Induced circular dichroism of stereoregular vinyl polymers

Chen, Lung Chi; Mao, Yung Cheng; Lin, Shih Chieh; Li, Ming‐Chia; Ho, Rong Ming; Tsai, Jing Cherng

doi:10.1039/c2cc18027h

Cited by 25 publications

(32 citation statements)

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“…T he crystallized iP2VP withc omplexedH MA showed twisted lamellae withc ontrolledh andednessb ut without ac hangei ni ts intrinsic crystallines tructure.T hus,b anded spherulites with specific opticala ctivity could be formed by collective growth of thet wisted lamellae to enable homochirale volutionf rom conformational to hierarchical chirality. [4] Also,the Cotton effect was found at ashorter wavelength (ca. Similar ICD behavior with mirror imaging of the CD spectra was observed for films of the iP2VP/HMA complex ( Figure 2b).…”

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confidence: 79%

“…[4] In brief,iP2VP was synthesizedbythe isospecific polymerization of 2-vinylpyridine with 4-tert-butylphenylmagnesiumb romide as the initiator.T he resulting polymerw as purified by removing the atactic P2VP through boiling cosolvent extraction (THF/methyl ethyl ketone,1:2) in aSoxhlet extractor. [4] In brief,iP2VP was synthesizedbythe isospecific polymerization of 2-vinylpyridine with 4-tert-butylphenylmagnesiumb romide as the initiator.T he resulting polymerw as purified by removing the atactic P2VP through boiling cosolvent extraction (THF/methyl ethyl ketone,1:2) in aSoxhlet extractor.…”

Section: Methodsmentioning

confidence: 99%

“…[2] Helical polymers can be classified into two types:s tatic and dynamic,d epending on the nature of the helical conformation. [4] In thiss tudy,w eu seds tereoregulari sotactic poly(2vinylpyridine) (iP2VP)f or self-assemblyw ith ICD and crystallization as banded spherulites,and observed concentric rings or extinctionbands by polarized-light microscopy(PLM) of the resulting crystals. [3] Most dynamic helical polymers with ICD have conjugated or peptide-based backbones,and the rigidity of the main chain stabilizes the forming helical conformation.…”

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confidence: 97%

“…As tatic helical polymer possesses as table helical conformation with optical activity,w hereas adynamic helical polymer may adopt an alternating sequence of left-and right-handed helices separated by helical reversals.F or adynamic helical polymer,the formation of astable helical conformation might be possible by the complexation of chiral dopants.T his effect is known as induced circular dichroism (ICD). [4] In thiss tudy,w eu seds tereoregulari sotactic poly(2vinylpyridine) (iP2VP)f or self-assemblyw ith ICD and crystallization as banded spherulites,and observed concentric rings or extinctionbands by polarized-light microscopy(PLM) of the resulting crystals. [3c] Examples of polyolefins and vinyl polymers with induced chirality are rare.R ecently,s tereoregular vinyl polymers with backbones composed of CÀCb onds were successfully used for the association of avariety of chiral guest molecules with functional side chains to give ICD signals.The ICD behaviour was found to be strongly dependent on the isotacticity of the poly(2-vinylpyridine) polymers and the acidity and bulkiness of chiral acids used as guests.…”

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confidence: 99%

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

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

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“…[3c] Examples of polyolefins and vinyl polymers with induced chirality are rare.R ecently,s tereoregular vinyl polymers with backbones composed of CÀCb onds were successfully used for the association of avariety of chiral guest molecules with functional side chains to give ICD signals.The ICD behaviour was found to be strongly dependent on the isotacticity of the poly(2-vinylpyridine) polymers and the acidity and bulkiness of chiral acids used as guests. [4] In thiss tudy,w eu seds tereoregulari sotactic poly(2vinylpyridine) (iP2VP)f or self-assemblyw ith ICD and crystallization as banded spherulites,and observed concentric rings or extinctionbands by polarized-light microscopy(PLM) of the resulting crystals. Thef ormationo fi P2VP banded spherulites is attributedtothe twisting of crystallinelamellae as ar esult of the imbalanced stresses at theo pposite folding surfaces.B yt he introduction of chiral dopants,t he crystallization of iP2VP withICD could be usedasamodel system to examinet he feasibility of controlling the handedness of the twistedl amellae.…”

