129 research outputs found

    M12L8 metallo-supramolecular cube with cyclotriguaiacylene-type ligand: spontaneous resolution of cube and its constituent host ligand.

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    Data to support study of Ag12L8 metallo-cube and clathrate complexes of tris-(4-methylthiazolyl)cyclotriguaiacylene, where both Ag12L8 cube and clathrate complexes show spontaneous chiral resolution on crystallisation

    Challenges relating to comparison of flavonoid glycosides dissolution profiles from Sutherlandia frutescens products

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    Unlike the case of conventional drug formulations, dissolution tests have hitherto not been required for herbal medicinal products commercially available in South Africa. This study investigated dissolution of the South African Sutherlandia frutescens using selected flavonoid glycosides as marker compounds. Dissolution of markers was assessed in three dissolution media at pH 1.2, 4.5 and 6.8, and samples were analysed using a validated HPLC method. The dissolution profile of each marker varied for the different materials investigated. All three media utilised showed differences in flavonoid glycoside dissolution between the S. frutescens products evaluated, with f2 values <50 for comparison of flavonoid dissolution from any two of the materials. Dissolution of S. frutescens materials could thus be characterised using the markers in all the media tested. This tool may be employed in the future for comparison of orally administered S. frutescens products, provided between batch variability is evaluated and found less than between-sample variability.IS

    Aryl-substituted acridine donor derivatives modulate the transition dipole moment orientation and exciton harvesting properties of donor–acceptor TADF emitters

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    Thermally activated delayed fluorescence (TADF) compounds are highly attractive as sensitizing and emitting materials for organic light-emitting diodes (OLEDs). The efficiency of the OLED depends on multiple parameters, most of which rely on the properties of the emitter including those that govern the internal quantum and outcoupling efficiencies. Herein, we investigate a series of aryl substituted acridine donor derivatives of the donor–acceptor TADF emitter DMAC-TRZ, with the objective of correlating their properties, such as triplet harvesting efficiency and transition dipole moment orientation, with their corresponding device efficiency. The decoration of the DMAC donor with substituted aryl groups not only modifies the molecular weight and length of the emitter but also affects the emission color and the capacity for the emitters to efficiently harvest triplet excitons. The presence of electron-withdrawing 4-cyanophenyl and 4-trifluoromethylphenyl groups in, respectively, CNPh-DMAC-TRZ and CF3Ph-DMAC-TRZ, blue-shifts the emission spectrum but slows down the reverse intersystem crossing rate constant (kRISC), while the opposite occurs in the presence of electron-donating groups in tBuPh-DMAC-TRZ and OMePh-DMAC-TRZ (red-shifted emission spectrum and faster kRISC). In contrast to our expectations, the OLED performance of the five DMAC-TRZ derivatives does not scale with their degree of horizontal emitter orientation but follows the kRISC rates. This, in turn, demonstrates that triplet harvesting (and not horizontal emitter orientation) is the dominant effect for device efficiency using this family of emitters. Nonetheless, highly efficient OLEDs were fabricated with tBuPh-DMAC-TRZ and OMePh-DMAC-TRZ as emitters, with improved EQEmax (∌28%) compared to the reference DMAC-TRZ devices

    Molecular asymmetry and rigidification as strategies to activate and enhance thermally activated delayed fluorescence in deep-blue MR-TADF emitters

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    Funding; This work was supported financially by Kyulux Inc, JSPS Grant-in-Aid for Specially Promoted Research (23H05406), JST CREST (JPMJCR22B3), JSPS KAKENHI (23K20039), ESPRC (EP/R035164/1, EP/W007517/1), City University of Hong Kong (Project No. 9610637 and 9231531).Two novel deep-blue multi-resonance thermally activated delayed fluorescence (MR-TADF) emitters, 1B-CzCrs and 2B-CzCrs, containing a fused carbazole unit were synthesized. The carbazole contributed to the emergence of TADF in these small molecules. Particularly, organic light-emitting diodes with 1B-CzCrs doped in the mCP host achieve a maximum external quantum efficiency of 12.8% at CIE coordinates of (0.146, 0.062).Peer reviewe

    A deep-blue-emitting heteroatom-doped MR-TADF nonacene for high-performance organic light-emitting diodes

