共查询到20条相似文献,搜索用时 15 毫秒
1.
Dr. Mohammad Mosharraf Hossain Joshua L. Atkinson Dr. C. Scott Hartley 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(33):13911-13917
Dissipative assembly has great potential for the creation of new adaptive chemical systems. However, while molecular assembly at equilibrium is routinely used to prepare complex architectures from polyfunctional monomers, species formed out of equilibrium have, to this point, been structurally very simple. In most examples the fuel simply effects the formation of a single short-lived covalent bond. Herein, we show that chemical fuels can assemble bifunctional components into macrocycles containing multiple transient bonds. Specifically, dicarboxylic acids give aqueous dianhydride macrocycles on treatment with a carbodiimide. The macrocycles are assembled efficiently as a consequence of both fuel-dependent and fuel-independent mechanisms; they undergo slower decomposition, building up as the fuel recycles the components, and are a favored product of the dynamic exchange of the anhydride bonds. These results create new possibilities for generating structurally sophisticated out-of-equilibrium species. 相似文献
2.
Ignacio Alfonso Dr. Miriam Bru Dr. M. Isabel Burguete Dr. Eduardo García‐Verdugo Dr. Santiago V. Luis Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(4):1246-1255
The self‐assembling abilities of several pseudopeptidic macrocycles have been thoroughly studied both in the solid (SEM, TEM, FTIR) and in solution (NMR, UV, CD, FTIR) states. Detailed microscopy revealed large differences in the morphology of the self‐assembling micro/nanostructures depending on the macrocyclic chemical structures. Self‐assembly was triggered by the presence of additional methylene groups or by changing from para to meta geometry of the aromatic phenylene backbone moiety. More interestingly, the nature of the side chain also plays a fundamental role in some of the obtained nanostructures, thus producing structures from long fibers to hollow spheres. These nanostructures were obtained in different solvents and on different surfaces, thus implying that the chemical information for the self‐assembly is contained in the molecular structure. Dilution NMR studies (chemical shift and self‐diffusion rates) suggest the formation of incipient aggregates in solution by a combination of hydrogen‐bonding and π–π interactions, thus implicating amide and aryl groups, respectively. Electronic spectroscopy further supports the π–π interactions because the compounds that lead to fibers show large hypochromic shifts in the UV spectra. Moreover, the fiber‐forming macrocycles also showed a more intense CD signature. The hydrogen‐bonding interactions within the nanostructures were also characterized by attenuated total‐reflectance FTIR spectroscopy, which allowed us to monitor the complete transition from the solution to the dried nanostructure. Overall, we concluded that the self‐assembly of this family of pseudopeptidic macrocycles is dictated by a synergic action of hydrogen‐bonding and π–π interactions. The feasibility and geometrical disposition of these interactions finally render a hierarchical organization, which has been rationalized with a proposal of a model. The understanding of the process at the molecular level has allowed us to prepare hybrid soft materials. 相似文献
3.
Lucile Fischer Marion Decossas Dr. Jean‐Paul Briand Dr. Claude Didierjean Dr. Gilles Guichard Dr. 《Angewandte Chemie (International ed. in English)》2009,48(9):1625-1628
The perfect blend : A new class of self‐assembling cyclooligomers with mixed urea/amide backbone is described (see figure). A high level of hierarchical and directional control is achieved: depending on the level of backbone preorganization, columnar or tubular arrangements with either parallel or antiparallel growing modes can be selected.
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Dissipative Synthetic DNA‐Based Receptors for the Transient Loading and Release of Molecular Cargo 下载免费PDF全文
Dr. Giulio Ragazzon Prof. Leonard J. Prins Prof. Francesco Ricci 《Angewandte Chemie (International ed. in English)》2018,57(33):10489-10493
Supramolecular chemistry is moving into a direction in which the composition of a chemical equilibrium is no longer determined by thermodynamics but by the efficiency with which kinetic states can be populated by energy consuming processes. Herein, we show that DNA is ideally suited for programming chemically fueled dissipative self‐assembly processes. Advantages of the DNA‐based systems presented in this study include a perfect control over the activation site for the chemical fuel in terms of selectivity and affinity, highly selective fuel consumption that occurs exclusively in the activated complex, and a high tolerance for the presence of waste products. Finally, it is shown that chemical fuels can be used to selectively activate different functions in a system of higher complexity embedded with multiple response pathways. 相似文献
5.
