Chemical Research in Chinese Universities

Mild Hydrothermal Synthesis, Characterization and Properties of Na₅Ce(PO₄)₃, Na₃Yb₂(PO₄)₃·H₂O and Na_5-2xYb₂xCe_1-x(PO₄)₃·yH₂O

XU Yao-hua, WANG Dan, FENG Shou-hua, PANG Wen-qin, YUE Yong

2000, 16(4): 287-300.

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Novel phosphates, Na_5-2xYb₂xCe_1-x(PO₄)₃·yH₂O(x=0-1, y=0-1), were synthesized under mild hydrothermal conditions at 240℃ with Ce(SO₄)₂·H₂O, Ce(SO₄)₂·2(NH₄)₂SO₄· 4H₂O, CeO₂, Yb₂O₃, 85 % H₃PO₄ and NaOHas the starting materials.The products were sensitively influenced by the pHvalue of the systems and reaction temperature.Under an acidic condition, CePO₄ was the product at 240℃, in which Ce(Ⅳ ) species was reduced to Ce(Ⅲ) species.Under a weak basic condition, Na₂Ce(PO₄)₂·0.79H₂Owas produced.Under a medium basic condition, the expected compound Na₅Ce(PO₄)₃ was the product.Under a basic condition, CeO₂ was the final product, amorphous phase was also produced in some cases.The structure of the compounds were investigated by X-ray diffraction, SEM, IR, Raman, ³¹P MAS NMR and XPS spectroscopies.To determine the valence of Ce in the compound, EPRand DRSof the compound were also recorded.The thermal properties of the compounds were determined with DTA-TGanalysis.Na₅Ce(PO₄)₃ was decomposed into Na₃Ce(PO₄)₂, Na₄P₂O₇ and O, at 694℃, in which Ce(Ⅳ) was reduced to Ce(Ⅲ) species.Na₃Yb₂(PO₄)₃·H₂O lost water and was transferred into a new phase at a high temperature 682℃.The thermal stability of Na_5-2xYb₂xCe_1-x(PO₄)₃·yH₂O could be improved by increasing x value.When x=0.54, the compound was stable even at the temperature ca.1000℃.The ionic conductivities of the compounds were increased when the amount of Yb in the compound was increased and when x=0.33, it reached the highest value (σ_300℃= 3.96 ×10^-6 S·cm^-1).

Infrared and MAS NMR Spectroscopic Studies of Al₁₈B₄O₃₃

YOU Hong-peng, HONG Guang-yan, ZENG Xiao-qing, DENG Feeng, YE Zhao-hui

2000, 16(4): 301-305.

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The IRspectrum and ¹¹B and ²⁷Al MAS NMR spectra of Al₁₈B₄O₃₃ are presented and discussed in relation to the possible existence of boron atoms substituting for aluminum atoms.The IRspectrum shows that the strong vibrations of the BO₃ groups are present in the 1500～1200 cm^-1 region, and very weak bands of BO₄ units are present in the region from 1000 to 1100 cm^-1.¹¹B MAS NMR spectrum indicates that the strong signal for BO₃ units appears in the region from δ+5 to δ+20, and the very weak signal for BO₄ units is at about δ- 1, while ²⁷Al MAS NMR spectrum shows five peaks at about δ+62, +42.1, +14, -4.7 and -6.4, originating from AlO₄, AlO₄, AlO₅, AlO₆ and AlO₆, respectively.These results reveal that there are minor BO₄ units in Al₁₈B₄O₃₃, indicating that a small amount of Batoms substitute for Al atoms in the 4-fold coordination.

Studies on the Synthesis, Properties and Preparation Methods of Zeolite ZK-4

ZHAO Zhen-hua, YIN Du-lin

2000, 16(4): 306-312.

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A zeolite designated as ZK-4 was synthesized hydrothermally in the system (TMA)₂ONa₂O-Al₂O₃- SiO₂- H₂Oat 80 - 100℃ with tetramethylammonium hydroxide as an organic templating agent.The pure zeolite ZK-4 could be prepared by using the mother liquor obtained after filtration as the source of templating agent.The effect of some synthetic conditions such as the amount of tetramethylammonium hydroxide used, n [ (TMA)₂O + Na₂O] /n (Al₂O₃) ratio, n (SiO₂)/n(Al₂O₃) ratio and crystallization time, etc.on the crystalline phase of the product was investigated.When the following molar ratios of the reaction mixture, n (SiO₂)/n (Al₂O₃)₄-10, n[(TMA)₂O+Na₂O]/ n (Al₂O₃ ) > 7, n (Na₂O)/n (Al₂O₃)=0.5-2.0, n (H₂O)/ n(Al₂O₃)=80-450, were used, pure zeolite ZK-4 could be obtained.The synthetic products were characterized by X-ray powder diffraction, atomic absorption spectrophotometry (AAS), adsorption measurement, thermogravimetric analysis(TGA), and 29Si magic angle spinning nuclear magnetic resonance technique.Zeolite ZK-4 has a higher thermal stability than sodium zeolite Adue to higher n(Si)/n(Al) ratio of zeolite ZK-4.

