Login In
2001 Volume 17 Issue 1
2001, 17(01): 1-4
doi: 10.3866/PKU.WHXB20010101
Abstract:
Organically modified MSUx mesophases containing phenyl, ureidopropyl and methyl along with phenyl two moieties were directly prepared by onepot synthesis method. Their texture and surface properties were characterized by means of XRD, HRTEM, FTIR, N2 adsorption/desorption, 29Si CPMAS NMR、13C CPMAS NMR and the microscopic structure was also characterized by small angle Xray scattering (SAXS) using synchrotron radiation as Xray source. The results showed that SAXS profiles were hardly constant with Porod′s law showing a negative slope, i.e. negative deviations (see fig.3). This suggested that the organic groups covalently linked with the matrix of mesoporous silica formed an interfacial layers, which led to the scattering of the pore distortion and gave a negative diviation from Porod′s law. The average thickness of the interfacial layer in each sample was further obtained by analyzing this deviation. SAXS analysis also showed that the organically functionalized MSUX displayed mass fractal and the uniform distribution of the organic groups within the mesoporous channels, implying that it′s formation was a nonequilibrium and nonlinear process.
Organically modified MSUx mesophases containing phenyl, ureidopropyl and methyl along with phenyl two moieties were directly prepared by onepot synthesis method. Their texture and surface properties were characterized by means of XRD, HRTEM, FTIR, N2 adsorption/desorption, 29Si CPMAS NMR、13C CPMAS NMR and the microscopic structure was also characterized by small angle Xray scattering (SAXS) using synchrotron radiation as Xray source. The results showed that SAXS profiles were hardly constant with Porod′s law showing a negative slope, i.e. negative deviations (see fig.3). This suggested that the organic groups covalently linked with the matrix of mesoporous silica formed an interfacial layers, which led to the scattering of the pore distortion and gave a negative diviation from Porod′s law. The average thickness of the interfacial layer in each sample was further obtained by analyzing this deviation. SAXS analysis also showed that the organically functionalized MSUX displayed mass fractal and the uniform distribution of the organic groups within the mesoporous channels, implying that it′s formation was a nonequilibrium and nonlinear process.
2001, 17(01): 5-9
doi: 10.3866/PKU.WHXB20010102
Abstract:
The geometric structures of molybdenum sulfide slabs,(n=0,1,2,3,4,6) and Mo7S24H12 were optimized by using ab initio method at HF/MINI/ECP and UHF/MINI/ECP level of theory.The optimized geometry parameters of Mo7S24 were in agreement with the experimental values found in literature.For the unique atoms in these structures,the bonding features were found to be different for the same type of atoms with different coordination positions in a structure.The charging or hydrogenation of the Mo7S24 structure caused significant change in these features and their total energy.
The geometric structures of molybdenum sulfide slabs,(n=0,1,2,3,4,6) and Mo7S24H12 were optimized by using ab initio method at HF/MINI/ECP and UHF/MINI/ECP level of theory.The optimized geometry parameters of Mo7S24 were in agreement with the experimental values found in literature.For the unique atoms in these structures,the bonding features were found to be different for the same type of atoms with different coordination positions in a structure.The charging or hydrogenation of the Mo7S24 structure caused significant change in these features and their total energy.
2001, 17(01): 10-14
doi: 10.3866/PKU.WHXB20010103
Abstract:
Using the mixture of cetyltrimethylammonium bromide(CTAB) and neutral alkylamine surfactant (CnNH2n＋3, n=8,10,12,14,16) as templated, hexa nal mesostructured titaniumcontaining silica TiMCM-41 was synthesized. XRD and TEM provided direct evidence for a wellordered hexa nal nano pore structure. N2 adsorption/desorption isotherm showed that highly ordered TiMCM41 materials exhibited sharp steps of capillary condensation and narrow pore size distributions. The effect of the ratio of titanium to silica(Ti/Si) and the chain length n of the alkylamine on the mesostructure were investigated. It was revealed that phase transition from hexa nal to amorphous structure occured with Ti/Si >0.15 and from hexa nal to lamellar structure appppeared with n=18.
