共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
Supramolecular Polymers Self‐Assembled from trans‐Bis(pyridine) Dichloropalladium(II) and Platinum(II) Complexes 下载免费PDF全文
Mingming Chen Chengsha Wei Jiaojiao Tao Xibo Wu Dr. Ningdong Huang Prof. Dr. Guobin Zhang Prof. Dr. Liangbin Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(10):2812-2818
Two structurally similar trans‐bis(pyridine) dichloropalladium(II)‐ and platinum(II)‐type complexes were synthesized and characterized. They both self‐assemble in n‐hexane to form viscous fluids at lower concentrations, but form metallogels at sufficient concentrations. The viscous solutions were studied by capillary viscosity measurements and UV/Vis absorption spectra monitored during the disassembly process indicated that a metallophilic interaction was involved in the supramolecular polymerization process. For the two supramolecular assemblies, uncommon continuous porous networks were observed by using SEM and TEM revealed that they were built from nanofibers that fused and crosslinked with the increase of concentration. The xerogels of the palladium and platinum complexes were carefully studied by using synchrotron radiation WAXD and EXAFS. The WAXD data show close stacking distances driven by π–π and metal–metal interactions and an evident dimer structure for the platinum complex was found. The coordination bond lengths were extracted from fitting of the EXAFS data. Moreover, close PtII–PtII (PdII–PdII) and Pt?Cl (Pd?Cl) interactions proposed from DFT calculations in the reported oligo(phenylene ethynylene) (OPE)‐based palladium(II) pyridyl supramolecular polymers were also confirmed by using EXAFS. The PtII–PtII interaction is more feasible for supramolecular interaction than the PdII–PdII interaction in our simple case. 相似文献
3.
Conjugated Polyelectrolyte‐Induced Self‐Assembly of Alkynylplatinum(II) 2,6‐Bis(benzimidazol‐2′‐yl)pyridine Complexes 下载免费PDF全文
Kevin Chan Dr. Clive Yik‐Sham Chung Prof. Dr. Vivian Wing‐Wah Yam 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16434-16447
Water‐soluble cationic alkynylplatinum(II) 2,6‐bis(benzimidazol‐2′‐yl)pyridine (bzimpy) complexes have been demonstrated to undergo supramolecular assembly with anionic polyelectrolytes in aqueous buffer solution. Metal–metal‐to‐ligand charge transfer (MMLCT) absorptions and triplet MMLCT (3MMLCT) emissions have been found in UV/Vis absorption and emission spectra of the electrostatic assembly of the complexes with non‐conjugated polyelectrolytes, driven by Pt???Pt and π–π interactions among the complex molecules. Interestingly, the two‐component ensemble formed by [Pt(bzimpy‐Et){C?CC6H4(CH2NMe3‐4)}]Cl2 ( 1 ) with para‐linked conjugated polyelectrolyte (CPE), PPE‐SO3?, shows significantly different photophysical properties from that of the ensemble formed by 1 with meta‐linked CPE, mPPE‐Ala. The helical conformation of mPPE‐Ala allows the formation of strong mPPE‐Ala– 1 aggregates with Pt???Pt, electrostatic, and π–π interactions, as revealed by the large Stern–Volmer constant at low concentrations of 1 . Together with the reasonably large Förster radius, large HOMO–LUMO gap and high triplet state energy of mPPE‐Ala to minimize both photo‐induced charge transfer (PCT) and Dexter triplet energy back‐transfer (TEBT) quenching of the emission of 1 , efficient Förster resonance energy transfer (FRET) from mPPE‐Ala to aggregated 1 molecules and strong 3MMLCT emission have been found, while the less strong PPE‐SO3?– 1 aggregates and probably more efficient PCT and Dexter TEBT quenching would account for the lack of 3MMLCT emission in the PPE‐SO3?– 1 ensemble. 相似文献
4.
5.
Anne C. H. Jans Dr. Adrián Gómez‐Suárez Prof. Dr. Steven P. Nolan Prof. Dr. Joost N. H. Reek 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(42):14836-14839
Dinuclear gold complexes have the ability to interact with one or more substrates in a dual‐activation mode, leading to different reactivity and selectivity than their mononuclear relatives. In this contribution, this difference was used to control the catalytic properties of a gold‐based catalytic system by site‐isolation of mononuclear gold complexes by selective encapsulation. The typical dual‐activation mode is prohibited by this catalyst encapsulation, leading to typical behavior as a result of mononuclear activation. This strategy can be used as a switch (on/off) for a catalytic reaction and also permits reversible control over the product distribution during the course of a reaction. 相似文献
6.
