Reversible Sol–Gel Transition of Oligo(<i>p</i>-phenylenevinylene)s by π–π Stacking and Dissociation

Yao, Chuan; Lu, Qi; Wang, Xianhong

doi:10.1021/jp412554w

Cited by 21 publications

(6 citation statements)

References 54 publications

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“…Organogels of semicrystalline polymers are important classes of materials, and they preserve the self-organization of the polymer chains in the submicron to nanometer level in the gel state without compromising their processability . A large number of π-conjugated oligophenylenevinylene oligomer-based organogels − and MEH-PPV polymer organogel have been reported in the literature. The organogel formation ability of the segmented polymers was investigated in a variety of solvents (hexane, dichloromethane, THF, cyclohexane, chloroform, and toluene), and toluene was found to be more suitable for gelation.…”

Section: Resultsmentioning

confidence: 99%

π-Conjugated Polymer Anisotropic Organogel Nanofibrous Assemblies for Thermoresponsive Photonic Switches

Narasimha

Jayakannan

2014

ACS Appl. Mater. Interfaces

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The present work demonstrates one of the first examples of π-conjugated photonic switches (or photonic wave plates) based on the tailor-made π-conjugated polymer anisotropic organogel. New semicrystalline segmented π-conjugated polymers are designed with rigid aromatic oligophenylenevinylene π-core and flexible alkyl chain along the polymer backbone. These polymers are found to be self-assembled as semicrystalline or amorphous with respect to the number of carbon atoms in the alkyl units. These semicrystalline polymers produce organogels having nanofibrous morphology of 20 nm thickness with length up to 5 μm. The polymer organogel is aligned in a narrow glass capillary, and this anisotropic gel device is further demonstrated as photonic switches. The glass capillary device behaves as typical λ/4 photonic wave plates upon the illumination of the plane polarized light. The λ/4 photonic switching ability is found to be maximum at θ = 45° angle under the cross polarizers. The orthogonal arrangements of the gel capillaries produce dark and bright spots as on-and-off optical switches. Thermoreversibility of the polymer organogel (also its xerogel) was exploited to construct thermoresponsive photonic switches for the temperature window starting from 25 to 160 °C. The organic photonic switch concept can be adapted to large number of other π-conjugated materials for optical communication and storage.

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Section: Resultsmentioning

confidence: 99%

π-Conjugated Polymer Anisotropic Organogel Nanofibrous Assemblies for Thermoresponsive Photonic Switches

Narasimha

Jayakannan

2014

ACS Appl. Mater. Interfaces

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“…As revealed by SEM, representative morphologies of the selfassemblies of BDTc and gelators BDTDd/CDTOd showed densely packed 3D networks, which resulted in the solvent immobilization. [40] Specifically, xerogels of BDTDd, obtained from cyclohexane, formed a closely packed 3D networks composed of wide, straight fibrous bundles (Figure 8b). A similar structure but composed of thinner interlocked and more flexible ribbons was observed in the case of CDTOd in THF and toluene (Figures 8d and S7h).…”

Section: Cpdsmentioning

confidence: 99%

Butterfly‐like Shape Liquid Crystals Based Fused‐Thiophene as Unidimensional Ambipolar Organic Semiconductors with High Mobility

Donnio

Zhong

et al. 2021

Chemistry An Asian Journal

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Mesomorphous butterfly-like shape molecules based on benzodithiophene, benzodithiophene-4,8-dione and cyclopentadithiophen-4-one core moieties were efficiently synthesized by the Suzuki-Miyaura coupling and Scholl oxidative cyclo-dehydrogenation reactions' tandem. Most of the butterfly molecules spontaneously self-organize into columnar hexagonal mesophase. The electron-deficient systems possess strong solvent-gelling ability but are not luminescent, whereas the electron-rich terms do not form gels but strongly emit light between 400 and 600 nm. The charge carrier mobility was also measured by time-of-flight transient photocurrent technique in the mesophases for some of the compounds. They display hole-transport performances with positive charge mobility in the 10 À 3 cm À 2 V À 1 s À 1 range, consistent with the high degree of ordering and stability of the columnar superstructures. In particular, the mesogen with a benzodithiophen-4,8-dione core shows ambipolar charge carrier transport with both high electron (μ e = 6.6 × 10 À 3 cm À 2 V À 1 s À 1 ) and hole (μ h = 4.5 × 10 À 3 cm À 2 V À 1 s À 1 ) mobility values.