Using the mixture of cetyltrimethylammonium bromide(CTAB) and neutral alkylamine surfactant (CnNH2n＋3, n=8,10,12,14,16) as templated, hexa nal mesostructured titaniumcontaining silica TiMCM-41 was synthesized. XRD and TEM provided direct evidence for a wellordered hexa nal nano pore structure. N2 adsorption/desorption isotherm showed that highly ordered TiMCM41 materials exhibited sharp steps of capillary condensation and narrow pore size distributions. The effect of the ratio of titanium to silica(Ti/Si) and the chain length n of the alkylamine on the mesostructure were investigated. It was revealed that phase transition from hexa nal to amorphous structure occured with Ti/Si >0.15 and from hexa nal to lamellar structure appppeared with n=18.
2001, 17(01): 15-22
doi: 10.3866/PKU.WHXB20010104
Abstract:
Ionization Potentials and electron affinities of 103 elements are calculated by density functional theory at local density approximation (LDA) level and the LDA/AN level with further nonlocal corrections for exchange and correlation included selfconsistently.The finitedifference method is used in calculations on electronegativity and hardness of 103 elements.The calculated results for the various quantities represent an improvement over previous calculations by Robles and Bartolotti under a spin polarized density function theory with the ΧGL and Χα approximations to the exchangecorrelation function.The present calculation is to examine both the LDA and LDA/NL approximations in calculations for the ionization potential and electron affinity of the elements with an improved slater transitionstate method,and relativistic effects have also been taken into account in the present paper for 103 elements as compared with 86 in the previous work.It is shown that the results calculated by LDA/NL and the improved slater transitionstate method in general agree well with experimental values presented by Pearson,and are better than the reported values in the literatures[11,12].
Ionization Potentials and electron affinities of 103 elements are calculated by density functional theory at local density approximation (LDA) level and the LDA/AN level with further nonlocal corrections for exchange and correlation included selfconsistently.The finitedifference method is used in calculations on electronegativity and hardness of 103 elements.The calculated results for the various quantities represent an improvement over previous calculations by Robles and Bartolotti under a spin polarized density function theory with the ΧGL and Χα approximations to the exchangecorrelation function.The present calculation is to examine both the LDA and LDA/NL approximations in calculations for the ionization potential and electron affinity of the elements with an improved slater transitionstate method,and relativistic effects have also been taken into account in the present paper for 103 elements as compared with 86 in the previous work.It is shown that the results calculated by LDA/NL and the improved slater transitionstate method in general agree well with experimental values presented by Pearson,and are better than the reported values in the literatures[11,12].
2001, 17(01): 23-27
doi: 10.3866/PKU.WHXB20010105
Abstract:
SnO2@TiO2 coated particles have been prepared with Ti(OC4H9)4 and SnO2•nH2O as precursors by coated on active surface.In order to improve the photocatalytic degradation activity of SnO2@TiO2 for DDVP,the conditions of preparation were studied and better photocatalytic activity was obtained.Its morphology and structure were characterized by XRD,SEM,TEM,XPS、IR and BET.The result indicated:That SnO2@TiO2 is composed of nanometer ranatase TiO2 and rutile SnO2,and the photocatalytic activities of SnO2@TiO2 are better than those of SnO2 and TiO2,the apparent rate constant k of the photocatalytic degradation of DDVP is related to the initial concentration of DDVP solution.The reaction is not a simple zeroorder reaction.
SnO2@TiO2 coated particles have been prepared with Ti(OC4H9)4 and SnO2•nH2O as precursors by coated on active surface.In order to improve the photocatalytic degradation activity of SnO2@TiO2 for DDVP,the conditions of preparation were studied and better photocatalytic activity was obtained.Its morphology and structure were characterized by XRD,SEM,TEM,XPS、IR and BET.The result indicated:That SnO2@TiO2 is composed of nanometer ranatase TiO2 and rutile SnO2,and the photocatalytic activities of SnO2@TiO2 are better than those of SnO2 and TiO2,the apparent rate constant k of the photocatalytic degradation of DDVP is related to the initial concentration of DDVP solution.The reaction is not a simple zeroorder reaction.
