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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

Possible mechanism of handedness switching.(a) (i) Top views, (ii) front views and (iii) positions of the carboxylic groups relative to the amino groups with rotation angles, θr, of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right) with supramolecular chiralities of supM and supP, respectively. (b) Two types of conformation of A(3-p) (left) and A(3-o) (right) with dihedral angles, θd. (c) Side views of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right); up and down are defined from concave to convex of the herringbone assemblies of the phenyl rings. The direction of herringbone-1 is the opposite of that of the hydrogen-bonding networks whereas that of herringbone-2 is the same. (d) A mechanism for the selected formation of herringbone-1 in A(3-p) (left) and herringbone-2 in A(3-o) (right). The length of the hydrogen bonds are unfavourable for (i) herringbone-2 and (ii) herringbone-1 in A(3-p) and A(3-o), respectively, and (iii) favourable for herringbone-1 and herringbone-2 in A(3-p) and A(3-o), respectively.
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f5: Possible mechanism of handedness switching.(a) (i) Top views, (ii) front views and (iii) positions of the carboxylic groups relative to the amino groups with rotation angles, θr, of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right) with supramolecular chiralities of supM and supP, respectively. (b) Two types of conformation of A(3-p) (left) and A(3-o) (right) with dihedral angles, θd. (c) Side views of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right); up and down are defined from concave to convex of the herringbone assemblies of the phenyl rings. The direction of herringbone-1 is the opposite of that of the hydrogen-bonding networks whereas that of herringbone-2 is the same. (d) A mechanism for the selected formation of herringbone-1 in A(3-p) (left) and herringbone-2 in A(3-o) (right). The length of the hydrogen bonds are unfavourable for (i) herringbone-2 and (ii) herringbone-1 in A(3-p) and A(3-o), respectively, and (iii) favourable for herringbone-1 and herringbone-2 in A(3-p) and A(3-o), respectively.

Mentions: The handedness switching of the SMC, which is a function of its substituents, corresponds to asymmetry generation, which is linked to MC. To clarify the switching mechanism, we compared three aspects of the detailed crystal structures: (i) tilt of the carboxylate group compared with the helical axis, (ii) conformations of the carboxylate group compared with the linked phenyl ring and (iii) herringbone stacking of the phenyl rings. Figure 5 exemplifies the comparative structures of a pair of A(3-p) and A(3-o), where the same amines with (R)-configurations yield reverse HB networks with supM and supP due to the para- and ortho-methoxy groups, respectively.


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)

Possible mechanism of handedness switching.(a) (i) Top views, (ii) front views and (iii) positions of the carboxylic groups relative to the amino groups with rotation angles, θr, of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right) with supramolecular chiralities of supM and supP, respectively. (b) Two types of conformation of A(3-p) (left) and A(3-o) (right) with dihedral angles, θd. (c) Side views of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right); up and down are defined from concave to convex of the herringbone assemblies of the phenyl rings. The direction of herringbone-1 is the opposite of that of the hydrogen-bonding networks whereas that of herringbone-2 is the same. (d) A mechanism for the selected formation of herringbone-1 in A(3-p) (left) and herringbone-2 in A(3-o) (right). The length of the hydrogen bonds are unfavourable for (i) herringbone-2 and (ii) herringbone-1 in A(3-p) and A(3-o), respectively, and (iii) favourable for herringbone-1 and herringbone-2 in A(3-p) and A(3-o), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f5: Possible mechanism of handedness switching.(a) (i) Top views, (ii) front views and (iii) positions of the carboxylic groups relative to the amino groups with rotation angles, θr, of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right) with supramolecular chiralities of supM and supP, respectively. (b) Two types of conformation of A(3-p) (left) and A(3-o) (right) with dihedral angles, θd. (c) Side views of the hydrogen-bonding 21-helical columns of A(3-p) (left) and A(3-o) (right); up and down are defined from concave to convex of the herringbone assemblies of the phenyl rings. The direction of herringbone-1 is the opposite of that of the hydrogen-bonding networks whereas that of herringbone-2 is the same. (d) A mechanism for the selected formation of herringbone-1 in A(3-p) (left) and herringbone-2 in A(3-o) (right). The length of the hydrogen bonds are unfavourable for (i) herringbone-2 and (ii) herringbone-1 in A(3-p) and A(3-o), respectively, and (iii) favourable for herringbone-1 and herringbone-2 in A(3-p) and A(3-o), respectively.
Mentions: The handedness switching of the SMC, which is a function of its substituents, corresponds to asymmetry generation, which is linked to MC. To clarify the switching mechanism, we compared three aspects of the detailed crystal structures: (i) tilt of the carboxylate group compared with the helical axis, (ii) conformations of the carboxylate group compared with the linked phenyl ring and (iii) herringbone stacking of the phenyl rings. Figure 5 exemplifies the comparative structures of a pair of A(3-p) and A(3-o), where the same amines with (R)-configurations yield reverse HB networks with supM and supP due to the para- and ortho-methoxy groups, respectively.

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