Photoinduced electron transfer of carbazole–acceptor dyads in solution and in a polymer solid

Ohkita, Hideo; Benten, Hiroaki; Anada, Arihiro; Noguchi, Hitoshi; Kido, Nobuaki; Ito, Shinzaburo; Yamamoto, Masahide

doi:10.1039/b401951b

Cited by 25 publications

(44 citation statements)

References 20 publications

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“…The 2-napthyl derivative 3d exhibited higher quantum yield of 0.5 and substantial decrease in the quantum yield for the anthracene derivative (3f) to be 0.26 because of low emission intensity which is attributed to the photoinduced intramolecular charge transfer (ICT) processes [31,32]. The decrease in quantum yield resulting from the photoinduced ICT process is a common phenomenon for organic compounds [33,34]. …”

Section: Quantum Yield (φ) and Life Time Measurements (τ)mentioning

confidence: 97%

Design, Synthesis and Optoelectronic Properties of Unsymmetrical Oxadiazole Based Indene Substituted Derivatives as Deep Blue Fluoroscent Materials

et al. 2015

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A series of novel unsymmetrically substituted indene-oxadiazole derivatives (3a-f) have been designed and synthesized by employing palladium catalysed Suzuki cross coupling reaction in high yields. The structural integrity of all the novel compounds was established by (1)H, (13)C NMR and LC/MS analysis. These compounds are amorphous in nature and are remarkably stable to long term storage under ambient conditions. The optoelectronic properties have been studied in detail using UV-Vis absorption and Fluorescence spectroscopy. All compounds emit intense blue to green-blue fluoroscence with high quantum yields. Time resolved measurments have shown life times in the range of 1.28 to 4.51 ns. The density functional theory (DFT) calculations were carried out for all the molecules to understand their structure-property relationships. Effect of concentration studies has been carried out in different concentrations for both absorption and emission properties and from this we have identified the optimized fluoroscence concentrations for all these compounds. The indene substituted anthracene-oxadiazole derivative (3f) showed significant red shift (λmax (emi) = 490 nm) and emits intense green-blue fluoroscence with largest stokes shift of 145 nm. This compound also exhibited highest fluoroscence life time (τ) of 4.51 ns, which is very close to the standard dye coumarin-540A (4.63 ns) and better than fluorescein-548 (4.10 ns). The results demonstrated that the novel unsymmetrical indene-substituted oxadiazole derivatives could play important role in organic optoelectronic applications, such as organic light-emitting diodes (OLEDs) or as models for investigating the fluorescent structure-property relationship of the indene-functionalized oxadiazole derivatives.

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Section: Quantum Yield (φ) and Life Time Measurements (τ)mentioning

confidence: 97%

Design, Synthesis and Optoelectronic Properties of Unsymmetrical Oxadiazole Based Indene Substituted Derivatives as Deep Blue Fluoroscent Materials

et al. 2015

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“…62 Above T g , photoinduced CS of Cz-S-A in CN-HPC and poly͑alkyl methacrylate͒ solids could be explained by the thermal equilibrium. 53,54 In CN-PUL glass, however, a wide distribution in should be considered to discuss CS below T g because there are various dielectric motions not only slower but also faster than the CS event. In Sec.…”

Section: A Temperature Dependence Of K Cs Of Cz-s-a In Cn-pul Glassymentioning

confidence: 99%

“…͑5͒ ͑Refs. 68 and 69͒ and ͑6͒, respectively, where E͑S 1 ͒ is the energy level of the lowest excited singlet state of EtCz, E ox D and E red A oxidation potential of donor ͑Cz͒ and reduction potential of acceptor ͑A͒, respectively, e the elementary charge, 0 the vacuum permittivity, S static dielectric constant of the matrix, r DA separation distance between the donor and acceptor, r D and r A spherical radii of donor and acceptor moieties, respectively, 53 and ϱ optical dielectric constant of the matrix which is equal to the squire of the refractive index of the matrix n 2 ,…”

Section: B Analysis Of K Cs Based On Dielectric Relaxation Dynamics mentioning

confidence: 99%

“…Our previous studies showed that photoinduced CS above T g can be explained by the ET formula with a quantum mode of intramolecular vibration and a classical mode of lowfrequency orientational motions of the polymer matrix under a thermal equilibrium condition. 53,54 In other words, even in polymer solids, thermal fluctuations of polar groups leading to the ET reaction can be considered in a thermal equilibrium above T g .…”

