18β-甘草次酸A环开环衍生物的合成及抗肿瘤活性

采用化学方法在18β-甘草次酸A环上进行结构修饰,合成了一系列新颖的A环具有不同官能团的开环衍生物.初步研究了它们对人体肝癌细胞HepG-2的体外细胞毒活性,结果表明,羟基的数目和位置对抑制HepG-2细胞增殖起着重要的作用.     

过冷等规聚丙烯熔体的流变学行为

采用毛细管流变仪研究低于表观熔点的过冷聚丙烯熔体的流变学行为.过冷聚丙烯熔体先经过一段诱导期后,熔体发生凝胶化,剪切黏度在短时间内大幅度升高,最终固化结晶.在诱导期中,过冷聚丙烯熔体的流变行为与高于聚丙烯熔点的常规熔体的流变行为相仿.诱导期的长度与温度有关.在160℃下,诱导期的长度足够长,于是使用过冷聚丙烯熔体进行纺丝加工成为可能.实验结果表明,由过冷熔体制备的初生纤维各项性能与由高温熔体制备的初生纤维亦相似,因此,通过降低喷丝头温度的方法发展一种节能降耗的聚丙烯纤维制造技术有潜在的可能性.     

密度泛函理论研究聚烯烃催化剂取代基电子效应与催化活性的关系

 采用密度泛函 BP/DNP 优化了五组 (每组化合物具有相同的框架结构和不同电子效应的取代基) 共 18 个最受关注的烯烃配位聚合催化剂, 分别计算了每个化合物中心金属上的 Hirshfeld、Mulliken 和 QEq 电荷, 中心金属的 Fukui 指数以及化合物的 HOMO 和 LUMO 能量值, 然后将这些结构参数和配合物催化乙烯聚合的活性相关联. 结果发现, 中心金属的 QEq 电荷能正确反映取代基的电子效应, 且与化合物的 HOMO 以及 LUMO 能量值与催化活性之间有良好的相关性, 可用来预测催化剂活性; 而 Hirshfeld 和 Mulliken 电荷不能正确反映取代基的电子效应, 不适合计算这些化合物的中心金属电荷. 中心金属的 Fukui 指数受取代基电子效应影响较小, 和催化剂活性之间的相关性不明显.     

铈酸钡和钇掺杂的铈酸钡复合氧化物的制备及其在钌基氨合成催化剂中的应用

 采用柠檬酸法合成了 BaCeO3 和掺杂 Y3+的 BaCe0.9Y0.1O3-δ 复合氧化物, 以 Ru3(CO)12 为前体, 利用浸渍法制备了 Ru/BaCeO3 和 Ru/BaCe0.9Y0.1O3-δ 催化剂. 通过 X 射线衍射、扫描电镜和透射电镜技术对样品进行了表征, 并在固定床反应器中考察了催化剂的氨合成反应活性. 结果表明, 载体 BaCeO3 的稳定性优于 BaCe0.9Y0.1O3-δ, 但 Ru/BaCe0.9Y0.1O3-δ 催化剂的氨合成活性明显高于 Ru/BaCeO3, 在 3.0 MPa, 15 000 h1, 425 oC 反应时, Ru/BaCe0.9Y0.1O3-δ 催化剂上氨合成反应速率达到 432.5 ml/(g•h), 是 Ru/BaCeO3 催化剂的 1.6 倍. 这种活性和稳定性的显著差异来自载体中 Ce4+ 与 Ru 纳米粒子间的电子作用.     

Co-crystallization of Resorcin[4]arene Tetracarboxylic Acid with Triethylamine: Synthesis and Crystal Structure

Treatment of resorcin[4]arene tetracarboxylic acid 1 with triethylamine in the presence of Co(CH3COO)2·4H2O and 4,4'-bipyridine gave a co-crystallization 14-·4Et3NH+(C32H20O164-·4Et3NH+,Mr=1069.27) from ethanol and water.The compound was structurally determined by single-crystal X-ray diffraction.The crystal belongs to monoclinic,space group P21/n,with a=8.1763(18),b=12.913(3),c=28.724(7) ,β=97.574(4)o,V=3006.3(12) 3,Z=2,Dc=1.181 g/cm3,F(000)=1152,Rint=0.0275,T=293(2) K,μ=0.086 mm-1,the final R=0.0634 and wR=0.1752 for 5082 observed reflections with Ⅰ 2σ(Ⅰ).The co-crystallization is very stable at room temperature.Possibly,a network of N-H···O(=C) plays an important role in the structure.Meanwhile,the compound emits a weak cyan luminescence with peak maximum band at 458 nm.     