Control over Electrochemical Water Oxidation Catalysis by Preorganization of Molecular Ruthenium Catalysts in Self‐Assembled Nanospheres 下载免费PDF全文
Dr. Fengshou Yu David Poole III Dr. Simon Mathew Dr. Ning Yan Joeri Hessels Nicole Orth Prof. Ivana Ivanović‐Burmazović Prof. Joost N. H. Reek 《Angewandte Chemie (International ed. in English)》2018,57(35):11247-11251
Oxygen formation through water oxidation catalysis is a key reaction in the context of fuel generation from renewable energies. The number of homogeneous catalysts that catalyze water oxidation at high rate with low overpotential is limited. Ruthenium complexes can be particularly active, especially if they facilitate a dinuclear pathway for oxygen bond formation step. A supramolecular encapsulation strategy is reported that involves preorganization of dilute solutions (10?5 m ) of ruthenium complexes to yield high local catalyst concentrations (up to 0.54 m ). The preorganization strategy enhances the water oxidation rate by two‐orders of magnitude to 125 s?1, as it facilitates the diffusion‐controlled rate‐limiting dinuclear coupling step. Moreover, it modulates reaction rates, enabling comprehensive elucidation of electrocatalytic reaction mechanisms. 相似文献
7.
8.
Lorenzo Catti Qi Zhang Prof. Dr. Konrad Tiefenbacher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9060-9066
Control over the local chemical environment of a molecule can be achieved by encapsulation in supramolecular host systems. In supramolecular catalysis, this control is used to gain advantages over classical homogeneous catalysis in bulk solution. Two of the main advantages concern influencing reactions in terms of substrate and product selectivity. Due to size and/or shape recognition, substrate selective conversion can be realized. Additionally, noncovalent interactions with the host environment facilitate alternative reaction pathways and can yield unusual products. This Concept article discusses and highlights literature examples utilizing self‐assembled molecular capsules to achieve catalytic transformations displaying a high degree of substrate and/or product selectivity. Furthermore, the advantage of supramolecular hosts in multicatalyst tandem reactions is covered. 相似文献
9.
Desymmetrization of an Octahedral Coordination Complex Inside a Self‐Assembled Exoskeleton 下载免费PDF全文
Dr. Mark D. Johnstone Eike K. Schwarze Jennifer Ahrens Prof. Dr. Dirk Schwarzer Dr. Julian J. Holstein Dr. Birger Dittrich Dr. Frederick M. Pfeffer Prof. Dr. Guido H. Clever 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(31):10791-10795
The synthesis of a centrally functionalized, ribbon‐shaped [6]polynorbornane ligand L that self‐assembles with PdII cations into a {Pd2 L 4} coordination cage is reported. The shape‐persistent {Pd2 L 4} cage contains two axial cationic centers and an array of four equatorial H‐bond donors pointing directly towards the center of the cavity. This precisely defined supramolecular environment is complementary to the geometry of classic octahedral complexes [M(XY)6] with six diatomic ligands. Very strong binding of [Pt(CN)6]2? to the cage was observed, with the structure of the host–guest complex {[Pt(CN)6]@Pd2L4} supported by NMR spectroscopy, MS, and X‐ray data. The self‐assembled shell imprints its geometry on the encapsulated guest, and desymmetrization of the octahedral platinum species by the influence of the D4h‐symmetric second coordination sphere was evidenced by IR spectroscopy. [Fe(CN)6]3? and square‐planar [Pt(CN)4]2? were strongly bound. Smaller octahedral anions such as [SiF6]2?, neutral carbonyl complexes ([M(CO)6]; M=Cr, Mo, W) and the linear [Ag(CN)2]? anion were only weakly bound, showing that both size and charge match are key factors for high‐affinity binding. 相似文献
10.
Neal P. Mankad 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(17):5822-5829
An emerging area of homogeneous catalysis is the use of catalysts featuring two closely associated metal sites. This approach complements the traditional focus on single‐site catalysts and makes available new parameters with which to optimize catalytic behavior. Single‐site catalysts are optimized through changing 1) the identity of the metal, and 2) the steric and electronic properties of the ligands. Bimetallic catalysts introduce new optimization parameters such as 3) catalyst nuclearity (mononuclear vs. binuclear), and 4) bimetallic pairing (relative compatibility of two metal sites). In order to harness these new optimization parameters in developing systems, it is necessary to first understand the origin of bimetallic selectivity effects that already have been documented. This Concept article highlights bimetallic effects on the chemo‐, regio‐, and stereoselectivity of catalytic transformations, using selected case studies from the recent literature as illustrative examples. 相似文献
11.
12.
