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2002 Volume 18 Issue 6
2002, 18(06): 481-485
doi: 10.3866/PKU.WHXB20020601
Abstract:
Two solid complexes of rare-earth compounds with alanine, [Ho2(Ala)4(H2O)8]Cl6 and [ErY(Ala)4(H2O)8](ClO4)6 (Ala=alanine) were synthesized,and a calorimetric study and thermal analysis for the two complexes were performed through adiabatic calorimetry and thermogravimetry. The low-temperature heat capacities of [Ho2(Ala)4(H2O)8]Cl6 and [ErY(Ala)4(H2O)8](ClO4)6 were measured with an automated adiabatic precision calorimeter over the temperature range from 78 to 377 K. Solid-solid phase transitions were found between 214 K and 255 K with a peak temperature of 235.09 K for [Ho2(Ala)4(H2O)8]Cl6,between 99 K and 121 K with a peak temperature of 115.78 K for [ErY(Ala)4(H2O)8](ClO4)6.The enthalpies and entropies of the phase transitions were determined to be 3.02 kJ•mol－1,12.83 J•K－1•mol－1 for [Ho2(Ala)4(H2O)8]Cl6; 1.96 kJ•mol－1,16.90 J•K－1•mol－1 for [ErY(Ala)4(H2O)8](ClO4)6, respectively. Thermal decomposition of the two complexes were investigated in the temperature range of 40～800 ℃ by using the thermogravimetric and differential thermogravimetric (TG/DTG ) analysis techniques. The TG/DTG curves showed that the decomposition started from 80 ℃ and ended at 479 ℃,completed in two steps for [Ho2(Ala)4(H2O)8]Cl6,and started from 120 ℃ and ended at 430 ℃,completed in three steps for [ErY(Ala)4(H2O)8](ClO4)6,respectively.The possible mechanisms of the thermal decompositions were elucidated.
Two solid complexes of rare-earth compounds with alanine, [Ho2(Ala)4(H2O)8]Cl6 and [ErY(Ala)4(H2O)8](ClO4)6 (Ala=alanine) were synthesized,and a calorimetric study and thermal analysis for the two complexes were performed through adiabatic calorimetry and thermogravimetry. The low-temperature heat capacities of [Ho2(Ala)4(H2O)8]Cl6 and [ErY(Ala)4(H2O)8](ClO4)6 were measured with an automated adiabatic precision calorimeter over the temperature range from 78 to 377 K. Solid-solid phase transitions were found between 214 K and 255 K with a peak temperature of 235.09 K for [Ho2(Ala)4(H2O)8]Cl6,between 99 K and 121 K with a peak temperature of 115.78 K for [ErY(Ala)4(H2O)8](ClO4)6.The enthalpies and entropies of the phase transitions were determined to be 3.02 kJ•mol－1,12.83 J•K－1•mol－1 for [Ho2(Ala)4(H2O)8]Cl6; 1.96 kJ•mol－1,16.90 J•K－1•mol－1 for [ErY(Ala)4(H2O)8](ClO4)6, respectively. Thermal decomposition of the two complexes were investigated in the temperature range of 40～800 ℃ by using the thermogravimetric and differential thermogravimetric (TG/DTG ) analysis techniques. The TG/DTG curves showed that the decomposition started from 80 ℃ and ended at 479 ℃,completed in two steps for [Ho2(Ala)4(H2O)8]Cl6,and started from 120 ℃ and ended at 430 ℃,completed in three steps for [ErY(Ala)4(H2O)8](ClO4)6,respectively.The possible mechanisms of the thermal decompositions were elucidated.
2002, 18(06): 486-489
doi: 10.3866/PKU.WHXB20020602
Abstract:
The reaction of OH radical with CO was investigated by time-resolved Fourier transform infrared (TR-FTIR) spectroscopy. OH radical was produced by laser photolysis of HNO3 at 248 nm. IR emission from vibrationally excited unsymmetric stretching mode (ν3) of product CO2 was observed for the first time (Fig.2). The simulated results for the IR emission spectrum of CO2 shows that the CO2 populates up to v=6 and the quantum number v=2 is the most populated vibration level (Fig.4). Comparison of the experimental distribution results of product CO2 with quantum or QCT calculation by Schatz and co-workers shows that experimental distributions agree well with the quantum predicting but is different from that of the QCT calculation. This consistency suggests that the SFH potential surface (Fig.1) is accurate and the quantum dynamics method but not QCT is proper approach for the chemical reaction involving H atom leaping.