2001, 17(01): 28-31
doi: 10.3866/PKU.WHXB20010106
Abstract:
TiO2 and /TiO2 photocatalysts were prepared by solgel method and characterized by Xray diffraction (XRD),BET N2 sorption analysis, IR spectroscopy and UVVis Diffuse Reflectance Spectroscopy (DRS).Photocatalytic degradation of CH3Br in air stream was studied over TiO2 and /TiO2 catalysts under various reaction conditions.The results indicated that the structural and photocatalytic properties of TiO2 were greatly improved by sulfation.The sulfated TiO2 (/TiO2) showed excellent reaction activity and stability for CH3Br photocatalytic decomposition even under the moist reaction conditions.It was found that both B acid sites and L acid sites exist on the /TiO2 catalyst,forming cooperative centers with superacidic characteristics.When compared to unmodified TiO2,the /TiO2 catalyst exhibited higher anatase content,smaller crystal size,higher specific surface area,centralized pore size distribution,and the blueshifted band edge of Uvvis adsorption spectra.
TiO2 and /TiO2 photocatalysts were prepared by solgel method and characterized by Xray diffraction (XRD),BET N2 sorption analysis, IR spectroscopy and UVVis Diffuse Reflectance Spectroscopy (DRS).Photocatalytic degradation of CH3Br in air stream was studied over TiO2 and /TiO2 catalysts under various reaction conditions.The results indicated that the structural and photocatalytic properties of TiO2 were greatly improved by sulfation.The sulfated TiO2 (/TiO2) showed excellent reaction activity and stability for CH3Br photocatalytic decomposition even under the moist reaction conditions.It was found that both B acid sites and L acid sites exist on the /TiO2 catalyst,forming cooperative centers with superacidic characteristics.When compared to unmodified TiO2,the /TiO2 catalyst exhibited higher anatase content,smaller crystal size,higher specific surface area,centralized pore size distribution,and the blueshifted band edge of Uvvis adsorption spectra.
2001, 17(01): 32-36
doi: 10.3866/PKU.WHXB20010107
Abstract:
A simple dopingcoating technique is described for immobilizing uricase using polyaniline and polystyrene and paraffin.The polyaniline uricase electrode with polystyrene coating has a fast response time (about 30 s at 0.35 V vs.SCE).The optimum pH and the dependence on potential are similar to those of polyaniline uricase electrode,the activation energy and stability of the polyaniline uricase electrode with polystyrene coating are 19.9 kJ•mol－1 and over 180 days,respectively.
A simple dopingcoating technique is described for immobilizing uricase using polyaniline and polystyrene and paraffin.The polyaniline uricase electrode with polystyrene coating has a fast response time (about 30 s at 0.35 V vs.SCE).The optimum pH and the dependence on potential are similar to those of polyaniline uricase electrode,the activation energy and stability of the polyaniline uricase electrode with polystyrene coating are 19.9 kJ•mol－1 and over 180 days,respectively.
2001, 17(01): 37-42
doi: 10.3866/PKU.WHXB20010108
Abstract:
Recently, high molecular weight additives such as proteins or synthetic polymer have been dissolved in water pools in W/O microemulsions, which served as microreacter for enzymatic or chemical reactions. However, the report on the effect of different molecular weight polymers on the state of water in W/O microemulsions made with zwitterionic surfactant has been so far scarcely investigated. We report here the results of research concerning the effect of different molecular weight polyvinylpyrrolidones(PVPK15, PVPK30, PVPK90, and PVPK120) on the state of water in two kinds W/O microemulsions made with water/dodecyl betaine (C12BE)/npentanol(C5OH)/nheptane (C7H16) (I), and water/ aerosol OT (AOT)/C7H16(Ⅱ) using Fourier Transform Infrared(FTIR) spetroscopy. FTIR spectra of all the samples were taken on a BIORED model 165 FTIR spectrometer using AgCl cells of a fixed path length of 0.025 nm. All spectra were recorded at room temperature (25 ℃). Two kinds of W/O microemulsions with PVP that the changes in the OH stretch peak of water molecule could be observed. The results indicate that the content of the bound water was increased, and the amount of the bulk water was decreased in the system (I)in the presence of the PVP. But the amount of bound water was decreased and the amount of the bulk water was increased in the system(Ⅱ) as PVP was added. This is contributed to the interaction of PVP macromolecules with the head groups of amphiphile: the polarity of C12BE molecule was increased but the polarity of AOT molecule was decreased as PVP was added.
