Mild and High-Yielding Syntheses of Diethyl Phosphoramidate-Stoppered [2]Rotaxanes

Hung, Wei-Chung; Liao, Kang‐Shyang; Liu, Yi-Hung; Peng, Shie‐Ming; Chiu, Sheng‐Hsien

doi:10.1021/ol0484557

Cited by 43 publications

(13 citation statements)

References 46 publications

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“…[12] We designed a porphyrin unit with four alkylammonium chains [1·4 H] 4+ and phthalocyanine unit with peripheral crown ethers 2 which are expected to form a facially stacked dimer through formation of a four-fold rotaxane (Figure 1) [13] ) and the phthalocyanine 2 in chloroform and acetone at a ratio of 4:1, followed by locking through Staudinger-phosphite reaction, which converts the azide groups to larger phosphoramidate units. [14] The structure of the four-fold (Figure 2 a). All signals in the spectrum were assignable as one-quarter part of the four-fold rotaxane.…”

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Switchable Intermolecular Communication in a Four‐Fold Rotaxane

et al. 2011

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In biological systems, precise intermolecular electronic communication occurs in, and is regulated by, proteins and their complexes. For example, light-harvesting complexes have metal ions or metal complexes, such as manganese clusters, and organic cofactors, such as chlorophylls, carotenoids, or ubiquinones, in the "right" spatial arrangement so that electrons and energy can be efficiently transferred. [1, 2] Electronic communication between molecules is sensitive to their relative orientation. Large molecular scaffolds of proteins provide precise frameworks for molecular arrays as well as the ability of dynamic switching intermolecular communication, accomplished by conformational changes induced by external stimuli. These natural molecular frameworks are programmed as sequences of amino acids, but we could achieve flexible intermolecular communication in a simpler molecular architecture by using mechanically interlocked supramolecular motives, such as catenanes and rotaxanes, in which two or more molecular components are inseparable but their interactions are flexibly convertible. [3,4] Syntheses of rotaxanes have been well-established, and a large variety of fascinating examples of rotaxane-based molecular systems has been reported. [3][4][5] As a specific example of switchable rotaxanes, Stoddart, Credi and co-workers reported elevatorlike motion of a molecule with crown ethers along the strings on another molecule in a three-fold rotaxane, in which the relative position between the molecules was switchable by redox or acid-base reactions.[6] Sauvage and co-workers made a porphyrin dimer in a cyclic [4]rotaxane and showed its ability to act as switchable receptor.[7] Porphyrin, phthalocyanine, and their metal complexes have been applied to a broad range of functionalized molecular systems. Intermolecular electronic communication in their programmed arrays particularly has attracted a lot of interests in a wide range of fields, from photomaterials [8] to pigments, [9] molecular devices, [10] and catalysts.[11]Herein, we report a mechanically linked cofacially stacked dimer of a metalloporphyrin and metallophthalocyanine units by formation of a four-fold rotaxane and its switchable spin-spin communication induced by external stimuli. A rotaxane consisting of a secondary ammonium ion and a crown ether has been recognized as a versatile building block for supramolecular systems. R 2 NH 2 + ions are complexed by dibenzo [24]crown-8 in a threaded manner as a result of electrostatic stabilization and hydrogen bonds between the negatively charged interior of the crown ether and the cationic ammonium moiety.[12] We designed a porphyrin unit with four alkylammonium chains [1·4 H] 4+ and phthalocyanine unit with peripheral crown ethers 2 which are expected to form a facially stacked dimer through formation of a four-fold rotaxane (Figure 1) [13] ) and the phthalocyanine 2 in chloroform and acetone at a ratio of 4:1, followed by locking through Staudinger-phosphite reaction, which converts the azide groups to larger ph...

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Switchable Intermolecular Communication in a Four‐Fold Rotaxane

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“…The four‐fold rotaxane [ 3 ⋅8 H] 4+ ⋅4 Cl − was obtained in 41 % yield through formation of a pseudo‐rotaxane between the porphyrin [ 1 ⋅5H] 5+ ⋅5 BARF − (BARF − =tetrakis[(3,5‐bistrifluoromethyl)phenyl]borate13) and the phthalocyanine 2 in chloroform and acetone at a ratio of 4:1, followed by locking through Staudinger‐phosphite reaction, which converts the azide groups to larger phosphoramidate units 14. The structure of the four‐fold [2]rotaxane [ 3 ⋅8 H] 4+ ⋅4Cl − was given unambiguously by ESI‐TOF mass spectrometry and NMR spectroscopy (Figure 2).…”

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Switchable Intermolecular Communication in a Four‐Fold Rotaxane

et al. 2011

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Fest verschnürt: Ein vierfaches Rotaxan wurde aus einem Porphyrin‐Molekül mit vier Alkylammoniumketten und einer Phthalocyanin‐Einheit mit vier Kronenetherresten erhalten. Das Rotaxan bildete einen zweikernigen Cu2+‐Komplex, in dem die Cu2+‐Porphyrin‐ und Cu2+‐Phthalocyanin‐Einheiten so effektiv geschichtet waren, dass die ungepaarten Elektronenspins, deren Zustände reversibel geschaltet wurden, in Wechselwirkung traten (siehe Bild).

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“…The four-fold rotaxane [3•4H] 4+ •4Cl − was obtained in 18% yield via pseudo-rotaxane formation between the Zn 2+ -phthalocyanine 1 and the tetradactyl porphyrin 18 ) in a mixed solvent of chloroform and acetone (5 : 1 (v/v)), followed by stoppering reaction by the Staudinger-phosphite reaction to convert the terminal azide moieties into the sufficiently larger phosphoramidate moieties. 17,19 The structure of [3•4H] 4+ •4Cl − obtained in the first rotaxaneforming step was confirmed by 1 H-NMR as shown in Fig. 1.…”

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confidence: 68%