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1.	Baryshnikov, Glib V., et al. (författare) Solvatochromic effect in absorption and emission spectra of star-shaped bipolar derivatives of 1,3,5-triazine and carbazole. A time-dependent density functional study 2017 Ingår i: Journal of Molecular Modeling. - : Springer-Verlag New York. - 1610-2940 .- 0948-5023. ; 23:2 Tidskriftsartikel (refereegranskat)abstract A series of three star-shaped compounds containing both donor (carbazole) and acceptor (2,4,6-triphenyl-1,3,5-triazine) moieties linked through various linking bridges was studied theoretically at the linear response TD-DFT level of theory to describe their absorption and fluorescence spectra. The concept of a localized charge-transfer excited state has been applied successfully to explain the observed strong solvatochromic effect in the emission spectra of the studied molecules, which can be utilized for the fabrication of color tunable solution-processable OLEDs. The concept is in particularly applicable to donor–acceptor species with a C3 symmetry point group where the static dipole moment changes dramatically upon electronic excitation. An important peculiarity of the studied molecules is that they are characterized by non-zero values of the HOMO and LUMO orbitals in the same common part of molecular space that provides a large electric dipole transition moment for both light absorption and emission. [Figure not available: see fulltext.]
2.	Begunovich, Lyudmila V., et al. (författare) Single-layer polymeric tetraoxa[8]circulene modified by s-block metals : toward stable spin qubits and novel superconductors 2021 Ingår i: Nanoscale. - : Royal Society of Chemistry. - 2040-3364 .- 2040-3372. ; 13:9, s. 4799-4811 Tidskriftsartikel (refereegranskat)abstract Tunable electronic properties of low-dimensional materials have been the object of extensive research, as such properties are highly desirable in order to provide flexibility in the design and optimization of functional devices. In this study, we account for the fact that such properties can be tuned by embedding diverse metal atoms and theoretically study a series of new organometallic porous sheets based on two-dimensional tetraoxa[8]circulene (TOC) polymers doped with alkali or alkaline-earth metals. The results reveal that the metal-decorated sheets change their electronic structure from semiconducting to metallic behaviour due to n-doping. Complete active space self-consistent field (CASSCF) calculations reveal a unique open-shell singlet ground state in the TOC-Ca complex, which is formed by two closed-shell species. Moreover, Ca becomes a doublet state, which is promising for magnetic quantum bit applications due to the long spin coherence time. Ca-doped TOC also demonstrates a high density of states in the vicinity of the Fermi level and induced superconductivity. Using the ab initio Eliashberg formalism, we find that the TOC-Ca polymers are phonon-mediated superconductors with a critical temperature T-C = 14.5 K, which is within the range of typical carbon based superconducting materials. Therefore, combining the proved superconductivity and the long spin lifetime in doublet Ca, such materials could be an ideal platform for the realization of quantum bits.
3.	Deksnys, T., et al. (författare) Synthesis and characterisation of a carbazole-based bipolar exciplex-forming compound for efficient and color-tunable OLEDs 2017 Ingår i: New Journal of Chemistry. - : RSC Publishing. - 1144-0546 .- 1369-9261. ; 41:2, s. 559-568 Tidskriftsartikel (refereegranskat)abstract A new ambipolar fluorophore, 3,6-di(4,4′-dimethoxydiphenylaminyl)-9-(1-naphthyl)carbazole, was synthesized and its physical properties were studied by differential scanning calorimetry, thermogravimetric analysis, UV-vis absorption, luminescence and photoelectron emission spectroscopy, cyclic voltammetry and a time of flight method. The latter technique indicates that the compound demonstrates bipolar semiconducting properties. Using the synthesized compound as an emissive material, a single-layer OLED with an electroluminescence spectrum containing a voltage-dependent electroplex emission band in the region of 550-650 nm was fabricated. Another OLED was fabricated with an additional electron transporting bathophenanthroline layer that forms a direct interface with the layer of 3,6-di(4,4′-dimethoxydiphenylaminyl)-9-(1-naphthyl)carbazole. A strong exciplex-type band in the electroluminescence spectrum of this OLED with an emission maximum at ca. 540 nm was observed. The electroluminescence spectra of both devices were found to be clearly dependent on the applied bias. This effect can be useful for the development of efficient and colour-tunable OLEDs.
