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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

Helicity and handedness of one-dimensional ladder-type hydrogen-bonding networks.(a) Primary ammonium carboxylates employed in this study. The organic salts are composed of chiral amine A or B with achiral benzoic acid derivatives (1–5). (b) Twofold helical hydrogen-bonding networks with repetition of deformed rings (inset (i)) based on discriminable O(α) and O(β) of carboxylate groups (inset (ii)). Right or left handedness are determined according to the supramolecular tilt chirality method (inset (iii)) and referred to as supP or supM, respectively. The rung N–O(α) portion (inset (iv)) is located on the front and back sides in the top views, which are indicated in green and yellow, respectively. The right or left tilt of the rung portions on the front sides defines the right- or left-handedness of the 21-helices (inset (iii)). The upward direction of the networks is defined along the direction of O(α) to O(β) on the leg portions (inset (ii)).
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f2: Helicity and handedness of one-dimensional ladder-type hydrogen-bonding networks.(a) Primary ammonium carboxylates employed in this study. The organic salts are composed of chiral amine A or B with achiral benzoic acid derivatives (1–5). (b) Twofold helical hydrogen-bonding networks with repetition of deformed rings (inset (i)) based on discriminable O(α) and O(β) of carboxylate groups (inset (ii)). Right or left handedness are determined according to the supramolecular tilt chirality method (inset (iii)) and referred to as supP or supM, respectively. The rung N–O(α) portion (inset (iv)) is located on the front and back sides in the top views, which are indicated in green and yellow, respectively. The right or left tilt of the rung portions on the front sides defines the right- or left-handedness of the 21-helices (inset (iii)). The upward direction of the networks is defined along the direction of O(α) to O(β) on the leg portions (inset (ii)).

Mentions: We employed chiral organic salts, A- or B-salts, composed of (R)- or (S)-α-methylbenzylamine (that is, A or B, respectively) with benzoic acid derivatives (1–5) (Fig. 2a). Crystallographic studies of the crystals, which were recrystallized from the salts, revealed that all of the crystals contained 21-helical columns with one-dimensional (1D) ladder-type HB networks1823. The charge-assisted hydrogen bonds between the amines and carboxylic acids have a length of 2.71–2.83 Å (see Supplementary Table S1). In addition, the crystals were subjected to powder X-ray diffraction (PXRD) analysis. The resulting peak patterns coincided with those calculated from the single-crystal X-ray analysis data (see Supplementary Figs S2 and S3 and Supplementary Tables S2 to S5). On the basis of these results, the diastereomers of the crystals do not exhibit polymorphic forms, with the exception of crystals formed from p-chloro- or p-bromobenzoic acid.


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)

Helicity and handedness of one-dimensional ladder-type hydrogen-bonding networks.(a) Primary ammonium carboxylates employed in this study. The organic salts are composed of chiral amine A or B with achiral benzoic acid derivatives (1–5). (b) Twofold helical hydrogen-bonding networks with repetition of deformed rings (inset (i)) based on discriminable O(α) and O(β) of carboxylate groups (inset (ii)). Right or left handedness are determined according to the supramolecular tilt chirality method (inset (iii)) and referred to as supP or supM, respectively. The rung N–O(α) portion (inset (iv)) is located on the front and back sides in the top views, which are indicated in green and yellow, respectively. The right or left tilt of the rung portions on the front sides defines the right- or left-handedness of the 21-helices (inset (iii)). The upward direction of the networks is defined along the direction of O(α) to O(β) on the leg portions (inset (ii)).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Helicity and handedness of one-dimensional ladder-type hydrogen-bonding networks.(a) Primary ammonium carboxylates employed in this study. The organic salts are composed of chiral amine A or B with achiral benzoic acid derivatives (1–5). (b) Twofold helical hydrogen-bonding networks with repetition of deformed rings (inset (i)) based on discriminable O(α) and O(β) of carboxylate groups (inset (ii)). Right or left handedness are determined according to the supramolecular tilt chirality method (inset (iii)) and referred to as supP or supM, respectively. The rung N–O(α) portion (inset (iv)) is located on the front and back sides in the top views, which are indicated in green and yellow, respectively. The right or left tilt of the rung portions on the front sides defines the right- or left-handedness of the 21-helices (inset (iii)). The upward direction of the networks is defined along the direction of O(α) to O(β) on the leg portions (inset (ii)).
Mentions: We employed chiral organic salts, A- or B-salts, composed of (R)- or (S)-α-methylbenzylamine (that is, A or B, respectively) with benzoic acid derivatives (1–5) (Fig. 2a). Crystallographic studies of the crystals, which were recrystallized from the salts, revealed that all of the crystals contained 21-helical columns with one-dimensional (1D) ladder-type HB networks1823. The charge-assisted hydrogen bonds between the amines and carboxylic acids have a length of 2.71–2.83 Å (see Supplementary Table S1). In addition, the crystals were subjected to powder X-ray diffraction (PXRD) analysis. The resulting peak patterns coincided with those calculated from the single-crystal X-ray analysis data (see Supplementary Figs S2 and S3 and Supplementary Tables S2 to S5). On the basis of these results, the diastereomers of the crystals do not exhibit polymorphic forms, with the exception of crystals formed from p-chloro- or p-bromobenzoic acid.

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