Electrochemically time-dependent oxidative coupling/coupling-cyclization reaction between heterocycles: tunable synthesis of polycyclic indole derivatives with fluorescence properties

Science China Chemistry - A mild and practical protocol for selectively time-dependent dehydrogenative C-C coupling, as well as tandem coupling-cyclization reaction between indoles or/and other...     

Exploration of the sum of flexoelectric coef ficients of nematic liquid crystals

We present a theoretical calculation of the dependence of reflectivity Rpp of the improved fully leaky waveguide geometry,which comprises pyramid,matching fluid,and strongly anchored hybrid aligned nematic liquid crystal(NLC) cell on the internal angle.The calculation is based on the multi layer optical theory and the elastic theory of liquid crystals.For different sums of flexoelectric coefficients e11 and e33,the curve of Rpp moves a distance to the left or the right relative to the case of ignoring the flexoelectric effect and the distance of the movement varies with different flexoelectric coefficients.Consequently,the sum of flexoelectric coefficients can be explored by measuring the distance of the movement.     

草酸在α-Fe_2O_3上吸附的磁性研究

α—Fe_2O_3是多种工业催化剂的主要成分,有反铁磁结构的特殊性.张和Matijevie的实验曾经发现,草酸在均匀α-Fe_2O_3胶体粒子上的吸附随温度的升高而增加,这可能暗示着草酸从物理吸附向化学吸附的过渡.考虑到磁学测量需要更为明显的表面效应,我们制备了较小的α-Fe_2O_3粒子,并测定其吸附草酸前后的磁化率变化。     

指导创新学习需要树立几个意识

基础教育课程改革的浪潮滚滚而来，给我们的教学带来了生机与活力．目前，教师的教学观念正在逐步更新，学生的学习方式也随之改变，课堂教学的成效有了显著的提高．然而，在自主、合作、探究的“热闹”背后，也透露出了浮躁、盲从和形式主义的倾向，有的甚至刻意回避教师的“主导”作用．今年6月，胡锦涛同志在两院院士大会上的讲话指出：“在尊重教师主导作用的同时，更加注重培养学生的主动精神，鼓励学生的创造思维．”这一讲话为我们广大教师指导学生创新学习指明了方向．要构建富有成效的创新学习，真正激活学生内在的情感和思维，发挥教师的主导作用，应树立几个意识．     

Structure and aggregation behavior of cobalt-di(2-ethylhexy1)-phosphoric acid complexes in solvent extraction systems

Ｔｈｅｓｏｌｖｅｎｔｅｘｔｒａｃｔｉｏｎｏｆｃｏｂａｌｔｗｉｔｈｏｒｇａｎｏｐｈｏｓｐｈｏｒｕｓａｃｉｄｉｃｅｘｔｒａｃｔａｎｔｓｉｓｃｈａｒａｃｔｅｒｉｚｅｄｂｙｉｔｓｈｉｇｈｅｒｅｘｔｒａｃｔｉｏｎｓｅｌｅｃｔｉｖｉｔｙｔｈａｎｎｉｃｋｅｌｆｒｏｍａｑｕｅｏｕｓｓｏｌｕｔｉｏｎｓ[1].Ｔｈｅｅｘｔｒａｃｔａｂｉｌｉｔｙａｎｄｓｅｌｅｃｔｉｖｉｔｙｏｆｍｅｔａｌｉｏｎｓａｒｅｃｌｏｓｅｌｙｒｅｌａｔｅｄｔｏｔｈｅｃｏｏｒｄｉｎａｔｉｏｎｓｔｒｕｃｔｕｒｅｏｆｍｅｔａｌｓｗｉｔｈｅｘｔｒａｃｔａｎ…     

Synthesis of Chiral 1,4‐Benzodioxanes and Chromans by Enantioselective Palladium‐Catalyzed Alkene Aryloxyarylation Reactions

A highly enantioselective alkene aryloxyarylation led to the high‐yielding formation of a series of 1,4‐benzodioxanes, 1,4‐benzooxazines, and chromans containing quaternary stereocenters with excellent enantioselectivity. The sterically bulky and conformationally well defined chiral monophosphorus ligand L4 or L5 was responsible for the high reactivity and enantioselectivity of these transformations. The application of this method to the synthesis of the chiral chroman backbone of α‐tocopherol was demonstrated.     

Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organo-phosphorus and naphthenic acid)

Three acidic extractants (Ⅰ) di(2-ethylhexyl) phosphoric acid (HDEHP),(Ⅱ) 2-ethylhexyl phos-phonic acid mono-2-ethylhexyl ester (KEHPEHE) and (Ⅲ) naphthenic acid were employed in preparing the samples for the characterization of the coordination structure of lanthanlde-extractant complexes and the physicochemical nature of aggregates formed in the organic diluent of the solvent extraction systems.Photo correlation spectroscopy (PCS) re-suits on the aggregates formed by the partially saponified HDEHP in n -heptane showed that the hydrodynamic radius of the aggregates was comparable to the molecular dimensions of HDEHP.The addition of 2-octanol into the diluent,by which the mixed solvent was formed,increased the dimensions of the corresponding aggregates.Aggregates formed from the ianthamde ions and HDEHP in the organic phase of the extraction systems were found very unstable.In the case of naphthenic acid,PCS data showed the formation of w/o microemulsion from the saponified naphthenic acid in the mix     

复杂流体的聚集态结构,性质及应用

综合报道了油－水、油－油分散体系中中各种聚集体，如胶团，微乳状液、凝胶、Ｌｉｅｓｅｇａｎｇｒｉｎｇ及分形图形等的形成机理，结构和特性，以及流体中聚集结构的形成在实际生产中的意义。     

Catalytic Asymmetric Dearomatization by Visible‐Light‐Activated [2+2] Photocycloaddition

A novel method for the catalytic asymmetric dearomatization by visible‐light‐activated [2+2] photocycloaddition with benzofurans and one example of a benzothiophene is reported, thereby providing chiral tricyclic structures with up to four stereocenters including quaternary stereocenters. The benzofurans and the benzothiophene are functionalized at the 2‐position with a chelating N‐acylpyrazole moiety which permits the coordination of a visible‐light‐activatable chiral‐at‐rhodium Lewis acid catalyst. Computational molecular modeling revealed the origin of the unusual regioselectivity and identified the heteroatom in the heterocycle to be key for the regiocontrol.