The reaction of OH radical with CO was investigated by time-resolved Fourier transform infrared (TR-FTIR) spectroscopy. OH radical was produced by laser photolysis of HNO3 at 248 nm. IR emission from vibrationally excited unsymmetric stretching mode (ν3) of product CO2 was observed for the first time (Fig.2). The simulated results for the IR emission spectrum of CO2 shows that the CO2 populates up to v=6 and the quantum number v=2 is the most populated vibration level (Fig.4). Comparison of the experimental distribution results of product CO2 with quantum or QCT calculation by Schatz and co-workers shows that experimental distributions agree well with the quantum predicting but is different from that of the QCT calculation. This consistency suggests that the SFH potential surface (Fig.1) is accurate and the quantum dynamics method but not QCT is proper approach for the chemical reaction involving H atom leaping.
2002, 18(06): 490-494
doi: 10.3866/PKU.WHXB20020603
Abstract:
The oli deoxynucleotides is anchoraged on the silver electrode surface by means of physical methods. The in situ Electrochemistry-Surface Enhanced Raman Scattering (SERS) Spectrum is used to study the adsorption state of 26-mers oli deoxynucleotides (ODN) and 13-mers ODN on the electrode surface respectively. The SERS spectra of oligdeoxynucleotides based on the silver electrode have obtained. The results of study of the SERS spectra change of ODN with the change of potential on the silver electrode demonstrate that the oli deoxynucleotides adsorbed on the silver electrode surface primarily through the special base-Adenine (A).The adsorption state changes with the variation of the potential on the electrode. The shorter ODN changes more quickly and is more sensitive to the change of potential than the longer ODN(see Table 1).
The oli deoxynucleotides is anchoraged on the silver electrode surface by means of physical methods. The in situ Electrochemistry-Surface Enhanced Raman Scattering (SERS) Spectrum is used to study the adsorption state of 26-mers oli deoxynucleotides (ODN) and 13-mers ODN on the electrode surface respectively. The SERS spectra of oligdeoxynucleotides based on the silver electrode have obtained. The results of study of the SERS spectra change of ODN with the change of potential on the silver electrode demonstrate that the oli deoxynucleotides adsorbed on the silver electrode surface primarily through the special base-Adenine (A).The adsorption state changes with the variation of the potential on the electrode. The shorter ODN changes more quickly and is more sensitive to the change of potential than the longer ODN(see Table 1).
2002, 18(06): 495-499
doi: 10.3866/PKU.WHXB20020604
Abstract:
The fluorescence quenching of dimethylamino chalcone modified β-cyclodextrin by different transition metal ions in various solvents has been studied. It was found that the modified β-cyclodextrin has a specific recognition ability to Cu2＋ in aqueous solution, and the quenching constant is about one order of magnitude larger than that of other metals which were studied in this work. But in non-aqueous solvents, such as in DMF, the specific recognition ability of Cu2＋ disappeared. And the Ni2＋, which has a planar configuration, presented the strongest ability of complex formation. It was resulted from the four ethylene groups connected each other by hetero-atom in linking chain of the modified β-cyclodextrin to make the formation of planar square configuration easily. The results demonstrated that the possibility of the special structure match of the host and the guest plays a very important role in the complex formation.
The fluorescence quenching of dimethylamino chalcone modified β-cyclodextrin by different transition metal ions in various solvents has been studied. It was found that the modified β-cyclodextrin has a specific recognition ability to Cu2＋ in aqueous solution, and the quenching constant is about one order of magnitude larger than that of other metals which were studied in this work. But in non-aqueous solvents, such as in DMF, the specific recognition ability of Cu2＋ disappeared. And the Ni2＋, which has a planar configuration, presented the strongest ability of complex formation. It was resulted from the four ethylene groups connected each other by hetero-atom in linking chain of the modified β-cyclodextrin to make the formation of planar square configuration easily. The results demonstrated that the possibility of the special structure match of the host and the guest plays a very important role in the complex formation.
2002, 18(06): 500-503
doi: 10.3866/PKU.WHXB20020605
Abstract:
Photoinduced electron transfer reaction of anthracene with phenothiazine(PTZ)occurs in the membrane phase of the SDS (sodium dodecyl sulfate)/benzyl alcohol/H2O microemulsion. PTZ exists in the membrane phase because the rate for the photoinduced reaction between CHCl3 and PTZ in microemulsion is much slower than that in BA. Anthracene locates in the membrane phase or the oil core of the O/W microemulsion and in the oil continuous phase of the W/O microemulsion. The quenching of the excited anthracene by PTZ occurs in the membrane phase either for the W/O microemulsion or for the O/W microemulsion.
