Recent Developments in the Thermally Activated Delayed Fluorescence of Fullerenes

Baleizão, Carlos; Berberan‐Santos, Mário N.

doi:10.1149/1.2998526

Cited by 3 publications

(3 citation statements)

References 24 publications

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“…The increasing Φ F with rising temperature found in glassy SOA is reminiscent of the delayed luminescence 43 observed in certain conducting polymers, 44,45 fullerenes, 46 and organic dyes. 47,48 A similar effect was reported 49 recently for a BODIPY dye equipped with a redox-active strap attached to the boron center.…”

Section: ̃= φsupporting

confidence: 76%

Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative

2018

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A boron dipyrromethene (BODIPY) derivative has been synthesized whereby a phenoxyl ring attached at the 3-position is bound through the oxygen atom to the boron center. This compound is structurally distorted, with the molecular surface being curved, and undergoes further geometrical perturbation at the excited-singlet state level. Fluorescence is readily observed in solution at ambient temperature, with the quantum yield rising with increasing viscosity of the surrounding solvent. Dual-exponential decay kinetics are observed, corresponding to E-type delayed fluorescence. In solution, the emission yield falls with increasing temperature but the opposite situation is found for the same compound dispersed in an amorphous sugar. These results are considered in terms of two radiationless decay channels. A viscosity-dependent avenue allows the fluorophore to function as a conventional fluorescent rotor for tracking changes in local rheology. A temperature-dependent channel leads to trapping within a new conformation, which is weakly coupled to the ground state but is able to repopulate the emitting state on a relatively slow timescale. Analysis of the experimental data allows estimation of some of the key kinetic parameters as a function of temperature.

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Section: ̃= φsupporting

confidence: 76%

Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative

2018

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“…Such a DF may be due to two kinetic pathways: unimolecular tripletsinglet upconversion via reverse ISC or a bimolecular annihilation of triplet manifolds. 45,46 The lifetime of the DF is expected to be equal to that of the triplet states for the former and half of the triplet lifetime for the latter. 46,47 Thus, the emission band at ca.…”

Section: Resultsmentioning

confidence: 99%

Direct Observation of a Triplet-State Absorption-Emission Conversion in a Fullerene-Functionalized Pt(II) Metallacycle

Zhang

Yang

et al. 2017

J. Phys. Chem. C

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An interesting triplet excited-state absorption-emission conversion of a fullerene-functionalized Pt(II) metallacycle (C 60 –Pt) caused by a concentration effect was directly observed by nanosecond transient absorption (ns TA) spectroscopy. In dilute solution, the triplet excited-state absorption (TESA) band was observed at about 750 nm with a lifetime of ca. 10.7 μs. However, with increasing the concentration, the absorption band converted to a triplet excited-state emission (TESE) band with a longer lifetime of ca. 15.4 μs. Femtosecond transient absorption experiments and quantum chemistry calculations were performed to reveal the excited-state decay pathways of C 60 –Pt in concentrated solution. This conversion was ascribed to the formation of a triplet excimer, which forms at localized 3C60 * states. This work demonstrates that radiative excimers with longer-lived triplet excited states can exist in concentrated solution, and this finding will provide useful information for applications of fullerene complexes, especially as photosensitizers.

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“…29 Both processes led to the formation of the fluorescent S 1 state of TPP (Figure 2). The thermally activated delay fluorescence typical for fullerenes 47 was not expected because of the high gap between the S 1 and T 1 states of TPP. The contribution of TPP from the water phase to delayed fluorescence can also be excluded because of the insolubility of TPP in water and/or extended aggregation.…”

Section: Methodsmentioning

confidence: 99%

Polystyrene and Poly(ethylene glycol)-b-Poly(ε-caprolactone) Nanoparticles with Porphyrins: Structure, Size, and Photooxidation Properties

et al. 2019

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The transport of a photosensitizer to target biological structures followed by the release of singlet oxygen is a critical step in photodynamic therapy. We compared the (photo)physical properties of polystyrene nanoparticles (TPP@PS) of different sizes and self-assembled poly(ethylene glycol)-b-poly(ε-caprolactone) core/shell nanoparticles (TPP@PEG-PCL) with different lengths of copolymer blocks, both suitable for the transport of the tetraphenylporphyrin (TPP) photosensitizer. The singlet oxygen was formed inside both nanoparticles after irradiation with visible light. Its kinetics was controlled by the size of TPP@PS; its lifetime (τΔ) increased with increasing nanoparticle size (from 6.5 to 16 μs) because of hindered diffusion into the external aqueous environment, where it was quickly deactivated. Accordingly, the prolongation of the singlet oxygen-sensitized delayed fluorescence kinetics was found for TPP@PS of high size. The TPP@PEG-PCL self-assemblies allowed for enhanced oxygen diffusion, and the estimated low values of τΔ ≈ 3.7 μs were independent of the size of building blocks. The delayed fluorescence in oxygen-free conditions originating from triplet–triplet annihilation indicated a high mobility of TPP in the PCL core in comparison with fixed molecules in the PS matrix. Photooxidation of uric acid revealed the highest efficacy for TPP@PS of small sizes, whereas the largest TPP@PS exhibited the lowest activity, and the efficacy of TPP@PEG-PCL remained independent of the sizes of the building blocks.

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Recent Developments in the Thermally Activated Delayed Fluorescence of Fullerenes

Cited by 3 publications

References 24 publications

Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative

Nonradiative Decay Channels for a Structurally-Distorted, Monostrapped BODIPY Derivative

Direct Observation of a Triplet-State Absorption-Emission Conversion in a Fullerene-Functionalized Pt(II) Metallacycle

Polystyrene and Poly(ethylene glycol)-b-Poly(ε-caprolactone) Nanoparticles with Porphyrins: Structure, Size, and Photooxidation Properties

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