Section: Introductionmentioning

confidence: 99%

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Photoinduced intramolecular charge separation in a polymer solid below the glass transition temperature

Benten

Ohkita

Ito

et al. 2005

The Journal of Chemical Physics

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Photoinduced intramolecular charge separation (CS) in a polar polymer glass, cyanoethylated pullulan (CN-PUL), was studied below the glass transition temperature (Tg=395 K). A series of three carbazole (Cz: donor)-cyclohexane (S: spacer)-acceptor (A: acceptor) molecules (Cz-S-A) was used as intramolecular donor-acceptor dyads. The photoinduced CS rate was evaluated by the fluorescence decay measurement at temperatures from 100 to 400 K. The CS rate (kCS) increased above 200 K even far below Tg where micro-Brownian motions of the whole polymer chain are frozen. Below 200 K, on the other hand, kCS showed weak dependence on temperature. The temperature dependence of kCS is discussed in terms of the dielectric relaxation time of the polymer matrix. Consequently, CS below Tg was well explained by a thermally nonequilibrium electron transfer (ET) formula above 200 K and by a two-mode quantum-mechanical ET formula below 200 K. The increase in kCS above 200 K is mainly caused by a thermally activated low-frequency matrix mode originating from the side-chain relaxation of polar cyano groups. The weak temperature dependence of kCS can be explained by a nuclear-tunneling effect caused by a high-frequency matrix mode (variant Planck's over 2piomegH=250 cm-1) and an intramolecular vibrational mode (variant Planck's over 2piomegaQ=1300 cm-1). The high-frequency mode of the polymer matrix was attributed to a vibrational or librational motion of polar groups in the CN-PUL glassy solid.

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“…The quantum yield of QUI-OCZ by the conventional optical method was calculated, which is 0.237 (23%) [33]. According to the electron transfer mechanism the low quantum yield was observed which is due to the photoinduced intra molecular charge transfer (ICT) process occurred between carbazole and quinoline.…”

Section: Measurement Of the Absolute Luminescence Quantum Yield (Qy)mentioning

confidence: 99%

Synthesis and opto-electrical properties of carbazole functionalized quinoline based conjugated oligomer for luminescent devices

Upadhyay

Karpagam

2015

J. Photopol. Sci. Technol.

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Carbazole and quinoline combined donor-acceptor (QUI-OCZ) conjugated oligomer was synthesized by Wittig route. The resulting oligomer structure was well established by FTIR, NMR, Gel permeation chromatography (GPC) and elemental analysis. The resulting oligomer exhibits good solubility in common organic solvents.The optical and potential charge transporting properties of the oligomer were investigated by UV-visible, fluorescence spectroscopy and cyclic voltammetry. The UV-visible spectrum of the oligomer exhibited a sharp absorption band at 275-325 nm with shoulder peak at 374 nm. The oligomer also showed the fluorescence emission at 420 -451 nm. The optical energy band gap and quantum yield of the oligomer was found to be 2.58eV and 0.237. In addition, quenching effect of QUI-OCZ was carried out by adding N, N-dimethyl aniline (electron donor) and dimethyl terephthalate (electron acceptor). The morphology of the oligomer film was examinedby atomic force microscopy (AFM) and observed spherical shape of particles with micrometre in size. The electrochemical studies of QUI-OCZ revealed that the HOMO and LUMO energy level was -5.74 and -3.17 eV respectively. Preliminary reports suggested that the oligomer will behighly useful for organic light emitting diode application.

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Photoinduced electron transfer of carbazole–acceptor dyads in solution and in a polymer solid

Cited by 25 publications

References 20 publications

Design, Synthesis and Optoelectronic Properties of Unsymmetrical Oxadiazole Based Indene Substituted Derivatives as Deep Blue Fluoroscent Materials

Design, Synthesis and Optoelectronic Properties of Unsymmetrical Oxadiazole Based Indene Substituted Derivatives as Deep Blue Fluoroscent Materials

Photoinduced intramolecular charge separation in a polymer solid below the glass transition temperature

Synthesis and opto-electrical properties of carbazole functionalized quinoline based conjugated oligomer for luminescent devices

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