Photoinduced electron transfer reaction of anthracene with phenothiazine(PTZ)occurs in the membrane phase of the SDS (sodium dodecyl sulfate)/benzyl alcohol/H2O microemulsion. PTZ exists in the membrane phase because the rate for the photoinduced reaction between CHCl3 and PTZ in microemulsion is much slower than that in BA. Anthracene locates in the membrane phase or the oil core of the O/W microemulsion and in the oil continuous phase of the W/O microemulsion. The quenching of the excited anthracene by PTZ occurs in the membrane phase either for the W/O microemulsion or for the O/W microemulsion.
2002, 18(06): 504-507
doi: 10.3866/PKU.WHXB20020606
Abstract:
β-hairpins are popular secondary structural elements in native protein and play important roles either in protein folds or functionalization. Here we describe the design and preliminary structural studies of two peptide sequences LTVd-PGLTV (n7) and LTVGDDTV(n5) synthesized by solid phase peptide synthetic strategy. The circular dichroism (CD)spectra of n5 show a negative minimum near 198 nm, random coil characteristics. On the contrary, the CD spectra of n7 show a minimum at about 218 nm and a maximum at about 196 nm, a typical β-hairpin characteristics, which have been concluded as the common contribution of a β-turn mixed with β-sheets. The results show that β-turn, sequence context and β-sheet forming tendency are determinant of β-hairpin formation and stability.
β-hairpins are popular secondary structural elements in native protein and play important roles either in protein folds or functionalization. Here we describe the design and preliminary structural studies of two peptide sequences LTVd-PGLTV (n7) and LTVGDDTV(n5) synthesized by solid phase peptide synthetic strategy. The circular dichroism (CD)spectra of n5 show a negative minimum near 198 nm, random coil characteristics. On the contrary, the CD spectra of n7 show a minimum at about 218 nm and a maximum at about 196 nm, a typical β-hairpin characteristics, which have been concluded as the common contribution of a β-turn mixed with β-sheets. The results show that β-turn, sequence context and β-sheet forming tendency are determinant of β-hairpin formation and stability.
2002, 18(06): 508-512
doi: 10.3866/PKU.WHXB20020607
Abstract:
Molten CuAlNi alloys have been investigated by X-ray diffractometer. Distinct pre-peaks have been found in the structure factors. For the liquid alloy Cu75Al25,the intensity of pre-peak decreases with increasing temperature but exists clearly up to temperature of 1300 ℃.This behaviour indicates the existence of medium-range order clusters up to nearly 250 ℃ above liquids temperature. The amount and size of atomic clusters increase as the concentration of Ni increases. The addition of Ni can improve the interaction between atoms, so it is favorable to the ability of medium-range order formation. According to the characteristics of the pre-peak, the atomic model of liquid CuAlNi is constructed, namely,the structure of liquid CuAlNi is a combination of clusters consisting of octahedrons with shared vertexes and other atoms with random dense atom distribution.
Molten CuAlNi alloys have been investigated by X-ray diffractometer. Distinct pre-peaks have been found in the structure factors. For the liquid alloy Cu75Al25,the intensity of pre-peak decreases with increasing temperature but exists clearly up to temperature of 1300 ℃.This behaviour indicates the existence of medium-range order clusters up to nearly 250 ℃ above liquids temperature. The amount and size of atomic clusters increase as the concentration of Ni increases. The addition of Ni can improve the interaction between atoms, so it is favorable to the ability of medium-range order formation. According to the characteristics of the pre-peak, the atomic model of liquid CuAlNi is constructed, namely,the structure of liquid CuAlNi is a combination of clusters consisting of octahedrons with shared vertexes and other atoms with random dense atom distribution.
Studies on the 3D-QSAR of Novel 1-aryl-1,4-dihydro-3-acylhydrazinocarbonyl-6-methyl- 4-pyridazinones
2002, 18(06): 513-516
doi: 10.3866/PKU.WHXB20020608
Abstract:
The three-dimensional quantitative structure-activity relationships of series of 1-aryl-1,4-dihydro-3-Acylhydrazinocarbonyl-6-methyl-4-pyridazinones, related to the promoting cucumber cotyledon root-formation activity, were studied using the comparative molecular field analysis(CoMFA). The results show that the contributions of steric and electrostatic fields to the activity are 0.734 and 0.266,respectively. This means that the steric influence plays a dominant role for the compounds studied. The cross-validated rcv2 and the relation coefficient r2 for the model established by the study are 0.643 and 0.977, respectively, with the F value of 102.622， and the standard deviation (s) of 0.041. These values indicate that the model is significant and have od predictability. This offers important structural insights for designing highly active compounds prior to their synthesis.
