环己硅烷类液晶化合物的量子化学研究

运用AM1和PM3两种SCF-MO方法，通过能量梯度全优化计算，给出20种环己硅烷类（苯基乙烷系）液晶化合物的稳定几何构型、电子结构和基本性质．联系有机电子结构理论进行了细致的讨论．     

The Chemical Constituents from the Aerial Part of Rosa laevigata

Eleven chemical constituents were isolated from the ethyl acetate soluble fraction of the aerial part of Rosa laevigata Michx. These compounds include the Henze's ketol (16), diethyl malate (17), three γ-lactones (18-20), loliolide (21), p-coumaric acid (22), 6,7-dimethoxycoumarin (23) and three flavonoids (24-26). The new compounds 19 and 20 were determined to be the cis- and trans-isomers of ethyl 2-benzyl-3-hydroxy-5-oxo-3-furancarboxylate.     

Reactions of Ru3(CO)12 with Diphosphenes — A New Route to 50‐Electron Ru3P2 nido‐Clusters

The reaction of the symmetric diphosphene 2, 4, 6‐(CF₃)₃‐C₆H₂‐P=P‐C₆H₂‐2, 4, 6‐(CF₃)₃ 4 with Ru₃(CO)₁₂ led to the 50‐electron Ru₃P₂ nido‐cluster Ru₃(CO)₉[μ‐P‐C₆H₂‐2, 4, 6‐(CF₃)₃]₂ 5 , which in solution at room temperature displays hindered rotation of the aromatic rings about the C(aryl)—P bonds. The structure of 5 was determined by X‐ray crystal structure analysis; its Ru₃P₂ centre forms a distorted square pyramid with one ruthenium atom at the apex. One of the two C₆H₂(CF₃)₃ groups is also appreciably distorted. Temperature‐dependent ¹⁹F NMR studies of the [A₃M₃X]₂ spin system (A = M = CF₃, X = ³¹P) of 5 indicated a rotational barrier ΔG^≠ of 82.3 kJ mol^‐1 at 141 °C. The same Ru₃P₂ core was obtained by the reaction of the unsymmetric diphosphene Mes*‐P=P‐Mes 11 with Ru₃(CO)₁₂; hindered rotation about the C(aryl)—P bonds was also observed, in this case.     

Synthesis and properties of coumarin-derived organogelators

A new family of coumarin derivatives containing amide group with different alkyl chain lengths was synthesized and their properties as organogelators were evaluated. It was found that the organogelation abilities were not obviously affected by the alkyl spacer length of amide group. Helical morphologies formed either in nonpolar or high polar solvents by most of the gelators. Occurrence of reversible and stereoselective photodimerization of the gel formed by 4-(7′-coumarinoxy)-N-octadecylbutanamide (3a) in cyclohexane was confirmed by ¹H NMR, UV absorption, and fluorescence spectra. The photoreaction of the gel proceeded without any dissolution, but the drastic microscopic changes of gel morphologies accompanied with the irradiation were identified using SEM and AFM investigations.     

Circular dichroism of sesquiterpene-umbelliferone ethers and structure elucidation of a new derivative isolated from the gum resin “Asa Foetida”

The CD spectra of 16 naturally occurring sesquiterpene-umbelliferone ethers, including the complete set of farnesiferol A isomers with all acetates and 6-oxoderivatives, are reported over the significant wavelength range of 350–200 nm. 11 compounds were isolated from an Asa Foetida sample and 5 further derivatives, already known as natural products, were obtained by acetylation orJones oxidation. In addition, a new compound — kamolonol (14) — was isolated. Its structure is characterized by twofold methyl migration in the drimenol derived sesquiterpene moiety.¹H-NMR, MS, IR, UV, and CD data of the new compound are discussed.Herrn Prof. Dr.K. Schlögl mit den besten Wünschen zum 60. Geburtstag gewidmet.     