Recently, high molecular weight additives such as proteins or synthetic polymer have been dissolved in water pools in W/O microemulsions, which served as microreacter for enzymatic or chemical reactions. However, the report on the effect of different molecular weight polymers on the state of water in W/O microemulsions made with zwitterionic surfactant has been so far scarcely investigated. We report here the results of research concerning the effect of different molecular weight polyvinylpyrrolidones(PVPK15, PVPK30, PVPK90, and PVPK120) on the state of water in two kinds W/O microemulsions made with water/dodecyl betaine (C12BE)/npentanol(C5OH)/nheptane (C7H16) (I), and water/ aerosol OT (AOT)/C7H16(Ⅱ) using Fourier Transform Infrared(FTIR) spetroscopy. FTIR spectra of all the samples were taken on a BIORED model 165 FTIR spectrometer using AgCl cells of a fixed path length of 0.025 nm. All spectra were recorded at room temperature (25 ℃). Two kinds of W/O microemulsions with PVP that the changes in the OH stretch peak of water molecule could be observed. The results indicate that the content of the bound water was increased, and the amount of the bulk water was decreased in the system (I)in the presence of the PVP. But the amount of bound water was decreased and the amount of the bulk water was increased in the system(Ⅱ) as PVP was added. This is contributed to the interaction of PVP macromolecules with the head groups of amphiphile: the polarity of C12BE molecule was increased but the polarity of AOT molecule was decreased as PVP was added.
2001, 17(01): 43-47
doi: 10.3866/PKU.WHXB20010109
Abstract:
Studies on the complex and its 4,4′disubstituted derivates on one bpy are carried out by using DFT method at B3LYP/LanL2DZ level. The regularities of the substituent effects of stronger electronpushing group (－OCH3)and stronger electrondrawing group (－NO2) on affecting the electronic structure and its related properties, e.g., the coordination bond lengths and the spectroscopy properties, etc., have been investigated. The results obtained may be useful as references for the synthesis of the complexes, the mechanism analysis on photochemistry , electrochemistry, catalysischemistry and biochemistry of the complexes , etc.
Studies on the complex and its 4,4′disubstituted derivates on one bpy are carried out by using DFT method at B3LYP/LanL2DZ level. The regularities of the substituent effects of stronger electronpushing group (－OCH3)and stronger electrondrawing group (－NO2) on affecting the electronic structure and its related properties, e.g., the coordination bond lengths and the spectroscopy properties, etc., have been investigated. The results obtained may be useful as references for the synthesis of the complexes, the mechanism analysis on photochemistry , electrochemistry, catalysischemistry and biochemistry of the complexes , etc.
2001, 17(01): 48-52
doi: 10.3866/PKU.WHXB20010110
Abstract:
The reaction between ciprofloxacin and bovine serum albumin(BSA) in aqueous solution was studied by fluorescence spectra and microcalorimetry.The binding constant K was found to be 8.39×104L•mol－1 and the binding sites n to be 1.18 by fluorescence quenching method.The binding distance (r=2.46 nm) and transfer efficiency (E=0.33) between ciprofloxacin and BSA were also obtained according to the Fōrster theory of non-radiation energy transfer.Microcalorimetric measurements showed that the molar change of enthalpy ΔrHm≈0 for the reaction.The interaction between ciprofloxacin and BSA is stronger and the main binding force is hydrophobic interaction.
The reaction between ciprofloxacin and bovine serum albumin(BSA) in aqueous solution was studied by fluorescence spectra and microcalorimetry.The binding constant K was found to be 8.39×104L•mol－1 and the binding sites n to be 1.18 by fluorescence quenching method.The binding distance (r=2.46 nm) and transfer efficiency (E=0.33) between ciprofloxacin and BSA were also obtained according to the Fōrster theory of non-radiation energy transfer.Microcalorimetric measurements showed that the molar change of enthalpy ΔrHm≈0 for the reaction.The interaction between ciprofloxacin and BSA is stronger and the main binding force is hydrophobic interaction.
