Dynamic and electrooptical properties of FH…F and FH…N hydrogen bridges

The dynamic and electrooptical parameters of the hydrogen bridges in (HF)₂, FH…FCD₃, FH…NCH, and FH…NCCH₃ complexes were calculated by the MINDO/3 method. Relationships between these parameters have been found. These parameters for the F−H…Y bridges mainly coincide with the relationships previously established for the hydrogen O−H…Y bridges. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1067–1069, May, 1997.     

冠醚PVC膜锂离子选择电极的研究

以冠醚为中性载体的PVC膜锂电极的研究,近年来十分活跃,所用的冠醚有16-冠、14-冠-4、12-冠-4等,但这些电极受一价离子的干扰严重,线性范围在10°～10~3M LiCl之间,Kimura等和黄枢等分别以长链烷基取代14-冠-4和苯并12-冠为活性物质研制的锂电极,抗一价离子的干扰性能有较大提高。为了探讨冠醚结构对电极能的影响,我们合成了七个新型冠醚Ⅰ—Ⅶ,并以它们为中性载体,研制了PVC膜锂离子择电极。     

手性四氢咪唑衍生物的合成及与醛的反应

用含有C2对称轴的手性1，2－二胺同n-Bu3Sn取代的醛类化合物反应，制得了 具有手性辅助基的烯醇化物等价体。再利用金属交换反应将生成的烯醇负离子同醛 类化合物进行缩合反应，制得具有立体选择性的羟基化合物。     

Synthesis and ionic conductivity of mixed substituted polysiloxanes with oligoethyleneoxy and cyclic carbonate substituents

New comb polysiloxanes with mixed substituents were synthesized by hydrosilylation of PMHS with 4-allyloxymethyl-[1,3]dioxolan-2-one and tri(ethylene glycol) allyl methyl ether (AMPEO₃). The effect of the incorporation of carbonate groups on ionic transport, viscosity and thermal properties has been investigated. When doped with lithium bis(trifluorosulfonyl) imide, LiTFSI, the mixed substituted polysiloxane polymers with varying carbonate content all exhibited conductivity higher than those for the polysiloxanes with pure carbonate or pure oligoethyleneoxy substituents. The maximum ambient conductivity in this series was 1.62× 10⁻⁴ S/cm, occurring for the polymer containing 8.5% polar carbonate groups at a doping level of EO/LiTFSI = 15. The impedance measurement results showed that polymers containing larger amounts of carbonate groups exhibited lower conductivity, probably because of their increased viscosity and higher glass transition temperature. The conduction mechanism for these new comb polymers obeys free volume theory, as indicated by conductivity data fit to the VTF equation. We dedicate this paper to Professor Dick Jones, polysilane pioneer and valued friend.     

Trialkylhydridoalanate RxR′3-xAlH⊖ [R = CMe3; R′ = CH(SiMe3)2]

Trialkylhydridoalanates R_xR′_3?xAlH^? [R = CMe₃; R′ = CH(SiMe₃)₂] The very strong base tert-butyl lithium reacts in the presence of chelating tetramethylethylendiamine with the aluminium organyls Al[CH(SiMe₃)₂]₂CMe₃ 1 and Al[CH(SiMe₃)₂](CMe₃)₂ 2 not under proton abstraction from the C? H acidic elementorganic substituent, but under β-elimination and addition of the thereby formed LiH to the coordinatively unsaturated aluminium atom. Two alanates — [Hal{CH(SiMe₃)₂}₂CMe₃]^? 3 and [HAl{CH(SiMe₃)₂}(CMe₃)₂]^? 4 each with Li(TMEDA)₂^⊕ as counterion — were isolated; they exhibit separate anions and cations in solid state as shown by a crystal structure determination on 3 . In absence of the chelating amine tert-butyl lithium decomposes under the catalytic effect of the aluminium compound to LiH, which does not add to aluminium and precipitates in a reactive form.     

Determination of fluoride after direct separation from acid medium by collection of its volatile compounds

A method is proposed for determination of fluoride by separation in acid medium followed by ion-selective electrode measurement. The separation is done at temperatures up to 200 °C, without any previous treatment of the sample, in a PTFE reactor designed to ensure the complete absorption of volatile fluoride compounds. The distillation variables (temperature, time and acid concentration) have been optimized and the interference of other various species in the separation step has been studied. The method has been applied to geological samples. The results obtained are statistically satisfactory.     

