Transfer of Chirality from Molecule to Phase in Self-Assembled Chiral Block Copolymers

Ho, Rong Ming; Li, Ming‐Chia; Lin, Shih Chieh; Wang, Hsiao Fang; Lee, Yu Der; Hasegawa, Hirokazu; Thomas, Edwin L.

doi:10.1021/ja303513f

Cited by 138 publications

(165 citation statements)

References 56 publications

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“…Unlike polypeptide, many polyesters, such as poly(lactic acid), cannot be studied well using ECD spectroscopy due to their negligibly small UV absorption. 39 The development of a technique to analyze the secondary structure of polyester will also advance biochemical studies of polypeptides containing α-hydroxy acid that can be obtained by a genetic code expansion 40,41 and chemical synthesis. 42 Considering the sensitivity of VCD spectroscopy toward the spatial orientation of carbonyl groups, it is reasonable to envision its potential as a tool for studying the secondary structures of polyesters.…”

Section: Structural Analysis Of Peptides and Proteinsmentioning

confidence: 99%

“…The left-handedness of PLLA in solution has also been suggested by other researchers. 39 (3) The VCD spectra of the PLLA solutions of CDCl 3 and DMSO-d 6 were nearly superimposable, suggesting the solvent has little influence on its secondary structure. (4) The VCD signals in the C = O stretching region for the PLLA-amylose complex were also virtually superimposable with the other two spectra.…”

Section: Structural Analysis Of Peptides and Proteinsmentioning

confidence: 99%

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Studying the stereostructures of biomolecules and their analogs by vibrational circular dichroism

Taniguchi

Hongen

Monde

2016

Polym J

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The functions of biomacromolecules are largely governed by their stereostructure (i.e., configuration and conformation). Therefore, detailed understanding of their structural properties should help in regulating the functions of artificial macromolecules. However, studying the stereostructure of a molecule in the solution state is typically difficult due to the lack of suitable analytical techniques. Vibrational circular dichroism (VCD) spectroscopy, which measures circular dichroism in the infrared region, exhibits high sensitivity toward molecular stereostructures. In this paper, we first discuss a method for the elucidation of the stereostructures of small to large molecules based on theoretical calculations of VCD. The rest of the paper is dedicated to the applications of a VCD exciton chirality method, a novel approach recently developed by the authors to interpret VCD data by observing a VCD couplet in the C = O stretching region, to various biomolecules such as peptides, carbohydrates, polyesters and lipids.

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Section: Structural Analysis Of Peptides and Proteinsmentioning

confidence: 99%

Section: Structural Analysis Of Peptides and Proteinsmentioning

confidence: 99%

Studying the stereostructures of biomolecules and their analogs by vibrational circular dichroism

Taniguchi

Hongen

Monde

2016

Polym J

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“…Indeed, recent experimental studies by Ho and coworkers provide direct evidence that chirality at the scale of monomers has a profound impact on the meso-scale assembly of certain block copolymers [10][11][12]. Unlike the standard cylinder (C) phase of achiral copolymers, melts of polystyrene-b-poly(L or D)lactide (PS-PLLA or PS-PDLA) assemble into hexagonally-ordered arrays of helices, denoted as the H * phase, where the handedness of helices is shown to switch with a reversal of monomer chirality [12].…”

mentioning

confidence: 99%

“…Unlike the standard cylinder (C) phase of achiral copolymers, melts of polystyrene-b-poly(L or D)lactide (PS-PLLA or PS-PDLA) assemble into hexagonally-ordered arrays of helices, denoted as the H * phase, where the handedness of helices is shown to switch with a reversal of monomer chirality [12]. Even in this homochiral system, transfer of chirality from the molecular-to the meso-scale is not automatic: at lower compositions of the chiral block, the achiral C phase is also observed [11].…”

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confidence: 99%

Chirality in Block Copolymer Melts: Mesoscopic Helicity from Intersegment Twist

2013

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We study the effects of chirality at the segment scale on the thermodynamics of block copolymer melts using self consistent field theory. In linear diblock melts where segments of one block prefer a twisted, or cholesteric, texture, we show that melt assembly is critically sensitive to the ratio of random coil size to the preferred pitch of cholesteric twist. For weakly-chiral melts (large pitch), mesophases remain achiral, while below a critical value of pitch, two mesocopically chiral phases are stable: an undulated lamellar phase; and a phase of hexagonally-ordered helices. We show that the non-linear sensitivity of meso-scale chiral order to preferred pitch derives specifically from the geometric and thermodynamic coupling of the helical mesodomain shape to the twisted packing of chiral segments within the core, giving rise to a second-order cylinder-to-helix transition.

