Synthesis and Crystal Structure of (C6N3H18)2Ti4O4(C2O4)7·4H2O

The title compound (C6N3H18)2Ti4O4(C2O4)7(4H2O 1 (C13H22N3O18Ti2, Mr = 604.14) was synthesized by the reaction of Ti(SO4)2, H2C2O4(2H2O and N-(2-ammonioethyl)- piperazinium (AEPP) in aqueous solution. The single-crystal X-ray analysis has revealed that 1 crystallizes in the triclinic system, space group Pī with a = 9.1437(6), b = 11.4991(10), c = 11.6975(8)A, α = 96.2915(18), β = 107.998(3), γ = 104.276(4)°, V = 1110.35(14)A3, Z = 2, Dc = 1.807 g/cm3, F(000) = 618, μ = 0.815 mm－1, the final R = 0.0463 and wR = 0.1264 for 3718 observed reflections with I > 2σ(I). X-ray crystal-structure analysis suggests that compound 1 consists of [Ti4O4(C2O4)7]6－ anion and two protonated N-(2-ammonioethyl)piperazinium cations. The anions are linked into an infinite chain through Ti4O4(C2O4)8 by sharing the oxalates as bridging ligands.     

运用pH滴定法测定弱酸的电离常数

运用pH传感器和滴数传感器,采取pH滴定法测定了乙酸的电离常数和草酸的二级电离常数,分析了实验误差以及不宜选用此法测定中强酸的电离常数的原因。     

低温固相法制备高比表面积的纳米MgO

 以草酸和乙酸镁为原料,采用低温固相化学反应合成出前体MgC2O4·2H2O, 再通过焙烧得到纳米MgO. 采用X射线衍射、 N2物理吸附、透射电镜和热重-差热技术对前体和MgO样品进行了表征,并考察了焙烧气氛的影响. 结果表明,在流动干燥的氮气中520 ℃焙烧4 h后制得了比表面积高达412 m2/g的纳米MgO; 此MgO为面心立方结构,晶粒尺寸为4～5 nm, 粒子堆积成在一定程度上长程有序的介孔结构,并具有十分优良的抗高温烧结性能, 600和800 ℃焙烧2 h后,其比表面积仍分别高达357和153 m2/g.     

DFT study of the hydrogen bond strength and IR spectra of formic,oxalic, glyoxylic and pyruvic acids in vacuum,acetone and water solution

The molecular geometries of the possible conformations of formic, oxalic, glyoxylic and pyruvic acids have been fully optimized at DFT B3LYP/6‐311++G(d,p) levels of calculation in vacuum as well as in water and acetone solution. Solutions were treated according to the SCRF PCM approach but some formic acid–water and formic acid–acetone clusters as well as adducts of oxalic acid with two or four water molecules were also taken into account for testing the importance of specific solute–solvent effects. All the most stable isomers of the title compounds are characterized by weak intramolecular hydrogen bonds, whose strengths (E_HB) cannot be correctly estimated as stability difference between the open and chelate forms since the energy of the former isomer is, in turn, stabilized by a weak hydrogen bridge due to the formic acid moiety. Following the Rotation Barrier Method (RBM), proposed some years ago, E_HB in the examined molecules (gas phase) falls in the range of 18–22 kJ/mol for oxalic acid (9.6 kJ/mol for the c‐C‐t isomer), 16.8 kJ/mol for glyoxylic acid and 19.8 kJ/mol for pyruvic acid. Most of them disappear at all, or nearly at all, both in acetone and aqueous solution, in consequence of the solvent effect. The frequencies of the OH and C?O stretching modes, calculated according to the anharmonic oscillator model, are in very good agreement with the experimental literature data, where available. Copyright © 2009 John Wiley & Sons, Ltd.     

Mixed-ligand complexes of copper VII. Polarographic studies on copper-carboxylate-aminocarboxylate complexes

The formation constants of mixed-ligand complexes with hetero donors of the type CuAB where A is a carboxylic acid such as lactic acid or oxalic acid and B is an α−or β-amino acid are studied by polarography. The mixed-ligand stabilisation constant clearly indicates the preferred formation of copper(II) mixedligand complexes with hetero donors over homo donors. The other driving forces leading to the favoured formation of mixed-ligand complexes are also discussed.     

新型高硅Y(NHSY)沸石的研究:Ⅰ.NHSY沸石的制备

新型高硅Ｙ（ＮＨＳＹ）沸石的研究　Ⅰ．ＮＨＳＹ沸石的制备刘兴云，裴站芬，佘励勤，李宣文（北京大学化学系，北京１００８７１）关键词ＮａＹ沸石，骨架改性，化学脱铝，ＮＨＳＹ沸石，草酸为了提高用于制备裂化催化剂的Ｙ沸石的稳定性，必须对其骨架进行改性．实用的...     

Mechanism of Dealumination of NaY Zeolite with Oxalic Acid

RemovalofalundnumfromNaYzeolitewithacidisanimportantprocessinthemodificationofzeolite.ItisdifficulttoremovealundnumfromNaYzeolitedirectlywithacidwhilekeepinghighcrystallinity.Intheworkreportedhere,alundnumisremoveddirectlyfromNaYwithoxalicacidandthemodifiedzeolitekeepshighcrystallinity.Reactionconditions:CSBlreflux,acidaddedin3ondn,allowedtoreactfor3OAnn.CSB2reflux,acidaddedrapidly,allowedtoreactfor3Owhn.CS2525-C,acidaddedraPidly,allowedtoreactfor3Omin.CSA25"C,acidaddedin3omin,a1lowe…     

Preparation of Porous Alumina Film on Aluminum Substrate by Anodization in Oxalic Acid

Self-ordering of the cell arrangement of the anodic porous alumina was preared in oxalic acid solution at a constant porential of 40V and a temperature of 20℃. The honeycomb structure made by one step anodization method and two step anodization method is different. Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.     

在缓冲溶液中探究高锰酸钾与草酸的反应

以硫酸氢钠-硫酸钠缓冲溶液为反应介质,研究了温度、溶液pH、高锰酸钾浓度以及草酸浓度等因素对高锰酸钾与草酸反应的反应速率的影响。研究发现,升高温度、降低溶液pH（即增大氢离子浓度）以及增大草酸浓度均能加快反应速率,而高锰酸钾浓度对反应速率的影响规律性不强。     

Influence of electrolyte composition on photoluminescent properties of anodic aluminum oxide

Luminescent properties of anodic alumina fabricated in anodizing solutions containing oxalic, sulfuric, and phosphoric acids in addition to those modified by thermal annealing are investigated. Comparison of the obtained data shows that F⁺-centers are responsible for the luminescence band at 390 nm. The intense photoluminescence band of porous anodic alumina substrates at 450–500 nm is associated with oxalate anions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 2, pp. 208–212, March–April, 2008.