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Paul D Beer - One of the best experts on this subject based on the ideXlab platform.
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chloride anion templated synthesis of a strapped porphyrin containing Catenane host system
Chemistry: A European Journal, 2015Co-Authors: Asha Brown, Matthew J Langton, Nathan L Kilah, Amber L Thompson, Paul D BeerAbstract:The synthesis, structure and anion-recognition properties of a new strapped-porphyrin-containing [2]Catenane anion host system are described. The assembly of the Catenane is directed by discrete chloride anion templation acting in synergy with secondary aromatic donor–acceptor and coordinative pyridine–zinc interactions. The [2]Catenane incorporates a three-dimensional, hydrogen-bond-donating anion-binding pocket; solid-state structural analysis of the Catenane⋅chloride complex reveals that the chloride anion is encapsulated within the Catenane’s interlocked binding cavity through six convergent CH⋅⋅⋅⋅Cl and NH⋅⋅⋅Cl hydrogen-bonding interactions and solution-phase 1H NMR titration experiments demonstrate that this complementary hydrogen-bonding arrangement facilitates the selective recognition of chloride over larger halide anions in DMSO solution.
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a halogen and hydrogen bonding 2 Catenane for anion recognition and sensing
RSC Advances, 2015Co-Authors: James M Mercurio, Antonio Caballero, James Cookson, Paul D BeerAbstract:A mixed halogen- and hydrogen-bonding hetero-[2]Catenane has been synthesised via an anion templated Grubbs' II-catalysed RCM clipping mechanical bond forming methodology. 1H NMR spectroscopy and fluorescence titration experiments demonstrated the interlocked Catenane host to be capable of binding and sensing anions, in particular forming strong associations with acetate and dihydrogen phosphate.
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rotaxane and Catenane host structures for sensing charged guest species
Accounts of Chemical Research, 2014Co-Authors: Matthew J Langton, Paul D BeerAbstract:ConspectusThe promise of mechanically interlocked architectures, such as rotaxanes and Catenanes, as prototypical molecular switches and shuttles for nanotechnological applications, has stimulated an ever increasing interest in their synthesis and function. The elaborate host cavities of interlocked structures, however, can also offer a novel approach toward molecular recognition: this Account describes the use of rotaxane and Catenane host systems for binding charged guest species, and for providing sensing capability through an integrated optical or electrochemical reporter group. Particular attention is drawn to the exploitation of the unusual dynamic properties of interlocked molecules, such as guest-induced shuttling or conformational switching, as a sophisticated means of achieving a selective and functional sensor response. We initially survey interlocked host systems capable of sensing cationic guests, before focusing on our accomplishments in synthesizing rotaxanes and Catenanes designed for the ...
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Progress in the synthesis and exploitation of Catenanes since the Millennium
Chemical Society Reviews, 2014Co-Authors: Nicholas H Evans, Paul D BeerAbstract:Catenanes – molecules consisting of interlocked macrocyclic rings – have been prepared by templation strategies for some thirty years. The utilization of CuI cation, aromatic donor–acceptor interactions and hydrogen bonding assisted self-assembly strategies has led to the construction of numerous examples of these aesthetically pleasing species. This review seeks to discuss key developments in the synthesis and functional application of Catenanes that have occurred since the Millennium. The much expanded range of metal cation templates; the genesis and growth of anion templation, as well as the use of alternative supramolecular interactions (halogen bonding and radical templation) and thermodynamically controlled reactions to synthesize Catenanes are detailed. The class of Catenanes that may be described as “molecular machines” are then highlighted and to conclude, attempts to fabricate Catenanes onto surfaces and into metal organic frameworks (MOFs) are discussed.
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a Catenane host system containing integrated triazole c h hydrogen bond donors for anion recognition
Chemical Communications, 2012Co-Authors: Nicholas G White, Paul D BeerAbstract:A 3,5-bis(triazole)-pyridinium motif is integrated into a Catenane structural framework via chloride anion templation. The Catenane host system displays a high degree of selectivity for halide anions over dihydrogen phosphate.
Fraser J Stoddart - One of the best experts on this subject based on the ideXlab platform.
