共查询到20条相似文献,搜索用时 0 毫秒
1.
Sabrina Freye David M. Engelhard Dr. Michael John Prof. Dr. Guido H. Clever 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(6):2114-2121
In solution, the eight BF4? counterions of a positively charged D4‐symmetric interpenetrated [Pd4ligand8]8+ double cage ( 1 ) are localized in distinct positions. At low temperatures, one BF4? ion is encapsulated inside the central pocket of the supramolecular structure, two BF4? ions are bound inside the equivalent outer pockets, and the remaining five BF4? ions are located outside the cage structure (expressed by the formula [3 BF4@ 1 ][BF4]5). On warming, the two BF4? ions in the outer pockets are found to exchange with the exterior ions in solution whereas the central BF4? ion stays locked inside the central cavity (here written as [BF4@ 1 ][BF4]7). The exchange kinetics were determined by exchange spectroscopy (EXSY) NMR experiments and line‐shape fitting in different solvents. The tremendously high affinity of this double cage for the binding of two chloride ions inside the outer pockets allows for complete exchange of two BF4? ions by the addition of solid AgCl to give [2 Cl+BF4@ 1 ][BF4]5. The uptake of the two chloride ions is allosteric and is thus accompanied by a structural rearrangement (compression along the Pd4 axis) of the double cage structure. An analysis by using 900 MHz NOESY NMR spectroscopy shows that this compression of about 3.3 % is associated with a helical twist of 8°, which together resemble a screw motion. As a consequence of squeezing each of the outer two pockets by 53 %, the volume of the central pocket is increased by 43 %, which results in an increase of 36 % in the 19F spin‐lattice relaxation time (T1) of the central BF4? ion. The packing coefficients (PC) for the ions in the outer pockets (103 % for BF4? and 96 % for Cl?) were calculated. 相似文献
2.
Cassandra C. Shaffer Dr. Wenqi Liu Dr. Allen G. Oliver Dr. Bradley D. Smith 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(2):751-757
A new supramolecular paradigm is presented for reliable capture and co-precipitation of haloauric acids (HAuX4) from organic solvents or water. Two classes of acyclic organic compounds act as complementary receptors (tectons) by forming two sets of directional non-covalent interactions, (a) hydrogen bonding between amide (or amidinium) NH residues and the electronegative X ligands on the AuX4−, and (b) electrostatic stacking of the electron deficient Au center against the face of an aromatic surface. X-ray diffraction analysis of four co-crystal structures reveals the additional common feature of proton bridged carbonyls as a new and predictable supramolecular design element that creates one-dimensional polymers linked by very short hydrogen bonds (CO⋅⋅⋅OC distance <2.5 Å). Two other co-crystal structures show that the amidinium-π⋅⋅⋅XAu interaction will reliably engage AuX4− with high directionality. These acyclic compounds are very attractive as co-precipitation agents within new “green” gold recovery processes. They also have high potential as tectons for controlled self-assembly or co-crystal engineering of haloaurate composites. More generally, the supramolecular paradigm will facilitate the design of next-generation receptors or tectons with high affinity for precious metal square planar coordination complexes for use in advanced materials, nanotechnology, or medicine. 相似文献
3.
Dr. Laure-Elie Carloni Dr. C. Grazia Bezzu Prof. Dr. Davide Bonifazi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(71):16179-16200
Two-dimensional (2D) porous networks are of great interest for the fabrication of complex organized functional materials for potential applications in nanotechnologies and nanoelectronics. This review aims at providing an overview of bottom-up approaches towards the engineering of 2D porous networks by using biomacromolecules, with a particular focus on nucleic acids and proteins. The first part illustrates how the advancements in DNA nanotechnology allowed for the attainment of complex ordered porous two-dimensional DNA nanostructures, thanks to a biomimetic approach based on DNA molecules self-assembly through specific hydrogen-bond base pairing. The second part focuses the attention on how polypeptides and proteins structural properties could be used to engineer organized networks templating the formation of multifunctional materials. The structural organization of all examples is discussed as revealed by scanning probe microscopy or transmission electron microscopy imaging techniques. 相似文献
4.
Hui Li Ruifu Wang Dr. You-lee Hong Zihao Liang Yidan Shen Dr. Yusuke Nishiyama Prof. Toshikazu Miyoshi Prof. Tianbo Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(22):5803-5808
Charged or neutral adamantane guests can be encapsulated into the cavity of cationic metal–organic M6L4 (bpy-cage, M=PdII(2,2′-bipyridine), L=2,4,6-tri(4-pyridyl)-1,3,5-triazine) cages through hydrophobic interaction. These encapsulations can provide an approach to control the net charge on the resulting cage–guest complexes and regulate their charge-dominated assembly into hollow spherical blackberry-type assemblies in dilute solutions: encapsulation of neutral guests will hardly influence their self-assembly process, including the blackberry structure size, which is directly related to the intercage distance in the assembly; whereas encapsulating negatively (positively) charged guests resulted in a shorter (longer) intercage distance with larger (smaller) assemblies formed. Therefore, the host–guest chemistry approach can be used to tune the intercage distance accurately. 相似文献
5.