4.	Ivaniuk, K. B., et al. (författare) New WOLEDs based on pi-extended azatrioxa[8]circulenes 2017 Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 5:17, s. 4123-4128 Tidskriftsartikel (refereegranskat)abstract New stable WOLEDs based on pi-extended azatrioxa[8]circulenes have been fabricated. Combining the own blue emission of the azatrioxa[8] circulenes with the yellow-green emission of the "m-MTDATA:azatrioxa[8]circulene'' exciplex a broad visible region, from 400 to 700 nm, is covered. The so constructed WOLEDs exhibit a luminance exceeding 23 700 cd m(-2) and an external quantum efficiency reaching 3%.
5.	Suresh, Rahul, et al. (författare) Cyclo[18]carbon Formation from C(18)Br(6) and C18(CO)(6) Precursors 2022 Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 13:44, s. 10318-10325 Tidskriftsartikel (refereegranskat)abstract Although cyclo[18]carbon has been isolated experimentally from two precursors, C18Br6 and C-18(CO)(6), no reaction mechanisms have yet been explored. Herein, we provide insight into the mechanism behind debromination and decarbon-ylation. Both neutral precursors demonstrate high activation barriers of similar to 2.3 eV, while the application of an electric field can lower the barriers by 0.1-0.2 eV. The barrier energy of the anion-radicals is found to be significantly lower for C18Br6 compared to C-18(CO)(6), confirming a considerably higher yield of cylco[18] carbon when the C18Br6 precursor is used. Elongation of the C-Br bond in the anion-radical confirms its predissociation condition. Natural bonding orbital analysis shows that the stability of C-Br and C-CO bonds in the anion-radicals is lower compared to their neutral species, indicating a possible higher yield. The applied analysis provides crucial details regarding the reaction yield of cyclo[18]carbon and can serve as a general scheme for tuning reaction conditions for other organic precursors.
6.	Baryshnikov, Glib V., et al. (författare) A computational study of structural and magnetic properties of bi- and trinuclear Cu(II) complexes with extremely long Cu–-Cu distances 2017 Ingår i: Chemical Physics. - : Elsevier. - 0301-0104 .- 1873-4421. ; 491, s. 48-55 Tidskriftsartikel (refereegranskat)abstract Three recently synthesized copper(II) complexes with aroylhydrazones of trifluoroacetic and benzenecarboxylic acids (Dalton Trans., 2013, 42, 16878) have been computationally investigated by density functional theory within the broken symmetry approximation accounting for empirical dispersion corrections. A topological analysis of electron density distributions has been carried out using Bader's “quantum theory of atoms in molecules” formalism. The calculated values of spin-spin exchange for the studied dinuclear complexes indicate a very weak ferromagnetic coupling of the unpaired electrons in good agreement with experimental data. At the same time, the trinuclear copper(II) complex possesses a low-spin doublet ground state with one ferromagnetic and two antiferromagnetic spin projections between the triangular-positioned Cu2+ ions. The estimated values of the coupling constants for the spin-spin exchange in this trinuclear complex are in a good agreement with experimental observations. The calculations support a mechanism of exchange coupling through the aromatic links in these strongly spin-separated systems.
7.	Baryshnikov, Glib V., et al. (författare) Anion-induced exchange interactions in binuclear complexes of Cu(II) with flexible hexadentate bispicolylamidrazone ligands 2016 Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 661, s. 48-52 Tidskriftsartikel (refereegranskat)abstract Two recently synthesized copper(II) complexes with spacer-armed bispicolylamidrazone ligands have been theoretically studied at the density functional theory (DFT) level accounting for empirical dispersion correction and intrinsic anionic environment by perchlorate ions. The exchange parameter between the open-shell singlet and triplet states of the studied complexes has been estimated by broken symmetry DFT calculations. The mechanism of spin-spin exchange interaction between the unpaired electrons via the σ-bond aliphatic chain (Gusev et al., 2015) is confirmed. Instead, a anion-induced mechanism is proposed which means that the anionic grid participates in the exchange interaction between the unpaired electrons.
