Crystal structure of [Cu2(II)(dmpa)2(p-Cl-C6H5COO)2] (Hdmpa = N,N-dimethyl-3-amino-1-propanol)

The copper complex, [Cu₂(II)(dmpa)₂(p-Cl-C₆H₅COO)₂], has been prepared and its structure determined using X-ray crystallography. The dimer is a di-₂-alkoxo complex which is a five-coordinate copper dimer with unsupported alkoxo bridges. The complex crystallizes in the triclinic space group P-1 with a = 11.384(2), b = 14.636(5), c = 9.609(2) Å, = 100.07(2), = 104.33(3), = 72.79(2)°, V = 1471.8(7) ų, and Z = 2. The structure is comprised of discrete binuclear clusters in which the metal atoms are bridged by two alkoxo oxygens of the dmpa^– ligands. The Cu-O and Cu-N distances are in good agreement with those found for other copper(II) aminoalcoholato complexes. The Cu···Cu distance is 2.9765(6) Å. In the crystal, every two dimeric coordination molecules are combined together by the recognition through intermolecular hydrogen-bonding interactions between the apical water molecule and the non-coordinated O atom from the p-chlorobenzoato ligand, forminga tetramer.     

高度可溶聚苝酰亚胺材料的合成及性能研究

聚酰亚胺是一类具有优异综合性能的聚合物材料 [1,2 ] .近年来 ,合成含荧光染料的可溶性聚酰亚胺材料在聚合物化学领域引起了广泛兴趣 [3～ 11] ,人们期望这类聚合物材料会比其小分子材料具有更加优越的性能 .小分子酰亚胺荧光染料具有极高的荧光量子效率、光化学和热稳定性 ,可广泛应用于光学开关[12 ] 、电致发光器件 [13,14 ] 和太阳能转换器 [15] 等领域 ,但是由于的大π键平面共轭结构 ,使得材料的溶解性能极差 ,难以加工 .最近 ,本实验室通过合成含叔丁基的芳香二胺 [4,4′-亚甲基双 ( 2 -叔丁基苯胺 ) ]与各种芳香四酸二酐反应…     

Two-dimensional Nitrogen-doped Mesoporous Carbon/Graphene Nanocomposites from the Self-assembly of Block Copolymer Micelles in Solution

The self-assembly of block copolymer in solution has proven to be an effective strategy for building up a wide range of nanomaterials with diverse structures and applications. This paper reports a facile self-assembly approach towards two-dimensional(2D) sandwich-like mesoporous nitrogen-doped carbon/reduced graphene oxide nanocomposites(denoted as m NC/r GO) with well-defined large mesopores. The strategy involves the synergistic self-assembly of polystyrene-block-poly(ethylene oxide)(PS-b-PEO) spherical micelles, m-phenylenediamine(m PD) monomers and GO in solution and the subsequent carbonization at 900 ℃. The resultant m NC/r GO nanosheets have an average pore size of 19 nm, a high specific surface of 812 m~2·g~(-1) and a nitrogen content of 2.2 wt%. As an oxygen reduction reaction(ORR) catalyst, the unique structural features render the metal-free nanosheets excellent electrocatalytic performance. In a 0.1 mol·L~(-1) KOH alkaline medium, m NC/r GO exhibits a four-electron transfer pathway with a high half-wave-potential(E_(1/2)) of +0.77 V versus reversible hydrogen electrode(RHE) and a limiting current density(JL) of 5.2 mA·cm~(-2), which are well comparable with those of the commercial Pt/C catalysts.     

