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81.
82.
Bian HD Gu W Xu JY Bian F Yan SP Liao DZ Jiang ZH Cheng P 《Inorganic chemistry》2003,42(14):4265-4267
The first mu(3)-oxalato-bridged copper(II) complex, [[Cu(3)(L)(3)(mu(3)-C(2)O(4))][Cu(L)(H(2)O)](ClO(4))(2)] x 0.5(H(2)O) x 0.5(CH(3)OH), where HL = N-ethyl-N'-salicylidene-1,2-diaminoethane, has been synthesized and characterized by variable-temperature magnetic susceptibility measurement. The complex exhibits ferromagnetic coupling between the oxalato-bridged copper atoms and antiferromagnetic coupling between the oxygen-bridged copper atoms. 相似文献
83.
Weitao Xu Jinglan Kan Bo Yang Timothy J. Prior Bing Bian Xin Xiao Zhu Tao Carl Redshaw 《化学:亚洲杂志》2019,14(1):235-242
The interaction between cucuribit[8]uril (Q[8]) and a series of 4‐pyrrolidinopyridinium salts bearing aliphatic substituents at the pyridinium nitrogen, namely 4‐(C4H8N)C5H5NRBr, where R=Et (g1), n‐butyl (g2), n‐pentyl (g3), n‐hexyl (g4), n‐octyl (g5), n‐dodecyl (g6), has been studied in aqueous solution by 1H NMR spectroscopy, electronic absorption spectroscopy, isothermal titration calorimetry and mass spectrometry. Single crystal X‐ray diffraction revealed the structure of the host–guest complexes for g1, g2, g3, and g5. In each case, the Q[8] contains two guest molecules in a centrosymmetric dimer. The orientation of the guest molecule changes as the alkyl chain increases in length. Interestingly, in the solid state, the inclusion complexes identified are different from those observed in solution, and furthermore, in the case of g3, Q[8] exhibits two different interactions with the guest. In solution, the length of the alkyl chain plays a significant role in determining the type of host–guest interaction present. 相似文献
84.
Guo‐Qing Bian Takayoshi Kuroda‐Sowa Hisashi Konaka Masahiko Maekawa Megumu Munakata 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(7):m338-m340
The title compound, [Mn2(μ‐O)(C6H3NO3)2(C5H5N)4]·H2O, was isolated from the reaction of 2,6‐pyridinedicarboxylic acid with [Mn12O12(CH3COO)16(H2O)4] in pyridine. The dimanganese complex has twofold symmetry; the MnIII atoms are bridged by one oxo and two amidate ligands and show compressed octahedral Jahn–Teller distortion. The molecular packing comprises a three‐dimensional structure constructed by means of extensive intermolecular interactions, including three kinds of hydrogen bonds and π–π interactions. 相似文献
85.
A new method for constructing nonorthogonal localized molecular orbitals (NOLMOs) is presented. The set of highly localized NOLMOs is obtained by minimization of the spread functional starting from an initial set of canonical orthogonal molecular orbitals. To enhance the stability and efficiency, the centroids of the NOLMOs are constrained to be those of the corresponding orthogonal localized molecular orbitals (OLMOs), which are obtained with the Boys criterion in advance. In particular, these centroid constraints make the optimization for each NOLMO independent of the others, which is an attractive feature for application to large systems. The minimization with the constraints incorporated through the multiplier-penalty function method is stable and efficient in convergence. While exhibiting the classical bonding pattern in chemistry and sharing a spatial distribution similar to that of the corresponding OLMOs, the obtained NOLMOs are more compact than the corresponding OLMOs with about 10%-28% reduction in the value of the spread functional and devoid of the troublesome "orthogonalization tails." 相似文献
86.