8.	Baryshnikov, Glib, V., et al. (författare) Aromaticity of Even-Number Cyclo[n]carbons (n=6-100) 2020 Ingår i: Journal of Physical Chemistry A. - : AMER CHEMICAL SOC. - 1089-5639 .- 1520-5215. ; 124:51, s. 10849-10855 Tidskriftsartikel (refereegranskat)abstract The recently synthesized cyclo[18]carbon molecule has been characterized in a number of studies by calculating electronic, spectroscopic, and mechanical properties. However, cyclo[18] carbon is only one member of the class of cyclo[n]carbons-standalone carbon allotrope representatives. Many of the larger members of this class of molecules have not been thoroughly investigated. In this work, we calculate the magnetically induced current density of cyclo[n]carbons in order to elucidate how electron delocalization and aromatic properties change with the size of the molecular ring (n), where n is an even number between 6 and 100. We find that the Hiickel rules for aromaticity (4k + 2) and antiaromaticity (4k) become degenerate for large C-n rings (n > 50), which can be understood as a transition from a delocalized electronic structure to a nonaromatic structure with localized current density fluxes in the triple bonds. Actually, the calculations suggest that cyclo[n]carbons with n > 50 are nonaromatic cyclic polyalkynes. The influence of the amount of nonlocal exchange and the asymptotic behavior of the exchange-correlation potential of the employed density functionals on the strength of the magnetically induced ring current and the aromatic character of the large cyclo[n]carbons is also discussed.
9.	Baryshnikov, Glib V., et al. (författare) The Electronic Structure and Spectra of Triphenylamines Functionalized by Phenylethynyl Groups 2018 Ingår i: Optics and Spectroscopy. - : Pleiades Publishing. - 0030-400X .- 1562-6911. ; 124:1, s. 57-64 Tidskriftsartikel (refereegranskat)abstract We study the features of the electronic structure and the IR, UV, and visible spectra of a series of triphenylamines substituted with phenylethynyl groups. The analysis is performed at the level of the density functional theory (DFT) and its nonstationary version in comparison with the experimental data of IR and electron spectroscopy. It is shown that, in the excited state, there is a change in the alternation of single, double, and triple bonds in accordance with the character of bonding and antibonding in the lowest vacant molecular orbital. The gradual introduction of additional phenylethynyl groups does not cause frequency shifts in the IR spectra of the molecules under study, but significantly affects the intensity of the corresponding IR bands. A similar effect is also observed in the electronic-absorption spectra of these compounds. This can be used for optical tuning of triphenylamines as promising materials for organic light-emitting diodes and solar cells.
10.	Danyliv, Iryna, et al. (författare) Derivatives of 2-Pyridone Exhibiting Hot-Exciton TADF for Sky-Blue and White OLEDs 2023 Ingår i: ACS APPLIED ELECTRONIC MATERIALS. - : American Chemical Society (ACS). - 2637-6113. ; 5:8, s. 4174-4186 Tidskriftsartikel (refereegranskat)abstract Development of emissivematerials for utilization inorganic light-emittingdiodes (OLEDs) remains a highly relevant research field. One of themost important aspects in the development of efficient emitters forOLEDs is the efficiency of triplet-to-singlet exciton conversion.There are many concepts proposed for the transformation of tripletexcitons to singlet excitons, among which thermally activated delayedfluorescence (TADF) is the most efficient and widespread. One of thevariations of the TADF concept is the hot exciton approach accordingto which the process of exciton relaxation into the lowest energyelectronic state (internal conversion as usual) is slower than intersystemcrossing between high-lying singlets and triplets. In this paper,we present the donor-acceptor materials based on 2-pyridoneacceptor coupled to the different donor moieties through the phenyllinker demonstrating good performance as components of sky-blue, green-yellow,and white OLEDs. Despite relatively low photoluminescence quantumyields, the compound containing 9,9-dimethyl-9,10-dihydroacridinedonor demonstrated very good efficiency in sky-blue OLED with thesingle emissive layer, which showed an external quantum efficiency(EQE) of 3.7%. It also forms a green-yellow-emitting exciplex with4,4 & PRIME;,4 & DPRIME;-tris[phenyl(m-tolyl)amino]triphenylamine.The corresponding OLED showed an EQE of 6.9%. The white OLED combiningboth exciplex and single emitter layers demonstrated an EQE of 9.8%together with excellent current and power efficiencies of 16.1 cdA(-1) and 6.9 lm W-1, respectively.Quantum-chemical calculations together with the analysis of photoluminescencedecay curves confirm the ability of all of the studied compounds toexhibit TADF through the hot exciton pathway, but the limiting factorreducing the efficiency of OLEDs is the low photoluminescence quantumyields caused mainly by nonradiative intersystem crossing dominatingover the radiative fluorescence pathway.