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
6.
Basem Moosa Lukman O. Alimi Aleksander Shkurenko Aliyah Fakim Prashant M. Bhatt Gengwu Zhang Mohamed Eddaoudi Niveen M. Khashab 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21551-21555
Developing the competence of molecular sorbents for energy-saving applications, such as C8 separations, requires efficient, stable, scalable, and easily recyclable materials that can readily transition to commercial implementation. Herein, we report an azobenzene-based cage for the selective separation of p-xylene isomer across a range of C8 isomers in both vapor and liquid states with selectivity that is higher than the reported all-organic sorbents. The crystal structure shows non-porous cages that are separated by p-xylene molecules through selective CH–π interactions between the azo bonds and the methyl hydrogen atoms of the xylene molecules. This cage is stable in solution and can be regenerated directly under vacuum to be used in multiple cycles. We envisage that this work will promote the investigation of the azo bond as well as guest-induced crystal-to-crystal phase transition in non-porous organic solids for energy-intensive separations. 相似文献
7.
Riley J. Petersen Brett J. Rozeboom Dr. Shalisa M. Oburn Nolan J. Blythe Tanner L. Rathje Javier A. Luna Steven K. Kibby Emily A. O'Brien Kayleigh G. Rohr Joshua R. Carpenter Taylor L. Sanders Andrew M. Johnson Dr. Kristin M. Hutchins Prof. Scott K. Shaw Prof. Leonard R. MacGillivray Prof. Jay Wm. Wackerly 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(9):1928-1930
A novel macrocyclic host molecule was synthesized that forms in a single step from commercially available starting materials. The core of the macrocycle backbone possesses two quinone rings and, thus, it is redox-active. Host–guest binding involving the clip-shaped cavity indicates selective binding of pyridine N-oxides based on the electron density of and steric bulk around the anionic oxygen. 相似文献
8.
Zsolt Csók Tamás Kégl László Párkányi Ágnes Varga Sándor Kunsági-Máté László Kollár 《Supramolecular chemistry》2013,25(10):710-719
A wide variety of 2-methyl-resorcinol-based deepened cavitands were synthesised from readily available reagents in a four-step procedure with overall yields of up to 62%. A systematic variation of the rim was carried out by building up a flexible upper aromatic wall on the rigid cavitand platform through CH2, CH2O and CH2OCH2 spacers. These aromatic walls were further extended by a Suzuki cross-coupling reaction. Full characterisation of the synthesised cavitands was carried out. The solid-state structure of tetrakis(phenoxymethyl)cavitand was determined by X-ray crystallography. Gas-phase theoretical calculations for this molecule predict the presence of weak T-shaped interactions between the upper phenyl rings. The host–guest complex formation ability of two deepened cavitand hosts towards 4-chloro-benzotrifluoride was proved by photoluminescence method. 相似文献
9.
Lynn S. Lisboa Dr. James A. Findlay Prof. L. James Wright Prof. Christian G. Hartinger Prof. James D. Crowley 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(27):11194-11200
A strategy is presented that enables the quantitative assembly of a heterobimetallic [PdPtL4]4+ cage. The presence of two different metal ions (PdII and PtII) with differing labilities enables the cage to be opened and closed selectively at one end upon treatment with suitable stimuli. Combining an inert PtII tetrapyridylaldehyde complex with a suitably substituted pyridylamine and PdII ions led to the assembly of the cage. 1H and DOSY NMR spectroscopy and ESI mass spectrometry data were consistent with the quantitative formation of the cage, and the heterobimetallic structure was confirmed using single-crystal X-ray crystallography. The structure of the host–guest adduct with a 2,6-diaminoanthraquinone guest molecule was determined. Addition of N,N′-dimethylaminopyridine (DMAP) resulted in the formation of the open-cage [PtL4]2+ compound and [Pd(DMAP)4]2+ complex. This process could then be reversed, with the reformation of the cage, upon addition of p-toluenesulfonic acid (TsOH). 相似文献
10.
