不同Al含量聚铝碳硅烷纤维空气不熔化及氧含量控制研究

利用低分子量聚碳硅烷(L-PCS)与乙酰丙酮铝间的热聚合反应,通过调节原料配比和反应条件,合成了不同Al含量,且具有良好可纺性的聚铝碳硅烷(PACS).研究了PACS的分子量分布和分子结构,PACS纤维空气不熔化特点并与PCS纤维进行比较.结果表明,[Al(Ac Ac)3]以-Al(Ac Ac)2悬挂和-Al(Ac Ac)-桥联两种方式接入L-PCS分子结构,PACS分子量呈双峰分布.PACS中Si—H含量和反应活性随Al含量增加而下降,氧化生成的Si—OH难以进一步形成Si—O—Si交联结构.这导致Al含量越高,凝胶点温度越高,凝胶含量随温度升高增加缓慢,同时引入多余氧.通过预氧化与高温处理相结合的方法,将不熔化纤维中氧含量控制在11 wt%以下.高温处理过程中发生自交联:Si—OH间脱水生成Si—O—Si;Si—H与Si—OH或Si—CH3脱氢生成Si—CH2—Si.     

Laser Spectroscopic Study of Cold Gas‐Phase Host‐Guest Complexes of Crown Ethers

The structure, molecular recognition, and inclusion effect on the photophysics of guest species are investigated for neutral and ionic cold host‐guest complexes of crown ethers (CEs) in the gas phase. Here, the cold neutral host‐guest complexes are produced by a supersonic expansion technique and the cold ionic complexes are generated by the combination of electrospray ionization (ESI) and a cryogenically cooled ion trap. The host species are 3n‐crown‐n (3nCn; n = 4, 5, 6, 8) and (di)benzo‐3n‐crown‐n ((D)B3nCn; n = 4, 5, 6, 8). For neutral guests, we have chosen water and aromatic molecules, such as phenol and benzenediols, and as ionic species we have chosen alkali‐metal ions (M⁺). The electronic spectra and isomer‐specific vibrational spectra for the complexes are observed with various laser spectroscopic methods: laser‐induced fluorescence (LIF); ultraviolet‐ultraviolet hole‐burning (UV‐UV HB); and IR‐UV double resonance (IR‐UV DR) spectroscopy. The obtained spectra are analyzed with the aid of quantum chemical calculations. We will discuss how the host and guest species change their flexible structures for forming best‐fit stable complexes (induced fitting) and what kinds of interactions are operating for the stabilization of the complexes. For the alkali metal ion?CE complexes, we investigate the solvation effect by attaching water molecules. In addition to the ground‐state stabilization problem, we will show that the complexation leads to a drastic effect on the excited‐state electronic structure and dynamics of the guest species, which we call a “cage‐like effect”.     

Synthesis and supramolecular interactions involved in the crystal structure of (2,4,10,12-tetrabromo-6,7,14,15-tetrahydro-6, 14-thiacycloocta[1,2-b:5,6-b’]diquinoline)2·(1,1,2,2-tetrachloroethane) inclusion compound

The tetrahalo aryl inclusion host 2,4,10,12-tetrabromo-6,7,14,15-tetrahydro-6,14-thiacycloocta[1,2-b:5,6-b’]diquinoline 3 was re-synthesized to explore its ability to trap toxic polychlorinated hydrocarbons such as 1,1,2,2-tetrachloroethane (TCE) in the form of host–guest compound. Host 3 crystallizes from a fresh sample of TCE to form an inclusion compound of the formula (3)₂·(TCE) in triclinic system, space group P-1, with a = 7.7732(16) Å, b = 10.739(2) Å, c = 14.816(3) Å, α = 97.329(4)°, β = 98.619(4)°, γ = 103.359(4)°, V = 1172.7(4) ų, and Z = 2. The X-ray crystal structure of the (3)₂·(1,1,2,2-TCE) is described and analyzed in terms of crystal engineering and supramolecular chemistry. The hosts assemble by means of different types of packing motifs. The included TCE molecules are enclosed within host molecular pens. Novel halogen···halogen intermolecular interactions as well as other non-covalent intermolecular interactions involved in the crystal structure are presented and proved to play an important role in linking these host–host, host–guest, and guest–guest building blocks.     

柏木油中倍半萜烃的乙酰化反应

70%高氯酸可作为柏木油中倍半萜烃进行乙酰化反应的第二催化剂组分,用以代替部分PPA。反应在常温下进行,乙酰化产物的产率和质量与原方法相当。该方法不仅节省PPA而且也减少乙酸酐的消耗,降低原料成本20%左右。     

基于IBM-PC/XT的图象工作站仿真软件开发

本文介绍基于IBM—PC/XT的图象工作站仿真软件。把IBM—PC/XT变成图象工作站的仿真软件,为在IBM—PC/XT(及其兼容机)上,开发图象功能软件的用户提供了一个有效的方法。     

双波长分光光度法测定痕量锌

本文研究了在稀硫酸介质中并有亚铁氰化钾存在时,锌与亚甲蓝所形成的配合物的双波长分光光度法。经摩尔比法测定,此配合物组成比为1∶2（锌∶亚甲蓝）,摩尔吸光系数为1.01L·mol-1·cm-1。桑德尔灵敏度为6.45×10-4μg/cm2。在25ml容积中,0—10μgZn遵守比尔定律,配合物可稳定2     

CMOS三值译码器

本文探讨了在常规CMOS集成电路基础上设计三值逻辑电路的方法。从三值倒相器入手,结合常规CMOS门电路,给出了CMOS三值译码器的设计方案及应用电路。     

在有组织和受限体系中的光化学反应研究

本文对超分子光化学中一个活跃的研究领域--在有组织和受限制体系中光化学反应进行了系统的讨论, 除对“主体”结构的尺寸大小、墙的刚性或柔性、活性或惰性等各种因子进行一般性讨论外, 还对这一问题在实际应用中的重要意义进行了介绍。     

Fluorescent Cyclodextrin/Peptide Hybrids with a Novel Guest‐Responsive Chemosensor in the Peptide Side Chain

Peptides bearing β‐cyclodextrin and 4‐(N,N‐dimethylamino)benzoyl (DMAB) units in the peptide side chains were prepared as chemosensors for molecule detection. The DMAB unit was expected to be included into the cyclodextrin cavity intramolecularly. However, these peptides exhibited no twisted intramolecular charge transfer fluorescence and the normal fluorescence intensity decreased upon the addition of 1‐adamantanol as an exogenous guest, indicating that the DMAB units are shallowly included in the cyclodextrin cavities.     

The Cyclobutanocucurbit[5–8]uril Family: Electronegative Cavities in Contrast to Classical Cucurbituril while the Electropositive Outer Surface Acts as a Crystal Packing Driver

The structural parameters for the cyclobutanoQ[5–8] family were determined through single crystal X-ray diffraction. It was found that the electropositive cyclobutano methylene protons (CH₂) are important in forming interlinking crystal packing arrangements driven by the dipole–dipole interactions between these protons and the portal carbonyl O of a near neighbor. This type of interaction was observed across the whole family. Electrostatic potential maps also confirmed the electropositive nature of the cyclobutano CH₂ but, more importantly, it was established that the cavities are electronegative in contrast to classical Q[5–8], which are near neutral.