The three-dimensional quantitative structure-activity relationships of series of 1-aryl-1,4-dihydro-3-Acylhydrazinocarbonyl-6-methyl-4-pyridazinones, related to the promoting cucumber cotyledon root-formation activity, were studied using the comparative molecular field analysis(CoMFA). The results show that the contributions of steric and electrostatic fields to the activity are 0.734 and 0.266,respectively. This means that the steric influence plays a dominant role for the compounds studied. The cross-validated rcv2 and the relation coefficient r2 for the model established by the study are 0.643 and 0.977, respectively, with the F value of 102.622， and the standard deviation (s) of 0.041. These values indicate that the model is significant and have od predictability. This offers important structural insights for designing highly active compounds prior to their synthesis.
2002, 18(06): 517-521
doi: 10.3866/PKU.WHXB20020609
Abstract:
4,4′-[1,n-alkanediylbis[(E)-2-(4-oxyphenyl)ethenyl]]bispyridine [n=2(Ia), 3(Ib),4(Ic), 6(Id)] were synthesized by the nucleophilic substitution of (E)-4-[2-(4-hydroxyphenyl)ethenyl] pyridine with 1,n-dibromoalkane.The structures of Ia～Id were identified by elemental analysis, IR, UV and 1H NMR. The dilute solution of Ia～Id was irradiated alternatively by medium pressure mercury lamp and low pressure mercury lamp. The intramolecular photocycloaddition was observed and this reaction speeds up with the extension of the alkanediyl chain. It was also found that the photocycloaddition was increased in the presence of zinc cation because of its chelation with the nitrogen atom of the pyridine group. The fluorescence of these compounds is weak and the intermolecular excimer fluorescence is detected at higher concentration.
4,4′-[1,n-alkanediylbis[(E)-2-(4-oxyphenyl)ethenyl]]bispyridine [n=2(Ia), 3(Ib),4(Ic), 6(Id)] were synthesized by the nucleophilic substitution of (E)-4-[2-(4-hydroxyphenyl)ethenyl] pyridine with 1,n-dibromoalkane.The structures of Ia～Id were identified by elemental analysis, IR, UV and 1H NMR. The dilute solution of Ia～Id was irradiated alternatively by medium pressure mercury lamp and low pressure mercury lamp. The intramolecular photocycloaddition was observed and this reaction speeds up with the extension of the alkanediyl chain. It was also found that the photocycloaddition was increased in the presence of zinc cation because of its chelation with the nitrogen atom of the pyridine group. The fluorescence of these compounds is weak and the intermolecular excimer fluorescence is detected at higher concentration.
2002, 18(06): 522-526
doi: 10.3866/PKU.WHXB20020610
Abstract:
The geometries of reactants, products and transition states of the rotation rearrangement of 3-hydroxy acrolein molecule have been optimized by density functional theory(DFT) using B3LYP method at 6-31G** and 6-311＋＋G** level. The zero point energy corrections were obtained by vibration analysis, and the transition states were verified by the only virtual frequency. A 4-member ring intermediate was found on the reaction path. The intrinsic reaction coordinates (IRC) were obtained. The results show that the rearrangement of ground state molecule proceeds in two steps. The barrier of the first step is 240.745 kJ•mol－1(B3LYP/6-31G**), 232.858 kJ•mol－1 (B3LYP/6-311＋＋G**), and the second step barrier is 40.412 kJ•mol－1 (B3LYP/6-31G**), 37.568 kJ•mol－1 (B3LYP/6-311＋＋G**). The calculation results show that the rearrangement of ground state 3-hydroxy acrolein molecule is possible.
The geometries of reactants, products and transition states of the rotation rearrangement of 3-hydroxy acrolein molecule have been optimized by density functional theory(DFT) using B3LYP method at 6-31G** and 6-311＋＋G** level. The zero point energy corrections were obtained by vibration analysis, and the transition states were verified by the only virtual frequency. A 4-member ring intermediate was found on the reaction path. The intrinsic reaction coordinates (IRC) were obtained. The results show that the rearrangement of ground state molecule proceeds in two steps. The barrier of the first step is 240.745 kJ•mol－1(B3LYP/6-31G**), 232.858 kJ•mol－1 (B3LYP/6-311＋＋G**), and the second step barrier is 40.412 kJ•mol－1 (B3LYP/6-31G**), 37.568 kJ•mol－1 (B3LYP/6-311＋＋G**). The calculation results show that the rearrangement of ground state 3-hydroxy acrolein molecule is possible.