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toward a charged homo 2 Catenane employing diazaperopyrenium homophilic recognition
Journal of the American Chemical Society, 2018Co-Authors: Xirui Gong, Jiawang Zhou, Karel J Hartlieb, Claire E Miller, Peng Li, Omar K Farha, Joseph T Hupp, Ryan M Young, Michael R Wasielewski, Fraser J StoddartAbstract:An octacationic diazaperopyrenium (DAPP2+)-based homo[2]Catenane (DAPPHC8+), wherein no fewer than eight positive charges are associated within a mechanically interlocked molecule, has been produced in 30% yield under ambient conditions as a result of favorable homophilic interactions, reflecting a delicate balance between strong π–π interactions and the destabilizing penalty arising from Coulombic repulsions between DAPP2+ units. This DAPPHC8+ Catenane is composed of two identical mechanically interlocked tetracationic cyclophanes, namely DAPPBox4+, each of which contains one DAPP2+ unit and one extended viologen (ExBIPY2+) unit, linked together by two p-xylylene bridges. The solid-state structure of the homo[2]Catenane demonstrates how homophilic interactions play an important role in the formation of DAPPHC8+, in which the mean ring planes of the two DAPPBox4+ cyclophanes are oriented at about 60° with respect to each other, with a centroid-to-centroid separation of 3.7 A between the mean planes of the...
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an exbox 2 Catenane
Chemical Science, 2014Co-Authors: Michal Juricek, Paul R. Mcgonigal, Jonathan C Barnes, Nathan L Strutt, Nicolaas A Vermeulen, Kala C Ghooray, Edward J Dale, Anthea K Blackburn, Alyssajennifer Avestro, Fraser J StoddartAbstract:A donor–acceptor [2]Catenane, in which an extended tetracationic cyclophane is mechanically interlocked by a porphyrin-containing macrocycle, was synthesised using a template-directed protocol and alkene metathesis as the ring-closing step. In the ground state of this [2]Catenane, the porphyrin ring resides inside the cavity of the cyclophane on account of favourable charge-transfer interactions between the electron-rich porphyrin and the electron-deficient cyclophane. The [2]Catenane can act as a push-button molecular switch where the co-conformations of the [2]Catenane can be controlled either chemically or electrochemically. Addition of acid protonates the porphyrin ring and a relative circumrotational motion of the macrocycle positions the charged porphyrin ring outside the cavity of the cyclophane. The switch can be reset to its ground-state co-conformation by the addition of base. Electrochemical reduction of the extended bipyridinium units of the cyclophane decreases the strength of the donor–acceptor interactions in the [2]Catenane, leading to a loss of recognition between the mechanically interlocked rings. The chemical and electrochemical switching mechanisms are both reversible.
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a push button molecular switch
Journal of the American Chemical Society, 2009Co-Authors: Jason M Spruell, William A. Goddard, Walter F Paxton, John Carl Olsen, Diego Benitez, Ekaterina Tkatchouk, Charlotte L Stern, Ali Trabolsi, Douglas C Friedman, Fraser J StoddartAbstract:The preparation, characterization, and switching mechanism of a unique single-station mechanically switchable hetero[2]Catenane are reported. The facile synthesis utilizing a “threading-followed-by-clipping” protocol features Cu2+-catalyzed Eglinton coupling as a mild and efficient route to the tetrathiafulvalene-based Catenane in high yield. The resulting mechanically interlocked molecule operates as a perfect molecular switch, most readily described as a “push-button” switch, whereby two discrete and fully occupied translational states are toggled electrochemically at incredibly high rates. This mechanical switching was probed using a wide variety of experimental techniques as well as quantum-mechanical investigations. The fundamental distinctions between this single-station [2]Catenane and other more traditional bi- and multistation molecular switches are significant.
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an electrochemical color switchable rgb dye tristable 2 Catenane
Journal of the American Chemical Society, 2005Co-Authors: Wei-qiao Deng, Amar H. Flood, Fraser J Stoddart, William A. GoddardAbstract:We propose a design for an electrochemically driven RGB dye based on a tristable [2]Catenane, in which the color of the molecule can be switched between Red, Green, and Blue by merely changing voltage. Based on DFT calculations, we conclude that the tristable [2]Catenane should consist of a CBPQT4+ ring interlocked with a polyether macrocyle containing DNP (red), TTF (green), and FBZD (blue) units as the tunable RGB color-generating donors. Thus, at controllable voltages 0, V1, and V2, the [2]Catenane is expected to display green, blue, and red colors, respectively. The advent of these RGB tristable molecules may have potential applications in low cost paperlike electronic displays.