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    This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkƂodowska Curie grant agreement No 838885 (NarrowbandSSL). S.M.S. acknowledges support from the Marie SkƂodowska-Curie Individual Fellowship (grant agreement No 838885 NarrowbandSSL). We would like to thank the Leverhulme Trust (RPG-2016-047) for financial support. E.Z-C. and I.D.W.S acknowledge support from EPSRC (EP/L017008, EP/P010482/1). Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifiques de Belgique (F. R. S.-FNRS) under Grant No. 2.5020.11, as well as the Tier-1 supercomputer of the FĂ©dĂ©ration Wallonie-Bruxelles, infrastructure funded by the Walloon Region under the grant agreement n1117545. Y.O. acknowledges funding by the Fonds de la Recherche Scientifique-FNRS under Grant n° F.4534.21 (MIS-IMAGINE). G. R. acknowledges a grant from the ‘‘Fonds pour la formation a la Recherche dans l’Industrie et dans l’Agriculture’’ (FRIA) of the FRS-FNRS.We present a p- and n-doped nonacene compound, NOBNacene, that represents a rare example of a linearly extended ladder-type multiresonant thermally activated delayed fluorescence (MR-TADF) emitter. This compound shows efficient narrow deep blue emission, with a λPL of 410 nm, full width at half maximum, FWHM, of 38 nm, photoluminescence quantum yield, ΊPL of 71 %, and a delayed lifetime, τd of 1.18 ms in 1.5 wt % TSPO1 thin film. The organic light-emitting diode (OLED) using this compound as the emitter shows a comparable electroluminescence spectrum peaked at 409 nm (FWHM=37 nm) and a maximum external quantum efficiency (EQEmax) of 8.5 % at Commission Internationale de l’Éclairage (CIE) coordinates of (0.173, 0.055). The EQEmax values were increased to 11.2 % at 3 wt % doping of the emitter within the emissive layer of the device. At this concentration, the electroluminescence spectrum broadened slightly, leading to CIE coordinates of (0.176, 0.068).Publisher PDFPeer reviewe

    Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells

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    M. K. would like to thank 2214-A International Research Fellowship Programme for Ph.D. students (1059B141900585). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkƂodowska Curie grant agreement No 838885 (NarrowbandSSL). S.M.S. acknowledges support from the Marie SkƂodowska-Curie Individual Fellowship (grant agreement No 838885 NarrowbandSSL). A. K. G. is grateful to the Royal Society for Newton International Fellowship NF171163. L.M acknowledges that the project who gave rise to these results received support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme Grant agreement No. 834431, the Spanish Ministry of Science, Innovation and Universities (MICIU, RTI2018-095362-A-I00, and EQC2018-004888-P) and the Comunitat Valenciana (IDIFEDER/2020/063 and PROMETEU/2020/077). D.T. acknowledges support from the Comunitat Valenciana (CIGE/2021/0).We designed and synthesized two new ionic thermally activated delayed fluorescent (TADF) emitters that are charged analogues of a known multiresonant TADF (MR-TADF) compound, DiKTa. The emission of the charged derivatives is red-shifted compared to the parent compound. For instance, DiKTa-OBuIm emits in the green (λPL = 499 nm, 1 wt % in mCP) while DiKTa-DPA-OBuIm emits in the red (λPL = 577 nm, 1 wt % in mCP). In 1 wt % mCP films, both emitters showed good photoluminescence quantum yields of 71% and 61%, and delayed lifetimes of 316.6 ÎŒs and 241.7 ÎŒs, respectively, for DiKTa-OBuIm and DiKTa-DPA-OBuIm, leading to reverse intersystem crossing rates of 2.85 × 103 s−1 and 3.04 × 103 s−1. Light-emitting electrochemical cells were prepared using both DiKTa-OBuIm and DiKTa-DPA-OBuIm as active emitters showing green (λmax = 534 nm) and red (λmax = 656 nm) emission, respectively.Publisher PDFPeer reviewe

    Two boron atoms versus one : high-performance deep-blue multi-resonance thermally activated delayed fluorescence emitters