2002, 18(06): 527-531
doi: 10.3866/PKU.WHXB20020611
Abstract:
Density functional theory (DFT) with the B3LYP method and 6-311＋G* basis set has been employed to investigate the geometries and other properties of ，NO2 and some other molecules, ions and their transitional or excited states that concern the mechanism of aromatic nitration. Furthermore, the relative energies and other properties of these substances have been studied with the bond angle ranging from 90° to 180° at fixed bond length at the same level. From the results obtained, the occurrence possibilities of various nitration mechanisms, including electrophilic reaction mechanism and electron transfer mechanism, have been discussed. Each possibility depends on the first ionization potential and electron richness of aromatic substrates. Polar solvents are considered to be favorable for nitration reactions. The works reported here are ready for the further theoretical and experimental studies of the mechanism of nitration.
Density functional theory (DFT) with the B3LYP method and 6-311＋G* basis set has been employed to investigate the geometries and other properties of ，NO2 and some other molecules, ions and their transitional or excited states that concern the mechanism of aromatic nitration. Furthermore, the relative energies and other properties of these substances have been studied with the bond angle ranging from 90° to 180° at fixed bond length at the same level. From the results obtained, the occurrence possibilities of various nitration mechanisms, including electrophilic reaction mechanism and electron transfer mechanism, have been discussed. Each possibility depends on the first ionization potential and electron richness of aromatic substrates. Polar solvents are considered to be favorable for nitration reactions. The works reported here are ready for the further theoretical and experimental studies of the mechanism of nitration.
2002, 18(06): 532-535
doi: 10.3866/PKU.WHXB20020612
Abstract:
Aluminum specimens were first anodized in a sulfuric acid bath to prepare the porous aluminum anodic oxide template, and then silver was electrodeposited into pores of the anodized aluminum by using alternating current (AC).The morphology of the silver in pores of anodized aluminum was characterized by transmission electron microscopy (TEM), and the micrographs exhibited that silver was assembled in the form of nanowires with a diameter of ac 25 nm. and length up to 5 μm. The nanowires have a structure of parallel bright stripes alternating with parallel dark stripes (see Fig.2e). Silver nanowires are parallel to each other in the pores of the porous aluminum anodic oxide template. Selected area electron diffraction (SAED) pattern revealed that silver nanowire is of polycrystalline structure. Additionally, the formation mechanism of the structure of parallel bright stripes alternating with parallel dark stripes was discussed.
Aluminum specimens were first anodized in a sulfuric acid bath to prepare the porous aluminum anodic oxide template, and then silver was electrodeposited into pores of the anodized aluminum by using alternating current (AC).The morphology of the silver in pores of anodized aluminum was characterized by transmission electron microscopy (TEM), and the micrographs exhibited that silver was assembled in the form of nanowires with a diameter of ac 25 nm. and length up to 5 μm. The nanowires have a structure of parallel bright stripes alternating with parallel dark stripes (see Fig.2e). Silver nanowires are parallel to each other in the pores of the porous aluminum anodic oxide template. Selected area electron diffraction (SAED) pattern revealed that silver nanowire is of polycrystalline structure. Additionally, the formation mechanism of the structure of parallel bright stripes alternating with parallel dark stripes was discussed.
2002, 18(06): 536-539
doi: 10.3866/PKU.WHXB20020613
Abstract:
Recovery of Ni-Cd batteries was studied by a self-designed vacuum-aided recycling system under laboratory conditions. The impacts of temperature, pressure and time were studied respectively. The mechanism of vacuum thermal recycling was also discussed. The results show that, at constant pressure, the increase of temperature can improve the separation efficiency of cadmium. When the temperature is 1173 K, the cadmium can evaporate completely from the residue during 3 h at 10 Pa. The reduction of pressure in a certain range is effective to separate cadmium by vacuum distillation. Distillation time is a very important factor affecting separation of cadmium.
Recovery of Ni-Cd batteries was studied by a self-designed vacuum-aided recycling system under laboratory conditions. The impacts of temperature, pressure and time were studied respectively. The mechanism of vacuum thermal recycling was also discussed. The results show that, at constant pressure, the increase of temperature can improve the separation efficiency of cadmium. When the temperature is 1173 K, the cadmium can evaporate completely from the residue during 3 h at 10 Pa. The reduction of pressure in a certain range is effective to separate cadmium by vacuum distillation. Distillation time is a very important factor affecting separation of cadmium.
