PREPARATION OF STRIPE-SHAPED DOMAIN STRUCTURE IN FERROELECTRIC LIQUID CRYSTAL AND THE FABRICATION OF SPATIAL LIGHT MODULATOR

The stripe-shaped domain (SSD) structure was prepared in the initial ferroelectric liquid crystal (FLC) alignment without the application of an external electric field, which was realized by the aligning layer modification through the doping of tin tetra-2, 4-dimethyl phenoxy phthalocyanine (SnPc) into the rubbed polyimide films. Atomic force microscopy was used to investigate the alignment films and the corresponding aligning ability was evaluated through the pre-tilt angle measurement. The memory capability and the contrast ratio of thus aligned SSFLC cells have been enhanced and improved with the appearance of the SSD structure. The electrically controlled 64×64 FLC spatial light modulator was fabricated using the improved ligning method, which proves valuable for the practical device fabrication.     

部花青染料与糖淀粉、羧甲基糖淀粉和环糊精包结络合的初步研究

对于糖淀粉(CMA)及环糊精(CD)与各种受物形成的包结络合物,其本质是非极性键合,即受物分子离开极性较大的体相,进入极性较小的宿主内穴,这种体相与内穴中极性的差异在很大程度上决定了宿主-受物包结络合物的稳定性.同时,宿主内穴所提供的低极性微环境也直接影响到内穴中受物的反应性.因此,对宿主内穴特性的研究是非常重要的.Bender曾通过脱酸反应速度的改变测得 CD 内穴的介电常数相当于二氧六环.我们也曾报道用     

疏水-亲脂作用对反应性的影响 Ⅲ.环糊精对碳氟表面活性剂的熵驱动包结以及亲脂作用对形成糖淀粉型包结物的贡献

用表面张力-浓度曲线法系统地研究了环糊精(CD)和羧甲基糖淀粉钠(Na-CMA)与H(CF_2)_(12)CO_2K(1),Cl(CF_2)_nCH_2CH_2N~+(CH_3)_3I~-[n=8(3),10(5)]和相应的碳氢表面活性剂(24和6)的相互作用。由于几何尺寸的限制,碳氟表面活性剂不能与α-CD形成包结络合物,但3与β-CD形成的包结络合物的稳定性远大于相应的碳氢受物4、3与β-CD的相互作用是熵驱动过程,而C_(12)H_(25)N~+(CH_3)_3I~-(6)则是焓有利的。与具有“预组织化”内穴的CD不同,糖淀粉的包结是与大分子从线团到螺旋构象变化的协同过程,由于缺乏宿主-受物间的亲脂相互作用,Na-CMA不能与所有的碳氟受物形成包结络合物。     

螺旋构象的微环境效应——羧甲基糖淀粉钠(Na-CMA)对各碘代N-烷基3-羟基吡啶羧酸酯水解的催化效应

本文在存在和不存在羰甲基糖淀粉钠盐(Na-CMA)的条件下对N-烷基吡啶羧酸酯(2—5)的水解进行了研究。在不存在Na-CMA时,以HPO_4~=和CH_3CO_2~-作为亲核试剂,4个受物的水解都遵循二级反应动力学。但当存在Na-CMA时,水解则随受物结构不同而各异,即2和3的水解不受加入Na-CMA浓度多少的影响,但具有长疏水链的受物4和5的表观水解速度常数k_(obs)与Na-CMA浓度的关系符合Michaelis-Menten饱和动力学,各种实验结果表明Na-CMA与受物形成了催化剂——受物的螺旋包结超分子络合物。超分子内催化(k_c/K_d)的效率与相应本体相中以CH_3CO_2~-为亲核试剂之催化碱水解速度常数k_2相比,对受物4和5分别为3.7×10~4和1.7×10~4倍。 活化参数的结果反映出4和5在螺旋内穴中所处地位的差异,对于4的水解,分子内催化是熵有利的,但是对于5则是活化焓项有利。活化自由能的减少与受物包结过程中释放的自由能相近,由此可能提供了通过络合能降低反应活化自由能的一个实例。     

