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961.
Bin Liu Yan Ouyang Qing-Lun Wang Dai-Zheng Liao Zong-Hui Jiang Shi-Ping Yan 《Transition Metal Chemistry》2005,30(8):964-967
Two novel oxamidato-bridged Mn[Cu(PMoxd)]3(ClO4)2 (1) Ni[Cu(PMoxd)]3(ClO4)2 (2) tetranuclear complexes were prepared and characterized by i.r., e.p.r., electronic spectra, cyclic voltammograms, and magnetic
properties. The magnetic analysis was carried out by means of the theoretical expression of the magnetic susceptibility deduced
from the spin Hamiltonian H=−2JSM(SCu1+ SCu2 + SCu3) (M=Mn, Ni), leading to J=−20.4 cm−1; −121.1 cm−1 for complexes (1) and (2) respectively. Magnetic measurements indicate that the overall magnetic behavior of the tetranuclear species are antiferromagnetic. 相似文献
962.
利用密度泛函的B3LYP方法, 在6-311G*基组水平对吡啶酮系偶氮类化合物进行构型优化, 并进行了自然键轨道(NBO)分析, 然后用TDDFT方法和ZINDO/S方法分别计算了它们的可见吸收光谱, 结果均与实验值十分吻合. 通过对比发现, 对于最高吸收波长的计算, ZINDO/S能以较快的速度得到较好的结果. 在用ZINDO/S计算的过程中, 回归分析发现π-π重叠加权因子(OWFπ-π)与染料分子吡啶环上两个羰基氧原子平均电荷ZO有较好的线性关系: OWFπ-π=0.11425-1.04178ZO, 这一关系不仅可从量子化学的角度进行解释, 而且可用于同类染料可见吸收光谱的预测. 分子轨道的研究表明, 这些化合物的最高可见吸收波长主要对应着共轭体系中给电子体到受电子体的电子跃迁. 相似文献
963.
Jian Yan Xiang‐Ming Zhang Zhong‐Rong Li Lin Zhou Jian‐Chao Chen Li‐Rong Sun Ming‐Hua Qiu 《Helvetica chimica acta》2005,88(2):240-244
Three new triterpenoids, (3β,8β,14α,21α)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 1 ), (3β,8β,14α,21β)‐26,27‐dinoronocerane‐3,8,14,21‐tetrol ( 2 ), and lycopodiin A ( 3 ), together with four known compounds, lycoclavanol ( 4 ), lycoclaninol ( 5 ), α‐onocerin ( 6 ), and 3‐epilycoclavanol ( 7 ), were isolated from Lycopodium japonicum Thunb (Lycopodiaceae). Their structures were established by means of spectroscopic analyses. Compounds 3 and 7 showed moderate antitumor activity. Compounds 4 and 6 exhibited acetylcholinesterase inhibition activity. 相似文献
964.
965.
p-tert-Butylcalix[6]-1,4-2,5-biscrown-4 is a typical member of the family of calix[6]crowns. In the literature, the compound was synthesized from calix[6]arene by two steps and the overall yield based on calix[6]arene was 24%.Herein we wish to report a one-pot method to do this work. By this method the yield was up to 48% and the reaction time was greatly reduced. 相似文献
966.
Huilan C Deyan H Tian L Hong Y Wenxia T Jian Chen J Peiju Zheng P Chenggang Chen C 《Inorganic chemistry》1996,35(6):1502-1508
Alkylcobalt(III) Schiff base B(12) model complexes with secondary alkyls or a bulky diamine in the equatorial position were synthesized and characterized. Structures have been first determined by X-ray diffraction analysis for i-C(4)H(9)Co(salen)(gamma-pic) (I), n-C(3)H(7)Co(salen)(gamma-pic) (II) and C(2)H(5)Co(SB) (III), where salen = N,N'-ethylenebis(salicylideneamine) dianion; SB = 1,1,2,2-tetramethyl-N,N'-ethylenebis(salicylideneamine) dianion, gamma-pic = gamma-picoline. Crystal data for I (CoC(26)N(3)O(2)H(30)): space group P2(1)/c with a = 6.661(5) ?, b = 18.612(2) ?, c = 19.533(3) ?, beta = 98.93(1) degrees, V = 2392.10 ?(3), D(calcd) = 1.320 g.cm(-3), Z = 4, and R = 0.048 for 4469 measured reflections. Crystal data for II (CoC(25)N(3)O(2)H(28)): space group P2(1)/c, a = 9.609(6) ?, b = 19.169(8) ?, c = 12.995(9) ?, beta = 106.9(7) degrees, V = 2290.4 ?(3), D(calcd) = 1.332 g.cm(-1), Z = 4, and R = 0.048 for 4358 measured reflections. Crystal data for III (CoC(22)N(2)O(2)H(27)): space group P2(1)/c, a = 8.318(3) ?, b = 21.579(2) ?, c = 11.572(2) ?, beta = 93.35(1) degrees, V = 2073.7 ?(3), D(calcd) = 1.314 g.cm(-1), Z = 4, and R = 0.060 for 3954 measured reflections. The crystal structure data reveal that complexes I and II display six-coordinate octahedral geometry; their Co-C, Co-N bond lengths, as well as the Co-C-C angles, are very close to those in 5'-deoxyadenosylcobalamin. Complex III is one of the very few compounds having five-coordinate square pyramidal geometry and observed instability of the Co-C bond. 相似文献
967.