Crystal structure of [Co(bipy)(maleato) (H2O)3]·H2O (bipy = 2,2′-bipyridine)

Preparation of the mononuclear cobalt(II) complex, [Co(bipy)(maleato) (H₂O)₃]·H₂O (1) where bipy = 2,2-bipyridine, were accomplished by reaction of an aqueous solution containing sodium maleate and an ethanolic solution of Co(NO₃)₂·6H₂O and bipy. The crystal structure of complex (1) was determined by X-ray crystallography. The complex crystallizes in the monoclinic space group P2₁/n with a = 9.477(3), b = 7.660(2), c =23.526 (3) Å, = 97.64(2)°, V = 1692.6(6) ų, and Z = 4. The structure consists of discrete mononuclear cobalt molecules. The cobalt atom is six-coordinate and presents a slightly distorted octahedral geometry, which consists of the two imine N atoms of bipy, a terminal carboxylate O atom from maleato ligand, and a water O atom in the basal plane with Co—N bond distances of 2.116(2) and 2.124(3) Å and Co—O distances of 2.075(2) and 2.088(2) Å, respectively. The relatively shorter Co—O distances are due to the trans effect of the bipy ligand. The octahedral coordination is completed the other two water molecules. The coordinate and the lattice water molecules were identified by TG study.     

Tuning an rf-SQUID flux qubit system＇s potential with magnetic flux bias

At an extremely low temperature of 20 mK, we measured the loop current in a tunable rf superconducting quantum interference device (SQUID) with a dc-SQUID. By adjusting the magnetic flux applied to the rf-SQUID loop (Φ f ) and the small dc-SQUID (Φ cjj f ), respectively, the potential shape of the system can be fully controlled in situ. Variation in the transition step and overlap size in the switching current with a barrier flux bias are analyzed, from which we can obtain some relevant device parameters and build a model to explain the experimental phenomenon.     

脉冲激光引发自由基聚合的动力学研究

处理了无链转移时脉冲激光引发自由基聚合中的动力学问题:推导出聚合产物数均和重均分子量的严格数学表达式,给出了链自由基、死聚物及总的聚合产物的归一化的分子量分布函数,计算结果表明:随着单体转化率的上升,各种分子参数,例如数均和重均分子量,以及多分散指数的数值周期性地振荡,且振幅逐渐下降,分子量分布曲线则包含一些特征峰,且随着每次脉冲激光产生的初级自由基浓度的降低,分布曲线峰的数目增加,另外,与歧化终止相比,偶合终止使产物的分子量分布略为变窄.     

由A2和CB2型单体合成端羟基超支化聚(脲-氨酯)

超支化聚合物是一类高度支化的具有三维椭球状立体构造的大分子[1]. 由于具有传统线型聚合物所没有的低熔体粘度、高流变性、良好的溶解性及大量末端官能团等一系列独特的物理化学特性, 超支化聚合物自 20世纪 80年代末在杜邦公司诞生以来[2]便很快成为高分子科学界研究的一个热点[3～7], 预计其将在医药载体、大分子建筑"砌块"、催化剂和流变添加剂等诸多领域得到广泛应用[8].     

Tuning rf-SQUID flux qubit system's potential with magnetic flux bias

At an extremely low temperature of 20 mK, we measured loop current in a tunable rf superconducting quantum interference device (SQUID) with a dc-SQUID. By adjusting the magnetic flux applied to the rf-SQUID loop (Φ_f) and the small dc-SQUID (Φ_f^cjj), respectively, the potential shape of the system can be fully controlled in situ. Variations of transition step and overlap size in switching current with the barrier flux bias are analyzed, from which we can obtain some relevant device parameters and built up a model to explain the experimental phenomenon.     

Influence of Termination and Transfer on Molecular Weight Distribution of Polymers. IV. Impurity Termination

The effect of impurity termination on molecular size distribution for anionic polymerization with instantaneous initiation is discussed. In order to derive rigorous expressions for the molecular size distribution function and other molecular parameters, this paper follows a mathematical procedure which has proved to be useful for the theoretical treatment of the kinetics of polymerizations in the previous parts of this series. The variation of all molecular parameters with the extent of polymerization is illustrated.     

Influence of Termination and Transfer on Molecular Weight Distribution of Polymers. III. Spontaneous Termination

This article deals with the kinetics of ionic polymerization with instantaneous initiation and spontaneous termination. The set of kinetic differential equations was solved rigorously by means of nonsteady-state analysis. Even though the expressions of the molecular size distribution function and other molecular parameters include an exponential integral function, all the molecular parameters can easily be computed numerically. Thus, this work is significant for controlling and regulating the relevant polymerizations.