Tongtong Zhang Dr. Laurent Le Corre Prof. Olivia Reinaud Dr. Benoit Colasson 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(1):434-443
The design of biomimetic models of metalloenzymes needs to take into account many factors and is therefore a challenging task. We propose in this work an original strategy to control the second coordination sphere of a metal centre and its distal environment. A biomimetic complex, reproducing the first coordination sphere, is encapsulated in a self-assembled hydrogen-bonded capsule. The cationic complex is co-encapsulated with its counter-anion or with solvent molecules. The capsule is dynamic, allowing a fast in/out exchange of the co-encapsulated species. It also provides both a hydrogen-bonding site in the second coordination sphere and a source of proton as it can be deprotonated in the presence of the complex, providing a globally neutral host-guest assembly. This simple and broad scope strategy is unprecedented in biomimetic studies. The approach appears to be a very promising method for the stabilisation of reactive species and for the study of their reactivity. 相似文献
11.
Honghong Duan Yawen Li Qingfang Li Pinpin Wang Xueru Liu Lin Cheng Yang Yu Liping Cao 《Angewandte Chemie (International ed. in English)》2020,59(25):10101-10110
We report the synthesis and characterization of a three‐dimensional tetraphenylethene‐based octacationic cage that shows host–guest recognition of polycyclic aromatic hydrocarbons (e.g. coronene) in organic media and water‐soluble dyes (e.g. sulforhodamine 101) in aqueous media through CH???π, π–π, and/or electrostatic interactions. The cage?coronene exhibits a cuboid internal cavity with a size of approximately 17.2×11.0×6.96 Å3 and a “hamburger”‐type host–guest complex, which is hierarchically stacked into 1D nanotubes and a 3D supramolecular framework. The free cage possesses a similar cavity in the crystalline state. Furthermore, a host–guest complex formed between the octacationic cage and sulforhodamine 101 had a higher absolute quantum yield (ΦF=28.5 %), larger excitation–emission gap (Δλex‐em=211 nm), and longer emission lifetime (τ=7.0 ns) as compared to the guest (ΦF=10.5 %; Δλex‐em=11 nm; τ=4.9 ns), and purer emission (ΔλFWHM=38 nm) as compared to the host (ΔλFWHM=111 nm). 相似文献
12.
13.
Jochen C. Lauer Ziwei Pang Paul Janßen Dr. Frank Rominger Tobias Kirschbaum Prof. Dr. Marcus Elstner Prof. Dr. Michael Mastalerz 《ChemistryOpen》2020,9(2):183-190
Three shape-persistent [4+4] imine cages with truncated tetrahedral geometry with different window sizes were studied as hosts for the encapsulation of tetra-n-alkylammonium salts of various bulkiness. In various solvents the cages behave differently. For instance, in dichloromethane the cage with smallest window size takes up NEt4+ but not NMe4 + , which is in contrast to the two cages with larger windows hosting both ions. To find out the reason for this, kinetic experiments were carried out to determine the velocity of uptake but also to deduce the activation barriers for these processes. To support the experimental results, calculations for the guest uptakes have been performed by molecular mechanics’ simulations. Finally, the complexation of pharmaceutical interested compounds, such as acetylcholine, muscarine or denatonium have been determined by NMR experiments. 相似文献
14.
Bin Tan Xiao-Dong Yang Li Sun Xiao-Ying Huang Jie Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(16):4136-4142
A flexible bipyridinium-linker-based porous host framework with electron-accepting pore surface, namely, [Zn2( L )(pmc)1.5] ⋅ 12 H2O ( 1 ; L⋅ Cl2=1,1′-[1,4-phenylene-bis(methylene)]bis(4,4′-bipyridinium) dichloride, H4pmc=pyromellitic acid) exhibits recognition of phenol and aromatic amine guests based on adsorbent–adsorbate charge-transfer interactions. Significantly, the resultant guest-encapsulated complexes 1@Guests can all be characterized by single-crystal X-ray diffraction. The host framework undergoes a reversible single crystal-to-single crystal transformation in response to the inclusion of different guests with flexible torsional motions of the hexagonal ring and the trapezoid-shaped bipyridinium groups. Such recognition can be visibly monitored and detected by obvious color changes. The host framework could also be recovered, and this suggested that guest sorption/desorption is reversible and that the host framework could be reused in potential applications. This work may provide an effective way to develop porous materials with special emphasis on applications involving guest recognition. 相似文献
15.
16.
