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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

Solid-state vibrational circular dichroism spectra.(a) The vibrational circular dichroism spectra of A(4-p)-c and B(4-p)-c and (b) A(4-p)-t and B(4-p)-t; the spectra of the A-salts and B-salts are represented by solid and dotted lines, respectively.
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f4: Solid-state vibrational circular dichroism spectra.(a) The vibrational circular dichroism spectra of A(4-p)-c and B(4-p)-c and (b) A(4-p)-t and B(4-p)-t; the spectra of the A-salts and B-salts are represented by solid and dotted lines, respectively.

Mentions: To further confirm the handedness switching of the SMC of the HB networks, solid-state vibrational circular dichroism (VCD) spectra and infrared spectra were measured for the A(4-p) crystal with a chirality of R-supM, R-supP and the B(4-p) crystal, with a chirality of S-supP, S-supM, which are denoted as A(4-p)-c, A(4-p)-t and B(4-p)-c, B(4-p)-t, respectively, using KBr pellets (Fig. 4). The terminal symbols -c and -t represent the coplanar and twisted conformations, respectively, of the carboxylic groups relative to the phenyl rings. The chiral properties can be measured using VCD spectra instead of electronic circular dichroism spectra, because the handedness of the SMC was defined by the HB networks between the amino and carboxylic groups, which have specific absorptions in the infrared region. The infrared spectra are nearly identical in all of the cases. For the VCD signals, a mirror-image relationship is observed between the enantiomeric pairs of A(4-p)-c and B(4-p)-c (Fig. 4a), as well as in A(4-p)-t and B(4-p)-t (Fig. 4b), confirming the reliability of the signals. The most discriminative VCD signals are at ~1,530 (number 1–3 in the figure) and 1,380 cm−1 (number 4–6), and inversion of the signals is clearly observed in the VCD signals of the diastereomeric pairs of A(4-p)-c and A(4-p)-t, as well as of B(4-p)-c and B(4-p)-t. This result strongly supports the handedness switching of the SMC of the HB networks.


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)

Solid-state vibrational circular dichroism spectra.(a) The vibrational circular dichroism spectra of A(4-p)-c and B(4-p)-c and (b) A(4-p)-t and B(4-p)-t; the spectra of the A-salts and B-salts are represented by solid and dotted lines, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Solid-state vibrational circular dichroism spectra.(a) The vibrational circular dichroism spectra of A(4-p)-c and B(4-p)-c and (b) A(4-p)-t and B(4-p)-t; the spectra of the A-salts and B-salts are represented by solid and dotted lines, respectively.
Mentions: To further confirm the handedness switching of the SMC of the HB networks, solid-state vibrational circular dichroism (VCD) spectra and infrared spectra were measured for the A(4-p) crystal with a chirality of R-supM, R-supP and the B(4-p) crystal, with a chirality of S-supP, S-supM, which are denoted as A(4-p)-c, A(4-p)-t and B(4-p)-c, B(4-p)-t, respectively, using KBr pellets (Fig. 4). The terminal symbols -c and -t represent the coplanar and twisted conformations, respectively, of the carboxylic groups relative to the phenyl rings. The chiral properties can be measured using VCD spectra instead of electronic circular dichroism spectra, because the handedness of the SMC was defined by the HB networks between the amino and carboxylic groups, which have specific absorptions in the infrared region. The infrared spectra are nearly identical in all of the cases. For the VCD signals, a mirror-image relationship is observed between the enantiomeric pairs of A(4-p)-c and B(4-p)-c (Fig. 4a), as well as in A(4-p)-t and B(4-p)-t (Fig. 4b), confirming the reliability of the signals. The most discriminative VCD signals are at ~1,530 (number 1–3 in the figure) and 1,380 cm−1 (number 4–6), and inversion of the signals is clearly observed in the VCD signals of the diastereomeric pairs of A(4-p)-c and A(4-p)-t, as well as of B(4-p)-c and B(4-p)-t. This result strongly supports the handedness switching of the SMC of the HB networks.

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