Spin Trapping of the Phosphorus-centered Radicals Generated from Hydrogen Abstraction Reaction by 2,2-Diphenyl-1-picrylhydrazyl

Yoshimi Sueishi, Yuko Nishihara

2000, 16(4): 313-319.

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Two kinds of the phosphorus-centered radicals produced from hydrogen atomion by 2, 2-diphenyl-1-picrylhydrazyl(DPPHwere trapped by N-tert-butyl-α-phenylnitrone(PBN) and 5, 5-dimethyl-1-pyrroline N-oxide (DMPO), and investigated by means of EPRspectroscopy.The spin adducts with a characteristic hyperfine coupling constant(hfcc) caused by a phosphorus atom were observed.Based on the hfcc values caused by the phosphorus and hydrogen atoms, the con formational positions of the adducts trapped by PBN and DMPO are discussed.

An Efficient System TiCl₄-Al for the Homocoupling Reaction of Aromatic Aldehydes

LI Ting-you, WANG Li-ping, CUI Wei, ZHAO Jian-zhang, WANG Zong-mu

2000, 16(4): 320-323.

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The reduction of TiCl₄(THF)₂ with Al in CH₂Cl₂ gave a green solution of [Ti₂(μ-Cl)₂Cl₄· (THF)₄] (1) which was found to promote the reductive homocoupling of aromatic aldehydes to yield symmetrical 1, 2-diols with high diasterepselectivities.

Synthesis of a Soluble Diacetylene with Phenylimidazole Ring

WANG Jiang-hong, CAO Ya-an, CAO Chang-sheng, SHI Yan-hui, SHONG Qing, WANG Li-jun, YAO Jian-nian

2000, 16(4): 324-327.

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6-(2-Methyl-4-phenyl)-N-imidazole-2, 4-hexadiyn-1-ol was synthesized in a good yield by asymmetric coupling, and the corresponding intermediates were also prepared.The diacetylene monomer could be dissolved in common organic solvents.In addition, all kinds of conditions were also discussed effectively improving the formation of the diacetylene monomer.

Energy Band Structure of Alq₃/TCAQ Heterostructure Complex Film Determined by Surface Photovoltage Spectroscopy(SPS)

CAO Ya-an, SONG Qing, MENG Qing-ju, CAO Chang-sheng, CHEN Chun-hai, BAI Yu-bai, LI Tie-jin, YAO Jian-nian

2000, 16(4): 328-333.

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8-Hydroxyquinoling aluminum (Alq₃) and 11, 11, 12, 12-tetracyano-9, 10-anthraquino dimethane(TCAQ) monolayer films and their heterostructure complex films were prepared by a vacuum deposition method.By means of surface photovoltage spectroscopy (SPS) and electric field-induced surface photovoltage spectroscopy (EFISPS), the band gaps of TCAQ and Alq₃ monolayer films and the properties of the Alq₃/TCAQ bilayer film were investigated.By analysing the mechanism and the results of the SPSand the EFISPS, a reasonable energy band structure of the Alq₃/TCAQ complex film was roughly determined.

Studies on Ion-molecule Reaction of Disubstituted Benzene with Ion System of Acetyl Chloride in Gas Phase

LI Zhi-li

2000, 16(4): 334-340.

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The ion-molecule reactions of disubstituted benzenes with the ion system of acetyl chloride under the chemical ionization condition were examined and the fragmentation reactions of the adduct ions formed by the ion-molecule reactions were studied by using collision-induced dissociation technique.It was found that the electron-releasing groups favored the adduct reactions and the electron-withdrawing groups did not.The position and properties of substituting groups had an effect on the relative abundance of the adduct ions.The fragmentation reaction of the adduct ions formed by ortho-benzene diamine with the acetyl ion was similar to the reductive alkylation reaction of amine in condensed phase.

FT-Infrared and FT-Raman Spectroscopic Studies of Complexes (C₅H₅)₂TiCl₂,(C₅H₄Me)₂TiCl₂ and (C₅HMe₄)₂TiCl₂

JIANG Shi-mei, ZHANG Ping, WANG Yue

2000, 16(4): 341-346.

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The FT-IR and FT-Raman spectra of complexes (C₅H₅)₂TiCl₂(Ⅰ), (C₅H₄Me)₂TiCl₂ (Ⅱ) and (C₅HMe₄)₂TiCl₂(Ⅲ) have been obtained and discussed.The FT-Raman spectral data pro- vide some new vibrational information about complexes (Ⅰ), (Ⅱ) and (Ⅲ).The assignments of cyclopentadienyl vibrational modes and skeletal vibrational modes have been made.

