Lamellar‐Twisting‐Induced Circular Dichroism of Chromophore Moieties in Banded Spherulites with Evolution of Homochirality

Li, Ming‐Chia; Wang, Hsiao Fang; Chiang, Chen Hung; Lee, Yu Der; Ho, Rong Ming

doi:10.1002/anie.201310078

Cited by 43 publications

(47 citation statements)

References 49 publications

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Section: Chiral Assemblies From Molecular Chirality In Condensed Statesmentioning

confidence: 99%

“…[ 31 ] The photoinduced chiral signals were generated upon the photoirradiation of CPL at room temperature. [ 32 ] However, the induced chirality did not demonstrate excellent stability because of the relaxation of segments in liquid‐crystalline homopolymers. BCs could help to limit relaxation by confining the photo‐addressable segments into nanoscale microphase separation, whereas alternative copolymers containing photo‐crosslinkable cinnamate moieties could help to fix the induced chirality.…”

Section: Hierarchical Chirality Transfer In Condensed Statesmentioning

confidence: 99%

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confidence: 99%

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Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self‐Assembly

2021

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Self-assembly, as a typical bottom-up strategy for the fabrication of functional materials, has been applied to fabricate chiral materials with subtle chiral nanostructures. The chiral nanostructures exhibit great potential in asymmetric catalysis, chiral sensing, chiral electronics, photonics, and even the realization of several biological functions. According to existing studies, the supramolecular chirality transfer process combined with hierarchical self-assembly plays a vital role in the fabrication of multiscale chiral structures. This progress report focuses on the hierarchical self-assembly of chiral or achiral molecules that aggregate with asymmetric spatial structures such as twisted bands, helices, and superhelices in different environments. Herein, recent studies on the chirality transfer induced self-assembly based on a variety of supramolecular interactions are summarized. In addition, the influence of different environments and the states of systems including solutions, condensed states, gel systems, interfaces on the asymmetric hierarchical self-assembly, and the expression of chirality are explored. Moreover, both the driving forces that facilitate chiral bias and the supramolecular interactions that play an important role in the expression, transfer, and amplification of the chiral sense are correspondingly discussed.

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Section: Chiral Assemblies From Molecular Chirality In Condensed Statesmentioning

confidence: 99%

Section: Hierarchical Chirality Transfer In Condensed Statesmentioning

confidence: 99%

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Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self‐Assembly

2021

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“…Twisting lamellar crystals may possess optical activity, such as circular birefringence [80], circular dichroism [81], and second harmonic generation [82], etc. Consequently, polymer banded spherulites may find potential applications in optical devices.…”

Section: Conclusion and Perspectivementioning

confidence: 99%

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Zhang

et al. 2017

Crystals

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Abstract:In this mini-review, we summarize the evidences of lamellar twisting in the birefringent banded polymer spherulites demonstrated by various characterization techniques, such as polarized optical microscopy, real-time atomic force microscopy, micro-focus wide angle X-ray diffraction, etc. The real-time observation of lamellar growth under atomic force microscopy unveiled the fine details of lamellar twisting and branching in the banded spherulites of poly(R-3-hydroxybutyrate-co-17 mol % R-3-hydroxyhexanoate). Organization of the twisting lamellar crystals in the banded spherulites was revealed as well. The lamellar crystals change the orientation via twisting rather than the macro screw dislocations. In fact, macro screw dislocation provides the mechanism of synchronous twisting of neighboring lamellar crystals. The driving force of lamellar twisting is attributed to the anisotropic and unbalanced surface stresses. Besides molecular chirality, variation of the growth axis and the chemical groups on lamellar surface can change the distribution of the surface stresses, and thus may invert the handedness of lamellar twisting. Thus, based on both experimental results and physical reasoning, the relation between crystal chirality and chemical molecular structures has been suggested, via the bridge of the distribution of surface stresses. The factors affecting band spacing are briefly discussed. Some remaining questions and the perspective of the topic are highlighted.Keywords: banded polymer spherulite; ringed spherulite; lamellar twisting; organization of lamellar crystals; surface stresses; chirality When crystallized from quiescent melt or concentrated solution, polymer chains usually form spherulites consisted of multiple lamellar crystals radiating from the spherulite center. Observed under polarized optical microscope (POM), a spherulite shows the characteristic Maltese-cross extinction. Besides the Maltese cross, some spherulites demonstrate alternative bright and dark bands under POM. These spherulites are termed as banded spherulites or ringed spherulites. The band structure with different light intensities may result from different thicknesses or different birefringences but similar thickness. In the former case, the bands are due to the periodical modulation of sample thickness and there is no variation of refractive index in the spherulite. These nonbirefringent banded spherulites have been observed in some polymer single crystals formed from thin melt films [1] or solutions [2] and are reviewed by Li et al. [3] in this special issue. In the latter case, the birefringent bands can result from the wavy bending growth or twisting growth of crystals. The wavy bands have been reported in sheared liquid crystals [4,5], which do not form spherulites under the condition. In this mini-review, we focus on the birefringent banded spherulites, which consist of synchronously twisted lamellar crystals. The organization of the twisted lamellar crystals in the banded spherulites and the driving force for lamell...

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“…The handedness of the twisted lamellae in the spherulites could be conveniently detected by a rotation experiment,2c, 9 for which the sample was rotated along the direction perpendicular to the light path, and a series of images were captured at different angles. The rotation of a twisted lamella in the sense of its own twist leads to a descent of the corresponding extinction rings, in the same way as a right‐handed positive rotation applied to a right‐handed screw leads to a visual descent of the apparent screw thread.…”

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confidence: 99%

Controlled Handedness of Twisted Lamellae in Banded Spherulites of Isotactic Poly(2‐vinylpyridine) as Induced by Chiral Dopants

et al. 2015

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Herein, we suggest a unique approach to control the handedness of twisted lamellae in banded spherulites of a stereoregular polymer, isotactic poly(2-vinylpyridine) (iP2VP). When (R)- or (S)-hexahydromandelic acid (HMA), which can associate with iP2VP, was introduced as a chiral dopant, mirror-image CD spectra in the complex systems showed induced circular dichroism (ICD) of the iP2VP by chiral HMA. Banded spherulites resulting from lamellar twisting due to the imbalanced stresses at the opposite folding surfaces could be formed by crystallization of the iP2VP/HMA complexes, which had a crystalline structure similar to that of neat iP2VP. A preferential sense of the twisted crystalline lamellae was found in the iP2VP/HMA complex, thus suggesting homochiral evolution from conformational to hierarchical chirality.

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Lamellar‐Twisting‐Induced Circular Dichroism of Chromophore Moieties in Banded Spherulites with Evolution of Homochirality

Cited by 43 publications

References 49 publications

Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self‐Assembly

Supramolecular Chirality Transfer toward Chiral Aggregation: Asymmetric Hierarchical Self‐Assembly

Organization of Twisting Lamellar Crystals in Birefringent Banded Polymer Spherulites: A Mini-Review

Controlled Handedness of Twisted Lamellae in Banded Spherulites of Isotactic Poly(2‐vinylpyridine) as Induced by Chiral Dopants

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