Inner-assembly singlet energy transfer in naphthalene-anthracene system linked by 2-ureido-4{1H}-pyrimidinone binding module

Naphthalene-naphthalene, anthracene-anthracene, and naphthalene-anthracene assemblies 1.1, 2.2, and 1.2 linked by 2-ureido-4{1H}-pyrimidinone binding module were synthesized. Fluorescence quenching and lifetime measurements demonstrate that the inner-assembly singlet energy transfer from naphthalene to anthracene in 1.2 occurs with the efficiency of ca. 89% and rate constant of ca. 9.8 × 10⁸ s⁻¹. Föster energy transfer mechanism operates in this energy transfer process.     

Improved loading and cleavage methods for solid-phase synthesis using chlorotrityl resins: synthesis and testing of a library of 144 discrete chemicals as potential farnesyltransferase inhibitors

The use of chlorotrityl resins for the immobilization of amines is sometimes deterred by the lengthy process of loading the reactants on the resins and product decomposition caused by the reactive chlorotrityl group in the presence of 1% TFA as a cleavage agent. Here, we report improved methods developed for selective and efficient loading of aminobenzoic acid derivatives on chlorotrityl resins and for cleavage of aniline-containing products from the resins without decomposition. These methods led to the synthesis of a library of 144 discrete chemicals as potential farnesyltransferase inhibitors (FTIs) using IRORI's radio-frequency-encoded sorting technique and to the study of the applicability of the bivalence approach to the development of FTIs.     

Stereocontrolled synthesis of onchidins

[structure: see text] The first total synthesis of a molecule possessing the stereochemistry proposed for onchidin is described. The structure synthesized appears to be different from that of the marine natural product.     

Morphology-dependent resonances in dielectric spheres with many tiny inclusions

The morphology-dependent resonances (MDRs) in a dielectric sphere that contains many tiny inclusions are studied by use of a recently developed degenerate perturbation method. Degenerate MDRs in the sphere split into multiplets because of the loss of spherical symmetry and manifest themselves as broadened spectral lines in the scattering cross section. Furthermore, the distribution of MDRs in a multiplet is found to obey Wigner's semicircular theorem.     

Synthesis of Mesoporous Silica Materials via Nonsurfactant Templated Sol-Gel Route by Using Mixture of Organic Compounds as Template

Mesoporous silica materials have been successfully prepared by employing a mixture of -cyclodextrin and urea as a template in a HCl-catalyzed sol-gel process, followed by extraction with water. The obtained materials are characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction patterns and transmission electron microscopy. The changes of the pore parameters depend on both the weight ratio of -cyclodextrin and urea and the template content in the final silica composite. The effects of the mixture as template (or pore-forming agent) on the physicochemical properties of the two synthesized systems, with different weight ratio and same template content, as well as varied template content and fixed weight ratio, were investigated in this paper. The results show that the hydrogen bonding interactions between -cyclodextrin and urea molecules or urea aggregates, the urea-holding -cyclodextrin molecules themselves as well as inorganic species are the driving force in the formation of mesoporous silica materials.     

酸度对苯基双胍合成反应的影响及其作用机理

苯基双胍;苯胺;双氰胺;脒基脲;高效液相色谱     

悬索桥线形分析的悬链线单元法

从悬链线方程出发,以节点坐标和无应力索长作为未知量,推导了增量型索单元的刚度方程,提出了悬索桥在恒载作用下初始线形和无应力索长的计算公式及基于Newton-Raphson的求解方法.算例分析表明本文方法具有较高的精度.     

Characterization of the dispersion process for NiFe2O4 nanocrystals in a silica matrix with infrared spectroscopy and electron paramagnetic resonance

The structural development of the NiFe₂O₄ nanocrystals dispersed in a silica matrix was followed by IR and EPR spectroscopies of the dried gel 10NiO–10Fe₂O₃–90SiO₂ after heat treatment. The dried gel obtained at 200°C was amorphous, in which Fe³⁺ and Ni²⁺ ions were distributed in the pores of silica matrix. When the dried gel was heat treated at 400°C, NiFe₂O₄ clusters were partially formed, showing an enhanced interaction with the silica matrix. NiFe₂O₄ clusters were completely formed in silica matrix when the heat treatment was increased to 600°C, at which the interactions between the clusters and silica matrix reached a maximum. The formation reaction of NiFe₂O₄ clusters was accompanied by a rearrangement of the silica matrix network. Further increase of the heat treatment temperature to 800°C led to superparamagnetic single domain NiFe₂O₄ nanocrystals (ca. 4 nm) dispersed in the silica matrix with the elimination of the interactions between magnetic nanocrystals and silica matrix.     

中能重离子反应中的在平面流和椭圆流

利用同位旋相关的量子分子动力学模型研究了⁴⁰Ca+⁴⁰Ca系统在能量从30MeV/u到150MeV/u的在平面流和椭圆流.发现随着入射能量的增加,在平面流出现从负到正的跃迁,而椭圆流则随入射能量的增大而减少并且出现从正到负的跃迁.椭圆流和在平面流对于入射能量和碰撞参数较为敏感,相反对于对称能和核态方程却不太敏感.最后对于不同质量的碎块的依赖性关系我们还作了进一步仔细的研究.     

基于PET过程的分子开关型荧光传感器研究进展

基于PET过程的分子开关型荧光传感器研究进展;光诱导电子转移;给体;受体;分子开关;光物理技术