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101.
102.
103.
Clément Schouwey Dr. Rosario Scopelliti Prof. Kay Severin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(20):6274-6281
The synthesis of a cylindrical, imine‐based cage composed of two trimeric metallamacrocycles is described. The cage acts as a heterotopic receptor for alkali metal cations. The small cations Li+, Na+, and K+ bind to the outside of the cage with good selectivity for Li+, whereas the larger cations Rb+ and Cs+ are bound inside the cage to form unusual π complexes with a good selectivity for Cs+. Negative heterotopic cooperativity between the two binding sites is observed. The complexation of Cs+ is associated with a color change, which enables the cage to be used as a specific sensor for Cs+. 相似文献
104.
Chen W Widawsky JR Vázquez H Schneebeli ST Hybertsen MS Breslow R Venkataraman L 《Journal of the American Chemical Society》2011,133(43):17160-17163
We measure electronic conductance through single conjugated molecules bonded to Au metal electrodes with direct Au-C covalent bonds using the scanning tunneling microscope based break-junction technique. We start with molecules terminated with trimethyltin end groups that cleave off in situ, resulting in formation of a direct covalent σ bond between the carbon backbone and the gold metal electrodes. The molecular carbon backbone used in this study consist of a conjugated π system that has one terminal methylene group on each end, which bonds to the electrodes, achieving large electronic coupling of the electrodes to the π system. The junctions formed with the prototypical example of 1,4-dimethylenebenzene show a conductance approaching one conductance quantum (G(0) = 2e(2)/h). Junctions formed with methylene-terminated oligophenyls with two to four phenyl units show a 100-fold increase in conductance compared with junctions formed with amine-linked oligophenyls. The conduction mechanism for these longer oligophenyls is tunneling, as they exhibit an exponential dependence of conductance on oligomer length. In addition, density functional theory based calculations for the Au-xylylene-Au junction show near-resonant transmission, with a crossover to tunneling for the longer oligomers. 相似文献
105.
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
106.
Dr. Mirela Pascu Mathieu Marmier Clément Schouwey Dr. Rosario Scopelliti Dr. Julian J. Holstein Dr. Gérard Bricogne Prof. Kay Severin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(19):5592-5600
The facile synthesis of anionic bipyridyl ligands with dinuclear clathrochelate cores is described. These metalloligands can be obtained in high yields by the reactions of M(ClO4)2(H2O)6 (M: Zn, Mn, or Co) with 4‐pyridylboronic acid and 2,6‐diformyl‐4‐methylphenol oxime or 2,6‐diformyl‐4‐tert‐butylphenol oxime, followed by deprotonation. The ligands are interesting building blocks for metallasupramolecular chemistry, as evidenced by the formation of a Pt‐based molecular square and four coordination polymers with 2D or 3D network structures. Competition experiments reveal that the utilization of anionic bipyridyl ligands can result in significantly more stable assemblies. 相似文献
107.
Dr. Ru-Jin Li Dr. Farzaneh Fadaei-Tirani Dr. Rosario Scopelliti Prof. Kay Severin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(36):9439-9445
Spherical assemblies of the type [PdnL2n]2n+ can be obtained from PdII salts and curved N-donor ligands, L. It is well established that the bent angle, α, of the ligand is a decisive factor in the self-assembly process, with larger angles leading to complexes with a higher nuclearity, n. Herein, we report heteroleptic coordination cages of the type [PdnLnL′n]2n+, for which a similar correlation between the ligand bent angle and the nuclearity is observed. Tetranuclear cages were obtained by combining [Pd(CH3CN)4](BF4)2 with 1,3-di(pyridin-3-yl)benzene and ligands featuring a bent angle of α=120°. The use of a dipyridyl ligand with α=149° led to the formation of a hexanuclear complex with a trigonal prismatic geometry; for linear ligands, octanuclear assemblies of the type [Pd8L8L′8]16+ were obtained. The predictable formation of heteroleptic PdII cages from 1,3-di(pyridin-3-yl)benzene and different dipyridyl ligands is evidence that there are entire classes of heteroleptic cage structures that are privileged from a thermodynamic point of view. 相似文献
108.
Concentration-Dependent Self-Assembly of an Unusually Large Hexameric Hydrogen-Bonded Molecular Cage
Severin Merget Dr. Lorenzo Catti Shani Zev Prof. Dr. Dan T. Major Dr. Nils Trapp Prof. Dr. Konrad Tiefenbacher 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(13):4447-4453
The sizes of available self-assembled hydrogen-bond-based supramolecular capsules and cages are rather limited. The largest systems have volumes of approximately 1400–2300 Å3. Herein, we report a large, hexameric cage based on intermolecular amide–amide dimerization. The unusual structure with openings, reminiscent of covalently linked cages, is held together by 24 hydrogen bonds. With a diameter of 2.3 nm and a cavity volume of ∼2800 Å3, the assembly is larger than any previously known capsule/cage structure relying exclusively on hydrogen bonds. The self-assembly process in chlorinated, organic solvents was found to be strongly concentration dependent, with the monomeric form prevailing at low concentrations. Additionally, the formation of host–guest complexes with fullerenes (C60 and C70) was observed. 相似文献
109.
Shalamova E. S. Severin A. V. Trofimova T. P. Belyshev S. S. Orlova M. A. 《Russian Chemical Bulletin》2021,70(10):2014-2018
Russian Chemical Bulletin - In order to characterize hydroxyapatite (HAP) as a possible carrier of medicinal drugs and radionuclides, the possibility of using HAP modified with zinc ions (HAP-Zn)... 相似文献
110.
Severin Johansson 《Mathematische Annalen》1906,62(2):184-193
Ohne Zusammenfassung 相似文献