Correlation of Intramolecular Excimer Emission with Lamellar Layer Distance in Liquid‐Crystalline Polymers: Verification by the Film‐Swelling Method

Lee, Wang-Eun; Kim, Jin-Woo; Oh, Chang-Jin; Sakaguchi, Toshikazu; Fujiki, Michiya; Kwak, Giseop

doi:10.1002/anie.200906621

Cited by 72 publications

(16 citation statements)

References 54 publications

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“…In the present PDPA derivatives, the wavelength of the FL emission band is a critical indicator of the degree of intramolecular stacking of the side phenyl rings . The FL band should appear at shorter wavelengths as the degree of intramolecular stacking decreases because the FL originates from intramolecular excimer emission based on the stacked structure.…”

Section: Resultsmentioning

confidence: 93%

Kinetic Study on Achiral-to-Chiral Transformation of Achiral Poly(diphenylacetylene)s via Thermal Annealing in Chiral Solvent: Molecular Design Guideline for Conformational Change toward Optically Dissymmetric Structures

et al. 2017

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Achiral poly(diphenylacetylene)s (PDPAs: pMe3, pEt3, piPr3, pMe2O1, pMe2OD1, and mMe3) with different alkyl side chains at the para or meta position of the side phenyl ring were prepared to examine achiral-to-chiral transformations upon thermal annealing in a chiral solvent. All the para-substituted PDPAs showed significant circular dichroism (CD) enhancement upon annealing, whereas the meta-substituted polymer, mMe3, was inert to the same treatment. To investigate the kinetics, the asymmetric conformational change was monitored by observing the changes in the magnitude of circular polarization (g CD ) or optical rotation. PDPAs with bulkier, round-shaped side groups (pEt3 and piPr3) had greater g CD values at equilibrium than pMe3 with a smaller side group. Moreover, the activation energy for the forward reaction (Ea f ) was lower in the bulkier polymers than in pMe3 owing to enhanced miscibility with the chiral solvent. Similarly, the long alkyl chains of pMe2O1 and pMe2OD1 acted as internal plasticizers to lower their Ea f values relative to that of pMe3, whereas their g CD values at equilibrium were smaller than that of pMe3. The kinetics of the achiral-to-chiral transformation is discussed in detail based on the spectroscopic changes observed during the annealing process.

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Section: Resultsmentioning

confidence: 93%

Kinetic Study on Achiral-to-Chiral Transformation of Achiral Poly(diphenylacetylene)s via Thermal Annealing in Chiral Solvent: Molecular Design Guideline for Conformational Change toward Optically Dissymmetric Structures

et al. 2017

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“…3a and Table 1). 43 This is unusual because conventional CPs have a highly dense cofacial chain packing structure in solid state, so that their FL is not affected.…”

Section: Alkyl Chain Length Effect On Fl Emissionmentioning

confidence: 97%

Properties, Functions, Chemical Transformation, Nano-, and Hybrid Materials of Poly(diphenylacetylene)s toward Sensor and Actuator Applications

Jin

Kwak

2016

Polymer Reviews

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This review examines poly(diphenylacetylene)s (PDPAs) as a special class of conjugated polymers. Various properties of PDPAs, including liquid crystallinity, fluorescence (FL) emission, and chirality are described in detail. The FL origin of PDPAs is intramolecular excimer emission that comes from the intramolecular stack structure of side phenyl rings. PDPAs show remarkable FL responses to external stimuli such as solvents, heat, surface tension, and pressure. PDPAs are easily transformed to desired forms via polymer reactions, chiral solvent annealing, and coupling with long alkyl chains. Very useful nanomaterials and hybrid materials can be prepared by chain quenching and in situ hybridization methods. PDPAs and their nanoand hybrid materials show highly advanced functions toward sensors and actuators.

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“…For example, in a polyacetyelene-based side-chain liquid crystal polymer, the spacer linking the mesogen with the polymer backbone should be a long alkyl chain to render suitable flexibility and attenuate the rigidity of the conjugated polyene. Meanwhile, the phase transition points of the polyacetyelene-based liquid crystal are relatively higher as compared with the liquid crystal polymers with saturated main-chains [20,21,22,23]. For helical polyacetylenes, a hot research topic of alkyne-based functional polymers, the synergetic cooperation of main-chain rigidity and side-chain bulkiness allows to generate stable single-handed helicity [24,25,26,27].…”

Section: Introductionmentioning

confidence: 99%

Pyrene-Functionalized Polyacetylenes: Synthesis and Photoluminescence Property

et al. 2019

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Four pyrene-functionalized polyacetylenes were designed and prepared through a typical post-polymerization modification route, which is the highly efficient reaction between activated ester and primary anime groups. The chemical structures of the resultant polymers were characterized with multiple spectroscopic techniques and the data indicated the successful functionalization of the polyacetylenes. The introduction of the pyrene moieties into the polymer structure allowed us to investigate the interactions between the polymer backbone and side chains. For the mono-substituted polyacetylenes, both the monomer and excimer emission features of the pyrene groups could be recorded, while for the di-substituted polyacetylenes, the fluorescence from the pyrene excimer vanished and the fluorescence intensity from the pyrene monomer decreased, the fluorescence from the polymer chain predominated the emission features. The concomitant energy transfer from the pyrene monomer and excimer to poly(diphenylacetylene) backbone was associated with the underlying mechanism. In addition to the substitution modes, the linkage between the poly(diphenylacetylene) backbone and the pyrene moiety also played a significant role in the determination of the emission species. A long alkyl spacer was beneficial to the pyrene monomer emission while a short one may be helpful to the formation of the excimer and intramolecular energy transfer.

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Correlation of Intramolecular Excimer Emission with Lamellar Layer Distance in Liquid‐Crystalline Polymers: Verification by the Film‐Swelling Method

Cited by 72 publications

References 54 publications

Kinetic Study on Achiral-to-Chiral Transformation of Achiral Poly(diphenylacetylene)s via Thermal Annealing in Chiral Solvent: Molecular Design Guideline for Conformational Change toward Optically Dissymmetric Structures

Kinetic Study on Achiral-to-Chiral Transformation of Achiral Poly(diphenylacetylene)s via Thermal Annealing in Chiral Solvent: Molecular Design Guideline for Conformational Change toward Optically Dissymmetric Structures

Properties, Functions, Chemical Transformation, Nano-, and Hybrid Materials of Poly(diphenylacetylene)s toward Sensor and Actuator Applications

Pyrene-Functionalized Polyacetylenes: Synthesis and Photoluminescence Property

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