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“…We have chosen oligo( p -phenyleneethnylene)s (OPE) − hydrocarbons as the π-conjugated core skeleton because of the flexibility in their synthetic strategies, though the system seems to have a disadvantage for the creation of fluorophore compared with OPV − hydrocarbons as shown in Figure , assuming that the Stokes shifts of OPV and OPE are almost close to each other. After some synthetic trials, we succeeded in the creation of the desired WRF using OPE as the π-conjugated core skeleton, which is described herein.…”

Section: Introductionmentioning

confidence: 99%

Highly Emissive Whole Rainbow Fluorophores Consisting of 1,4-Bis(2-phenylethynyl)benzene Core Skeleton: Design, Synthesis, and Light-Emitting Characteristics

et al. 2015

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To create the whole-rainbow-fluorophores (WRF) having the small Δλem (the difference of λem between a given fluorophore and nearest neighboring fluorophore having the same core skeleton) values (<20 nm) in full visible region (λem: 400-650 nm), the high log ε (>4.5), and the high Φf (>0.6), we investigated molecular design, synthesis, and light-emitting characteristics of the π-conjugated molecules (D/A-BPBs) consisting of 1,4-bis(phenylethynyl)benzene (BPB) modified by donor groups (OMe, SMe, NMe2, and NPh2) and an acceptor group (CN). As a result, synthesized 20 D/A-BPBs (1a-5d) were found to be the desired WRF. To get the intense red fluorophore (Φf> 0.7, λem > 610 nm), we synthesized new compounds (5e-5i) and elucidated their photophysical properties in CHCl3 solution. As a result, 5h, in which a 4-cyanophenyl group is introduced to the para-position of two benzene rings in the terminal NPh2 group of 5d, was found to be the desired intense red fluorophore (log ε = 4.56, Φf = 0.76, λem = 611 nm). The intramolecular charge-transfer nature of the S1 state of WRF (1a-5d) was elucidated by the positive linear relationship between optical transition energy (νem) from the S1 state to the S0 state and HOMO(D)-LUMO(A) difference, and the molecular orbitals calculated with the DFT method. It is demonstrated that our concept (Φf = 1/(exp(-Aπ) + 1)) connected with the relationship between Φf and magnitude (Aπ) of π conjugation length in the S1 state can be applied to WRF (1a-5d). It is suggested that the prediction of Φf from a structural model can be achieved by the equation Φf = 1/(exp(-((ν̃a - ν̃f)(1/2) × a(3/2)) + 1), where ν̃a and ν̃f are the wavenumber (cm(-1)) of absorption and fluorescence peaks, respectively, and a is the calculated molecular radius. From the viewpoint of application of WRF to various functional materials, the light-emitting characteristics of 1a-5i in doped polymer films were examined. It was demonstrated that 1a-5i dispersed in two kinds of polymer film (PST and PMMA) emit light at the whole visible region and have the small Δλem values (<20 nm) and the high Φf values (>0.6). Therefore, the present D/A-BPBs can be said to be the desired WRF even in the doped polymer film.

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Reversible Sol–Gel Transition of Oligo(p-phenylenevinylene)s by π–π Stacking and Dissociation

Cited by 21 publications

References 54 publications

π-Conjugated Polymer Anisotropic Organogel Nanofibrous Assemblies for Thermoresponsive Photonic Switches

π-Conjugated Polymer Anisotropic Organogel Nanofibrous Assemblies for Thermoresponsive Photonic Switches

Butterfly‐like Shape Liquid Crystals Based Fused‐Thiophene as Unidimensional Ambipolar Organic Semiconductors with High Mobility

Highly Emissive Whole Rainbow Fluorophores Consisting of 1,4-Bis(2-phenylethynyl)benzene Core Skeleton: Design, Synthesis, and Light-Emitting Characteristics

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