Supramolecular Crowding Can Avoid Oxygen Quenching of Photon Upconversion in Water

Kouno, Hironori; Sasaki, Yōichi; Yanai, Nobuhiro; Kimizuka, Nobuo

doi:10.1002/chem.201806076

Cited by 27 publications

(25 citation statements)

References 70 publications

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“…Hence, Φ TTET and Φ TTA depend on the concentration of excited triplets T 1 and thus on the excitation power density, as well as on T 1 –T 1 distances and the annihilator mobility . A general challenge of TTA‐UC is its oxygen sensitivity due to the efficient energy transfer from the T 1 states to 3 O 2 , generating reactive 1 O 2 and reducing Φ UC …”

Section: Figurementioning

confidence: 99%

“…Current work aims to reduce the oxygen sensitivity and to increase the retention of the trapped annihilators in organic environments, for example, by tuning the chain length of the carboxylic acid and by coating the MOF surface . In addition, the TTA‐UC efficiency will be further enhanced by reducing the reabsorption of the UC emission caused by Pd(TCPP) and by optimizing the sensitizer/annihilator interface …”

Section: Figurementioning

confidence: 99%

“…[8][9][10][11] Ag eneral challenge of TTA-UC is its oxygen sensitivity due to the efficiente nergyt ransfer from the T 1 states to 3 O 2 ,g enerating reactive 1 O 2 and reducing F UC . [12][13][14] Rationally designing an efficient TTA-UCsystem requires sensitizers with F ISC close to unity like platinum and palladium porphyrins, such as PtOEP andPdOEP (H 2 OEP = 2,3,7,8,12,13,17,18-octaethylporphyrin) in combinationw ith annihilators, which feature appropriate energyl evels and very high fluorescenceq uantum yields like 9,10-diphenylanthracene (DPA, F f (DPA) = 95 %, Figure1a). [8][9][10][11] Such dyec ombinations resulti nh igh F UC for optimizedc oncentrations in solution.…”

mentioning

confidence: 99%

“…As DPA( Supporting Information, Figure S6) and DPAd erivatives show an excimer emission at about5 70 nm in neat films, [39] we decided to provide the DPAm olecules in the channel with ah ydrophobic environment, such as af atty acid to preventd ye aggregation and to increaset he mobility of DPA. [12] Hence, oleic acid [(9Z)-octadec-9-enoic acid] was mixed with DPAa nd the fluorescencer ecorded. However,u nder laser irradiation, DPAa nd oleic acid seemed to react, possibly by a cycloaddition reaction.…”

mentioning

confidence: 99%

“…[43] In addition, the TTA-UC efficiencyw ill be furthere nhanced by reducing the reabsorption of the UC emission caused by Pd(TCPP) and by optimizing the sensitizer/annihilator interface. [12,22,39,44,45]…”

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confidence: 99%

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Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels

Gharaati

Wang

Förster

et al. 2019

Chemistry A European J

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Figure 3. a) TTA-UC luminescence( UCL) intensity of solid CA/DPA@PCN-222(Pd)a sf unction of increasing excitationp ower density( emission slit width 15 nm) and b) integratedUCL intensity of CA/DPA@PCN-222(Pd)asa function of the excitationpower density (l exc = 532 nm). To avoid directe xcitation of DPA, a4 95 nm long-pass filter was placed between the 532 nm laser and the CA/DPA@PCN-222(Pd) sample.

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Section: Figurementioning

confidence: 99%

Section: Figurementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels

Gharaati

Wang

Förster

et al. 2019

Chemistry A European J

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Highly Ordered 2D‐Assemblies of Phase‐Segregated Block Molecules for Upconverted Linearly Polarized Emission