Qian Wang Sudip Pan Yan‐Bo Wu Guohai Deng Jian‐Hong Bian Guanjun Wang Lili Zhao Mingfei Zhou Gernot Frenking 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(48):17526-17535
We report the synthesis and spectroscopic identification of the trisbenzene complexes of strontium and barium M(Bz)3 (M=Sr, Ba) in low‐temperature Ne matrix. Both complexes are characterized by a D3 symmetric structure involving three equivalent η6‐bound benzene ligands and a closed‐shell singlet electronic ground state. The analysis of the electronic structure shows that the complexes exhibit metal–ligand bonds that are typical for transition metal compounds. The chemical bonds can be explained in terms of weak donation from the π MOs of benzene ligands into the vacant (n?1)d AOs of M and strong backdonation from the occupied (n?1)d AO of M into vacant π* MOs of benzene ligands. The metals in these 20‐electron complexes have 18 effective valence electrons, and, thus, fulfill the 18‐electron rule if only the metal–ligand bonding electrons are counted. The results suggest that the heavier alkaline earth atoms exhibit the full bonding scenario of transition metals. 相似文献
87.
In this study, a facile one-step redox polymerization method for the preparation of highly dispersed palladium (Pd)/polypyrrole (PPy) nanocapsules has been demonstrated. During the polymerizaion process, the formation of RB-PdCl(4)(2-) complex via an electrostatic interaction plays a key role for the preparation of Pd/PPy composite nanocapsules. The well-dispersed Pd nanocrystals with small sizes of 2-4 nm embedded in PPy nanocapsules exhibited a good catalytic activity during the catalytic reduction of p-nitrophenol into p-aminophenol by NaBH(4) in aqueous solution. The kinetic apparent rate constant (k(app)) was about 8.87×10(-3) s(-1). Moreover, the as-prepared Pd/PPy composite nanocapsules exhibited a good reusability, which could be repeatedly used for the reduction of p-nitrophenol with a high catalytic activity for at least 10 successive cycles. 相似文献
88.
We investigated the structural stability of colloidal PbS nanocrystals (NCs) self-assembled into superlattice (SL) allotropes of either face-centered cubic (fcc) or body-centered cubic (bcc) symmetry. Small-angle X-ray scattering analysis showed that the NC packing density is higher in the bcc than in the fcc SL; this is a manifestation of the cuboctahedral shape of the NC building block. Using the high-pressure rock-salt/orthorhombic phase transition as a stability indicator, we discovered that the transition pressure for NCs in a bcc SL occurs at 8.5 GPa, which is 1.5 GPa higher than the transition pressure (7.0 GPa) observed for a fcc SL. The higher structural stability in the bcc SL is attributed primarily to the effective absorption of loading force in specific SL symmetry and to a lesser extent to the surface energy of the NCs. The experimental results provide new insights into the fundamental relationship between the symmetry of the self-assembled SL and the structural stability of the constituent NCs. 相似文献
89.
用连续前沿色谱法和断续前沿色谱法测定了七种标准蛋白在疏水色谱填料上的吸附等温线,两种方法之间存在着一定的差别。从流出曲线突跃处斜率测定的不确定性、色谱过程中动力学因素和实验方法本身存在的问题等几个方面探讨了误差的来源,指出了可能解决这一问题的途径。 相似文献
90.
This paper presents a microsensor chip integrated with a gold nanoparticles‐modified ultramicroelectrode array (UMEA) as the working electrode for the detection of copper ions in water. The microsensor chip was fabricated with Micro‐Electromechanical System technique. Gold nanoparticles were electrodeposited onto the surface of UMEA at a constant potential of ?0.3 V. The ratio d/Rb of interelectrode spacing (d) over the individual electrode’s radius (Rb) was investigated to improve the electrochemical performance. The UMEA with a d/Rb of 20 showed the best hemispherical diffusion mode, resulted in fast response time and high current response. The gold nanoparticles increased the active surface area of UMEA by not changing the geometries of UMEA, and the current response was increased further. Incorporating the optimized characteristic of UMEA and gold nanoparticles, the microsensor showed a good linear range from 0.5 to 200 µg L?1 of copper ions in the acetate buffer solutions with the method of square wave stripping voltammetry. Compared with the gold nanoparticles‐modified disk electrode, the gold nanoparticles‐modified UMEA showed higher sensitivity (0.024 µA mm?2 µg?1 L) and lower limit of detection (0.2 µg L?1). Water samples from river water and tap water were analyzed by the microsensor chip with recovery ranging from 100.7 % to 107.8 %. 相似文献