A Thermochemical Study of the Reaction of Lanthanum Nitrate with Alanine

LI Qiang-guo

2000, 16(4): 347-350.

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The standard molar reaction enthalpy of the solid-solid coordination reaction La(NO₃)₃·6H₂O (s) +4Ala(s) (Ala is Alanine)=La(NO₃)₃·(Ala)₄·H₂O(s) + 5H₂O(1) was studied by using classical solution calorimetry.The molar dissolution enthalpies of the reactants and the product of the solid-solid coordination reaction in₂ mol/L HCl were measured by using an isoperibol calorimeter.From the results and other auxiliary quantities, the standard molar formation enthalpy of [La (NO₃)₃·(Ala)₄·H₂O, s, 298.15 K] has been determined to be

[La(NO₃)₃·(Ala)₄·H₂O, s, 298.15 K]=-3864.248 kJ/mol.

Performance of Hyperspherical Harmonic Expansionon the Low-lying P and D States of Helium Atom

WANG Yi-xuan, ZHUANG Bing-you, LIU Cheng-bu

2000, 16(4): 351-355.

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The wave functions of the n_1,3p (n=2, 3, 4) and the n_1,3D (n=3, 4, 5) low-lying states of the helium atom are expanded into the complete sets of the symmetrically adapted basis functions from hyperspherical harmonic functions in the angle part and of generalized Laguerre functions in the radial part respectively, and are then augmented by the simplest type of Jastrow correlation factor to incorporate electron-nucleus cusp only.The excellent agreement between the present nonrelativistic eigen-energies and those from the sophisticated configuration interaction (CI) method for the examined states indicates that the hyperspherical harmonic method can also be applied to the Pand the Dexcited states of the helium atom.

Miscibility of Semi-flexible Thermotropic Liquid Crystalline Copolyesteramide with Polyamide 66

XIE Xiao-Lin, TJONG S. C., LI R. K. Y.

2000, 16(4): 356-362.

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Liquid crystalline polymer-polyamide 66 (LCP/PA66) blends were compounded by using a Brabender mixing followed by compression moulding.The LCPemployed was a semi-flexible liquid crystalline copolyesteramide based on 30% (molar fraction ) of p-amino benzoic acid (ABA ) and 70% (molar fraction) of poly (ethylene terephthalate) (PET).The LCP/PA66 blends were investigated in terms of the thermal and dynamic mechanical properties.It was found that PA66 and LCPcomponents of the blends are miscible in the molten state, but are partially miscible in the solid state.The inclusion of the semi-flexible LCPinto PA66 retards the crystallization rate of PA66.Furthermore, the melting temperature and the degree of crystallinity of PA66 are reduced considerably due to the LCP addition.

Studies on the Condensed Structure of Vacuum Cast Atactic Polystyrene Films

WANG You, HE Chu-ning, SHEN Jing-shu, WU Li-heng, SONG Qing

2000, 16(4): 363-368.

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The condensed structure of atactic-polystyrene (a - PS ) films cast from the solutions of differ- ent concentrations in dichloromethane under vacuum and atmospheric conditions was studied by differential scanning calorimetry(DSC).It was found that only under vacuum evaporating conditions did the endothermic peak in the DSCcurves of a-PSfilms depend on the concentration of the a-PSsolution.For the samples cast from the solution of concentration below 0.010 g/mL, no endothermal peak was observed, but for those cast from the solution of concentration above 0.020 g/mL, obvious endothermal peaks appeared.The onset of the endothermal peak is correlated with the critical overlapping concentration c^* (0.010-0.020 g/mL), which is in agreement with the theoretically calculated one (C^*_cal=0.014 g/mL).

Pig Liver Esterase-catalyzed Hydrolysis of Three Diesters of meso-Bicyclic Dicarboxylic Acid and Three Tetraesters of Tetrahydrofuran-2,3,4,5-tetracarboxylic Acid

MA Guang-En, Tamm Ch.

2000, 16(4): 369-374.

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Three diesters of exo- syn-meso-oxabicyclo (2, 2, 1)-hept-5-ene-2,3-dicarboxylic acid and three tetraesters of tetrahydrofuran-2, 3, 4, 5-tetracarboxylic acid were synthesized and tested with enantioselective hydrolysis catalyzed by pig liver esterase(PLE).The results of the PLEcatalyzed hydrolysis were discussed.

Synthesis and Structure of a Mixed Phosphine- Thiolato Polymer with a Linear Chain Network [Ag₂(μ₂-dppe)₃ (S-mbo)₂]_n·2nDMF[dppe = 1,2-Bis(diphenylphosphino) ethane, Hmbo=2-Mercaptobenzoxazole]

DENG Liang-rong, WANG Xiu-jian, XIAO Wen, ZHANG Hua-xin, SU Cheng-yong, KANG Bei-sheng

2000, 16(4): 375-377.

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