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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 aunique approach to control the handedness of twisted lamellae in banded spherulites of as tereoregular polymer,i sotactic poly(2-vinylpyridine) (iP2VP). When (R)-or (S)-hexahydromandelic acid (HMA), which can associate with iP2VP,w as introduced as ac hiral 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,w hichh ad ac rystalline structure similar to that of neat iP2VP.Apreferential sense of the twisted crystalline lamellae was found in the iP2VP/HMA complex, thus suggesting homochiral evolution from conformational to hierarchical chirality.Chirality at the molecular scale is vital for driving the formation of helical structures with different length scales.In polymers,as tereogenic center could be introduced in either the backbone or side chains.S uch chirality usually leads to ah elical conformation of the polymer owing to steric hindrance from intramolecular chiral interactions.B yt aking advantage of ordering through self-assembly,t hose helical chains can be collectively packed as hierarchical helical superstructures as ar esult of intermolecular chiral interactions. [1] Owing to the effect of steric hindrance,i tm ay be possible to generate helical morphologies and superstructures with exclusive handedness through chirality transfer from the molecular level. [2] Helical polymers can be classified into two types:s tatic and dynamic,d epending on the nature of the helical conformation. As tatic helical polymer possesses as table helical conformation with optical activity,w hereas adynamic helical polymer may adopt an alternating sequence of left-and right-handed helices separated by helical reversals.F or adynamic helical polymer,the formation of astable helical conformation might be possible by the complexation of chiral dopants.T his effect is known as induced circular dichroism (ICD). [3] Most dynamic helical polymers with ICD have conjugated or peptide-based backbones,and the rigidity of the main chain stabilizes the forming helical conformation. [3c] Examples of polyolefins and vinyl polymers with induced chirality are rare.R ecently,s tereoregular vinyl polymers with backbones composed of CÀCb onds were successfully used for the association of avariety of chiral guest molecules with functional side chains to give ICD signals.The ICD behaviour was found to be strongly dependent on the isotacticity of the poly(2-vinylpyridine) polymers and the acidity and bulkiness of chiral acids used as guests. [4] In thiss tudy,w eu seds tereoregulari sotactic poly(2vinylpyridine) (iP2VP)f or self-assemblyw ith ICD and crystallization as banded spherulites,and observed concentric rings or extinctionbands by polarized-light microscopy(PLM) of the resulting crystals. Thef ormationo fi P2VP banded spherulites is attributedtothe twisting of crystallinelam...

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Chirality Transfer in Chiral Polymers and Block Copolymers

Wang

2014

Encyclopedia of Polymer Science and Technology

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This article deals with the chirality transfer of chiral polymers and chiral block copolymers (BCPs*) on different length scales. Helical conformation can form at the molecular level due to the stereoregularity of chiral entities in the chiral polymers and the BCPs*. Helical superstructures and phases can be fabricated by self‐assembling polymer chains with helical conformation through intramolecular and intermolecular interactions. The transfer of chiral information from molecules to macroscopic level and the control of the handedness of the helical architectures are discussed. In the first part of this article, examples of chirality transfer in self‐assembled chiral polymers and BCPs* are introduced. As found, the molecular chirality of constituted chiral entities in the chiral polymers and BCPs* and their corresponding conformational chirality plays an important role in the formation of helical hierarchical structures with exclusive handedness. The second part of this article illustrates the chirality transfer in specific model systems, chiral polylactides, and polylactide‐containing BCPs*, at which homochiral evolution from a chiral entity to a helical phase is demonstrated. A methodology for systematic studies of the chirality transfer from molecular level to a phase scale is suggested. Through the design and synthesis of macromolecules and the operation of self‐assembly, the mechanisms of chirality transfer on different length scales can be understood, giving supplementary information to disclose the mysteries of morphological evolution from the molecular level.

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Induced circular dichroism of stereoregular vinyl polymers

Cited by 25 publications

References 44 publications

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

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

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

Chirality Transfer in Chiral Polymers and Block Copolymers

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