Dr. Matthias Georg Schwab Dr. Tianshi Qin Dr. Wojciech Pisula Dr. Alexey Mavrinskiy Dr. Xinliang Feng Dr. Martin Baumgarten Hun Kim Dr. Frédéric Laquai Sebastian Schuh Roman Trattnig Prof. Emil J. W. List Prof. Dr. Klaus Müllen 《化学:亚洲杂志》2011,6(11):3001-3010
A set of cyclo‐7,10‐tris‐triphenylenyl macrocycles have been prepared by a Yamamoto cyclotrimerization protocol. In these novel macrocycles, three triphenylene units are covalently linked to each other, resulting in the formation of triangular‐shaped molecules. The fully planar derivative revealed pronounced self‐assembly behavior. NMR spectroscopy was used to determine the association constant in solution. 2D wide‐angle X‐ray scattering was applied to the study of the liquid crystallinity of this new discotic mesogen in the bulk state. Furthermore, nonplanar, laterally substituted derivatives were successfully tested as blue emitters in organic light‐emitting diodes owing to their unique optoelectronic properties and their high stability. In this case, substitution with sterically demanding phenyl groups was efficiently used to suppress intermolecular packing, thus preventing undesired quenching effects. 相似文献
6.
Joseph K.‐H. Hui Peter D. Frischmann Chien‐Hsin Tso Carl A. Michal Prof. Dr. Mark J. MacLachlan Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(8):2453-2460
Schiff base macrocycle 1 , which has a crown ether like central pore, was combined with different alkali‐metal and ammonium salts in chloroform, resulting in one‐dimensional supramolecular aggregates. The ion‐induced self‐assembly was studied with solid‐state NMR spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was found that the lengths and widths of the superstructures depend on the cation and counteranion of the salts. Among the salts being used, Na+ and NH4+ ions with BF4? ions showed the most impressive fibrous structures that can grow up to 1 μm in diameter and hundreds of microns in length. In addition, the size of the fibers can be controlled by the evaporation rate of the solvent. A new macrocycle with bulky triptycenyl substituents that prevent supramolecular assembly was prepared and did not display any nanofibers with alkali‐metal ions in chloroform when studied with TEM. 相似文献
7.
Dr. Peter D. Frischmann Brian J. Sahli Dr. Samuel Guieu Dr. Brian O. Patrick Prof. Mark J. MacLachlan 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(43):13712-13721
We report a template‐free strategy based on steric repulsion for the isolation of discrete columnar aggregates of macrocycles. Specifically, introduction of sterically‐demanding trityl‐derived substituents at the periphery of Pt4 Schiff base macrocycles limits the otherwise infinite one‐dimensional columnar aggregation to discrete tetrameric and hexameric assemblies. Single crystal X‐ray diffraction studies of these compounds reveal discrete nanotubes of finite length that pack inefficiently resulting in three‐dimensional networks of interconnected void space. The discrete assemblies were studied by N2 adsorption and show enhanced surface area when stacked. In the absence of bulky substituents the macrocycles are nonporous. This strategy for engineering discrete supramolecular macrocyclic aggregates may be generalized to other columnar assembling systems. 相似文献
8.
Torands Revisited: Metal Sequestration and Self‐Assembly of Cyclo‐2,9‐tris‐1,10‐phenanthroline Hexaaza Macrocycles 下载免费PDF全文
Dr. Matthias Georg Schwab Dr. Masayoshi Takase Dr. Alexey Mavrinsky Dr. Wojciech Pisula Prof. Dr. Xinliang Feng Dr. José A. Gámez Prof. Dr. Walter Thiel Dr. Kunal S. Mali Prof. Dr. Steven de Feyter Prof. Dr. Klaus Müllen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8426-8434
A series of novel toroidal cyclo‐2,9‐tris‐1,10‐phenanthroline macrocycles with an unusual hexaaza cavity are reported. Nickel‐mediated Yamamoto aryl–aryl coupling was found to be a versatile tool for the cyclotrimerization of functionalized 1,10‐phenathroline precursors. Due to the now improved processability, both liquid‐crystalline behavior in the bulk phase and two‐dimensional self‐assembly at the molecular level could be studied, for the first time, for a torand system. The macrocycles exhibited a strong affinity for the complexation of different metal cations, as evidenced by MALDI‐TOF analysis and spectroscopic methods. Experimental results were correlated to an extensive computational study of the cyclo‐2,9‐tris‐1,10‐phenanthroline cavity and its binding mode for metal cations. Due to the combination of several interesting features, toroidal macrocycles may find future applications in the field of ion and charge transport through molecular channels, as well as for chemical sensing and molecular writing in surface‐confined monolayers under STM conditions. 相似文献
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Summary: Dissipative particle dynamics simulations are performed on the distribution of binary nanoparticle mixtures in lamellar diblock copolymers. The results show that the self‐assembly of nanoparticle mixtures in polymer matrix is a cooperative assembly that is affected by various factors, providing molecular‐level information for the rational design of new polymer nanocomposites with tailored properties.