11.	Danyliv, Yan, et al. (författare) Carbazole-s-sulfobenzimide derivative exhibiting mechanochromic thermally activated delayed fluorescence as emitter for flexible OLEDs : Theoretical and experimental insights 2022 Ingår i: Dyes and pigments. - : Elsevier. - 0143-7208 .- 1873-3743. ; 208 Tidskriftsartikel (refereegranskat)abstract For the first time exploiting sulfobenzimide moiety as an acceptor unit, the new type of donor-sigma-acceptor emitter exhibiting thermally activated delayed fluorescence (TADF) is demonstrated. In different solutions, the synthesized compound emits light resulting from either locally excited carbazole moiety or trough-space charge transfer (exciplex-like) between carbazole and sulfobenzimide units. In the solid state, this emitter demonstrates aggregation-induced emission enhancement and different emission colours due to its different conformations. The mechanoluminescence of the donor-sigma-acceptor compound was observed and studied in detail by experimental and theoretical approaches including single-crystal and powder X-ray analyses. Electroluminescence of the different colours was observed when the compound was utilized as non-doped TADF emitter in rigid and flexible organic light-emitting diodes fabricated on glass or poly(ethylene terephthalate) substrates. The device fabricated on the rigid substrate exhibited the best performance with maximum current efficiency, power efficiency, and external quantum efficiency of 11.0 cd A(-1), 3.0 lm W-1, and 4.3%, respectively.
12.	Deng, Xuefan, et al. (författare) A new strategy for boron cluster-based metal boride (Co2B) synthesis and its applicability to electrocatalytic nitrate reduction 2024 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 485 Tidskriftsartikel (refereegranskat)abstract To achieve efficient conversion of nitrate to ammonia, it is necessary to design and develop electrode materials with high activity and efficiency for the electrocatalytic reduction reaction of nitrate (NO3RR). Due to its unique semi-metallic properties, the vacancy orbitals of boron are prone to accommodate electrons, so doping element B with transition metals is expected to change the local electronic configuration of the metal, which in turn affects the corresponding catalytic reaction. Here, we propose a new strategy for the preparation of metal borides by using dodecahydro-closo-dodecaborate and Co2+ complexed and calcined to prepare a novel metal boride-Co2B for electrocatalytic nitrate reduction. This modification considerably enhances the performance of NO3RR. Co2B exhibited a Faradaic efficiency of NH4+ (FENH4+) as high as 96.61 % at -0.5 V vs. RHE, achieving a remarkable NH4+ yield of 5.73 mg h-1 mgcat - 1. This study provides a new approach for designing catalysts for environmentallyfriendly ammonia synthesis.
