Synthetic control over intra- and intermolecular charge transfer can turn on the fluorescence emission of non-emissive coumarin

Jhun, Byung Hak; Ohkubo, Kei; Fukuzumi, Shunichi; You, Youngmin

doi:10.1039/c6tc00639f

Cited by 40 publications

(25 citation statements)

References 101 publications

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“…In an attempt to develop highly fluorescent n –π* fluorophores, we recently performed an investigation into the aryl derivatives of 1-benzopyran-2-one (coumarin), a prototypical n –π* platform . Our study revealed that coumarin-based n –π* molecules become highly fluorescent upon the activation of charge transfer.…”

Section: Introductionmentioning

confidence: 99%

Aggregation of an n–π* Molecule Induces Fluorescence Turn-on

Jhun

Jeong

et al. 2017

J. Phys. Chem. C

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Although n–π* molecules can serve as electroluminescent materials because of the harvesting of singlet and triplet excitons through El-Sayed-rule-allowed reverse intersystem crossing, the weak fluorescence emissions of such molecules have prevented applications into devices. We have discovered a 1 order of magnitude enhancement of the fluorescence of a prototypical n–π* fluorophore, 7-phenylcoumarin (PC), upon aggregation. We performed a mechanistic study consisting of structural, photophysical, and quantum chemical investigations, and found that the aggregation positioned the fluorescent electronic state below the nonemissive triplet n–π* transition state. Our studies, for the first time, demonstrate intramolecular geometry and intermolecular arrangements in the solid state to be significant factors in the photoluminescence quantum yields of n–π* fluorophores.

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Section: Introductionmentioning

confidence: 99%

Aggregation of an n–π* Molecule Induces Fluorescence Turn-on

Jhun

Jeong

et al. 2017

J. Phys. Chem. C

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“… f Radiative lifetime: τ rad = τ F /Φ F g Radiative rate constant: k r = Φ F /τ F h Non-radiative rate constant: k nr = (1 – Φ F )/τ F …”

Section: Resultsmentioning

confidence: 99%

“…f Radiative lifetime: τ rad = τ F /Φ F 22. g Radiative rate constant: k r = Φ F /τ F 85. h Non-radiative rate constant: k nr = (1 − Φ F )/τ F 85.…”

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confidence: 99%

Amplified Heavy-Atom Free Phosphorescence from meta-Dimethoxy Difluoroboron β-Diketonate Charge-Transfer Materials

2019

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Difluoroboron β-diketonate materials are used for biomedical oxygen-sensing applications. These fluorophores show both fluorescence (F) and phosphorescence (P) when the dye is embedded in a polymer matrix. The fluorescence is insensitive to oxygen quenching, while the phosphorescence changes intensity depending on the oxygen concentration. This enables oxygen quantification by ratiometric methods with good spatial and temporal resolution. Here, we produce ratiometric-capable oxygen sensors without the need of a heavy atom. This is achieved by substituting methoxyl groups at the meta positions of an aromatic ring, dramatically influencing the electronic transitions of the fluorophore. Altering the aromatic group on the opposing ring tailors the absorption wavelength, luminescence colors, and relative fluorescence to phosphorescence ratio (F/P), which are important for oxygen sensing. The phosphorescence lifetimes are also hundreds of milliseconds long, achieving ultra-sensitivity to oxygen. This study presents the synthesis, optical characterization in solution and polylactide blends, and computational analysis of 3,5-dimethoxy-difluoroboron β-diketonate materials as oxygen-sensing materials.

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“…Two types of TADF emitters, donor‐acceptor type intramolecular charge transfer (CT) emitters, and intermolecular CT emitters, that have separate donor and acceptor molecules, are under development. [ 21 ]…”

Section: Introductionmentioning

confidence: 99%

Highly Efficient and Long‐Range Charge‐Transfer Complex Emission Between Two Blue Phosphorescent Emitters for White Organic Light‐Emitting Diodes

Lim

Han

Lee

2022

Adv Funct Materials

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Herein, the authors report on charge-transfer (CT) complex emission-based organic light-emitting diodes (OLEDs), which emit light by electric field-induced intermolecular CT complex formation in the light-emitting layer. Two phosphorescent materials are chosen to have energy level offset for the CT complex formation. This process generates the CT complex, which efficiently emits only in the electroluminescent device by electric-field-induced complex formation. A phenylpyridine-ligand-based Ir compound and phenylimidazole-based Ir compounds are selected as the CT complex-forming materials, and the CT complex exhibits yellow emission under an electric field. Moreover, the doping of the two compounds in the host material produces white OLEDs, exhibiting both blue emission and yellow emission at a quantum efficiency of 13.7%. In particular, the color of the CT complex device can be tuned by the content of each material in the emitting layer. As an initial result, the quantum efficiency is acceptable, and further material development would enhance the quantum efficiency of the CT complex OLEDs. This light-emitting device can be used in various applications, e.g., a mono-color or a white-color light-emitting diode.

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Synthetic control over intra- and intermolecular charge transfer can turn on the fluorescence emission of non-emissive coumarin

Cited by 40 publications

References 101 publications

Aggregation of an n–π* Molecule Induces Fluorescence Turn-on

Aggregation of an n–π* Molecule Induces Fluorescence Turn-on

Amplified Heavy-Atom Free Phosphorescence from meta-Dimethoxy Difluoroboron β-Diketonate Charge-Transfer Materials

Highly Efficient and Long‐Range Charge‐Transfer Complex Emission Between Two Blue Phosphorescent Emitters for White Organic Light‐Emitting Diodes

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