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Linkage control between molecular and supramolecular chirality in 2₁-helical hydrogen-bonded networks using achiral components.

Sasaki T, Hisaki I, Miyano T, Tohnai N, Morimoto K, Sato H, Tsuzuki S, Miyata M - Nat Commun (2013)

Bottom Line: The mechanism of the handedness selectivity or switching phenomenon remains ambiguous, and most phenomena are observed by chance.Here we demonstrate the construction of chiral hydrogen-bonded twofold helical assemblies with controlled handedness in the crystalline state based on crystallographic studies.This study clearly reveals a connection between molecular chirality and supramolecular chirality in the crystalline state.

View Article: PubMed Central - PubMed

Affiliation: Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

ABSTRACT
Chiral molecules preferentially form one-handed supramolecular assemblies that reflect the absolute configuration of the molecules. Under specific conditions, however, the opposite-handed supramolecular assemblies are also obtained because of flexibility in the bond length and reversibility of non-covalent interactions. The mechanism of the handedness selectivity or switching phenomenon remains ambiguous, and most phenomena are observed by chance. Here we demonstrate the construction of chiral hydrogen-bonded twofold helical assemblies with controlled handedness in the crystalline state based on crystallographic studies. Detailed investigation of the obtained crystal structures enabled us to clarify the mechanism, and the handedness of the supramolecular chirality was successfully controlled by exploiting achiral factors. This study clearly reveals a connection between molecular chirality and supramolecular chirality in the crystalline state.

No MeSH data available.


Related in: MedlinePlus

Diastereomers with two different chiralities.(a) Conventional diastereomers resulting from two chiral carbons in molecular chirality. (b) Polymeric diastereomers with different molecular helicity. (c) Diastereomers with both molecular chirality and supramolecular chirality. (d) Supramolecular diastereomers with different supramolecular helicity for the 21-helical hydrogen-bonding networks.
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f1: Diastereomers with two different chiralities.(a) Conventional diastereomers resulting from two chiral carbons in molecular chirality. (b) Polymeric diastereomers with different molecular helicity. (c) Diastereomers with both molecular chirality and supramolecular chirality. (d) Supramolecular diastereomers with different supramolecular helicity for the 21-helical hydrogen-bonding networks.

Mentions: In general, the linkage can be expressed by a combination of two chiral centres producing two enantiomers and four diastereomers (Fig. 1). A typical example of molecular chirality (MC) lies in the combination of two absolute configurations (Fig. 1a). In macromolecules, changes in handedness are evident in helicity (Fig. 1b). For example, polypeptide chains comprising L-amino acids primarily occur as right-handed α-helices, whereas special chains, such as poly(L-benzyl aspartate) form left-handed helices14. Similarly, MC may be connected to supramolecular chirality (SMC; Fig. 1c). Helical hydrogen-bonding (HB) networks have become a target in the elucidation of the linkage between MC and SMC (Fig. 1d); organic molecules with (R)- or (S)-configurations produce two enantiomers and four diastereomers to form supP or supM helical HB networks. The symbols “supP” or “supM” represent the right- and left-handedness of the supramolecular helical assemblies15. The handedness control of these diastereomers may be based on subtle structural changes in the original molecules.


Linkage control between molecular and supramolecular chirality in 2₁-helical hydrogen-bonded networks using achiral components.

Sasaki T, Hisaki I, Miyano T, Tohnai N, Morimoto K, Sato H, Tsuzuki S, Miyata M - Nat Commun (2013)

Diastereomers with two different chiralities.(a) Conventional diastereomers resulting from two chiral carbons in molecular chirality. (b) Polymeric diastereomers with different molecular helicity. (c) Diastereomers with both molecular chirality and supramolecular chirality. (d) Supramolecular diastereomers with different supramolecular helicity for the 21-helical hydrogen-bonding networks.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3644081&req=5

f1: Diastereomers with two different chiralities.(a) Conventional diastereomers resulting from two chiral carbons in molecular chirality. (b) Polymeric diastereomers with different molecular helicity. (c) Diastereomers with both molecular chirality and supramolecular chirality. (d) Supramolecular diastereomers with different supramolecular helicity for the 21-helical hydrogen-bonding networks.
Mentions: In general, the linkage can be expressed by a combination of two chiral centres producing two enantiomers and four diastereomers (Fig. 1). A typical example of molecular chirality (MC) lies in the combination of two absolute configurations (Fig. 1a). In macromolecules, changes in handedness are evident in helicity (Fig. 1b). For example, polypeptide chains comprising L-amino acids primarily occur as right-handed α-helices, whereas special chains, such as poly(L-benzyl aspartate) form left-handed helices14. Similarly, MC may be connected to supramolecular chirality (SMC; Fig. 1c). Helical hydrogen-bonding (HB) networks have become a target in the elucidation of the linkage between MC and SMC (Fig. 1d); organic molecules with (R)- or (S)-configurations produce two enantiomers and four diastereomers to form supP or supM helical HB networks. The symbols “supP” or “supM” represent the right- and left-handedness of the supramolecular helical assemblies15. The handedness control of these diastereomers may be based on subtle structural changes in the original molecules.

Bottom Line: The mechanism of the handedness selectivity or switching phenomenon remains ambiguous, and most phenomena are observed by chance.Here we demonstrate the construction of chiral hydrogen-bonded twofold helical assemblies with controlled handedness in the crystalline state based on crystallographic studies.This study clearly reveals a connection between molecular chirality and supramolecular chirality in the crystalline state.

View Article: PubMed Central - PubMed

Affiliation: Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

ABSTRACT
Chiral molecules preferentially form one-handed supramolecular assemblies that reflect the absolute configuration of the molecules. Under specific conditions, however, the opposite-handed supramolecular assemblies are also obtained because of flexibility in the bond length and reversibility of non-covalent interactions. The mechanism of the handedness selectivity or switching phenomenon remains ambiguous, and most phenomena are observed by chance. Here we demonstrate the construction of chiral hydrogen-bonded twofold helical assemblies with controlled handedness in the crystalline state based on crystallographic studies. Detailed investigation of the obtained crystal structures enabled us to clarify the mechanism, and the handedness of the supramolecular chirality was successfully controlled by exploiting achiral factors. This study clearly reveals a connection between molecular chirality and supramolecular chirality in the crystalline state.

No MeSH data available.


Related in: MedlinePlus