Kentaro Harada Prof. Dr. Ryo Sekiya Prof. Dr. Takeharu Haino 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(26):5810-5817
Covalent organic capsules, such as carcerands and hemicarcerands, are an interesting class of molecular hosts. These container molecules have confined spaces capable of hosting small molecules, although the fact that the size of the inner cavities cannot be changed substantially limits the scope of their applications. The title covalently linked container was produced by metal-directed dimerization of a resorcinarene-based cavitand having four 2,2′-bipyridyl arms on the wide rim followed by olefin metathesis at the vertices of the resulting capsule with a second-generation Grubbs catalyst. The covalently linked bipyridyl arms permit expansion of the inner cavity by demetalation. This structural change influences the molecular recognition properties; the metal-coordinated capsule recognizes only 4,4′-diacetoxybiphenyl, whereas the metal-free counterpart can encapsulate not only 4,4′-diacetoxybiphenyl, but also 2,5-disubstituted-1,4-bis(4-acetoxyphenylethynyl)benzene, which is 9.4 Å longer than the former guest. Molecular mechanics calculations predict that the capsule expands the internal cavity to encapsulate the long guest by unfolding the folded conformation of the alkyl chains, which demonstrates the flexible and regulable nature of the cavity. Guest competition experiments show that the preferred guest can be switched by metalation and demetalation. This external-stimuli-responsive guest exchange can be utilized for the development of functional supramolecular systems controlling the uptake, transport, and release of chemicals. 相似文献
17.
Angela B. Grommet Dr. Jeanne L. Bolliger Dr. Colm Browne Prof. Jonathan R. Nitschke 《Angewandte Chemie (International ed. in English)》2015,54(50):15100-15104
Host–guest chemistry is usually carried out in either water or organic solvents. To investigate the utility of alternative solvents, three different coordination cages were dissolved in neat ionic liquids. By using 19F NMR spectroscopy to monitor the presence of free and bound guest molecules, all three cages were demonstrated to be stable and capable of encapsulating guests in ionic solution. Different cages were found to preferentially dissolve in different phases, allowing for the design of a triphasic sorting system. Within this system, three coordination cages, namely Fe4L6 2 , Fe8L12 3 , and Fe4L4 4 , each segregated into a distinct layer. Upon the addition of a mixture of three different guests, each cage (in each separate layer) selectively bound its preferred guest. 相似文献
18.
Dr. Hui Guo Prof. Dominique Hourdet Dr. Alba Marcellan Dr. François Stoffelbach Dr. Joel Lyskawa Lieselot de Smet Aurélien Vebr Prof. Richard Hoogenboom Prof. Patrice Woisel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(6):1292-1297
The regulation of the concentration of a wide range of small molecules is ubiquitous in biological systems because it enables them to adapt to the continuous changes in the environmental conditions. Herein, we report an aqueous synthetic system that provides an orchestrated, temperature and pH controlled regulation of the complexation between the cyclobis(paraquat-p-phenylene) host ( BBox ) and a 1,5-dialkyloxynaphthalene ( DNP ) guest attached to a well-defined dual responsive copolymer composed of N-isopropylacrylamide as thermoresponsive monomer and acrylic acid as pH-responsive monomer. Controlled, partial release of the BBox , enabling control over its concentration, is based on the tunable partial collapse of the copolymer. This colored supramolecular assembly is one of the first synthetic systems providing control over the concentration of a small molecule, providing great potential as both T and pH chromic materials and as a basis to develop more complex systems with molecular communication. 相似文献
19.
Iron Porphyrins Embedded into a Supramolecular Porous Organic Cage for Electrochemical CO2 Reduction in Water 下载免费PDF全文
Peter T. Smith Dr. Bahiru Punja Benke Dr. Zhi Cao Younghoon Kim Dr. Eva M. Nichols Prof. Kimoon Kim Prof. Christopher J. Chang 《Angewandte Chemie (International ed. in English)》2018,57(31):9684-9688
A porous organic cage composed of six iron tetraphenylporphyrins was used as a supramolecular catalyst for electrochemical CO2‐to‐CO conversion. This strategy enhances active site exposure and substrate diffusion relative to the monomeric catalyst, resulting in CO generation with near‐quantitative Faradaic efficiency in pH 7.3 water, with activities reaching 55 250 turnovers. These results provide a starting point for the design of supramolecular catalysts that can exploit the properties of the surrounding matrix yet retain the tunability of the original molecular unit. 相似文献
20.
Jarosław M. Granda Dr. Olga Staszewska‐Krajewska Prof. Janusz Jurczak 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(40):12790-12795
We have designed anion receptor 4 based on a conformationally labile bispyrrolylbenzene framework, the conformation of which can be changed by appropriate anionic stimuli. In the absence of fluoride anion, the pyrrole moieties rotate freely at room temperature. However, when the concentration of fluoride anion exceeds 2 equivalents, the rotation of the pyrrole units slows down and the conformation of the receptor changes to anti‐anti. DFT calculations have shown that this change is due to binding of a third fluoride anion through C?H interaction. Anion receptor 4 can also serve as a molecular logic gate. Anionic inputs such as fluoride and dihydrogenphosphate allow the realization of INHIBIT and NAND logic gate functions with absorption and fluorescence as readouts, respectively. 相似文献