苯基-[雌(甾)-17β-醇-3]-偶氮化合物(PED)在聚甲基丙烯酸甲酯薄膜中的光化学异构化反应研究

本文研究了PED偶氮化合物在聚甲基丙烯酸甲酯固体介质中的光化学顺反异构化反应。对此种体系在π,π^*和n,π^*激发条件下光化学顺反异构化的量子产率、光稳态组成以及所在聚合物体系中的自由体积分布等的测定方法和原理进行了详细的介绍。这些方法对其它类似的光致变色体系同样也是适用的。     

Simulation of Incompressible Flows with Coupled FEM/EFG shape functions

A method for the simulation of incompressible flows is described which is able to handle geometrically complex situations, such as those including moving and rotating objects in the flow field. In these situations, standard meshbased methods such as the finite element method (FEM) may fail if a suitable mesh can not be maintained at reasonable cost throughout the simulation. The proposed method introduces the desirable features of meshfree methods in parts of the domain where the mesh generates problems. This is realized by coupling FEM and element-free Galerkin (EFG) shape functions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Lithiated Stannasilanes – Building Blocks for Monocyclic Si–Sn Rings

Dilithiated di(stannyl)oligosilanes (^tBu₂Sn(Li)– (SiMe₂)_n–Sn(Li)^tBu₂; 4 , n = 2; 5 , n = 3) were synthesized by the reaction of lithium diisopropylamide (LDA) with the α,ω‐hydrido tin substituted oligosilanes (^tBu₂Sn(H)– (SiMe₂)_n–Sn(H)^tBu₂; 1 , n = 2; 2 , n = 3). Surprisingly, the reaction of 1 and 3 (^tBu₂Sn(H)–(SiMe₂)₄–Sn(H)^tBu₂) with LDA resulted not in the formation of the lithiated compound, but what one can find is the formation of the 5,5‐ditert.butyl‐octamethyl‐1,2,3,4‐tetrasila‐5‐stannacyclopentane ( 8 ) (n = 4) in addition to the expected product 4 (n = 4) and the 3,3,6,6‐tetratert.butyl‐octamethyl‐1,2,4,5‐tetrasila‐3,6‐distannacyclohexane ( 7 ) (n = 3). Reactions of 4 and 5 with dimethyl and diphenyldichlorosilanes yielding monocyclic Si–Sn derivatives ( 9 – 11 ) are also discussed. The solid‐state structures of 7 and 11 were determined by X‐ray crystallography.