Ultrastable Hydroxyapatite/Titanium‐Dioxide‐Supported Gold Nanocatalyst with Strong Metal–Support Interaction for Carbon Monoxide Oxidation 下载免费PDF全文
Hailian Tang Dr. Fei Liu Jiake Wei Dr. Botao Qiao Dr. Kunfeng Zhao Yang Su Dr. Changzi Jin Dr. Lin Li Prof. Jingyue Liu Prof. Junhu Wang Prof. Tao Zhang 《Angewandte Chemie (International ed. in English)》2016,55(36):10606-10611
Supported Au nanocatalysts have attracted intensive interest because of their unique catalytic properties. Their poor thermal stability, however, presents a major barrier to the practical applications. Here we report an ultrastable Au nanocatalyst by localizing the Au nanoparticles (NPs) in the interfacial regions between the TiO2 and hydroxyapatite. This unique configuration makes the Au NP surface partially encapsulated due to the strong metal–support interaction and partially exposed and accessible by the reaction molecules. The strong interaction helps stabilizing the Au NPs while the partially exposed Au NP surface provides the active sites for reactions. Such a catalyst not only demonstrated excellent sintering resistance with high activity after calcination at 800 °C but also showed excellent durability that outperforms a commercial three‐way catalyst in a simulated practical testing, suggesting great potential for practical applications. 相似文献
13.
14.
15.
Dr. Tania Lasanta Prof. Dr. José M. López‐de‐Luzuriaga Dr. Miguel Monge Dr. M. Elena Olmos David Pascual 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(15):4754-4766
Heteronuclear complexes {[Hg(R)2][Au(R′)(PMe3)]2}n (R=R′=C6Cl2F3 ( 3 ); R=R′=C6F5 ( 4 ); R=C6Cl2F3, R′=C6F5 ( 5 ); R=C6F5, R′=C6Cl2F3 ( 6 )) were prepared by the treatment of the corresponding organomercury compounds, [Hg(C6X5)2], with two equivalents of [Au(C6X5)(PMe3)]. Their crystal structures, as determined by using X‐ray diffraction methods, display Au???Hg interactions. Although only compound 4 and 5 show luminescence in the solid state, all of these compounds quench the fluorescence of naphthalene in solution. Solution studies of these derivatives suggest a cooperative effect of the gold(I) center in switching on the quenching capabilities of the [Hg(C6X5)2] synthon with naphthalene. Theoretical studies confirmed the quenching ability of the organomercury species in the presence of gold. 相似文献
16.
Eduardo J. Fernández Dr. Christopher Hardacre Prof. Antonio Laguna Prof. M. Cristina Lagunas Dr. José M. López‐de‐Luzuriaga Dr. Miguel Monge Dr. Manuel Montiel Dr. M. Elena Olmos Dr. Raquel C. Puelles Eva Sánchez‐Forcada 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(25):6222-6233
Metallophilic Au???Ag interactions exist in concentrated solutions as well as in the 2D polymeric solid‐state structure of [AuAg3(C6F5)(CF3CO2)3(CH2PPh3)]n (see picture for the asymmetric unit) according to EXAFS and pulsed‐gradient spin‐echo NMR spectroscopy measurements. Calculations support both the emission assignments and the existence of the metallophilic interactions in solution.
17.
Inside Back Cover: Designed Enclosure Enables Guest Binding Within the 4200 Å3 Cavity of a Self‐Assembled Cube (Angew. Chem. Int. Ed. 19/2015) 下载免费PDF全文
William J. Ramsay Filip T. Szczypiński Dr. Haim Weissman Dr. Tanya K. Ronson Dr. Maarten M. J. Smulders Prof. Boris Rybtchinski Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(19):5793-5793
18.
Inside Cover: Detailed Investigation of the Structural,Thermal, and Electronic Properties of Gold Isocyanide Complexes with Mechano‐Triggered Single‐Crystal‐to‐Single‐Crystal Phase Transitions (Chem. Eur. J. 6/2016) 下载免费PDF全文
Dr. Tomohiro Seki Kenta Sakurada Mai Muromoto Prof. Dr. Shu Seki Prof. Dr. Hajime Ito 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(6):1866-1866
19.
20.
《化学:亚洲杂志》2017,12(9):968-972
Hybridization of a self‐assembled, spherical complex with oligosaccharides containing Lewis X, a functional trisaccharide displayed on various cell surfaces, yielded well‐defined glycoclusters. The self‐assembled glycoclusters exhibited homophilic hyper‐assembly in aqueous solution in a Ca2+‐dependent manner through specific carbohydrate–carbohydrate interactions, offering a structural scaffold for functional biomimetic systems. 相似文献