2001, 17(01): 53-58
doi: 10.3866/PKU.WHXB20010111
Abstract:
Tb3＋ ions were incorporated in SiO2 glasses using a solgel process with appropriate heat treatment.Glasses incorporated with Tb3＋ showed emission peaks at 488,544,585,and 620 nm,respectively,exhibiting,respectively,5D4—7FJ(J=3,4,5,6) transition of the Tb3＋ ions.The structural evolution during the transition from gel to glass of Tb3＋ doped SiO2 glasses and the effect on luminescence properties were studied by excitation spectra,emission spectra,IR,farIR and DTATG at differential heat treatment conditions.The results show that most of absorbed water molecules in gel were removed during heat treatment at 50～100 ℃,conversion from gel to glasses was the main structural changes when gel was heattreated in the range 150～500 ℃,and the luminescence intensity increased remarkably also,becoming stable structure at 800 ℃.This observation leads to a conclusion that the radiation electronic transitions of Tb3＋ were quenched strongly by O－H group and were enhanced by temperature elevation.
Tb3＋ ions were incorporated in SiO2 glasses using a solgel process with appropriate heat treatment.Glasses incorporated with Tb3＋ showed emission peaks at 488,544,585,and 620 nm,respectively,exhibiting,respectively,5D4—7FJ(J=3,4,5,6) transition of the Tb3＋ ions.The structural evolution during the transition from gel to glass of Tb3＋ doped SiO2 glasses and the effect on luminescence properties were studied by excitation spectra,emission spectra,IR,farIR and DTATG at differential heat treatment conditions.The results show that most of absorbed water molecules in gel were removed during heat treatment at 50～100 ℃,conversion from gel to glasses was the main structural changes when gel was heattreated in the range 150～500 ℃,and the luminescence intensity increased remarkably also,becoming stable structure at 800 ℃.This observation leads to a conclusion that the radiation electronic transitions of Tb3＋ were quenched strongly by O－H group and were enhanced by temperature elevation.
2001, 17(01): 59-61
doi: 10.3866/PKU.WHXB20010112
Abstract:
The pressure dependence of partial molar volumes was calculated in detail by RK equation of state for the dehydrogenation of dodecane to internal dodecane.The results showed that clustering between supercritical medium and internal dodecane and hydrogen was much stronger in supercritical phase than in gas phase,and that,clustering between supercritical medium and the reaction products was more remarkable.This provided a quantitative description of the change in cluster size resulted by an increase in solutesolvent attraction force.
The pressure dependence of partial molar volumes was calculated in detail by RK equation of state for the dehydrogenation of dodecane to internal dodecane.The results showed that clustering between supercritical medium and internal dodecane and hydrogen was much stronger in supercritical phase than in gas phase,and that,clustering between supercritical medium and the reaction products was more remarkable.This provided a quantitative description of the change in cluster size resulted by an increase in solutesolvent attraction force.
2001, 17(01): 62-65
doi: 10.3866/PKU.WHXB20010113
Abstract:
The dynamic interfacial tensions between hydrocarbons and solutions of surfactants having different hydrophiliclipophilic ability are measured.The effects of ionic strength and alkyl chain carbonnumber on dynamic interfacial tensions are also studied.It is found that adsorptiondesorption barriers are connected with the hydrophiliclipophilic ability of surfactants.There exists a large or small adsorptiondesorption barrier to the transfer of surfactant having strong hydrophilic or lipophilic ability from water to oil.The influences of ionic strength and alkyl chain carbon-number on adsorptiondesorption barriers are discussed.
The dynamic interfacial tensions between hydrocarbons and solutions of surfactants having different hydrophiliclipophilic ability are measured.The effects of ionic strength and alkyl chain carbonnumber on dynamic interfacial tensions are also studied.It is found that adsorptiondesorption barriers are connected with the hydrophiliclipophilic ability of surfactants.There exists a large or small adsorptiondesorption barrier to the transfer of surfactant having strong hydrophilic or lipophilic ability from water to oil.The influences of ionic strength and alkyl chain carbon-number on adsorptiondesorption barriers are discussed.