2002, 18(06): 540-544
doi: 10.3866/PKU.WHXB20020614
Abstract:
In the present work, the combination of both the Langmuir adsorption and the spectral correction (MPASC) technique are described. It provides a very helpful experimental method for the study of aggregation of a dye on biomacromolecules. The helix, winding and folding of DNA form double electrostatic films and their surface will selectively attract charged organic compounds in only monolayer untill kinetic equilibrium approached. The physico-chemical constants such as equilibrium constant and binding stoichiometry of the aggregate may be determined. The adsorption of polychrome blue (PCB) on nucleic acids has been investigated at pH 7.24 and it obeys Langmuir monolayer adsorption. Results showed that the adsorption ratio of PCB to DNA-PCB is 0.5 :1 and that to RNA-PCB 0.3 :1, their adsorption constants are KDNA-PCB=5.42×104 and KRNA-PCB=2.82×104（30 ℃） respectively, and their real adsorptivity ε(DNA-PCB, 625 nm)=5.65×103 andε(RNA-PCB, 625 nm)=3.85×103 (mol－1•L)•cm. By varying the operation condition, we observed that the adsorption ratio of PCB to DNA decreased with increasing ionic strength and temperature. This indicates that the interaction is an adsorption but not a complexation. This interaction was applied to the quantitative determination of DNA. In the presence of EDTA, many ions or compounds such as protein, alkali earths, Mn(II), Cu(II),Fe(II), Zn(II), Pb(II), Ni(II), Co(II) and Cd(II) have no interference to the direct determination of nucleic acids.
In the present work, the combination of both the Langmuir adsorption and the spectral correction (MPASC) technique are described. It provides a very helpful experimental method for the study of aggregation of a dye on biomacromolecules. The helix, winding and folding of DNA form double electrostatic films and their surface will selectively attract charged organic compounds in only monolayer untill kinetic equilibrium approached. The physico-chemical constants such as equilibrium constant and binding stoichiometry of the aggregate may be determined. The adsorption of polychrome blue (PCB) on nucleic acids has been investigated at pH 7.24 and it obeys Langmuir monolayer adsorption. Results showed that the adsorption ratio of PCB to DNA-PCB is 0.5 :1 and that to RNA-PCB 0.3 :1, their adsorption constants are KDNA-PCB=5.42×104 and KRNA-PCB=2.82×104（30 ℃） respectively, and their real adsorptivity ε(DNA-PCB, 625 nm)=5.65×103 andε(RNA-PCB, 625 nm)=3.85×103 (mol－1•L)•cm. By varying the operation condition, we observed that the adsorption ratio of PCB to DNA decreased with increasing ionic strength and temperature. This indicates that the interaction is an adsorption but not a complexation. This interaction was applied to the quantitative determination of DNA. In the presence of EDTA, many ions or compounds such as protein, alkali earths, Mn(II), Cu(II),Fe(II), Zn(II), Pb(II), Ni(II), Co(II) and Cd(II) have no interference to the direct determination of nucleic acids.
2002, 18(06): 545-549
doi: 10.3866/PKU.WHXB20020615
Abstract:
The effective inducer of differentiation,3,3’-(pentane-1,5-diyl)bis(5,5- dimethylhydantoin) (PMDH), was synthesized and identified by MS, NMR , IR and element analysis. Its synthetic method and route were optimized. The structure of the compound was determined by single crystal X-ray diffraction and compared with other Hexamethylenbisamide(HMBA) derivatives. The crystal structure of PMDH belongs to triclinic space group P. Crystallographic data are: a=0.874 1(4) nm, b=1.114 6(2) nm, c=1.721 0(3) nm; α= 87.20(3)°, β=89.77(3)°, γ=85.12(3)°，V=1.668 6(6) nm3， Dc=1.291 g•cm－3， Z=4， F(000)=696,μ=0.095 mm－1, R1= 0.065 1(for observed data)， wR2=0.165 7(for unique data), S=1.081. The hyndantoin rings are planar. The molecules are linked by intermolecular hydrogen bonds to form infinite one-dimensional molecular chain almost parallel to the b axis.