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Wojciech Pisula Dr. Marcel Kastler Dr. Changduk Yang Dr. Volker Enkelmann Dr. Klaus Müllen Prof. Dr. 《化学:亚洲杂志》2007,2(1):51-56
Two novel discotic macrocycles, substituted cyclohexa‐m‐phenylene (CHP) and cyclo‐3,6‐trisphenanthrylene (CTP), and the linear oligomer 3,3′:6′,3′′‐terphenanthrene (TP) as a model substance have been synthesized by repetitive cross‐coupling reactions. To correlate the molecular design with the supramolecular architecture and the established macroscopic order, 2D wide‐angle X‐ray scattering experiments were performed on mechanically extruded filaments. At room temperature in their crystalline phases, all three compounds revealed columnar assemblies in which the macrocycles self‐organized by π‐stacking interactions. The degree of macroscopic order was found to depend upon the planarity and stiffness of the aromatic core. The flexible CHP ring showed a poor macroscopic order of the columnar structures and a low isotropization temperature, whereas the more‐planar, less‐flexible CTP self‐assembled into well‐defined superstructures. The larger π‐stacking area and the more‐pronounced intermolecular interactions for CTP led to the formation of a mesophase over a very large temperature range. The surprising columnar organization of the “open” TP system was explained by back‐folding of the molecule into a ringlike structure. 相似文献
12.
Yadong Sun Zhao Wang Yiwen Li Zhengbiao Zhang Wei Zhang Xiangqiang Pan Nianchen Zhou Xiulin Zhu 《Macromolecular rapid communications》2015,36(14):1341-1347
Herein, the first example of photosensitive cyclic amphiphilic homopolymers consisting of multiple biphenyl azobenzene chromophores in the cyclic main chain tethered with hydrophilic tetraethylene glycol monomethyl ether units is presented. The synthetic approach involves sequentially performed thermal catalyzed “click” step‐growth polymerization in bulk, and Cu(I)‐catalyzed azide–alkyne cycloaddition (CuAAC) intramolecular cyclization from α‐alkyne/ω‐azide linear precursors. It is observed that such amphiphilic macrocycles exhibit increased glass transition temperatures (Tg), slightly faster trans–cis–trans photoisomerization, and enhanced fluorescence emission intensity compared with the corresponding linear polymers. In addition, the cyclic amphiphilic homopolymers self‐assemble into spherical nanoparticles with smaller sizes which possess slower photoresponsive behaviors in a tetrahydrofuran/water mixture compared with those of the linear ones. All these interesting observations suggest that the cyclic topology has a great influence on the physical properties and self‐assembly behavior of these photoresponsive amphiphilic macrocycles in general.
13.
