CH···O Hydrogen Bonds in “Clicked” Diketopiperazine-Based Amide Rotaxanes

Dzyuba, Egor V.; Kaufmann, Lena; Löw, Nora L.; Meyer, Annika K.; Winkler, Henrik D. F.; Schalley, Christoph A.

doi:10.1021/ol201915j

Cited by 34 publications

(19 citation statements)

References 47 publications

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“…The tetralactam macrocycle nicely binds diketopiperazines in its cavity through four hydrogen bonds between the guest's carbonyl groups and the converging amide NH groups of the macrocycle. 46,47 Benzo [21] crown-7 is just large enough to allow pseudorotaxane formation with secondary alkyl ammonium axles. 48 Hexyne HEX was used as a reference to investigate triazole formation during the "click" reaction.…”

Section: Introductionmentioning

confidence: 99%

The versatility of “click” reactions: molecular recognition at interfaces

et al. 2014

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In order to investigate molecular recognition on surfaces, an azide-functionalized monolayer was deposited on gold. The monolayer was characterized by X-ray photoelectron spectroscopy (XPS) and angle-resolved near-edge X-ray absorption fine structure (NEXAFS) experiments and the decomposition of the azide upon irradiation with X-ray beams was investigated. Subsequently, various alkynefunctionalized host and guest molecules were attached to the azide by 1,3-dipolar cycloaddition. These modified surfaces and their host-guest chemistry were analysed by XPS and angle-resolved NEXAFS.The reversibility of guest binding was shown for one example as a proof of principle.

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Section: Introductionmentioning

confidence: 99%

The versatility of “click” reactions: molecular recognition at interfaces

et al. 2014

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“…The sterically demanding tritylphenyl stopper groups have been attached to the axle alkynes by a Cu I -catalyzed “click” reaction with 2 . 6 For surface deposition, alkyne and terpyridine side chains have been introduced by Sonogashira 48 and Suzuki 49 cross-coupling reactions with (trimethylsilyl)acetylene and boronic acid pinacol ester 3 , respectively. After trimethylsilyl (TMS) deprotection, Rot3 is ready to be clicked covalently to an azide-functionalized surface.…”

Section: Results and Discussionmentioning

confidence: 99%

Coupled Molecular Switching Processes in Ordered Mono- and Multilayers of Stimulus-Responsive Rotaxanes on Gold Surfaces

et al. 2015

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Interfaces provide the structural basis for function as, for example, encountered in nature in the membrane-embedded photosystem or in technology in solar cells. Synthetic functional multilayers of molecules cooperating in a coupled manner can be fabricated on surfaces through layer-by-layer self-assembly. Ordered arrays of stimulus-responsive rotaxanes undergoing well-controlled axle shuttling are excellent candidates for coupled mechanical motion. Such stimulus-responsive surfaces may help integrate synthetic molecular machines in larger systems exhibiting even macroscopic effects or generating mechanical work from chemical energy through cooperative action. The present work demonstrates the successful deposition of ordered mono- and multilayers of chemically switchable rotaxanes on gold surfaces. Rotaxane mono- and multilayers are shown to reversibly switch in a coupled manner between two ordered states as revealed by linear dichroism effects in angle-resolved NEXAFS spectra. Such a concerted switching process is observed only when the surfaces are well packed, while less densely packed surfaces lacking lateral order do not exhibit such effects.

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“…This also shows the importance of such stopper groups for the interactions within the rotaxanes, as they have notable electronic influence. Thus, their role is not necessarily restricted to the mere mechanical prevention of a dethreading of the axle, which was also witnessed for diketopiperazine-based amide rotaxanes [57]. …”

Section: Resultsmentioning

confidence: 99%

Substitution effect and effect of axle’s flexibility at (pseudo-)rotaxanes

Malberg¹,

Brandenburg²,

Reckien³

et al. 2014

Beilstein J. Org. Chem.

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SummaryThis study investigates the effect of substitution with different functional groups and of molecular flexibility by changing within the axle from a single C–C bond to a double C=C bond. Therefore, we present static quantum chemical calculations at the dispersion-corrected density functional level (DFT-D3) for several Leigh-type rotaxanes. The calculated crystal structure is in close agreement with the experimental X-ray data. Compared to a stiffer axle, a more flexible one results in a stronger binding by 1–3 kcal/mol. Alterations of the binding energy in the range of 5 kcal/mol could be achieved by substitution with different functional groups. The hydrogen bond geometry between the isophtalic unit and the carbonyl oxygen atoms of the axle exhibited distances in the range of 2.1 to 2.4 Å for six contact points, which shows that not solely but to a large amount the circumstances in the investigated rotaxanes are governed by hydrogen bonding. Moreover, the complex with the more flexible axle is usually more unsymmetrical than the one with the stiff axle. The opposite is observed for the experimentally investigated axle with the four phenyl stoppers. Furthermore, we considered an implicit continuum solvation model and found that the complex binding is weakened by approximately 10 kcal/mol, and hydrogen bonds are slightly shortened (by up to 0.2 Å).

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CH···O Hydrogen Bonds in “Clicked” Diketopiperazine-Based Amide Rotaxanes

Cited by 34 publications

References 47 publications

The versatility of “click” reactions: molecular recognition at interfaces

The versatility of “click” reactions: molecular recognition at interfaces

Coupled Molecular Switching Processes in Ordered Mono- and Multilayers of Stimulus-Responsive Rotaxanes on Gold Surfaces

Substitution effect and effect of axle’s flexibility at (pseudo-)rotaxanes

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