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991.
Alyssa‐Jennifer Avestro Daniel M. Gardner Dr. Nicolaas A. Vermeulen Eleanor A. Wilson Dr. Severin T. Schneebeli Dr. Adam C. Whalley Dr. Matthew E. Belowich Prof. Raanan Carmieli Prof. Michael R. Wasielewski Prof. J. Fraser Stoddart 《Angewandte Chemie (International ed. in English)》2014,53(17):4442-4449
The controlled self‐assembly of well‐defined and spatially ordered π‐systems has attracted considerable interest because of their potential applications in organic electronics. An important contemporary pursuit relates to the investigation of charge transport across noncovalently coupled components in a stepwise fashion. Dynamic oligorotaxanes, prepared by template‐directed methods, provide a scaffold for directing the construction of monodisperse one‐dimensional assemblies in which the functional units communicate electronically through‐space by way of π‐orbital interactions. Reported herein is a series of oligorotaxanes containing one, two, three and four naphthalene diimide (NDI) redox‐active units, which have been shown by cyclic voltammetry, and by EPR and ENDOR spectroscopies, to share electrons across the NDI stacks. Thermally driven motions between the neighboring NDI units in the oligorotaxanes influence the passage of electrons through the NDI stacks in a manner reminiscent of the conformationally gated charge transfer observed in DNA. 相似文献
992.
Georgakilas V Gournis D Bourlinos AB Karakassides MA Petridis D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(16):3904-3908
A new approach for the synthesis of amide macrocycles, based on the use of organo-clay derivatives as controlling template, is proposed as an alternative to the rotaxane method. Dications of p-xylylene diamine inserted in the clay interlayer space act as molding pillars around which neutral diamine molecules are erected via hydrogen bonding and pi-pi interactions to form supramolecular arrays. Condensation of diamines in the supramolecular arrays with diacetyl dichlorides yields various tetramide macrocycles in good yields. Shape, aromaticity and dimensions of the reactants are factors affecting the condensation reaction. 相似文献
993.
采用模板法在水热条件下合成了掺La的NiO多孔空心球。采用X射线衍射(XRD)、X射线光电子能谱(XPS)、扫描电镜(SEM)、透射电子显微镜(TEM)和X射线能谱(EDS)对其结构和形貌进行了表征。采用循环伏安、恒流充放电技术对其电化学性能进行了测试,研究结果表明,La掺杂对NiO空心球的粒径、壳层厚度和电化学性能均有显著影响,当La掺杂量为1.30mol%时,掺杂后NiO的单电极比电容达到205 F.g-1,比未掺杂的提高了50%,并且表现出良好的循环稳定性和可逆性。 相似文献
994.
We report on the electrochemical synthesis of free‐standing aluminium nanowire architectures through a template‐assisted electrodeposition technique. For this purpose, nuclear track‐etched polycarbonate membranes were employed as templates. One side of the template was sputtered with a thin gold film to serve as a working electrode. Subsequently the nanowires were made in the ionic liquid 1‐ethyl‐3‐methylimidazolium chloride ([EMIm]Cl)/AlCl3 (40/60 mol %) under potentiostatic conditions. Two different electrodeposition procedures were employed to fabricate strongly adherent Al nanowire structures on an electrodeposited Al layer. In the first procedure, electrodeposition simultaneously occurs along the pores of the template and on the Au‐sputtered side of the template. In the second procedure, electrodeposition takes place in two different steps: first a thick supporting film of Al is deposited on the sputtered side of the membrane and second Al nanowires are grown within the pores. After chemical dissolution of the membrane in dichloromethane, an aluminium foil of a controlled thickness with a three‐dimensional nanowire structure on one side was obtained. Different nanowire architectures, such as free‐standing nanowires, vertically aligned tree‐shaped arrays, and bunched nanowire films, were obtained. Such nanowire architectures are of particular interest for applications in Li‐ion micro‐batteries. 相似文献
995.
建立了用EDTA-2Na法测定甲紫糊中氧化锌含量的方法,方法简便,准确,线性范围0.0194-0.2011g,r=0.99999(n=5),方法的平均加样回收率为100.02%,RSD为0.082%(n=5)。 相似文献
996.
997.
