Substituent-controlled racemization of dissymmetric coordination capsules

Harada, Kentaro; Sekiya, Ryo; Maehara, Takeshi; Haino, Takeharu

doi:10.1039/c9ob00388f

Cited by 4 publications

(2 citation statements)

References 35 publications

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“…The UV/Vis absorption spectra were consistent with the trans stereoisomer.T he metal-to-ligand charget ransfer (MLCT) band of the coordination capsules was found to be sensitive to the coordination environment of the metal centers. [35,40] For example, the MLCT band of the methyl-substitutedc apsule was observed at l max = 462 nm (green line in Figure 3b), while that of the p-methoxyphenyl-substituted one was shifted to l max = 547 nm (blue line in Figure 3b). The dihedrala ngles of the bipyridyl arms of the methyl-and p-methoxyphenyl-substituted capsules were determined by single-crystal XRD to be 98.6 and 124.48,r espectively.…”

Section: Resultsmentioning

confidence: 99%

A Regulable Internal Cavity inside a Resorcinarene‐Based Hemicarcerand

Harada

Sekiya

Haino

2020

Chemistry A European J

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Covalent organic capsules, such as carcerands and hemicarcerands, are an interesting class of molecular hosts. These container molecules have confined spaces capable of hostingsmall molecules, although the fact that the size of the inner cavities cannot be changed substantially limits the scope of their applications. The title covalently linked container was produced by metal-directed dimerizationo faresorcinarene-based cavitand having four 2,2'-bipyridyl arms on the wide rim followed by olefin metathesis at the vertices of the resultingc apsulew ith as econd-generation Grubbs catalyst. The covalently linked bipyridyl arms permit expansion of the inner cavity by demetalation. This structural changei nfluences the molecular recognition properties;t he metal-coordinated capsule recognizes only 4,4'-diacetoxybi-phenyl,w hereas the metal-free counterpart can encapsulate not only 4,4'-diacetoxybiphenyl, but also 2,5-disubstituted-1,4-bis(4-acetoxyphenylethynyl)benzene, which is 9.4 longert han the former guest. Molecular mechanics calculations predict that the capsulee xpands the internal cavity to encapsulate the long guest by unfolding the folded conformationo ft he alkyl chains, which demonstrates the flexible and regulable nature of the cavity.Guest competitionexperimentss how that the preferred guest can be switched by metalation and demetalation. This external-stimuli-responsive guest exchange can be utilizedf or the development of functional supramolecular systems controlling the uptake, transport, and releaseo fchemicals.

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Section: Resultsmentioning

confidence: 99%

A Regulable Internal Cavity inside a Resorcinarene‐Based Hemicarcerand

Harada

Sekiya

Haino

2020

Chemistry A European J

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“…The racemization was also influenced by the substituent on the 2,2'-bipyridyl arms. 30 The introduction of p-methoxyphenyl groups and methoxy groups instead of methyl groups decreased the stability of 1Cub,c. These substituents increase the dihedral angles of the coordinated 2,2'-bipyridyl arms, which most likely permits the coordinative solvents to interact with the metal centers; thus, the racemization is accelerated.…”

Section: Guest-induced Chiralitymentioning

confidence: 99%

Resorcinarene-Based Supramolecular Capsules: Supramolecular Functions and Applications

Sekiya

Harada

Nitta

et al. 2021

Synlett

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A resorcinarene is a synthetic macrocycle comprising four resorcinol molecules covalently linked by methylene bridges. The interannular bridges produce a cavitand, which possesses a bowl-shaped structure. We have developed supramolecular capsules formed through Ag(I) and Cu(I) coordination-driven self-assembly of cavitands possessing 2,2’-bipyridyl arms at the upper rim. The self-assembled capsules accommodate various molecular guests and supramolecular assemblies possessing acetoxy groups. The host-guest chemistry of the molecular capsules is applied to fabricate supramolecular polymers. This account describes the recent developments in supramolecular chemistry of resorcinarene-based coordination capsules and describes the brief history of resorcinarene-based capsules and related capsules.

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