et al. 2020

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Materials based on the laminar ordering of self‐assembled molecules have a unique potential for applications requiring efficient energy migration through densely packed chromophores. Here, employing molecular assemblies of coil–rod–coil block molecules for triplet–triplet annihilation upconversion (TTA‐UC) based on triplet energy migration with linearly polarized emission is reported. By covalently attaching discrete‐length oligodimethylsiloxane (oDMS) to 9,10‐diphenylanthracene (DPA), highly ordered 2D crystalline DPA sheets separated by oDMS layers are obtained. Transparent films of this material doped with small amounts of triplet sensitizer PtII octaethylporphyrin show air‐stable TTA‐UC under non‐coherent excitation. Upon annealing, an increase in TTA‐UC up to two orders of magnitude is observed originating from both an improved molecular ordering of DPA and an increased dispersion of the sensitizer. The molecular alignment in millimeter‐sized domains leads to upconverted linearly polarized emission without alignment layers. By using a novel technique, upconversion imaging microscopy, the TTA‐UC intensity is spatially resolved on a micrometer scale to visually demonstrate the importance of molecular dispersion of sensitizer molecules for efficient TTA‐UC. The reported results are promising for anti‐counterfeiting and 3D night‐vision applications, but also exemplify the potential of discrete oligodimethylsiloxane functionalized chromophores for highly aligned and densely packed molecular materials.

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Magnetic‐Field‐Switchable Laser via Optical Pumping of Rubrene

et al. 2021

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crystalline materials, garnets, or rare earth-doped paramagnetic glasses and are thus poorly suited to large-area and volumetric imaging. [4] Nitrogen vacancy (NV) centers provide high sensitivity to magnetic fields (on the order of 1 nT Hz −1/2 for a single NV center), [5] but NVs suffer from weak optical cross section, a requirement for high resolution detection of their emission wavelength, and difficult calibration. [6] Magnetic imaging applications would benefit from stronger optomagnetic interactions within biocompatible materials such as molecules or nanoparticles, which could be directly incorporated within a sample or bioassay. [7] Nanomaterials for magnetic imaging are ideally also capable of high-resolution imaging and operation at high photon flux, potentially even in microlasers, where brilliant emission and high spectral sensitivity creates new opportunities to monitor a wide range of physiological parameters with cellular resolution. [8] New optomagnetic effects in fluorescent or electroluminescent materials could be used to modulate lasers and may even find new applications in optical modulators, which presently rely on weak thermal or electro-optic effects.One alternative to conventional magneto-optical materials is suggested by proposed explanations for the sensitivity of birds to Earth's magnetic field. Recent studies suggest that birds are able to orient themselves to Earth's magnetic field by exploiting the magnetic sensitivity of electronic interactions in their retinas. [9,10] Photoexcitation of proteins in avian retinas produce radical (unpaired electron) intermediate states, which then interact with spin-1 excitons (electron-hole pairs), also known as triplet excitons. To understand the basis for the magnetic dependence of these interactions, consider an asymmetric molecule, for which the three triplet states of the spin-1 exciton are energetically split even in the absence of a magnetic field. Typically, without substantial spin-orbit coupling, this zero-field splitting is less than about 10 μeV. [11] Therefore, an external magnetic field on the order of 10 μeV μ B −1 (≈0.2 T), where μ B is the Bohr magneton, can reorder the triplet states via the Zeeman effect, modulating their involvement in spindependent interactions. The magnetic field sensitivity is typically even higher for an unpaired electron with no zero-field splitting. Consequently, both triplet-triplet and triplet-charge interactions can undergo magnetic field modulation. Given its Volumetric optical imaging of magnetic fields is challenging with existing magneto-optical materials, motivating the search for dyes with strong magnetic field interactions, distinct emission spectra, and an ability to withstand high photon flux and incorporation within samples. Here, the magnetic field effect on singlet-exciton fission is exploited to demonstrate spatial imaging of magnetic fields in a thin film of rubrene. Doping rubrene with the highquantum yield dye dibenzotetraphenylperiflanthene (DBP) is shown to enable optically pumped, slab...

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Supramolecular Crowding Can Avoid Oxygen Quenching of Photon Upconversion in Water

Cited by 27 publications

References 70 publications

Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels

Triplet–Triplet Annihilation Upconversion in a MOF with Acceptor‐Filled Channels

Highly Ordered 2D‐Assemblies of Phase‐Segregated Block Molecules for Upconverted Linearly Polarized Emission

Magnetic‐Field‐Switchable Laser via Optical Pumping of Rubrene

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