Jeremy K. M. Sanders - One of the best experts on this subject based on the ideXlab platform.
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Molecular motion of donor–acceptor Catenanes in water
Organic and Biomolecular Chemistry, 2015Co-Authors: Fabien B. L. Cougnon, Nandhini Ponnuswamy, G. Dan Pantoş, Jeremy K. M. SandersAbstract:In this article, we use 1H NMR spectroscopy to study the spontaneous molecular motion of donor–acceptor [2]Catenanes in water. Our data supports the hypothesis that conformational motion dominantly occurs through a pirouetting mechanism, which involves less exposure of hydrophobic surfaces than in a rotation mechanism. Motion is controlled by the size of the Catenane rings and the arrangement of the electron-deficient and electron-rich aromatic units.
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templated dynamic synthesis of a 3 Catenane
Angewandte Chemie, 2012Co-Authors: Fabien B. L. Cougnon, Nicholas A Jenkins, Dan G Pantos, Jeremy K. M. SandersAbstract:The self-assembly of a water-soluble [3]Catenane from a library composed of two linear building blocks, both terminated by cysteine components, is promoted either by a high salt concentration or by the presence of spermine. The spermine-templated synthesis of the [3]Catenane shows that such structures can exhibit strong binding interactions with a biologically relevant target in water under near-physiological conditions.
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molecular recognition and self assembly special feature dynamic combinatorial synthesis of a Catenane based on donor acceptor interactions in water
Proceedings of the National Academy of Sciences of the United States of America, 2009Co-Authors: Ho Yu Auyeung, G D Pantos, Jeremy K. M. SandersAbstract:A new type of neutral donor–acceptor [2]-Catenane, containing both complementary units in the same ring was synthesized from a dynamic combinatorial library in water. The yield of the water soluble [2]-Catenane is enhanced by increasing either building-block concentrations or ionic strength, or by the addition of an electron-rich template. NMR spectroscopy demonstrates that the template is intercalated between the 2 electron-deficient naphthalenediimide units of the Catenane.
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Reversible synthesis of π-associated [2]Catenanes by ring-closing metathesis: towards dynamic combinatorial libraries of Catenanes
New Journal of Chemistry, 1998Co-Authors: Darren G. Hamilton, Neil Feeder, Simon J. Teat, Jeremy K. M. SandersAbstract:Ring-closing metathesis of aromatic diimides substituted with olefin-terminated alkyl chains in the presence of a dinaphtho crown ether affords neutral [2]Catenanes. Templating π-donor/π-acceptor interactions are exploited to drive mechanical interlocking and favour production of the more thermodynamically stable Catenane products. Structure proof was provided by single-crystal X-ray synchrotron diffraction of a representative Catenane.
Nicholas H Evans - One of the best experts on this subject based on the ideXlab platform.
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the rapid synthesis and dynamic behaviour of an isophthalamide 2 Catenane
Organic and Biomolecular Chemistry, 2015Co-Authors: Calum N Marrs, Nicholas H EvansAbstract:A serendipitous [2]Catenane has been prepared in three steps from commercially available starting materials. The interlocked topology of the Catenane has been confirmed by single crystal X-ray structural determination. The rings of the Catenane may rotate relative to one another – a process that may be controlled by varying solvent or temperature.
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Progress in the synthesis and exploitation of Catenanes since the Millennium
Chemical Society Reviews, 2014Co-Authors: Nicholas H Evans, Paul D BeerAbstract:Catenanes – molecules consisting of interlocked macrocyclic rings – have been prepared by templation strategies for some thirty years. The utilization of CuI cation, aromatic donor–acceptor interactions and hydrogen bonding assisted self-assembly strategies has led to the construction of numerous examples of these aesthetically pleasing species. This review seeks to discuss key developments in the synthesis and functional application of Catenanes that have occurred since the Millennium. The much expanded range of metal cation templates; the genesis and growth of anion templation, as well as the use of alternative supramolecular interactions (halogen bonding and radical templation) and thermodynamically controlled reactions to synthesize Catenanes are detailed. The class of Catenanes that may be described as “molecular machines” are then highlighted and to conclude, attempts to fabricate Catenanes onto surfaces and into metal organic frameworks (MOFs) are discussed.