吸附/一级热解吸/气相色谱联用测定室内空气中的挥发性有机物

本文以高聚物TenaxTA动态吸附,一级热解吸/毛细管气相色谱法联用测定室内空气中的挥发性有机物。优化了热解吸温度和热解吸时间,建立了苯、甲苯、乙酸正丁酯、乙苯、对二甲苯、苯乙烯、邻二甲苯、正十一烷等8种典型有机污染物的外标定量曲线,各化合物线性范围为103,相关系数R为0.9983～0.9999,最低检出浓度可达2×10-4mg/m3;考察了方法的重复性、热解吸率和残留率,并分析了实际空气样品。     

(Nd1-xYx)3Fe27.31Ti1.69化合物的结构与磁性研究

制备了(Nd1-xYx)3Fe27.31Ti1.69(0≤x≤0.6)系列化合物,通过X射线衍射和磁性测量等手段研究了它们的结构和磁性.这些化合物均为Nd3(Fe,Ti)29型结构,A2/m空间群.化合物晶胞体积随Y含量增加而单调减少,居里温度Tc随Y含量增加略有降低,说明化合物的居里温度主要由Fe-Fe之间的交换相互作用所决定.温度为5K时,饱和磁化强度Ms随Y含量的增加而单调降低,与一个简单的稀释模型预期结果一致.所得化合物在低温下均发生自旋重取向,自旋重取向温度Tsr随Y含量增加而单调降低,从x=0时的232K减小到x=0.6时的121K.基于磁晶各向异性的研究结果确定了所得化合物的自旋相图.     

Bismuth(III) nitrate pentahydrate—a mild and inexpensive reagent for synthesis of coumarins under mild conditions

Bismuth(III) nitrate pentahydrate is found to be an efficient catalyst for the Pechmann condensation reaction of phenols and β-ketoesters under solvent-free conditions. The reaction protocol is simple and is followed by aqueous work-up leading to the formation of the corresponding coumarin derivatives in good yield and high purity.     

The Crystal Structures of Eu5Ge3 and EuIrGe2

Eu₅Ge₃ and EuIrGe₂ were prepared from the elements in tantalum tubes, and their crystal structures were determined from single crystal X-ray data. Eu₅Ge₃ adopts the structure of Cr₅B₃: I4/mcm, a = 799.0(1)pm, c = 1 536.7(1)pm, Z = 4, wR2 = 0.0421 for 669 F² values and 16 variables. The structure of Eu₅Ge₃ contains isolated germanium atoms and germanium atom pairs with a Ge? Ge distance of 256.0 pm. Eu₅Ge₃ may be described as a Zintl phase with the formulation [5 Eu²⁺]¹⁰⁺[Ge]^4?[Ge₂]^6?. Magnetic investigations of Eu₅Ge₃ show Curie-Weiss behaviour above 50 K with a magnetic moment of μ_exp = 7.6(1) μ_B which is close to the free ion value of μ_eff = 7.94 μ_B for Eu²⁺. EuIrGe₂ is isotypic with CeNiSi₂: Cmcm, a = 445.5(2) pm, b = 1 737.4(4) pm, c = 426.6(1) pm, Z = 4, wR2 = 0.0507 for 295 F² values and 18 variables. The structure of EuIrGe₂ is an intergrowth of ThCr₂Si₂-like slabs with composition EuIr₂Ge₂ and AlB₂-like slabs with composition EuGe₂ in an AB stacking sequence. Both slabs are distorted when compared to the symmetry of the prototypes. The Ge? Ge distance of 256.6 pm in the AlB₂-like fragment is comparable to that in Eu₅Ge₃.     

Synthesis and structural revision of naturally occurring ayapin derivatives

The synthesis of three highly oxygenated naturally occurring coumarins, 8-methoxy-6,7-methylenedioxycoumarin, 5-methoxy-6,7-methylenedioxycoumarin and 5,8-dimethoxy-6,7-methylenedioxycoumarin is described for the first time, together with a new method for the preparation of ayapin (6,7-methylenedioxycoumarin). Comparison of the spectroscopic data of the synthetic tetraoxygenated coumarin 5,8-dimethoxy-6,7-methylenedioxycoumarin with literature reports resulted in the structural revision of several natural coumarins. Two coumarins, both identified as 5,8-dimethoxy-6,7-methylenedioxycoumarin must have other structures, while the structure of another coumarin, described as the isomeric 7,8-dimethoxy-5,6-methylenedioxycoumarin has to be revised to 5,8-dimethoxy-6,7-methylenedioxycoumarin.