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“…To this end, a series of electron-deficient perylenediimide (PDI)-guests with a bulky 3,5-di-tert-butylbenzyl stopper at one end and a triethylene glycol (Tg) (G2 Tg ), a poly(ethylene glycol) (PEG) with a different chain length (n = 50 (G3 PEG ) and 259 (G4 PEG )), or polystyrene (PS) (G5 PS ) 10 at the other end were prepared 11 and their threading kinetics through the helicate macrocycle 1 Na2 resulting from the inclusion complex formation of 1 Na2 with the PDI unit of the guests were investigated under various conditions by fluorescence spectroscopy (Figure 1).…”

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confidence: 99%

Alkali Metal Ion-enhanced Threading of a Perylenediimide-bound Polymer Chain through a Double-stranded Spiroborate Helicate with a Bisporphyrin Unit

et al. 2017

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Threading of a poly(ethylene glycol) (PEG) chain linked to a perylenediimide unit at one end with a bulky stopper at the other end through an inner cavity of a bisporphyrin-based doublestranded spiroborate helicate was remarkably accelerated in a specific solvent, in which the PEG chain enfolded sodium cations coordinating to the negatively charged spiroborate helicate, thus forming a 1:1 inclusion complex with the perylenediimide sandwiched between the bisporphyrin unit. The threading of a short or long axle molecule through an inner space of macrocycles provides a class of unique mechanically-interlocked molecules, namely, rotaxanes that have become one of the key structural motifs to develop artificial molecular machines 1 and functional nano-and biorelated intelligent materials.2 Such rotaxane-like structures are widely utilized in sophisticated biological events, such as DNA replication, 3 in which a single-stranded DNA chain is threaded through a toroidal-shaped polymerase enzyme while moving along the strand. 4 Nolte, Rowan, and co-workers took advantage of this unique biological rotaxane formation and succeeded in the construction of an artificial rotaxane system composed of a catalyticallyactive porphyrin-based macrocycle that threaded onto a reactive polymer chain during oxidation along the polymer, 5 and further proposed a unique threading mechanism of porphyrin-based macrocycles onto a viologen-appended polymer chain bearing a bulky stopper at one end as a model system, 6 through which the macrocycles thread from the polymer chain in one direction to form a 1:1 inclusion complex with the terminal viologen residue of the polymer. Although a large number of supramolecular rotaxane and pseudorotaxane formations have been reported, 1,2,7 biomimetic pseudorotaxane complex formation between macrocycles and polymers focusing on such a polymer threading process before complexation remains limited. 6We previously reported a double-stranded spiroborate helicate with a bisporphyrin unit in the middle (1 Na2 , Figure 1a) that formed a 1:1 inclusion complex with an electron-deficient aromatic guest, such as 1,4,5,8-naphthalenetetracarboxylic dianhydride (NDA). This complexation is accompanied by unique unidirectional dual rotary and twisting motions of the helicate triggered by the guest-encapsulation. 8,9 We envisioned that the macrocyclic helicate 1 Na2 would also form an inclusion complex with an analogous polymer-bound electron-deficient aromatic (b) Schematic representation of the inclusion complex formation between a double-stranded bisporphyrin helicate 1 Na2 and a perylenediimide (PDI) derivative carrying a polymer chain and a bulky substituent (stopper) at each end. Inclusion complexation is entirely possible by one-way threading of the polymer chain through the bisporphyrin cavity of 1 Na2 due to the bulky stopper at the other end of PDI.

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Transfer of Chirality from Molecule to Phase in Self-Assembled Chiral Block Copolymers

Cited by 138 publications

References 56 publications

Studying the stereostructures of biomolecules and their analogs by vibrational circular dichroism

Studying the stereostructures of biomolecules and their analogs by vibrational circular dichroism

Chirality in Block Copolymer Melts: Mesoscopic Helicity from Intersegment Twist

Alkali Metal Ion-enhanced Threading of a Perylenediimide-bound Polymer Chain through a Double-stranded Spiroborate Helicate with a Bisporphyrin Unit

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