中央开耦合槽矩形双间隙谐振腔中的TM高次模

 用解析方法导出了中央开耦合槽矩形双间隙谐振腔中π-TM模式频率的本征方程和特性阻抗的计算公式,分析了耦合槽大小对几种π-TM模式频率和特性阻抗的影响。对TM₃₁₀模的具体计算结果显示,解析方法与模拟方法的计算结果符合得很好,可以用于计算谐振频率和特性阻抗。研究表明,耦合壁的厚度对π-TM模式频率的影响不大,耦合槽的大小和位置对谐振频率影响则较大。同时发现,在TM高次模双间隙腔中,出现了π₁模消失现象。     

温和条件下Pd/π-酸配体催化的芳基碘化物和烷基铟试剂的交叉偶联反应

过渡金属催化的偶联反应是构建C—C键的重要途径. 目前主要的催化剂为钯络合物, 且对于Csp²-Csp²报道的是最多的, 而Csp³相关成键的报道则相对少一些, 主要是因为其涉及的还原消除较慢. 我们曾发现π-酸类配体可以很好地促进Csp³-Pd-Csp²的还原消除, 这对于Csp³相关的成键具有重要意义. 报道了以膦烯烃、双烯化合物等π-酸化合物作为配体时, 在温和条件下高选择性地实现了钯催化的芳基碘化物和烷基铟试剂的交叉偶联反应, 构建Csp³-ArCsp²键. 其中伯碳和仲碳的烷基铟试剂均可以很好的兼容; 另外, 进一步的研究表明, 反应可以在敞口的条件下进行, 对水和氧气可以兼容, 并可以得到较高的产率.     

Design,synthesis and photoelectrical properties of diphenylamine-containing triphenylamine-based D-D-π-A-type fluorescence dyes

Available online A series of diphenylamine (DPA)-containing triarylamine-based D-D-π-A organic fluorescence dyes were designed under the guidance of theoretical calculations and then synthesized (cyanoacrylic acid, methylene malononitrile or isophorone served as the electron acceptor while ethylene served as the π-bridge). The results of theoretical calculations, electrochemical properties and optical properties tests indicated that the new dyes possessed high thermal stability, desirable HOMO levels and intramolecular charge transfer property. Some of them possessed high fluorescence quantum yields and performed very well as luminescent material as expected..     

Synthesis of pyrone-annulated 2-oxabicyclo[3.3.1]nonanes by palladium-catalyzed cyclization of 4-hydroxy-2-pyrones with allylic bisacetates

Cyclization of 4-hydroxy-2-pyrones with allylic bisacetates by a palladium catalyst is described. Pyrone-annulated 2-oxabicyclo[3.3.1]nonane derivatives were regioselectively produced from the reaction of 4-hydroxy-2-pyrones with 1,4-diacetoxy-2-cyclohexene at high temperature. The reaction would proceed via a migration of the π-allylpalladium intermediate.     

Ring-size controlled dimerization of synthetic zinc chlorophyll derivatives possessing a 1-azacycloalkyl group through mutual coordination of amino moiety to central zinc atom

Zinc methyl 3-devinyl-pyropheophorbides-a bearing a (1-azacycloalkyl)methyl group at the 3-position were prepared by chemically modifying naturally occurring chlorophyll-a. The azacyclobutylated molecules closely dimerized through double coordination of the 3¹-nitrogen atom to the central zinc atom in 1%(v/v) dichloromethane and hexane to give red-shifted visible absorption and reverse S-shaped circular dichroism (CD) bands. The azacyclopentyl analog formed similarly π–π interacted and A-ring overlapped dimers with relatively weakened and lengthened Zn–N bonds to show less split excitonic bands, and its cofacial and anti-parallel supramolecule giving S-shaped CD bands was inversely twisted by the insertion of a methylene group in the 1-azacycloalkyl moiety. One more methylene insertion as in the azacyclohexyl derivative induced a least coordination ability and no more dimerization, so the compound with the most sterically crowded 3¹-N was monomeric in the less polar organic solvent. Steric factor at around the 3¹-nitrogen atom controlled the dimerization and affected the supramolecular structure with excitonically coupling visible absorption and CD bands.     

Hexacoordinated Tetrel-Bonded Complexes between TF4 (T=Si,Ge, Sn,Pb) and NCH: Competition between σ- and π-Holes

In order to accommodate the approach of two NCH bases, a tetrahedral TF₄ molecule (T=Si, Ge, Sn, Pb) distorts into an octahedral structure in which the two bases can be situated either cis or trans to one another. The square planar geometry of TF₄, associated with the trans arrangement of the bases, is higher in energy than its see-saw structure that corresponds to the cis trimer. On the other hand, the square geometry offers an unobstructed path of the bases to the π-holes above and below the tetrel atom and hence enjoys a higher interaction energy than is the case for the σ-holes approached by the bases in the cis arrangement. When these two effects are combined, the total binding energies are more exothermic for the cis than for the trans complexes. This preference amounts to some 3 kcal mol⁻¹ for Sn and Pb, but is amplified for the smaller tetrel atoms.     

P型NFDE的(h_0,h,M_0)稳定性

本文将M0稳定性结合欢度量的概念推广到P型NFDE，并给出了稳定性的几个定理．     

Characteristic properties of large subgroups in primary abelian groups

SupposeG is an arbitrary additively written primary abelian group with a fixed large subgroupL. It is shown thatG is (a) summable; (b) σ-summable; (c) a Σ-group; (d) p^ω+1-projecrive only when so isL. These claims extend results of such a kind obtained by Benabdallah, Eisenstadt, Irwin and Poluianov,Acta Math. Acad. Sci. Hungaricae (1970) and Khan,Proc. Indian Acad. Sci. Sect. A (1978).     

A Generalization of <Emphasis Type="Italic">T</Emphasis>-Groups

This paper identifies a certain class of locally supersoluble groups (called soluble hall-T groups) which contains the soluble T-groups as well as the nilpotent groups. The main result states that the product of a normal soluble hall-T subgroup and a subnormal locally supersoluble subgroup is always locally supersoluble.AMS Subject Classification (1991): 20E25, 20F16, 20F19     

Magnetic Interactions in Insulating BEDT-TTF Salts

Inter-dimer magnetic interactions J in BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) salts in the Mott insulator regime are estimated from the intermolecular overlap integrals. The estimated J values are compared with the experimental results, and the stable spin alignment and the dimensionality of the spin systems are discussed.