13.	Gao, Lei, et al. (författare) Hydrophilic Cocrystals with Water Switched Luminescence 2024 Ingår i: Angewandte Chemie International Edition. - : John Wiley & Sons. - 1433-7851 .- 1521-3773. ; 63:8 Tidskriftsartikel (refereegranskat)abstract Utilizing water molecules to regulate the luminescence properties of solid materials is highly challenging. Herein, we develop a strategy to produce water-triggered luminescence-switching cocrystals by coassembling hydrophilic donors with electron-deficient acceptors, where 1,2,4,5-Tetracyanobenzene (TCNB) was used as the electron acceptor and pyridyl benzimidazole derivatives were used as the electron donors enabling multiple hydrogen-bonds. Two cocrystals, namely 2PYTC and 4PYTC were obtained and showed heat-activated emission, and such emission could be quenched or weakened by adding water molecules. The cocrystal structure exhibited the donor molecule that can form multiple hydro bonds with water and acceptor molecules due to the many nitrogen atoms of them. The analyses of the photophysical data, powder X-ray diffraction, and other data confirmed the reversible fluorescence "on-off" effects were caused by eliminating and adding water molecules in the crystal lattice. The density functional theory calculations indicate that the vibration of the O-H bond of water molecules in the cocrystal can absorb the excitation energy and suppress fluorescence. Furthermore, the obtained cocrystals also showed temperature, humidity, and H+/NH4+ responsive emission behavior, which allows their applications as thermal and humidity sensors, and multiple information encryptions. This research paves the way for preparing intelligent hydrophilic organic cocrystal luminescent materials. Hydrophilic donors with electron-deficient acceptors were coassembled to achieve luminescence-switching cocrystals triggered by water molecules. The obtained cocrystals show a strong water absorption ability and excellent fluorescence properties. The emission of cocrystals can be reversibly switched by heating and water. Finally, the obtained cocrystals show potential applications in temperature-humidity and acid-base responses.+image
14.	Gorski, Krzysztof, et al. (författare) Quadrupolar Dyes Based on Highly Polarized Coumarins 2021 Ingår i: Organic Letters. - : AMER CHEMICAL SOC. - 1523-7060 .- 1523-7052. ; 23:17, s. 6770-6774 Tidskriftsartikel (refereegranskat)abstract The fluorescence and other photophysical parameters of highly polarized, quadrupolar bis-coumarins possessing an electron-rich pyrrolo[3,2-b]pyrrole bridging unit are highly dependent on the linking position between both chromophores. Delocalization of the LUMO on the entire pi-system results in intense emission and strong two-photon absorption.
15.	Gusev, Alexey N., et al. (författare) Schiff Base Zinc(II) Complexes as Promising Emitters for Blue Organic Light-Emitting Diodes 2021 Ingår i: ACS Applied Electronic Materials. - : American Chemical Society (ACS). - 2637-6113. ; 3:8, s. 3436-3444 Tidskriftsartikel (refereegranskat)abstract Organometallic blue fluorescent Zn(II) Schiff base complexes are synthesized and explored computationally in order to use them in organic electroluminescent heterostructures. Characterization of these pyrazolone-based azomethine-zinc complexes was accomplished by various physicochemical techniques to get insight into their applicability as an active layer in light-emitting diodes. All the complexes demonstrate high thermal stability and remarkable photoluminescence both in solution and in the solid state with maximum in the blue region. Quantum chemical calculations of the first exited electronic state and vertical singlet-singlet electronic transitions by means of time-dependent density functional theory calculations and results show that the origin of the luminescence for the target complexes refers to the intraligand charge transfer within the Schiff bases. The constructed light-emitting diodes demonstrate low input voltage (3.2-4.0 V), brightness at a level of 4300-11,600 Cd m(-2), and external quantum efficiency of up to 3.2%, which is a good value for purely fluorescent organic light-emitting diodes.
