the diameter of TiO2 particles is about 20～80 nm and the pore quantity and the diameter of nanosized TiO2 film increase with the increasing of sintering temperature. The photoelectrochemical performance of the prepared TiO2 photoelectrode is determined by cyclic voltammitric method. It is found that the photocurrent of the photoelectrode increases with the increasing of the sintering temperature and thickness of TiO2 film.
Nanosized porous TiO2 films supported on nickel are prepared by solgel process. The STM morphology of the nanosized TiO2 films has been given. It is known by STM, that the diameter of TiO2 particles is about 20～80 nm and the pore quantity and the diameter of nanosized TiO2 film increase with the increasing of sintering temperature. The photoelectrochemical performance of the prepared TiO2 photoelectrode is determined by cyclic voltammitric method. It is found that the photocurrent of the photoelectrode increases with the increasing of the sintering temperature and thickness of TiO2 film.
2002, 18(05): 477-480
doi: 10.3866/PKU.WHXB20020520
Abstract:
Core/shell structures of CdS/SiO2 were synthesized through the ammonium hydroxide catalyzed hydrolysis of tetraethylorthosilicate(TEOS) in alcohol media containing presynthesized CdS nanorods. Xray diffraction(XRD), transmission electron microscopy(TEM), UVVis spectroscopy and photoluminescence spectroscopy were employed to characterize the obtained coreshell structures. The thickness of the amorphous SiO2 shell ranges from 10 to 30 nm, and increases with the concentration of the TEOS used. The photoluminescence intensity of the coreshell structures is enhanced for the CdS nanorod samples with only a thin layer (< 10 nm) of SiO2 shell on the CdS nanorod, and is reduced for the sample with a thicker SiO2 shell. Possible reasons contributing to the variations of the photoluminescence were discussed.
Core/shell structures of CdS/SiO2 were synthesized through the ammonium hydroxide catalyzed hydrolysis of tetraethylorthosilicate(TEOS) in alcohol media containing presynthesized CdS nanorods. Xray diffraction(XRD), transmission electron microscopy(TEM), UVVis spectroscopy and photoluminescence spectroscopy were employed to characterize the obtained coreshell structures. The thickness of the amorphous SiO2 shell ranges from 10 to 30 nm, and increases with the concentration of the TEOS used. The photoluminescence intensity of the coreshell structures is enhanced for the CdS nanorod samples with only a thin layer (< 10 nm) of SiO2 shell on the CdS nanorod, and is reduced for the sample with a thicker SiO2 shell. Possible reasons contributing to the variations of the photoluminescence were discussed.