MICROENVIRONMENTAL EFFECTS OF THE HELICAL CONFORMATIONS OF AMYLOSE AND ITS DERIVATIVES——THE FORMATION OF INCLUSION COMPLEXES WITH A SUBSTRATE BY AMYLOSE IN THE DMSO-H_2O MIXED-SOLVENT SYSTEM

The conformational behavior of amylose and the formation of helical inclusion complexesof amylose with a substrate, N-ethyl-4-hexadecyloxycarbonyl pyridinium iodide (1) -- asolvent-polarity probe, have been investigated in the DMSO--H_2O mixed-solvent system bymeans of surface tension, viscosity, UV, electrical conductance and ORD measurements. Thedecrease of the volume-fraction of DMSO, Φ_(DMSO) of the mixed-solvent system inducesconformational changes of the amylose from tight helices to loose and extended helicesinterrupted by short disordered regions. Such a transition is accompanied by abrupt changesof the viscosity and ORD curves. The mechanism of interaction between amylose and the substrate 1 also depends on thesolvent composition. When Φ_(DMSO) is larger than 0.70, the interaction of amylose with 1is apparently similar to those cases in which superhelices are formed between a macromo-lecule and some azo dyes; the latter are known to be bound exteriorly around the macro-molecular helices by oriented association. However, when Φ_(DMSO) begins to drop below0.70, the substrate molecules start to be bound in the helical cavities of the host and thussupramolecular inclusion complexes are formed. At Φ_(DMSO)<0.70, ORD shows a new nega-tive Cotton peak at a wavelength which coincides with the λ_(max) of 1 (276 nm). This implicatesinduced asymmetry for the achiral substrate 1 in a chiral microenvironment. Intrinsicdissociation constants (K_(d~*)) for the inclusion complexes can be obtained from the surface ten-sion- substrate concentration (σ-[1]) curves and the largest number of binding sites isfound to be below 30. The K_(d~*) values decrease with decreasing Φ_(DMSO), apparently inagreement with the results from conductance measurements. Presumably, the driving forcefor the transfer of the substrate molecules from the solvent-mixture bulk phase to the non-polar cavities of the host molecules comes from hydrophobic-lipophilic interactions.     

糖淀粉和环糊精催化的β-酮酸酯的去质子反应以及在糖淀粉体系中首次观察到的“位置效应”

在宿主-客体化学中,环糊精(CD)是受到最广泛研究的宿主之一.近年来,糖淀粉(A)及其衍生物也已被确认为一类新的宿主化合物.由于 A 和 CD 分子都由 C_1椅式构型的 D-葡萄糖残基所组成,A 的螺旋内穴应与 CD 的环状内穴相当类似.因此,比较同一反     

自组装成膜技术制备TiO2薄膜的XPS研究

采用自组装成膜技术制备里TiO2薄膜,应用X射线光电子能谱研究自组装膜及其氧化膜和淀积的TiO2薄膜，结果表明，硅烷偶联剂成功地组装在玻璃基片上，足够长时间的氧化对使端基（-SH）完全氧化为磺酸基，淀积在基片上的TiO2膜牢固性好，平均膜厚在10nm．淀积膜中的钛可能有几种不同的氧化态，不同的酸度影响TiO2的淀积效果     

双波长系数补偿法同时测定铜铁

研究了以5-Br-PADAP为显色剂,双波长系数补偿法同时测定铜、铁.根据试验结果,选择铜测定波长对为542/570nm,铁测定波长对为560/512nm.对混合物中铜、铁测定,本法比相应的双波长法灵敏度高,铜提高87%,铁提高38%.铜线性范围为0.5～15.0μg/25ml,铁线性范围为0.5～15.0μg/25ml,应用于食品中铜、铁的测定,均得到较满意的结果.