A Radically Configurable Six-State Compound

Barnes, Jonathan C.; Fahrenbach, Albert C.; Cao, Dennis; Dyar, Scott M.; Frasconi, Marco; Giesener, Marc A.; Benítez, Diego; Tkatchouk, Ekaterina; Chernyashevskyy, O.; Shin, Weon Ho; Li, Hao; Sampath, S.; Stern, Charlotte L.; Sarjeant, Amy A.; Hartlieb, Karel J.; Liu, Zhichang; Carmieli, Raanan; Botros, Youssry Y.; Choi, Jang Wook; Slawin, Alexandra M. Z.; Ketterson, J. B.; Wasielewski, Michael R.; Goddard, William A.; Stoddart, J. Fraser

doi:10.1126/science.1228429

Cited by 164 publications

(125 citation statements)

References 42 publications

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“…We had already employed radical templation [72] to synthesize ( Figure 25 )a [2]rotaxane-as well as ahomo [2]catenane [73] and demonstrated ( Figure 26) the strong repulsion that comes into play when the ring and recognition unit are oxidized back to CBPQT 4+ and BIPY 2+ ,respectively.…”

Section: +mentioning

confidence: 99%

Mechanically Interlocked Molecules (MIMs)—Molecular Shuttles, Switches, and Machines (Nobel Lecture)

2017

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Section: +mentioning

confidence: 99%

Mechanically Interlocked Molecules (MIMs)—Molecular Shuttles, Switches, and Machines (Nobel Lecture)

2017

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“…Kinetic template-directed protocols have employed a large range of noncovalent interactions to hold together the template and reactive substrates. These templation strategies make use of a wide range of noncovalent bonding interactions, including hydrogen bonding [27,28], π-π donor-acceptor forces between π-electron-rich and π-electron-poor species [29], metal-ligand coordination [30,31] and radical pairing [32,33].…”

Section: Methodsmentioning

confidence: 99%

“…The energy required to separate [12] them is that of the weakest covalent bond in the structure. A case in point is the template-directed synthesis [33] of the homo [2]catenane HC 8+ (Fig. 7) composed of two identical mechanically interlocked CBPQT 4+ rings.…”

Section: Template-product Dead Endsmentioning

confidence: 99%

Template-directed nonenzymatic oligonucleotide synthesis: lessons from synthetic chemistry

Fahrenbach

2015

Pure and Applied Chemistry

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The nonenzymatic synthesis of nucleic acids, in particular, RNA, and the template-directed synthesis of artificial organic molecules, such as macrocycles, catenanes and rotaxanes, have both undergone significant development since the last half of the 20 th century. The intersection of these two fields affords insights into how template effects can lead to information copying and storage at the molecular level. Mechanistic examples of model template-directed RNA replication experiments as well as those for totally artificial organic template-directed syntheses will be discussed. The fact that templates typically bind to their reacted products more tightly than their unreacted substrates may be a mechanistic feature necessary to store information in the form of nucleic acids. Understanding the mechanisms of nonenzymatic RNA synthesis is not only essential for testing the RNA world hypothesis in the context of the origin of life on Earth and other planetary bodies, but may one day afford chemists the insights to construct their own artificial molecular replicators.

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“…The viologen unit (47) at the center of the half-dumbbell 1 2+ was chosen as a recognition site to promote complexation with CBPQT 4+ by virtue of radical templation (46)(47)(48)(49)(50)(51)(52)(53)(54). A bulky 3,5-di-tert-butylphenyl stopper situated at the other end of the viologen unit ensures that the semirotaxanes become mechanically interlocked once the benzoic acid group is capped by the Zr cluster.…”

Section: +mentioning

confidence: 99%

“…It is only in their radical cation redox states that favorable interactions (47)(48)(49)(50)(51)(52)(53)(54)(55)(56) between the electrons of the viologen centers bring the components together to form (Fig. 4B) the trisradical semirotaxane 1…”

Section: (•+)mentioning

confidence: 99%

Electrochemically addressable trisradical rotaxanes organized within a metal–organic framework

McGonigal

Deria

Hod

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The organization of trisradical rotaxanes within the channels of a Zr 6 -based metal-organic framework (NU-1000) has been achieved postsynthetically by solvent-assisted ligand incorporation. Robust Zr IV -carboxylate bonds are forged between the Zr clusters of NU-1000 and carboxylic acid groups of rotaxane precursors (semirotaxanes) as part of this building block replacement strategy. Ultravioletvisible-near-infrared (UV-Vis-NIR), electron paramagnetic resonance (EPR), and 1 H nuclear magnetic resonance (NMR) spectroscopies all confirm the capture of redox-active rotaxanes within the mesoscale hexagonal channels of NU-1000. Cyclic voltammetry measurements performed on electroactive thin films of the resulting material indicate that redox-active viologen subunits located on the rotaxane components can be accessed electrochemically in the solid state. In contradistinction to previous methods, this strategy for the incorporation of mechanically interlocked molecules within porous materials circumvents the need for de novo synthesis of a metal-organic framework, making it a particularly convenient approach for the design and creation of solid-state molecular switches and machines. The results presented here provide proof-of-concept for the application of postsynthetic transformations in the integration of dynamic molecular machines with robust porous frameworks.mechanically interlocked molecules | metal-organic framework | molecular switches | rotaxanes | radicals T he predictability and reliability with which metal-organic frameworks (MOFs) are assembled (1-11) has accelerated the rate at which porous materials can be developed for applications as diverse as gas storage and separation (7), sensing (8), catalysis (9), and light harvesting (10, 11). Metal oxide joints and organic struts are arranged regularly within MOFs, giving rise to hybrid materials with permanent porosities. It has been proposed (12, 13) that integrating the rigidity and periodicity of MOFs with the addressability and workings of molecular switches and machines, such as bistable mechanically interlocked molecules (MIMs) (14-16), stands a good chance of giving rise to a new class of functional materials that are simultaneously both robust and dynamic. Most switchable MIMs that have been developed operate in solution where they are stochastically oriented and the net movement of a population of switches averages to zero. By integrating such rudimentary molecular switches within highly ordered MOFs, however, they can be organized periodically and precisely in 3D space, allowing their otherwise incoherent motions to be rectified. Although steady progress has been made (17-26) toward this goal in recent years, it still remains a considerable challenge to design such systems that can be addressed by stimuli in the solid state. Electrochemical potential and light would be particularly appealing stimuli on account of their ease of interfacing with current technologies. The avenues of investigation that have been explored up to this point have entailed t...

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A Radically Configurable Six-State Compound

Cited by 164 publications

References 42 publications

Mechanically Interlocked Molecules (MIMs)—Molecular Shuttles, Switches, and Machines (Nobel Lecture)

Mechanically Interlocked Molecules (MIMs)—Molecular Shuttles, Switches, and Machines (Nobel Lecture)

Template-directed nonenzymatic oligonucleotide synthesis: lessons from synthetic chemistry

Electrochemically addressable trisradical rotaxanes organized within a metal–organic framework

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