| 1. |
- Gorski, Krzysztof, et al.
(författare)
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The interplay of intersystem crossing and internal conversion in quadrupolar tetraarylpyrrolo[3,2-b]pyrroles
- 2024
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534.
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Tidskriftsartikel (refereegranskat)abstract
- Adding nitro groups to aromatic compounds usually quenches their fluorescence via intersystem crossing (ISC) or internal conversion (IC). Herein, we investigated centrosymmetric 1,4-dihydropyrrolo[3,2-b]pyrroles linked to variously substituted nitro-heteroaryls. A 1,4-orientation of the nitro substituent versus the electron rich 1,4-dihydropyrrolo[3,2-b]pyrrole core invokes a strong fluorescence in non-polar solvents and intense two-photon absorption while a 1,3-orientation of push-pull substituents results in a dramatic hypsochromic shift of absorption, weak, bathochromically shifted emission and weak two-photon absorption. The combined experimental and computational study indicates that the primary responsible factors are: (1) the difference in electron density distribution in the LUMO; (2) the difference in mu 10. IC is a dominant mechanism of non-radiative dissipation of energy in all these dyes but as long as the distribution of electron density within the HOMO and LUMO is delocalized on the 1,4-dihydropyrrolo[3,2-b]pyrrole core as well as on the nitroaromatic moieties its rate is slower than the fluorescence rate in non-polar solvents.
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| 2. |
- Li, Yiran, et al.
(författare)
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Long-wavelength dual-state luminescent naphthalimide derivatives for bio-imaging
- 2024
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Ingår i: Journal of Materials Chemistry C. - : ROYAL SOC CHEMISTRY. - 2050-7526 .- 2050-7534.
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Tidskriftsartikel (refereegranskat)abstract
- Developing fluorescent materials with long-wavelength emission, a large Stokes shift, dual-state emission, and long emissive lifetime is highly challenging. Herein, we combined the donor-pi-acceptor (D-pi-A) structure, alkyl chain, and J-aggregation to obtain four-in-one long-wavelength emission dyes. By introducing a triphenylamine or N,N-dimethylaminomine moiety into naphthalimide to construct large conjugate D-pi-A structures, long-wavelength luminescence with a large Stokes shift can be obtained in the solution state due to the large conjugate structure and the intramolecular charge transfer effect. The distorted donor structure and long alkyl chains inhibit the face-to-face stacking of molecules to achieve long-wavelength fluorescence in the powder state. Moreover, the naphthalimide group with a planar rigid structure can specifically drive molecules to form J-aggregates in the powder state, prolonging the excited state lifetimes for a longer fluorescence lifetime. The longest emission wavelength was up to 831 nm with the largest Stokes shift of 383 nm in the solution of compound 2. However, the longest fluorescence lifetime of 7.28 ns can be observed in the powder state of compound 1. Hence, these naphthalimide derivatives can effectively be applied to viscosity-responsive fluorescence lifetime imaging. This work provides a new strategy for developing multi-state and long-lifetime emissive long-wavelength luminescent molecules. A series of naphthalimide derivatives with long-wavelength emission, large Stokes shift, dual-state emission, and long emissive lifetime were obtained by constructing D-pi-A structures applying in viscosity-responsive fluorescence lifetime imaging.
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| 3. |
- Sahoo, Smruti, et al.
(författare)
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A Review of Concepts, Benefits, and Challenges for Future Electrical Propulsion-Based Aircraft
- 2020
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Ingår i: Aerospace. - : MDPI AG. - 2226-4310. ; 7:4
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Forskningsöversikt (refereegranskat)abstract
- Electrification of the propulsion system has opened the door to a new paradigm of propulsion system configurations and novel aircraft designs, which was never envisioned before. Despite lofty promises, the concept must overcome the design and sizing challenges to make it realizable. A suitable modeling framework is desired in order to explore the design space at the conceptual level. A greater investment in enabling technologies, and infrastructural developments, is expected to facilitate its successful application in the market. In this review paper, several scholarly articles were surveyed to get an insight into the current landscape of research endeavors and the formulated derivations related to electric aircraft developments. The barriers and the needed future technological development paths are discussed. The paper also includes detailed assessments of the implications and other needs pertaining to future technology, regulation, certification, and infrastructure developments, in order to make the next generation electric aircraft operation commercially worthy.
