Triplet energy migration-based photon upconversion by amphiphilic molecular assemblies in aerated water

Kouno, Hironori; Ogawa, Taku; Amemori, Shogo; Mahato, Prasenjit; Yanai, Nobuhiro; Kimizuka, Nobuo

doi:10.1039/c6sc01047d

Cited by 59 publications

(67 citation statements)

References 45 publications

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“…Self-assembly employing amphiphilic acceptors that can be used in aqueous media was also reported. 110 This time, hydrophilic quaternary ammonium groups were functionalized at both ends of the DPA emitter through an amine bond. Hydrogen bond networks were observed in the hydrophobic interior.…”

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confidence: 99%

Triplet transport in thin films: fundamentals and applications

Tang

2017

Chem. Commun.

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Triplet excitons are key players in multi-excitonic processes like singlet fission and triplet-triplet annihilation based photon upconversion, which may be useful in next-generation photovoltaic devices, photocatalysis and bioimaging. Here, we present an overview of experimental and theoretical work on triplet energy transfer, with a focus on triplet transport in thin films. We start with the theory describing Dexter-mediated triplet energy transfer and the fundamental parameters controlling this process. Then we summarize current experimental methods used to measure the triplet exciton diffusion length. Finally, the use of hierarchically ordered structures to improve the triplet diffusion length is presented, before concluding with an outlook on the remaining challenges.

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confidence: 99%

Triplet transport in thin films: fundamentals and applications

Tang

2017

Chem. Commun.

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“…Based on the correlation between the diffusion rate constant and the threshold value [Eq. (2)], the diffusion rate constant for aggregates of A2 was estimated to be 4.2×10 −4 cm 2 s −1 , which is significantly higher than that of DPA (1.2×10 −5 cm 2 s −1 ) in low‐viscosity solvent. This outcome is slightly unexpected because it revealed a triplet energy transfer that is faster than molecular diffusion.…”

Section: Resultsmentioning

confidence: 90%

“…The overall upconversion capability ( η = ϵ × Φ UC , where ϵ is the molar extinction coefficient of the triplet sensitizer and Φ UC is the upconversion quantum yield) of the assemblies are significant considering the large ϵ value of the sensitizer at the excitation wavelength. The largest quantum yield of 13 % (see Table S1 see the Supporting Information) in water has been reported, but with much smaller ϵ values at the excitation wavelength …”

Section: Resultsmentioning

confidence: 99%

Supramolecular Assembly‐Improved Triplet–Triplet Annihilation Upconversion in Aqueous Solution

Liang

et al. 2018

Chemistry A European J

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Water-soluble 9,10-diphenylanthracene-modified γ-cyclodextrin derivatives A1 and A2, in which the γ-cyclodextrin unit serves as a molecular host for a binding sensitizer, and the 9,10-diphenylanthracene moiety plays a role as an emitter/annihilator, were synthesized to investigate the supramolecular triplet-triplet annihilation (TTA) upconversion in aqueous solution. Both A1 and A2 readily aggregate and form nanoscale assemblies in water as a combined result of host-guest complexation and π-π stacking among the 9,10-diphenylanthracenes. The aggregation behavior of the supramolecular emitters was fully characterized by using a diversity of methods, including dynamic light scattering (DLS), SEM, NMR, fluorescence, and circular dichroism studies. Fluorescence spectroscopic analysis reveals that the emitters have high fluorescence quantum yields in water (82 and 90 % for A1 and A2, respectively), thus demonstrating that aggregation does not quench the fluorescence. By using a coordinated ruthenium sensitizer, a high TTA upconversion quantum yield of up to 6.9 % was observed for this supramolecular TTA system, which is significantly higher than the value (<0.5 %) obtained with nonassembled emitters in organic solvent and in contrast to the fact that TTA upconversion emission in aqueous solution is usually low or negligible. We ascribe the strong TTA upconversion emission in the present supramolecular assembly system to an efficient TTA process, which is facilitated along the stacked emitters by triplet energy migration and improved triplet-triplet energy transfer through host-guest complexation.

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“…[10] The triplet energy migrationbased UC in air-saturated aqueous mediah as been limited to a single-chained, bola-type cationic amphiphilic acceptor,w here the hydrogen bondingn etworks among chromophores play a key role in exerting the oxygen blocking ability. [11] However,i t required high acceptorc oncentration (1 mm)t oo bserve the TTA-UCe mission. The development of self-assembled systems that possess cellular nontoxicp oly(ethylene glycol) (PEG) units and work at even much lower concentrationi sd esired for the biological applicationss ince the chromophores spread in the blood after injection to the body.…”

Section: Introductionmentioning

confidence: 99%

Oligo(ethylene glycol)/alkyl‐modified Chromophore Assemblies for Photon Upconversion in Water

Haruki

Kouno

Hosoyamada

et al. 2019

Chemistry An Asian Journal

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Molecular self-assembly is ap owerful meanst o construct nanoscale materials with advanced photophysical properties. Although the protection of the photo-excited states from oxygen quenching is ac riticali ssue, it stillh as been in an early phase of development. In this work, we demonstrate that as imple and typical molecular design for aqueous supramolecular assembly,m odification of the chromophoric unit with hydrophilic oligo(ethyleneg lycol) chains and hydrophobic alkyl chains, is effective to avoid oxygen quenching of triplet-triplet annihilation-based photon upconversion (TTA-UC). While aT TA-UC emission is completely quenched when the donor and acceptor are molecularly dispersed in chloroform, their aqueous co-assemblies exhibit a clear upconverted emission in air-saturatedw ater even under extremelyl ow chromophore concentrations down to 40 mm.T he generalization of this nano-encapsulation approach offers new functions and applicationsu sing oxygensensitive species for supramolecular chemistry.

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Triplet energy migration-based photon upconversion by amphiphilic molecular assemblies in aerated water

Abstract: A molecular self-assembly approach is developed to resolve an outstanding issue in triplet energy migration-based photon upconversion (TEM-UC), that is, air-stable TEM-UC in water.

Cited by 59 publications

References 45 publications

Triplet transport in thin films: fundamentals and applications

Triplet transport in thin films: fundamentals and applications

Supramolecular Assembly‐Improved Triplet–Triplet Annihilation Upconversion in Aqueous Solution

Oligo(ethylene glycol)/alkyl‐modified Chromophore Assemblies for Photon Upconversion in Water

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