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a 2 Catenane displaying pirouetting motion triggered by debenzylation and locked by chloride anion recognition
Chemistry: A European Journal, 2011Co-Authors: Nicholas H Evans, Christopher J Serpell, Paul D BeerAbstract:Chloride locks the rings: Debenzylation of a chloride-templated N-benzyl pyridinium Catenane, allows for a 180° “pirouetting” of the rings in the resulting neutral pyridyl Catenane (see scheme). The Catenane may be returned to its original co-conformation by chloride recognition as evidenced in solution and in the solid state.
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chloride anion templated synthesis and crystal structure of a handcuff Catenane
Angewandte Chemie, 2011Co-Authors: Nicholas H Evans, Christopher J Serpell, Paul D BeerAbstract:Chloride, you're nicked! A novel handcuff Catenane was prepared by anion templation and π–π stacking interactions. In addition, the first crystal structure determination of such a Catenane is reported.
Jonathan C Barnes - One of the best experts on this subject based on the ideXlab platform.
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solid state characterization and photoinduced intramolecular electron transfer in a nanoconfined octacationic homo 2 Catenane
Journal of the American Chemical Society, 2014Co-Authors: Paul R. Mcgonigal, Jonathan C Barnes, Ryan M Young, Marco Frasconi, Nezar H Khdary, Scott M Dyar, Ian C Gibbshall, Christian S Diercks, Amy A SarjeantAbstract:An octacationic homo[2]Catenane comprised of two mechanically interlocked cyclobis(paraquat-p-phenylene) rings has been obtained from the oxidation of the septacationic monoradical with nitrosonium hexafluoroantimonate. The nanoconfinement of normally repulsive bipyridinium units results in the enforced π-overlap of eight positively charged pyridinium rings in a volume of <1.25 nm3. In the solid state, the torsional angles around the C–C bonds between the four pairs of pyridinium rings range between 16 and 30°, while the π–π stacking distances between the bipyridinium units are extended for the inside pair and contracted for the pairs on the outside—a consequence of Coulombic repulsion between the inner bipyridinium subunits. In solution, irradiation of the [2]Catenane at 275 nm results in electron transfer from one of the paraphenylene rings to the inner bipyridinium dimer, leading to the generation of a temporary mixed-valence state within the rigid and robust homo[2]Catenane.
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an exbox 2 Catenane
Chemical Science, 2014Co-Authors: Michal Juricek, Paul R. Mcgonigal, Jonathan C Barnes, Nathan L Strutt, Nicolaas A Vermeulen, Kala C Ghooray, Edward J Dale, Anthea K Blackburn, Alyssajennifer Avestro, Fraser J StoddartAbstract:A donor–acceptor [2]Catenane, in which an extended tetracationic cyclophane is mechanically interlocked by a porphyrin-containing macrocycle, was synthesised using a template-directed protocol and alkene metathesis as the ring-closing step. In the ground state of this [2]Catenane, the porphyrin ring resides inside the cavity of the cyclophane on account of favourable charge-transfer interactions between the electron-rich porphyrin and the electron-deficient cyclophane. The [2]Catenane can act as a push-button molecular switch where the co-conformations of the [2]Catenane can be controlled either chemically or electrochemically. Addition of acid protonates the porphyrin ring and a relative circumrotational motion of the macrocycle positions the charged porphyrin ring outside the cavity of the cyclophane. The switch can be reset to its ground-state co-conformation by the addition of base. Electrochemical reduction of the extended bipyridinium units of the cyclophane decreases the strength of the donor–acceptor interactions in the [2]Catenane, leading to a loss of recognition between the mechanically interlocked rings. The chemical and electrochemical switching mechanisms are both reversible.