Enantiopure Laterally Functionalized Alleno–Acetylenic Macrocycles: Synthesis,Chiroptical Properties,and Self‐Assembly in Aqueous Media 下载免费PDF全文
Dr. Manolis D. Tzirakis Dr. Mariza N. Alberti Dr. Haim Weissman Prof. Dr. Boris Rybtchinski Prof. Dr. François Diederich 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(49):16070-16073
A family of shape‐persistent alleno–acetylenic macrocycles (SPAAMs), peripherally decorated with structurally diverse pendant groups, has been synthesized and characterized in enantiomerically pure form. Their electronic circular dichroism (ECD) spectra feature a strong chiroptical response, which is more than two times higher than for open‐chain tetrameric analogues. A water‐soluble oligo(ethylene glycol)‐appended SPAAM undergoes self‐assembly in aqueous solution. Morphology studies by cryogenic transmission electron microscopy (cryo‐TEM) revealed the formation of aggregates with fibrous fine structures that correspond to tubular, macrocyclic stacks. 相似文献
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Two‐Dimensional Nanoporous Networks Formed by Liquid‐to‐Solid Transfer of Hydrogen‐Bonded Macrocycles Built from DNA Bases 下载免费PDF全文
Nerea Bilbao Iris Destoop Prof. Steven De Feyter Dr. David González‐Rodríguez 《Angewandte Chemie (International ed. in English)》2016,55(2):659-663
We present an approach that makes use of DNA base pairing to produce hydrogen‐bonded macrocycles whose supramolecular structure can be transferred from solution to a solid substrate. A hierarchical assembly process ultimately leads to two‐dimensional nanostructured porous networks that are able to host size‐complementary guests. 相似文献
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Dong Hwan Kim Dr. Nem Singh Jihun Oh Eun‐Hee Kim Dr. Jaehoon Jung Dr. Hyunuk Kim Prof. Ki‐Whan Chi 《Angewandte Chemie (International ed. in English)》2018,57(20):5669-5673
Molecular knots have become highly attractive to chemists because of their prospective properties in mimicking biomolecules and machines. Only a few examples of molecular knots from the billions tabulated by mathematicians have been realized and molecular knots with more than eight crossings have not been reported to date. We report here the coordination‐driven [8+8] self‐assembly of a higher‐generation molecular knot comprising as many as sixteen crossings. Its solid‐state X‐ray crystal structure and multinuclear 2D NMR findings confirmed its architecture and topology. The formation of this molecular knot appears to depend on the functionalities and geometries of donor and acceptor in terms of generating appropriate angles and strong π‐π interactions supported by hydrophobic effects. This study shows coordination‐driven self‐assembly offers a powerful potential means of synthesizing more and more complicated molecular knots and of understanding differences between the properties of knotted and unknotted structures. 相似文献
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Inside Cover: Torands Revisited: Metal Sequestration and Self‐Assembly of Cyclo‐2,9‐tris‐1,10‐phenanthroline Hexaaza Macrocycles (Chem. Eur. J. 23/2015) 下载免费PDF全文
Dr. Matthias Georg Schwab Dr. Masayoshi Takase Dr. Alexey Mavrinsky Dr. Wojciech Pisula Prof. Dr. Xinliang Feng Dr. José A. Gámez Prof. Dr. Walter Thiel Dr. Kunal S. Mali Prof. Dr. Steven de Feyter Prof. Dr. Klaus Müllen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(23):8302-8302
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Trevor A. Shear Fuding Lin Lev N. Zakharov Darren W. Johnson 《Angewandte Chemie (International ed. in English)》2020,59(4):1496-1500
Cyclophanes are a venerable class of macrocyclic and cage compounds that often contain unusual conformations, high strain, and unusual properties. However, synthesis of complex, functional derivatives remains difficult due to low functional group tolerance, high dilution, extreme reaction conditions, and sometimes low yields using traditional stepwise synthetic methods. “Design of experiments” (DOE) is a method employed for the optimization of reaction conditions, and we showcase this approach to generate a dramatic increase in the yield of specific targets from two different self‐assembling systems. These examples demonstrate that DOE provides an additional tool in tuning self‐assembling, dynamic covalent systems. 相似文献
20.
Yuta Takaki Ryota Ozawa Dr. Takashi Kajitani Prof. Takanori Fukushima Prof. Masaaki Mitsui Prof. Kenji Kobayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(47):16760-16764
Cyclic arylene ethynylene hexamer 1 , composed of alternating 2,7‐anthrylene ethynylene units and meta‐phenylene ethynylene units, was synthesized. It shows C3 symmetry and possesses a flat and rigid conformation with a large equilateral triangle‐like cavity. Macrocycle 1 self‐associates through π–π stacking interactions between the anthracene‐containing macrocyclic aromatic cores with indefinite‐association constant KE=6980 m ?1 in CDCl3 at 303 K. Macrocycle 1 also self‐assembles into π‐stacked nanofibers in the drop‐cast film. 相似文献