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    This work was supported financially by the JSPS Core-to-Core Program (grant number: JPJSCCA20180005) and Kyulux Inc. S. M. S. acknowledges support from the Marie SkƂodowska-Curie Individual Fellowship (grant agreement No 838885 NarrowbandSSL). We would like to thank the Leverhulme Trust (RPG-2016-047) for financial support. E. Z.-C. is a Royal Society Leverhulme Trust Senior Research fellow (SRF\R1\201089). We thank the EPRSC for funding (EP/R035164/1). Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifiques de Belgique (F. R. S.-FNRS) under Grant No. 2.5020.11, as well as the Tier-1 supercomputer of the FĂ©dĂ©ration Wallonie-Bruxelles, infrastructure funded by the Walloon Region under the grant agreement n1117545. Y. O. acknowledges funding by the Fonds de la Recherche Scientifique-FNRS under Grant no. F.4534.21 (MIS-IMAGINE). D. B. is a FNRS Research Director.Two new deep-blue narrowband multi-resonant emitters, 1B-DTACrs and 2B-DTACrs, one of which shows thermally activated delayed fluorescence (TADF), based on boron, nitrogen, and oxygen doped nanographenes are reported. Devices based on 2B-DTACrs showed an EQEmax of 14.8% and CIE coordinates of (0.150, 0.044), which are very close to the BT.2020 requirement for blue pixels.Publisher PDFPeer reviewe

    Judicious heteroatom doping produces high performance deep blue/near UV multiresonant thermally activated delayed fluorescence OLEDs

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    Funding: Horizon 2020 Framework Programme - 838885; Leverhulme Trust - RPG-2016-047; Engineering and Physical Sciences Research Council - EP/L017008, EP/P010482/1; Fonds de la Recherche Scientifiques de Belgique - 2.5020.11; Walloon Region - n1117545; Fonds De La Recherche Scientifique - FNRS - F.4534.21.Two multiresonant thermally activated delayed fluorescence (MR-TADF) emitters are presented and it is shown how further borylation of a deep-blue MR-TADF emitter, DIDOBNA-N, both blueshifts and narrows the emission producing a new near-UV MR-TADF emitter, MesB-DIDOBNA-N, are shown. DIDOBNA-N emits bright blue light (ΊPL = 444 nm, FWHM = 64 nm, ΊPL = 81%, τd = 23 ms, 1.5 wt% in TSPO1). The deep-blue organic light-emitting diode (OLED) based on this twisted MR-TADF compound shows a very high maximum external quantum efficiency (EQEmax) of 15.3% for a device with CIEy of 0.073. The fused planar MR-TADF emitter, MesB-DIDOBNA-N shows efficient and narrowband near-UV emission (λPL = 402 nm, FWHM = 19 nm, ΊPL = 74.7%, τd = 133 ms, 1.5 wt% in TSPO1). The best OLED with MesB-DIDOBNA-N, doped in a co-host, shows the highest efficiency reported for a near-UV OLED at 16.2%. With a CIEy coordinate of 0.049, this device also shows the bluest EL reported for a MR-TADF OLED to date.Publisher PDFPeer reviewe

    Aryl-Substituted Acridine Donor Derivatives Modulate the Transition Dipole Moment Orientation and Exciton Harvesting Properties of Donor–Acceptor TADF Emitters

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    Thermally activated delayed fluorescence (TADF) compounds are highly attractive as sensitizing and emitting materials for organic light-emitting diodes (OLEDs). The efficiency of the OLED depends on multiple parameters, most of which rely on the properties of the emitter including those that govern the internal quantum and outcoupling efficiencies. Herein, we investigate a series of aryl substituted acridine donor derivatives of the donor–acceptor TADF emitter DMAC-TRZ, with the objective of correlating their properties, such as triplet harvesting efficiency and transition dipole moment orientation, with their corresponding device efficiency. The decoration of the DMAC donor with substituted aryl groups not only modifies the molecular weight and length of the emitter but also affects the emission color and the capacity for the emitters to efficiently harvest triplet excitons. The presence of electron-withdrawing 4-cyanophenyl and 4-trifluoromethylphenyl groups in, respectively, CNPh-DMAC-TRZ and CF3Ph-DMAC-TRZ, blue-shifts the emission spectrum but slows down the reverse intersystem crossing rate constant (k RISC), while the opposite occurs in the presence of electron-donating groups in t BuPh-DMAC-TRZ and OMePh-DMAC-TRZ (red-shifted emission spectrum and faster k RISC). In contrast to our expectations, the OLED performance of the five DMAC-TRZ derivatives does not scale with their degree of horizontal emitter orientation but follows the k RISC rates. This, in turn, demonstrates that triplet harvesting (and not horizontal emitter orientation) is the dominant effect for device efficiency using this family of emitters. Nonetheless, highly efficient OLEDs were fabricated with t BuPh-DMAC-TRZ and OMePh-DMAC-TRZ as emitters, with improved EQEmax (∌28%) compared to the reference DMAC-TRZ devices
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