The effective inducer of differentiation,3,3’-(pentane-1,5-diyl)bis(5,5- dimethylhydantoin) (PMDH), was synthesized and identified by MS, NMR , IR and element analysis. Its synthetic method and route were optimized. The structure of the compound was determined by single crystal X-ray diffraction and compared with other Hexamethylenbisamide(HMBA) derivatives. The crystal structure of PMDH belongs to triclinic space group P. Crystallographic data are: a=0.874 1(4) nm, b=1.114 6(2) nm, c=1.721 0(3) nm; α= 87.20(3)°, β=89.77(3)°, γ=85.12(3)°，V=1.668 6(6) nm3， Dc=1.291 g•cm－3， Z=4， F(000)=696,μ=0.095 mm－1, R1= 0.065 1(for observed data)， wR2=0.165 7(for unique data), S=1.081. The hyndantoin rings are planar. The molecules are linked by intermolecular hydrogen bonds to form infinite one-dimensional molecular chain almost parallel to the b axis.
2002, 18(06): 550-553
doi: 10.3866/PKU.WHXB20020616
Abstract:
In order to assemble polystyrene nanoparticles onto glasses and enhance combining force between polystyrene nanoparticles and the glasses, surface-functional polystyre nanoparticles were prepared by emulsion polymerization, characterized by FTIR、TEM、XRD, etc., rich of carboxyl can be seen on the surface of the polystyrene nanoparticles and the diameter of which is about 50 nm. A thin film with uniformity and wide coverage was firstly obtained on glasses based on self-assembly. A best experimental project was proposed.
In order to assemble polystyrene nanoparticles onto glasses and enhance combining force between polystyrene nanoparticles and the glasses, surface-functional polystyre nanoparticles were prepared by emulsion polymerization, characterized by FTIR、TEM、XRD, etc., rich of carboxyl can be seen on the surface of the polystyrene nanoparticles and the diameter of which is about 50 nm. A thin film with uniformity and wide coverage was firstly obtained on glasses based on self-assembly. A best experimental project was proposed.
2002, 18(06): 554-557
doi: 10.3866/PKU.WHXB20020617
Abstract:
In this paper, we demonstrate the temperature-sensitive precipitation of chitosan in chitosan-HCl solution. The precipitation and precipitation temperature were determined by the change of turbidity of the solution. The precipitation was verned by the degree of deacylation of chitosan, the concentration of chitosan and that of HCl, these effects could be interpreted by the DLVO theory. After precipitation, amidogen of chitosan was combined with HCl, which was proved by FTIR and changed to be amorphous, which was proved by the X-ray diffraction .The SEM of precipitation showed the novel form of chitosan.
In this paper, we demonstrate the temperature-sensitive precipitation of chitosan in chitosan-HCl solution. The precipitation and precipitation temperature were determined by the change of turbidity of the solution. The precipitation was verned by the degree of deacylation of chitosan, the concentration of chitosan and that of HCl, these effects could be interpreted by the DLVO theory. After precipitation, amidogen of chitosan was combined with HCl, which was proved by FTIR and changed to be amorphous, which was proved by the X-ray diffraction .The SEM of precipitation showed the novel form of chitosan.
2002, 18(06): 558-562
doi: 10.3866/PKU.WHXB20020618
Abstract:
The BVStr is a software for studying crystal structure and surface structure. It is compiled by Visual C＋＋ and can be used in the Windows operational system of PC and based on the cell structures of crystal and the bond valence (BV) theory, such as the parameter of crystal cell, space group, a fraction of coordinates (or a few atoms), and the BV constants, etc. It can give display of arrangements of atoms in two or three dimensions of crystal, and, on the various crystal planes with their BV data as well as the coordination structure data. These are very useful for both the research and teaching of crystal and its surface.
The BVStr is a software for studying crystal structure and surface structure. It is compiled by Visual C＋＋ and can be used in the Windows operational system of PC and based on the cell structures of crystal and the bond valence (BV) theory, such as the parameter of crystal cell, space group, a fraction of coordinates (or a few atoms), and the BV constants, etc. It can give display of arrangements of atoms in two or three dimensions of crystal, and, on the various crystal planes with their BV data as well as the coordination structure data. These are very useful for both the research and teaching of crystal and its surface.
2002, 18(06): 563-566
doi: 10.3866/PKU.WHXB20020619
Abstract:
A polynuclear complex was synthesized by the reaction of CoCl2 with 2,2’-bipyridine-1,1’-dioxide in DMF solution. Elemental analysis, IR, UV and molar conductivity measurements indicated the composition of the complex corresponding to the formula [Co3(bipyO2)4Cl4]Cl2.Study of the properties showed that the complex has od sensitivity and selectivity for ammonia. The output voltage of sensor produced by the complex responses non-linearly to the change of ammonia concentration in the range of 3.0×10－5～1.2×10－4 mol•L－1,but linear response was found in the range of 1.4×10－4～1.3×10－3 mol•L－1.The sensor manufactured by the complex could be used to detect and control the concentration of NH3 in production.