2001, 17(01): 66-69
doi: 10.3866/PKU.WHXB20010114
Abstract:
Differential scanning calorimetry （DSC） was used to measure the thermal hysteresis activity(THA) of plant antifreeze proteins(AFPs). The results reveal that DSC is a od method to screen and study AFPs. In the sixteen components extracted from Ammopipanthus mon licus leaves, one(P3S1) was found to have apparent thermal hysteresis activity by DSC. As the amount of ice nuclei in the sample decreased, the THA of P3S1 increased from 0.01 ℃ to 0.65 ℃. It is notable that the twopeak thermal hysteresis effect was observed. Two endothermic peaks appeared in the melting process of P3S1, while the freezing peak also consisted of two peaks. The peaks appeared antecedently showed larger thermal effect. This phenomenon shows P3S1 has two different kinds of interaction with water and ice crystal. It is probably an important property of a class of AFPs.
Differential scanning calorimetry （DSC） was used to measure the thermal hysteresis activity(THA) of plant antifreeze proteins(AFPs). The results reveal that DSC is a od method to screen and study AFPs. In the sixteen components extracted from Ammopipanthus mon licus leaves, one(P3S1) was found to have apparent thermal hysteresis activity by DSC. As the amount of ice nuclei in the sample decreased, the THA of P3S1 increased from 0.01 ℃ to 0.65 ℃. It is notable that the twopeak thermal hysteresis effect was observed. Two endothermic peaks appeared in the melting process of P3S1, while the freezing peak also consisted of two peaks. The peaks appeared antecedently showed larger thermal effect. This phenomenon shows P3S1 has two different kinds of interaction with water and ice crystal. It is probably an important property of a class of AFPs.
2001, 17(01): 70-73
doi: 10.3866/PKU.WHXB20010115
Abstract:
The thermal decompositions of two systems(NO.1,KClO3(52.2%)/CuO(26.0%)/S(9.6%)/Mg-Al(3.5%)/C6Cl6(4.35%)) and NO.2,(KClO3(52.2%)/CuO(26.0%)/S(9.6%)/Mg-Al(3.5%)/C6Cl6(4.35%)) are studied using Accelerating Rate Caorimeter (ARC).Temperature vs time curve and pressure vs time curve of reactions are shown in Fig.1 and Fig.2 respectively.The basic data including reaction time(1.3 and 7.3 min respectively),initial temperature (159 and 150℃ respectively),temperature at the maximum rate(272 and 272℃ respectively),the maximum pressure (420 and 190kPa respectively) and the activation energies(175.6 and 135.2 kJ mol-1 respectively) of the thermal decomposition are given to evaluate the safety of the two systems.Results indicate that system NO.2 is safer than NO.1.Compared with the traditional methods,ARC technique can be used to measure temperature and pressure of exothermic reaction concurrently,to find the tiny exothermicity and to determine the initial temperature of exothermic reaction.
The thermal decompositions of two systems(NO.1,KClO3(52.2%)/CuO(26.0%)/S(9.6%)/Mg-Al(3.5%)/C6Cl6(4.35%)) and NO.2,(KClO3(52.2%)/CuO(26.0%)/S(9.6%)/Mg-Al(3.5%)/C6Cl6(4.35%)) are studied using Accelerating Rate Caorimeter (ARC).Temperature vs time curve and pressure vs time curve of reactions are shown in Fig.1 and Fig.2 respectively.The basic data including reaction time(1.3 and 7.3 min respectively),initial temperature (159 and 150℃ respectively),temperature at the maximum rate(272 and 272℃ respectively),the maximum pressure (420 and 190kPa respectively) and the activation energies(175.6 and 135.2 kJ mol-1 respectively) of the thermal decomposition are given to evaluate the safety of the two systems.Results indicate that system NO.2 is safer than NO.1.Compared with the traditional methods,ARC technique can be used to measure temperature and pressure of exothermic reaction concurrently,to find the tiny exothermicity and to determine the initial temperature of exothermic reaction.
