Interconverting Two Classes of Architectures by Reduction of a Self‐Sorting Mixture

Kumar, P. S. Anil; Witlicki, Edward H.; Flood, Amar H.

doi:10.1002/anie.201001003

Cited by 52 publications

(28 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Understanding the mechanism by which intramolecular noncovalent bonding interactions occur-especially in those systems that can undergo reversible switching eventsholds the key to how artificial molecular machines (14) can be engineered to fit the demands of a given function. Gaining intimate knowledge of the mechanisms (15)(16)(17)(18) governing the relative molecular motions of their components is, therefore, a pursuit that yields crucial information for the design of artificial molecular machines. Bistable mechanically interlocked molecules (MIMs) [namely, bistable catenanes (19,20) and rotaxanes (21), whose syntheses are often templated by noncovalent bonding interactions that "live-on" in the MIMs] have experienced a frenzy of intense research activity in recent years.…”

mentioning

confidence: 99%

Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

Fahrenbach

Barnes

Li³

et al. 2011

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

View full text Add to dashboard Cite

In donor-acceptor mechanically interlocked molecules that exhibit bistability, the relative populations of the translational isomerspresent, for example, in a bistable [2]rotaxane, as well as in a couple of bistable [2]catenanes of the donor-acceptor vintage-can be elucidated by slow scan rate cyclic voltammetry. The practice of transitioning from a fast scan rate regime to a slow one permits the measurement of an intermediate redox couple that is a function of the equilibrium that exists between the two translational isomers in the case of all three mechanically interlocked molecules investigated. These intermediate redox potentials can be used to calculate the ground-state distribution constants, K. Whereas, (i) in the case of the bistable [2]rotaxane, composed of a dumbbell component containing π-electron-rich tetrathiafulvalene and dioxynaphthalene recognition sites for the ring component (namely, a tetracationic cyclophane, containing two π-electron-deficient bipyridinium units), a value for K of 10 AE 2 is calculated, (ii) in the case of the two bistable [2]catenanes-one containing a crown ether with tetrathiafulvalene and dioxynaphthalene recognition sites for the tetracationic cyclophane, and the other, tetrathiafulvalene and butadiyne recognition sites-the values for K are orders (one and three, respectively) of magnitude greater. This observation, which has also been probed by theoretical calculations, supports the hypothesis that the extra stability of one translational isomer over the other is because of the influence of the enforced side-on donor-acceptor interactions brought about by both π-electron-rich recognition sites being part of a macrocyclic polyether.density functional theory | donor-acceptor molecules | electrochemistry | isomerism | switches T he ability to control the relative motions (1) of molecules is crucial for understanding many biological processes such as cell division and intracellular transport (2), muscle contraction (3), and ATP production (4). This control is essential to the development of potential applications as diverse as catalysis (5), drug delivery (6), elastic materials (7), molecular actuators (8), molecular transport (9), ion sensors (10), motors (11), and information storage (12). Supramolecular chemistry (13) has been one of the sources from which the inspiration and desire to build artificial molecular machines, as the counterpart to biological motors, has sprung. Understanding the mechanism by which intramolecular noncovalent bonding interactions occur-especially in those systems that can undergo reversible switching eventsholds the key to how artificial molecular machines (14) can be engineered to fit the demands of a given function. Gaining intimate knowledge of the mechanisms (15-18) governing the relative molecular motions of their components is, therefore, a pursuit that yields crucial information for the design of artificial molecular machines. Bistable mechanically interlocked molecules (MIMs) [namely, bistable catenanes (19, 20) and rotaxanes (21), wh...

show abstract

mentioning

confidence: 99%

Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

Fahrenbach

Barnes

Li³

et al. 2011

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

View full text Add to dashboard Cite

show abstract

“…The most well known of these involve the use of redox active catenanes, [5][6][7][8] metal coordination compounds, [9][10][11][12][13][14][15] rotaxanes, [11,12,14,[16][17][18][19][20][21][22] π-systems, [23][24][25][26][27][28] and crowded alkenes [29]. These systems are finding increasing application in solid-state electronic devices.…”

Section: Open Accessmentioning

confidence: 99%

“…The methyl ester resonance was unaffected by oxidation, presumably due to its isolation para to the alkyne. Lastly, 12 was oxidized with copper(II) chloride; the partially oxidized spectra of 12 and [12] + are shown in Figure 6c. In this case the FcA NH broadens but is not shifted, while the benzamide NH is not identifiable.…”

Section: Paramagnetic Nmr Characterization Of the Solution Phase Confmentioning

confidence: 99%

“…A switch of the H-bond acceptor towards the Fc + amide NH, causing this proton to become deshielded, would explain the downfield shift in the spectrum of [3] + . To estimate the effect of partial oxidation on the conformational equilibrium, the spectra of [3] + , [5] + and [12] H-NMR resonances corresponding to the parent unoxidized species are not evident it is probable that there is fast exchange between the unoxidized and oxidized forms, leading to average peak positions. Whilst this makes precise quantification of the bias more difficult to establish, the overall trends hold thus providing a semi-quantitative measurement.…”

Section: Paramagnetic Nmr Characterization Of the Solution Phase Confmentioning

confidence: 99%

“…The organic layer was dried and concentrated in vacuo. The product was purified by column chromatography on silica gel (2:1 hexanes/ethyl acetate) to give the title compound 11 (12). A solution of ferrocenoyl chloride 2 in dichloromethane (2.1 mL, 0.065 M, 0.137 mmol) was added dropwise over 10 min to a solution of amine 11 (0.025 g, 0.068 mmol) and 4-dimethylaminopyridine (ca.…”

Section: Methyl 2-((2-benzamido-6-(ferrocenecarboxamido)phenyl)ethynymentioning

confidence: 99%

See 2 more Smart Citations

Redox-Dependent Conformational Switching of Diphenylacetylenes

et al. 2014

View full text Add to dashboard Cite

Herein we describe the design and synthesis of a redox-dependent single-molecule switch. Appending a ferrocene unit to a diphenylacetylene scaffold gives a redox-sensitive handle, which undergoes reversible one-electron oxidation, as demonstrated by cyclic voltammetry analysis. 1 H-NMR spectroscopy of the partially oxidized switch and control compounds suggests that oxidation to the ferrocenium cation induces a change in hydrogen bonding interactions that results in a conformational switch.

show abstract

Supramolecular Electrochemistry

Flood

Kaifer

2012

Supramolecular Chemistry

View full text Add to dashboard Cite

Electron transfer reactions afford a very powerful method to introduce controlled changes in supramolecular structures. This chapter provides a brief introduction to electrochemical parameters and voltammetric techniques that are commonly used to investigate supramolecular systems containing redox‐active groups. A discussion of redox‐active host–guest complexes is presented, alongside their corresponding diagnostic cyclic voltammetry titrations. Then we move on to describe the electrochemistry of redox‐switchable, mechanically interlocked molecules, such as rotaxanes and catenanes. The discussion includes thermodynamic considerations, as well as kinetic effects. We have strived to provide a number of selected examples that illustrate the power of electrochemical techniques, not only for characterization purposes but also as a versatile methodology to stimulate supramolecular systems and to control their structure and other chemical and physical properties.

show abstract

Interconverting Two Classes of Architectures by Reduction of a Self‐Sorting Mixture

Cited by 52 publications

References 37 publications

Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

Redox-Dependent Conformational Switching of Diphenylacetylenes

Supramolecular Electrochemistry

Contact Info

Product

Resources

About