一种新的环糊精衍生物手性固定相的合成及其在对映异构体过量值测定中的应用

 以 β 环糊精为原料 ,合成了一种新的环糊精衍生物 2 ,6 二 O 苄基 3 O 戊酰基 β 环糊精 ,用核磁氢谱和红外光谱对产物进行了表征 ,并将所得环糊精衍生物用作毛细管气相手性固定相制备成柱 ,用于 2 ,4 二氯苯乙酮的不对称催化氢化产物 2 ,4 二氯苯乙醇和反式 2 己烯醇的Sharpless环氧化产物 反式 3 正丙基环氧乙烷甲醇的对映异构体过量值 (e.e .值 )测定和催化反应评价 ,取得了很好的结果。     

Combining the best in triplex recognition: synthesis and nucleic acid binding of a BQQ-neomycin conjugate

Synthesis of a BQQ-neomycin conjugate is reported. The conjugate combines two ligands, one known to intercalate triplexes (BQQ) and another known to bind in the triplex groove (neomycin). The conjugate stabilizes T.A.T, as well as mixed base DNA triplex, better than neomycin, BQQ, or a combination of both. The conjugate selectively stabilizes the triplex (in the presence of physiological salt concentrations), with as little as 4 muM of the ligand leading to a DeltaTm of >60 degrees C. Competition dialysis studies show a clear preference for the drug binding to triplex DNA/RNA over the duplex/single strand structures. Modeling studies suggest a structure of neomycin bound to the larger W-H (Watson-Hoogsteen) groove with BQQ intercalated between the triplex bases.     

高效石墨浮选剂的合成

高效石墨浮选剂的合成金婵，薛玉，汪进，刘欣荣，秦英海（哈尔滨工业大学应用化学系哈尔滨１５０００１）（大庆石化总公司大庆）关键词石墨，浮选剂，合成，混合烃由于石墨具有良好的力学性能、导电、高熔点等性质，广泛用于原子能、宇航和民用工业。隐晶质石墨属于微晶...     

Synthesis of 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives

Six new 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives were synthesized from avermectin Bla by the selective protection of C-5-hydroxy group,oxidation of C-4″-hydroxy group,and deprotection followed by reaction with O-substituted hydroxylamine hydrochlorides.Their structures were confirmed by IR,~1H NMR,~(13)C NMR and MS.Insecticidal activities of the derivatives against Phopalosiphum pseudobrassicae,Spodoptera exigua and Pluteua xylosteua were evaluated.     

酚醛树脂固化过程的红外光谱分析

利用红外光谱(IR)及其变温样品池、定量分析程序对酚醛树脂固化过程中的结构变化进行了研究,它对于酚醛树脂固化过程的质量控制具有重要意义。     

探究Cu/ZnO相互作用对CO2加氢制甲醇反应性能的影响

Using renewable green hydrogen and carbon dioxide (CO₂) to produce methanol is one of the fundamental ways to reduce CO₂ emissions in the future, and research and development related to catalysts for efficient and stable methanol synthesis is one of the key factors in determining the entire synthesis process. Metal nanoparticles stabilized on a support are frequently employed to catalyze the methanol synthesis reaction. Metal-support interactions (MSIs) in these supported catalysts can play a significant role in catalysis. Tuning the MSI is an effective strategy to modulate the activity, selectivity, and stability of heterogeneous catalysts. Numerous studies have been conducted on this topic; however, a systematic understanding of the role of various strengths of MSI is lacking. Herein, three Cu/ZnO-SiO₂ catalysts with different strengths of MSI, namely, normal precipitation Cu/ZnO-SiO₂ (Nor-CZS), co-precipitation Cu/ZnO-SiO₂ (Co-CZS), and reverse precipitation Cu/ZnO-SiO₂ (Re-CZS), were successfully prepared to determine the role of such interactions in the hydrogenation of CO₂ to methanol. The results of temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) characterization illustrated that the MSI of the catalysts was considerably affected by the precipitation sequence. Fourier transform infrared reflection spectroscopy (FT-IR) results indicated that the Cu species existed as CuO in all cases and that copper phyllosilicate was absent (except for strong Cu-SiO₂ interaction). Transmission electron microscopy (TEM), X-ray diffraction (XRD), and N₂O chemical titration results revealed that strong interactions between the Cu and Zn species would promote the dispersion of Cu species, thereby leading to a higher CO₂ conversion rate and improved catalytic stability. As expected, the Re-CZS catalyst exhibited the highest activity with 12.4% CO₂ conversion, followed by the Co-CZS catalyst (12.1%), and the Nor-CZS catalyst (9.8%). After the same reaction time, the normalized CO₂ conversion of the three catalysts decreased in the following order: Re-CZS (75%) > Co-CZS (70%) > Nor-CZS (65%). Notably, the methanol selectivity of the Re-CZS catalyst was found to level off after a prolonged period, in contrast to that of Co-CZS and Nor-CZS. Investigation of the structural evolution of the catalyst with time on stream revealed that the high methanol selectivity of the catalyst was caused by the reconstruction of the catalyst, which was induced by the strong MSI between the Cu and Zn species, and the migration of ZnO onto Cu species, which caused an enlargement of the Cu/ZnO interface. This work offers an alternative strategy for the rational and optimized design of efficient catalysts.     

聚偏氟乙烯取向薄膜的结晶形态

本文用小角激光散射法研究了聚偏氟乙烯薄膜在拉伸取向过程中晶体形态及结构的变化。拉伸使球晶形变为椭球,同时伴随着局部熔融与重结晶过程,散射图案由原来的四叶瓣发展为八叶瓣。红外测量及X-射线衍射分析表明,拉伸引起分子链构象改变,使晶型发生了转变。     

氟烷基化C_(60)与四（N，N-二甲基）氨基乙烯电荷转移复合物磁性的EPR研究

变温ERP研究揭示氟烷基化富勒烯C_(60)(R_f)_n与四(N,N-二甲基)氨基乙烯 (TDAE)间稳定的电荷转移络合物TDAE-C_(60)(R_f)_n的居里温度高达190K[R_f = C_3F_7，H（CF_2）_4]。而非氟烷基化络合物TDAE-C_(60)的相应值仅为16.1K。 这种铁磁性可能是络合物分子中氟烷基化富勒烯多价阴离子基在相应居里温度下具 有某种有序排列的缘故。     

低头-头链含量的聚偏氟乙烯合成

研究了偏氟乙烯的聚合条件与其聚合物的头-头链含量的关系。实验表明聚合物的头-头链的含量与聚合温度有关,而与引发剂的种类无关。因而,可以在较低的聚合温度下聚合制得带有低的头-头结构(约3％)的聚偏氟乙烯。将聚合物链的A结构含量对其熔点作图,得一直线,可表示为方程式A=24.8+0.362T_m(％)。