锐钛矿光催化降解苯酚:氟离子吸附的影响大于磷酸根

已知氟离子和磷酸根能加快锐钛矿和P25 TiO₂光催化降解苯酚等有机物，但作用机理仍存在争议.合成了不含无机阴离子的锐钛矿，并在其表面沉积0.52 wt% Pt（Pt/TiO₂）.在初始pH 5.2的水溶液中，99%的氟离子和磷酸根分别为F^-和H₂PO₄^-.加入0.1～30 mmol/L阴离子，苯酚的光催化降解速率常数（k_obs）都增大，证实了氟离子和磷酸根均具有正效应.有趣的是，k_obs增加倍数均与阴离子吸附量呈线性关系，其中氟离子的斜率大于磷酸根，而Pt/TiO₂的斜率大于TiO₂.这表明阴离子的正效应源于吸附于固体表面的阴离子，并且氟离子的活性大于磷酸根.（光）电化学测试表明，氟离子和磷酸根分别抑制和促进O₂还原，但它们都促进苯酚氧化.此外，氟离子和磷酸根分别使TiO₂平带电位移动-159 mV和89 mV.前者有利于TiO₂价带与苯酚发生轨道重叠，后者有利于TiO₂导带分别与O₂发生轨道重叠，进而加快界面电荷转移.由于阴离子广泛存在，该结果将有助于半导体光催化的机理研究及其环境应用.     

Formation of Organolithium Hetero‐Aggregates [Li4Ar2(nBu)2] (Ar=C6H4CH(Me)NMe2‐2) during the Directed ortho‐Lithiation of [1‐(Dimethylamino)ethyl]benzene

(R)‐[1‐(Dimethylamino)ethyl]benzene reacts with nBuLi in a 1:1 molar ratio in pentane to quantitatively yield a unique hetero‐aggregate ( 2 a ) containing the lithiated arene, unreacted nBuLi, and the complexed parent arene in a 1:1:1 ratio. As a model compound, [Li₄(C₆H₄CH(Me)NMe₂‐2)₂(nBu)₂] ( 2 b ) was prepared from the quantitative redistribution reaction of the parent lithiated arene Li(C₆H₄CH(Me)NMe₂‐2) with nBuLi in a 1:1 molar ratio. The mono‐Et₂O adduct [Li₄(C₆H₄CH(Me)NMe₂‐2)₂(nBu)₂(OEt₂)] ( 2 c ) and the bis‐Et₂O adduct [Li₄(C₆H₄CH(Me)NMe₂‐2)₂(nBu)₂(OEt₂)₂] ( 2 d ) were obtained by re‐crystallization of 2 b from pentane/Et₂O and pure Et₂O, respectively. The single‐crystal X‐ray structure determinations of 2 b – d show that the overall structural motifs of all three derivatives are closely related. They are all tetranuclear Li aggregates in which the four Li atoms are arranged in an almost regular tetrahedron. These structures can be described as consisting of two linked dimeric units: one Li₂Ar₂ dimer and a hypothetical Li₂nBu₂ dimer. The stereochemical aspects of the chiral Li₂Ar₂ fragment are discussed. The structures as observed in the solid state are apparently retained in solution as revealed by a combination of cryoscopy and ¹H, ¹³C, and ⁶Li NMR spectroscopy.     

合成CFC-12替代物HFC-134a用CrF_3/AlF_3催化剂的研究 Ⅳ.AlF3基催化剂的制备及性能

本文探讨了γＡｌＦ３的热稳定性和酸性以及活性组分Ｃｒ３＋含量与活性的关系．考察了研制的ＡｌＦ３基催化剂的活性、稳定性及再生性，并对催化剂反应前后的结构进行比较．结果表明，催化剂的强酸中心是ＨＣＦＣ１３３ａ氟化生成ＨＦＣ１３４ａ的活性中心，催化剂晶格的氟离子参与了氟氯交换反应．ＡｌＦ３基催化剂具有高的活性和稳定性，在３５０℃，经２４００ｈ连续运行后，催化剂的晶相结构及比表面积未发生明显的变化．催化剂有较高的热稳定性，在４００℃反应８００ｈ催化剂仍具有一定的活性（３０％）．催化剂结炭失活可在３５０℃通空气或空气与ＨＦ的混合气进行再生     

Eu^2＋和Ce^3＋激活的BaYF5荧光性质

本文讨论了BaYF_5中Eu~(2 )和Ce~(3 )的光谱特征及浓度对光谱的影响。Eu~(2 )和Ce~(3 )均表现为d—f跃迁的特征激发和发射。由于Eu~(2 )—Eu~(2 ),Ce~(3 )—Ce~(3 )能量迁移的存在,两者猝灭浓度偏低,其猝灭机理为偶极-偶极相互作用。根据BaYF_5基质中Eu~(2 )和Ce~(3 )的能级关系,发现Ce~(3 )对Eu~(2 )的发射具有明显的敏化作用。其机理主要为非辐射多极子作用,但也存在辐射传递。