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| 4. |
- Shen, Shen, et al.
(författare)
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Edible Long-Afterglow Photoluminescent Materials for Bioimaging
- 2024
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Ingår i: Advanced Materials. - : WILEY-V C H VERLAG GMBH. - 0935-9648 .- 1521-4095.
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Tidskriftsartikel (refereegranskat)abstract
- Confining luminophores into modified hydrophilic matrices or polymers is a straightforward and widely used approach for afterglow bioimaging. However, the afterglow quantum yield and lifetime of the related material remain unsatisfactory, severely limiting the using effect especially for deep-tissue time-resolved imaging. This fact largely stems from the dilemma between material biocompatibility and the quenching effect of water environment. Herein an in situ metathesis promoted doping strategy is presented, namely, mixing approximate to 10-3 weight ratio of organic-emitter multicarboxylates with inorganic salt reactants, followed by metathesis reactions to prepare a series of hydrophilic but water-insoluble organic-inorganic doping afterglow materials. This strategy leads to the formation of edible long-afterglow photoluminescent materials with superior biocompatibility and excellent bioimaging effect. The phosphorescence quantum yield of the materials can reach dozens of percent (the highest case: 66.24%), together with the photoluminescent lifetime lasting for coupes of seconds. Specifically, a long-afterglow barium meal formed by coronene salt emitter and BaSO4 matrix is applied into animal experiments by gavage, and bright stomach afterglow imaging is observed by instruments or mobile phone after ceasing the photoexcitation with deep tissue penetration. This strategy allows a flexible dosage of the materials during bioimaging, facilitating the development of real-time probing and theranostic technology. A universal strategy is proposed to construct edible photoluminescent long-afterglow materials by embedding luminophore multicarboxylates into a series of inorganic salt lattices. Particularly, edible afterglow barium meal formed by coronene salt doped BaSO4 can be applied into gastrointestinal afterglow imaging captured by instruments or mobile phone. image
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| 5. |
- Szymanski, Bartosz, et al.
(författare)
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The effect of rigidity on the emission of quadrupolar strongly polarized dyes
- 2024
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Ingår i: New Journal of Chemistry. - : ROYAL SOC CHEMISTRY. - 1144-0546 .- 1369-9261.
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid dyes comprising 1,4-dihydropyrrolo[3,2-b]pyrrole and two strongly electron-withdrawing benzoxadiazole substituents, differing in their level of planarization, offer an insightful window into the interplay between internal conversion and intersystem crossing as relaxation pathways from the excited state. The emission intensity is strong for non-fused systems whilst it is minimal for fused dyes. Computational evaluation has revealed that internal conversion, and not inter-system crossing, is the main non-radiative process for planar, fused quadrupolar dyes. Planarization of the pyrrolopyrrole chromophore switches the mechanism of non-radiative deactivation from intersystem crossing to internal conversion.
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| 6. |
- Ye, Danfeng, et al.
(författare)
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Deoxygenation-Promoted Aggregation-Induced TADF-RTP Dual Emission for High-Contrast Channel-Selectable Hypoxia Probing
- 2024
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Ingår i: The Journal of Physical Chemistry C. - : AMER CHEMICAL SOC. - 1932-7447 .- 1932-7455.
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Tidskriftsartikel (refereegranskat)abstract
- Thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) are two highly applicable emissive processes due to their time-resolved characteristics and their ability to respond to external stimuli. They have recently been integrated for comprehensive use in some solid-state luminogens; however, there remains a lack of molecular systems that can integrate them in the solution aggregated state, which considerably limits relevant biological applications. In this study, we present a molecular design enabling aggregation-induced TADF-RTP dual emission in the solution aggregated state, relying on the coexistence of T-1-to-S-1 and T-1-to-S-0 electronic processes in push-pull structures. This dual emission feature constitutes a broad spectral band with full width at half-maximum up to 175 nm, providing the ability to select different channels for biological detection and imaging. Moreover, deoxygenation is shown to promote molecular aggregation, leading to a significantly strengthened dual emission that enables a high-contrast hypoxia probing effect. These results not only reveal new photophysical mechanisms on organic molecules but also expand the detection functionality of luminescent materials in the biological field.
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