Synthesis and Single-crystal Structure of a Silver(Ⅰ) Carboxyarylphosphonate: [Ag(H_2BCP)(4,4'-bipy)]·2H_2O

The title compound, a novel Ag(Ⅰ) carboxyarylphosphonate [Ag(H2BCP)(4,4'- bipy)]·2H2O (H3BCP = p-H2O3PCH2C6H4COOH, 4,4'-bipy = 4,4'-bipyridine), was synthesized by a hydrothermal reaction and characterized by elemental analysis, IR spectra and single-crystal X-ray diffraction. It belongs to monoclinic system, space group P21/c with a = 5.7038(11), b = 22.397(4), c = 5.602(4) ?, β = 106.26(3)°, V = 1913.4(7) 3, Z = 4, C18H20N2O7PAg, Mr = 515.20, Dc = 1.788 g/cm3, μ = 1.182 mm-1, F(000) = 1040, the final R = 0.0404 and wR = 0.1216 for 4178 observed reflections with I 2σ(Ⅰ). In the structure, the Ag(Ⅰ) cations are bridged by 4,4'-bipy to give rise to 1D chains running along the b axis. These chains are linked further by the interactions of O (from BCP ligands) and Ag atoms to yield 2D layers. Hydrogen bonding interactions and weak π-π stacking interactions between 4,4'-bipy rings assemble such adjacent layers to generate a 3D supramolecular architecture.     

Synthesis and Crystal Structure of a New Mn8 Compound with Tripodal Ligand

A new manganese compound [Mn8(tmp)2(Htmp)4((CH3)3CCO2)4(py)2Cl2]·2py (1·2py, H3tmp = 1,1,1-tri(hydroxymethyl)propane, py = pyramid) has been synthesized and its structure was characterized by IR, elemental analysis and X-ray diffraction. Compound 1 belongs to the triclinic system, space group P1 with a = 13.378(5), b = 14.334(5), c = 15.012(6) , α = 107.637(5), β = 95.635(3), γ = 92.825(4)°, V = 2720.7(17) 3, Z = 1, C76H124N4O26Cl2Mn8, Mr = 2022.23, Dc = 1.234 Mg/m3, μ = 1.007 mm-1, F(000) = 1052, T = 293(2) K, the final R = 0.0755 and wR = 0.2163 for all 6463 observed reflections (I > 2σ(I)). X-ray analysis shows that the core of 1 contains a [Mn8] mixed-valence rod-like unit consisting of six edge-sharing triangles (Mn3), each of which is bridged by a μ3-oxygen atom.     

Two Discrete Cu-Complexes Constructed from a Multidentate N-Containing Dinucleating Ligand

Two comparable discrete complexes [CuⅡ(CH3CN)2L2]·2(ClO4) 1 and [CuI2I2L2]·(DMF)2 2 were successfully synthesized by the reaction of CuⅡ and CuⅠ salts with a novel dinucleating ligand 2,5-bis(3-pyridinylmethylthio)-1,3,4-thiadiazole)(L),respectively.Complex 1 presents a single nuclear structure while 2 has a dimeric structure where two CuI ions are doubly bridged by halide ions in a μ2-fashion.Both discrete molecules were outspreaded into a one-dimensional supramolecular chain via aromatic interactions such as C-H…π and π…π interactions.     

Theoretical Study on the Reaction of FeS+(6∑+,4Ф)with COS in the Gas Phase

The possible reaction mechanisms of FeST(6∑+and 4Ф states)with COS in the gas phase have been studied by using density functional theory at the B3LYP/TZVP and B3LYP/6-311+G*levels:the O/S exchange reaction(FeS++COS=FeO++CS2),O-transfer reaction(FeS++COS=FeSO++CS)and S-transfer reaction(FeS++COS=FeS2++CO).The calculation results show that the large barriers(205.7 and 310.1 kJ/mol)and the small probability of forming the preceding intermediate indicate a much lower efficiency of the O/S exchange and the O-transfer reactions and their corresponding products may not be observed experimentally.FeS2+,the product of S-transfer reaction,is predicted to be the main product.But the reactivity of the 6∑+ground state of FeS+toward COS is lower than the earlier transition metal sulfide cations MS+(M=Sc,Ti and V),although it has more reaction channels and different mechanisms.     

Synthesis and Crystal Structure of a New Coordination Polymer: {[AgL]ClO_4}_n(L = 2,5-Bis(3-pyridinylmethylthio)-l,3,4-thiadiazole)

The title complex {[AgL]ClO4}n(L=2,5-bis(3-pyridinylmethylthio)-1,3,4-thiadiazole) was synthesized by the reaction of Ag(I) salt and a novel flexible ligand L.Its structure was determined by X-ray crystallography with the following data:monoclinic,space group P21/n,a=16.5068(13),b=7.6548(4),c=16.5521(13),β=115.119(3)o,V=1893.7(2)3,Z=4,Dc=1.893 g/cm3,μ=1.565 mm-1,F(000)=1072,C14H12AgClN4O4S3,Mr=539.78,T=293(2) K,S=1.067,the final R=0.0342 and wR=0.0870.The silver ion in the complex is in a trigonal coordin...