Molecular chirality induction to an achiral π-conjugated polymer by circularly polarized light

Wang, Yue; Sakamoto, Takeshi; Nakano, Tamaki

doi:10.1039/c2cc17027b

Cited by 92 publications

(99 citation statements)

References 31 publications

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“…Chemists have successfully realized the helical chirality switching by means of external stimuli, such as solvent, temperature, light irradiation, pH and so on. [21][22][23][24][25][26][27][28][29][30][31] In particular, intrinsic chirality exists in many organic solvents (e.g., limonene), and it tends to influence the solute conformation, then results in complete helical chirality inversion. Gin and Moore demonstrated that [This article is part of the Special Issue: Proceedings of 28th International Symposium on Molecular Chirality, Heidelberg 2016.…”

Section: Introductionmentioning

confidence: 99%

Helical screw sense bias in chiral polyfluorene stimulated by solvent

et al. 2017

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Conjugated homopolymer poly(9,9-bis(3-((S)-2-methylbutylpropanoate))fluorene) (PSF) with chiral pendants was synthesized and characterized. Dissolution experiments show that PSF is well dissolved in racemic limonene at high temperature and begins aggregating upon sequential cooling treatment. The corresponding assemblies were transferred to quartz plate by the spin-coating method. Comparably, film casting from chloroform solution was also prepared. Upon annealing thermal treatments, these PSF films exhibited perfect mirror circular dichroism (CD) Cotton effects and dissymmetry ratios. Optical absorption spectroscopy (UV-vis), CD, and fluorescence spectroscopy results reveal that chiral side chains successfully induced M- and P-helical structures in aggregates and films, and this significant difference was ascribed to their differential supramolecular conformations.

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Section: Introductionmentioning

confidence: 99%

Helical screw sense bias in chiral polyfluorene stimulated by solvent

et al. 2017

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“…Similar mechanisms have been proposed for photo-induced helixhelix transition of poly(BBPFA) and for CPL-assisted helix induction to a polyfluorene derivative. 25 It should be noted that the polymer behaved differently on irradiation in the absence of the scavenger under air, i.e., the sidechain alkyl group came off in the form of 2-methylbutanol (Fig. S4).…”

Section: Chart 1 Structure Of Poly(bmbpst)mentioning

confidence: 99%

Photo-induced helix–helix transition of a polystyrene derivative

et al. 2014

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Poly(2,5-bis[4-((S)-2-methylbutyloxy)phenyl]styrene)having a helical conformation underwent helix-helix transition on photo irradiation. Conformational transition can significantly alter polymer properties, and so far thermal stereomutaion have been studied. However, as for photo-induced mutation, only helix-helix transition (irreversible CD-active to CD-silent helix transition) of a polyacrylate has been explored. Here, we present mutation of the polystyrene derivative. Chiroptical, viscometric, and vibrational spectroscopic analyses indicated the polymer mutated from an optically active helix to another, optically inactive helix with a different shape.Functions and properties of natural 1 and artificial 2 macromolecules are sensitive to chain conformation. For example, denaturation, mutation from a functional shape to a disordered one, of proteins makes them lose their precise functions.2 Some artificial polymers undergo helix-helix transition governed by chemical, thermal and photo stimuli.2-4 Such polymers revert their helix sense, showing a broad range of applications. [5][6][7][8] As the first artificial helical polymer which undergoes helix-helix transition by light and not by heat, we reported poly(2,7-bis(4-tert-butylphenyl)fluoren-9-ylacrylate) [poly(BBPFA)]. 4,9 A polystyrene derivative bearing a terphenyl structure in the side chain, poly(2,5-bis[4-((S)-2-methylbutyloxy)phenyl]styrene) [poly(BMBPSt)] (Chart 1) and its derivatives were synthesized by radical polymerization, and its preferred-handed helicity was evidenced. [10][11][12] This series of polymers contain terphenyl group in the side-chain. Since the main-chain stereomutaion of poly(BBPFA) has been proposed to be triggered by twist-coplanar mutation 13 on excitation, we expected some main-chain mutation also on excitation of poly(BMBPSt). However, this polymer exhibited responses to light distinctive to those of poly(BBPFA). An optically active helix turned into an optically inactive, racemic helix where the shape helical chain remarkably changed, i.e., apparent chain length decreased and width of helix increased; the original slim helix became stocky by light. Chart 1 Structure of poly(BMBPSt).The polymer sample (M n 79,320, M w /M n 2.01 vs. polystyrene) was prepared by radical polymerization in benzene at 60 o C according to the literature.11 Photo irradiation to the sample was conducted using a 500 W Hg-Xe lamp without polarization. The sample was a solution in either tetrahydrofuran (THF) containing 2,2,6,6-tetramethyl-4-piperidinol 14 as an achiral radical scavenger. The scavenger was used to avoid any side reaction that could be caused by a radical species generated by irradiation.14 The polymer solution in THF indicated intense Cotton effects in circular dichroism (CD) spectra attributable. The spectra are ascribed not to monomeric unit chirality but to a main-chain helix, because BMBPSt monomer shows CD spectra with much lower intensity and a completely different spectral shape from that of the polymer. The spectral intensity was no...

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“…Chirality induction for polyfluorene derivatives having no photochromic groups in thin film form upon irradiation of CPL was reported [19].…”

Section: Introductionmentioning

confidence: 99%

Absolute asymmetric electrochemical polymerization

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2016

Philosophical Magazine Letters

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Electrochemical polymerization of thiophene-based achiral monomer having azobenzene as a chromophore irradiated by circular polarized light (CPL) was carried out to obtain chiroptically active polymer film on indium-tin-oxide (ITO) coated glass. Circular dichroism and optical absorption spectroscopy measurements indicate the samples show chiroptical activity. This result indicates occurrence of absolute asymmetric polymerization by laser CPL.

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Molecular chirality induction to an achiral π-conjugated polymer by circularly polarized light

Abstract: A preferred-handed helical conformation was induced to poly(9.9-dioctylfluren-2,7-diyl) (PDOF) in a thin film form upon irradiation with single-handed circularly polarized light (CPL) where the induction was reversible.

Cited by 92 publications

References 31 publications

Helical screw sense bias in chiral polyfluorene stimulated by solvent

Helical screw sense bias in chiral polyfluorene stimulated by solvent

Photo-induced helix–helix transition of a polystyrene derivative

Absolute asymmetric electrochemical polymerization

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