A polynuclear complex was synthesized by the reaction of CoCl2 with 2,2’-bipyridine-1,1’-dioxide in DMF solution. Elemental analysis, IR, UV and molar conductivity measurements indicated the composition of the complex corresponding to the formula [Co3(bipyO2)4Cl4]Cl2.Study of the properties showed that the complex has od sensitivity and selectivity for ammonia. The output voltage of sensor produced by the complex responses non-linearly to the change of ammonia concentration in the range of 3.0×10－5～1.2×10－4 mol•L－1,but linear response was found in the range of 1.4×10－4～1.3×10－3 mol•L－1.The sensor manufactured by the complex could be used to detect and control the concentration of NH3 in production.
2002, 18(06): 567-571
doi: 10.3866/PKU.WHXB20020620
Abstract:
Nanostuctured LaNiO3 was prepared by coprecipitation under ultrasonic radiation. Using XRD, TEM, BET, XPS, TPR and evaluation of catalytic activity, the effects of ultrasound on the structured properties and catalytic activity of LaNiO3 were studied. The result of TEM showed that the ultrasound could cause decrease of particle size. The average particle size of LaNiO3 prepared by sonochemistry is 20 nm (see Fig.2b). The specific surface area of LaNiO3 is 11.27 m2•g－1 by BET. The Oads/Oads on surface are 1.25 (ultrasound) and 1.01(without ultrasound) by XPS (see Fig.4). It showed that ultrasound could lead to increase surface content oxide and increase number of surface crystal oxygen vacancies. The result of TPR showed LaNiO3 prepared by sonochemistry has lower reduction temperature and bigger ratio of surface oxygen to crystal oxygen (see Table 1). The result of evaluation of catalytic activity showed that ultrasound could increase that catalytic activity of LaNiO3 for NO decomposition (see Fig.6). The role played by of ultrasound was discussed.
Nanostuctured LaNiO3 was prepared by coprecipitation under ultrasonic radiation. Using XRD, TEM, BET, XPS, TPR and evaluation of catalytic activity, the effects of ultrasound on the structured properties and catalytic activity of LaNiO3 were studied. The result of TEM showed that the ultrasound could cause decrease of particle size. The average particle size of LaNiO3 prepared by sonochemistry is 20 nm (see Fig.2b). The specific surface area of LaNiO3 is 11.27 m2•g－1 by BET. The Oads/Oads on surface are 1.25 (ultrasound) and 1.01(without ultrasound) by XPS (see Fig.4). It showed that ultrasound could lead to increase surface content oxide and increase number of surface crystal oxygen vacancies. The result of TPR showed LaNiO3 prepared by sonochemistry has lower reduction temperature and bigger ratio of surface oxygen to crystal oxygen (see Table 1). The result of evaluation of catalytic activity showed that ultrasound could increase that catalytic activity of LaNiO3 for NO decomposition (see Fig.6). The role played by of ultrasound was discussed.
2002, 18(06): 572-576
doi: 10.3866/PKU.WHXB20020621
Abstract:
Vinyl-functionalized MSU-X silicates were prepared by one-pot synthesis methodology at the pre-sence of Tx-15 and AEO9 surfactants respectively. The solids were characterized by XRD, FT-IR, 29Si MASNMR, HRTEM, SEM, N2 physisorption techniques. The surface morphology and textural properties of such materials varied with the synthesis mechanism and content of vinyl groups in the channel. The effects of the organic groups on the modified MSU-2 were investigated carefully. The vinyl-modified mesopore with 10％(x) VTES templated by AEO9 was of 3.1nm pore diameter, but that templated by Tx-15 displayed a bimodal mesoporous channels, in which the smaller pore size was about 3 nm, while the bigger one was in the range of 40～46 nm.
Vinyl-functionalized MSU-X silicates were prepared by one-pot synthesis methodology at the pre-sence of Tx-15 and AEO9 surfactants respectively. The solids were characterized by XRD, FT-IR, 29Si MASNMR, HRTEM, SEM, N2 physisorption techniques. The surface morphology and textural properties of such materials varied with the synthesis mechanism and content of vinyl groups in the channel. The effects of the organic groups on the modified MSU-2 were investigated carefully. The vinyl-modified mesopore with 10％(x) VTES templated by AEO9 was of 3.1nm pore diameter, but that templated by Tx-15 displayed a bimodal mesoporous channels, in which the smaller pore size was about 3 nm, while the bigger one was in the range of 40～46 nm.