2001, 17(01): 74-78
doi: 10.3866/PKU.WHXB20010116
Abstract:
Cationic Gemini surfactants, alkanediylα,ωbis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid in the presence of strong sulfuric acid. Dodecylbromide was then reacted with N,Ntetramethyl ethane diamine(or N,Ntetramethyl hexana diamine) to prepare the title compounds. Micellization of these Gemini surfactants was investigated using conductivity measurement. The results showed that the critical micelle concentration(cmc) of the Gemini surfactants has a much lower value compared with that of the corresponding “monomer”. For a series of the Geminis with the same length(s) in the spacer chain, the cmc decreased with increasing the carbon number (m) in the alkyl chain. The aggregation number(N) of the micelle also drastically decreased with m. For the same value of m, the cmc varied slightly with s, which indicated that the electrostatic interaction between the ionicgroups of the “monomer” has been naturally changed duo to a link between the two ionicgroups of the “monomer” through a spacer. However, N was strongly decreased with s,which may be a reason of steric inhibition coming from the ionicgroups due to a link of spacer. With increasing temperature, micellization of the Gemini surfactants was slightly enhanced.
Cationic Gemini surfactants, alkanediylα,ωbis(dimethyl dodecylammonium bromide) have been synthesized by the following method: firstly dodecyl bromide was prepared by the reaction of dodecanol with bromic acid in the presence of strong sulfuric acid. Dodecylbromide was then reacted with N,Ntetramethyl ethane diamine(or N,Ntetramethyl hexana diamine) to prepare the title compounds. Micellization of these Gemini surfactants was investigated using conductivity measurement. The results showed that the critical micelle concentration(cmc) of the Gemini surfactants has a much lower value compared with that of the corresponding “monomer”. For a series of the Geminis with the same length(s) in the spacer chain, the cmc decreased with increasing the carbon number (m) in the alkyl chain. The aggregation number(N) of the micelle also drastically decreased with m. For the same value of m, the cmc varied slightly with s, which indicated that the electrostatic interaction between the ionicgroups of the “monomer” has been naturally changed duo to a link between the two ionicgroups of the “monomer” through a spacer. However, N was strongly decreased with s,which may be a reason of steric inhibition coming from the ionicgroups due to a link of spacer. With increasing temperature, micellization of the Gemini surfactants was slightly enhanced.
2001, 17(01): 79-82
doi: 10.3866/PKU.WHXB20010117
Abstract:
Molybdenum oxide films were fabricated successfully by spin coating from Li＋doped peroxopolymolybdate solution via solgel technique.Their electrochemical and electrochromic properties were investigated by cyclic voltammetry and insitu UV transmittance measurements.The results showed that the films possessed excellent electrochemical stability and reversibility.The electrochromic mechanism of the MoO3 was discussed by using results obtained from Xray photoelectron spectroscopy (XPS).The results showed that the most part of the Mo6＋ in MoO3 film was reduced to Mo5＋ and Mo4＋ ions during the Li＋ intercalation process,Mo4＋ was oxidized to Mo5＋ and part of Mo5＋ was oxidized to Mo6＋ again during the Li＋ deintercalation process.So it was considered that Mo4＋ ions existed in the colored MoO3 films.
Molybdenum oxide films were fabricated successfully by spin coating from Li＋doped peroxopolymolybdate solution via solgel technique.Their electrochemical and electrochromic properties were investigated by cyclic voltammetry and insitu UV transmittance measurements.The results showed that the films possessed excellent electrochemical stability and reversibility.The electrochromic mechanism of the MoO3 was discussed by using results obtained from Xray photoelectron spectroscopy (XPS).The results showed that the most part of the Mo6＋ in MoO3 film was reduced to Mo5＋ and Mo4＋ ions during the Li＋ intercalation process,Mo4＋ was oxidized to Mo5＋ and part of Mo5＋ was oxidized to Mo6＋ again during the Li＋ deintercalation process.So it was considered that Mo4＋ ions existed in the colored MoO3 films.