Mixed dissociation constants of four drug acids, i.e. silychristin, silybinin, silydianin and mycophenolate at various ionic strengths I of range 0.01 and 0.30 and at temperatures of 25 and 37 °C were determined using the SQUAD(84) regression analysis program applied to pH-spectrophotometric titration data. The proposed strategy of an efficient experimentation in a protonation constants determination, followed by a computational strategy for the chemical model with a protonation constants determination, is presented on the protonation equilibria of silychristin. The thermodynamic dissociation constant pKaT was estimated by non-linear regression of {pKa, I} data at 25 and 37 °C: for silychristin pKa,1T=6.52(16) and 6.62(1), pKa,2T=7.22(13) and 7.41(5), pKa,3T=8.96(9) and 8.94(9), pKa,4T=10.17(7) and 10.03(8), pKa,5T=11.89(4) and 11.63(7); for silybin pKa,1T=7.00(4) and 6.86(5), pKa,2T=8.77(11) and 8.77(3), pKa,3T=9.57(8) and 9.62(1), pKa,4T=11.66(3) and 11.38(1); for silydianin pKa,1T=6.64(7) and 7.10(6), pKa,2T=7.78(5) and 8.93(1), pKa,3T=9.66(9) and 10.06(11), pKa,4T=10.71(7) and 10.77(7), pKa,5T=12.26(5) and 12.14(5); for mycophenolate pKaT=8.32(1) and 8.14(1). Goodness-of-fit tests for various regression diagnostics enabled the reliability of parameter estimates to be found. 相似文献
998.
999.
Pomeranc D Jouvenot D Chambron JC Collin JP Heitz V Sauvage JP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(17):4247-4254
A rotaxane containing a ruthenium bisphenanthroline complex, acting as an axis, and a macrocycle incorporating a 2,2'-bipyridine (bpy) unit, threaded by the axis, has been synthesized. The bisphenanthroline ligand is such that its ruthenium(II) complexes possess a clearly identified axis, making such compounds ideal components of rotaxanes constructed around an octahedral ruthenium(II) center, which serves as a template. The ring is threaded by the axial ruthenium(II) precursor complex, to afford the corresponding pseudorotaxane in moderate yield. The X-ray structure analysis of this compound reveals the threaded nature of the complex. The length of the threaded ring (35 atoms in the periphery) is too short to allow easy threading of the axis through the macrocycle. As a consequence, an isomer is also obtained for which the axial ruthenium complex is attached in an exo fashion. (1)H NMR studies have been carried out, which reveal various conformational equilibria for the pseudorotaxane. Light-induced decoordination of the bpy-containing cyclic fragment was shown to be quantitative and to lead to the free ring and the axial ruthenium(II) complex, regardless of the starting compound (pseudorotaxane or exo isomer). Finally, the real rotaxane could be prepared, although it could not be separated from its exo isomer. 相似文献
1000.
Prof. Hsien‐Ming Kao Chih‐Hsuan Chung Dr. Diganta Saikia Shih‐Hsiang Liao Pei‐Ying Chao Yu‐Han Chen Prof. Kevin C.‐W. Wu 《化学:亚洲杂志》2012,7(9):2111-2117
Functionalization of periodic mesoporous organosilicas (PMOs) with high loadings of pendant organic groups to form bifunctional PMOs with ordered mesostructures remains a challenging objective. Herein, we report that well‐ordered ethane‐bridged PMOs functionalized with exceptionally high loadings of pendant carboxylic acid groups (up to 80 mol % based on silica) were synthesized by the co‐condensation of 1,4‐bis(trimethoxysilyl)ethane (BTME) and carboxyethylsilanetriol sodium salt (CES) with Pluronic P123 as the template and KCl as an additive under acidic conditions. The bifunctional materials were characterized by using a variety of techniques, including powder X‐ray diffraction, nitrogen‐adsorption/desorption, TEM, and solid‐state 13C and 29Si NMR spectroscopy. Zeta‐potential measurements showed that the surface negative charges increased with increasing the CES content. This property makes them potential candidates for applications in drug adsorption. The excellent adsorption capacity of these bifunctional PMOs towards an anticancer drug (doxorubicin) was also demonstrated. 相似文献