968.
以甲基丙烯酸缩水甘油酯为单体,二甲基丙烯酸乙二醇酯为交联剂,甲苯与正庚烷为有机致孔剂,20%的甘油水溶液为内水相(超孔致孔剂),利用二次乳化法制备了(W/O)/W乳液,通过紫外光引发悬浮聚合生成两类孔型高分子微球(BiPB).BiPB孔径为双峰分布,范围分别在10~100nm和1000~7300nm之间;而其体积平均粒径、比表面积、湿密度、静态吸附容量与不含超孔的微孔介质(MiPB)接近.修饰相同二乙胺密度的BiPB和MiPB介质虽在较低流速(5cm/min)下有相近的动态吸附容量,但在高流速(40cm/min)下BiPB的动态吸附容量约为MiPB的动态吸附容量的3倍,表明BiPB介质的超孔结构对孔内传质的强化作用,因而其更适合于高速的蛋白质色谱分离. 相似文献
969.
Two new triterpene lactones, polysperlactones A ( 2 ) and B ( 3 ), were isolated from the stems of Kadsura polysperma, together with the known compounds heteroclitalactone D ( 1 ) and schisanlactone E ( 4 ). Their structures were elucidated by spectroscopic methods, including 2D‐NMR and HR‐MS techniques. The configuration of 1 was confirmed by X‐ray analysis. Compounds 2 and 3 are members of a rare class of 3,4‐secolanostane metabolites with ring‐expanded or cyclized structures, respectively. 相似文献
970.
Understanding effect of wall structure on the hydrothermal stability of mesostructured silica SBA-15
Zhang F Yan Y Yang H Meng Y Yu C Tu B Zhao D 《The journal of physical chemistry. B》2005,109(18):8723-8732
Mesostructured silica SBA-15 materials with different structural parameters, such as pore size, pore volume, and wall thickness, etc., were prepared by varying the postsynthesis hydrothermal treatment temperature and adding inorganic salts. The hydrothermal stabilities of these materials in steam (100% water vapor) were systematically investigated using a variety of techniques including powder X-ray diffraction, transmission electron microscopy, nitrogen sorption, and (29)Si solid-state NMR. The effect of the pore size, microporosity or mesoporosity, and wall thickness on the stability was discussed. The results show that all of the SBA-15 materials have a good hydrothermal stability under steam of 600 degrees C for at least 24 h. N(2) sorption measurements show that the Brumauer-Emmett-Teller surface area of SBA-15 materials is decreased by about 62% after treatment under steam at 600 degrees C for 24 h. The materials with thicker walls and more micropores show relatively better hydrothermal stability in steam of 600 degrees C. Interestingly, we found that the microporosity of the mesostructured silica SBA-15 is a very important factor for the hydrothermal stability. To the materials with more micropores, the recombination of Si-O-Si bonds during the high-temperature steam treatment may not cause direct destruction to the wall structure. As a result, SBA-15 materials with more micropores show better stability in pure steam of 600 degrees C. Nevertheless, these materials are easily destroyed in steam of 800 degrees C for 6 h. Two methods to effectively improve the hydrothermal stability are introduced here: one is a high-temperature treatment, and another is a carbon-propping thermal treatment. Thermal treatment at 900 degrees C can enhance the polymerization degree of Si-O-Si bonds and effectively improve the hydrothermal stability of these SBA-15 materials in 800 degrees C steam for 12 h. But, this approach will cause very serious shrinkage of the mesopores, resulting in smaller pore diameter and low surface area. A carbon-propping thermal treating method was employed to enhance the polymerization of Si-O-Si bonds and minimize the serious shrinkage of mesopores at the same time. It was demonstrated to be an effective method that can greatly improve the hydrothermal stability of SBA-15 materials in 800 degrees C steam for 12 h. Furthermore, the SBA-15 materials obtained by using the carbon-propping method possess larger pores and higher surface area after the steam treatment at 800 degrees C compared to the materials from the direct thermal treatment method after the steam treatment. 相似文献