2001, 17(01): 83-86
doi: 10.3866/PKU.WHXB20010118
Abstract:
In this paper, the formation of the CuxC60 films has been described briefly. The UVVis absorption spectrum of CuxC60 film have been discussed in detail, the electronic structure of CuxC60 film is discussed qualitatively. For x< 1, there exists only Cu＋ in the CuxC60 films. However, for x=4, not only Cu＋, but also atomCu exists in them. In CuxC60 films three strong peaks have been shiffed compared with that of C60 films. The shift of these strong peaks shows that in the CuxC60 films C60 molecule accepts only one electron and becomes . Because of the existence of the atomCu in the CuxC60 films, in visible region there is a wide peak which is the plasmons resonance absorb peak of the Cucluster in it.
In this paper, the formation of the CuxC60 films has been described briefly. The UVVis absorption spectrum of CuxC60 film have been discussed in detail, the electronic structure of CuxC60 film is discussed qualitatively. For x< 1, there exists only Cu＋ in the CuxC60 films. However, for x=4, not only Cu＋, but also atomCu exists in them. In CuxC60 films three strong peaks have been shiffed compared with that of C60 films. The shift of these strong peaks shows that in the CuxC60 films C60 molecule accepts only one electron and becomes . Because of the existence of the atomCu in the CuxC60 films, in visible region there is a wide peak which is the plasmons resonance absorb peak of the Cucluster in it.
2001, 17(01): 87-90
doi: 10.3866/PKU.WHXB20010119
Abstract:
EPR spectra of three new quaternary gadolinium complexes(I：[Gd(C6H5COO)2(NO3)(bipy)]2,Ⅱ：[Gd(mCH3C6H4COO)2(NO3)(phen)]2 and Ⅲ：[Gd(pCH3C6H4COO)(NO3)(phen)]2) with mixed anion ligands in polycrystalline powders and solutions have been investigated at different temperatures and solvents.New behavior of EPR spectra of complex Ⅲ was first observed in polycrystalline powder at 77K and three types of EPR spectra for three complexes,symmetry resonance spectrum for the complex Ⅱ,U spectrum for the complex Ⅲ,and asymmetry resonance spectrum for the complex I.The relationship of EPR features between the crystalfield strength in the complexes and local symmetry around Gd(Ⅲ) was discussed.The crystalfield parameters b20 and asymmetry parameters λ′ of the complexes I and Ⅲ were estimated.
EPR spectra of three new quaternary gadolinium complexes(I：[Gd(C6H5COO)2(NO3)(bipy)]2,Ⅱ：[Gd(mCH3C6H4COO)2(NO3)(phen)]2 and Ⅲ：[Gd(pCH3C6H4COO)(NO3)(phen)]2) with mixed anion ligands in polycrystalline powders and solutions have been investigated at different temperatures and solvents.New behavior of EPR spectra of complex Ⅲ was first observed in polycrystalline powder at 77K and three types of EPR spectra for three complexes,symmetry resonance spectrum for the complex Ⅱ,U spectrum for the complex Ⅲ,and asymmetry resonance spectrum for the complex I.The relationship of EPR features between the crystalfield strength in the complexes and local symmetry around Gd(Ⅲ) was discussed.The crystalfield parameters b20 and asymmetry parameters λ′ of the complexes I and Ⅲ were estimated.
2001, 17(01): 91-94
doi: 10.3866/PKU.WHXB20010120
Abstract:
This paper reports the results of solubility calculation of the phase system HClNaClH2O at 25 ℃ when θHNa (interactions of two species with the same charge) and ΨHNaCl (interactions of three species) were changed by ＋10％ and －10％. The results indicated that the effects of the two kinds of interactions on the calculated solubility of the system were regular. The calculated solubilities of the system did not vary while the two interactions were increased and decreased simultaneously. The solubility data of the system changed greatly as one interaction was increased and the other decreased. This study is significant for the chemical technology of salting out salts from the watersalt system.
This paper reports the results of solubility calculation of the phase system HClNaClH2O at 25 ℃ when θHNa (interactions of two species with the same charge) and ΨHNaCl (interactions of three species) were changed by ＋10％ and －10％. The results indicated that the effects of the two kinds of interactions on the calculated solubility of the system were regular. The calculated solubilities of the system did not vary while the two interactions were increased and decreased simultaneously. The solubility data of the system changed greatly as one interaction was increased and the other decreased. This study is significant for the chemical technology of salting out salts from the watersalt system.