16.	Guzauskas, Matas, et al. (författare) Polymorph acceptor-based triads with photoinduced TADF for UV sensing 2021 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 425 Tidskriftsartikel (refereegranskat)abstract In contrast to many donor–acceptor type organic luminophores exhibiting thermally activated delayed fluorescence (TADF), two deep blue TADF emitters designed in this work contain only typical electron accepting moieties with different electron accepting abilities. Derivatives of benzophenone and diphenylsulfone substituted with phenothiazine-5,5-dioxide donor moieties were synthesized and studied. In addition to the TADF, green to blue emission color switching and strong fluorescence intensity enhancement by more than 60 times was detected for THF solution of the derivative of phenothiazine-5,5-dioxide and benzophenone under increase of UV excitation dose. We proved by a variety of experimental and theoretical studies that the unusual photophysical properties of the derivative of benzophenone are mainly related to the formation of different conformers. The photostimulated intensity enhancement of the compound is due to the rise of the quantity of triplet states and their further crossing to singlet states. To our knowledge, this is the first observation of a combination of photoinduced color switching and triplet-dependent emission intensity enhancement. These properties are shown to be useful for UV sensing with very low detection limits (less than 10 μW/cm2 for the toluene solution). Under gradual increase of UV excitation dose, the DMF solution demonstrated a green → blue color swishing from (0.34; 0.44) to (0.17; 0.18) of CIE coordinates that can be detected by naked eye.
17.	Ivaniuk, Khrystyna, et al. (författare) (Tetrafluorovinylphenyl)carbazole as a Multifunctional Material for OLED Applications 2023 Ingår i: ACS APPLIED ELECTRONIC MATERIALS. - : AMER CHEMICAL SOC. - 2637-6113. ; 5:4, s. 2156-2168 Tidskriftsartikel (refereegranskat)abstract The multifunctional materials for application in organic light-emitting devices (OLEDs) based on a single structural motif are very desired but quite rare species. Such structures allow simplifying the chemical variety within OLED heterostructures and thus reducing their cost, manufacturing time, and logistic efforts. In this paper, we report the 9-(2,3,5,6-tetrafluoro-4-vinylphenyl)carbazole molecule (Cz4FS) utilized as a fluorescent emitter, host material for quantum dot based OLEDs (QLEDs), acceptor part of the exciplex active layer, and monomer that can be used for the preparation of emissive polymers and copolymers. The external quantum efficiency (EQE) of the corresponding fluorescent OLED based on a Cz4FS single emitter doped into a 1,3-bis(carbazol-9-yl)benzene matrix is 4.2%, which is close to the theoretical limit and maximum brightness at the level of 3600 cd/m2. An OLED based on exciplex emission obtained utilizing Cz4FS as an acceptor demonstrates higher efficiency (5.3%) and much higher brightness near 25 000 cd/m2. A QLED based on Cz4FS as a host for CdSeS/ZnS core-shell quantum dots demonstrates excellent energy transfer from the Cz4FS matrix that results in a clear spectrum of quantum dots with an EQE of 2.3%, maximum of 19 000 cd/m2, and narrow spectral distribution. An OLED based on a Cz4FS-based polymer and copolymer demonstrates not extraordinary efficiency but low-efficiency roll-off in a wide range of current densities.
18.	Pander, Piotr, et al. (författare) Thermally activated delayed fluorescence in a deep red dinuclear iridium(iii) complex: a hidden mechanism for short luminescence lifetimes 2023 Ingår i: Chemical Science. - : ROYAL SOC CHEMISTRY. - 2041-6520 .- 2041-6539. ; 14:47, s. 13934-13943 Tidskriftsartikel (refereegranskat)abstract The high luminescence efficiency of cyclometallated iridium(III) complexes, including those widely used in OLEDs, is typically attributed solely to the formally spin-forbidden phosphorescence process being facilitated by spin-orbit coupling with the Ir(III) centre. In this work, we provide unequivocal evidence that an additional mechanism can also participate, namely a thermally activated delayed fluorescence (TADF) pathway. TADF is well-established in other materials, including in purely organic compounds, but has never been observed in iridium complexes. Our findings may transform the design of iridium(III) complexes by including an additional, faster fluorescent radiative decay pathway. We discover it here in a new dinuclear complex, 1, of the form [Ir(N<^>C)(2)](2)(mu-L), where N<^>C represents a conventional N<^>C-cyclometallating ligand, and L is a bis-N<^>O-chelating bridging ligand derived from 4,6-bis(2-hydroxyphenyl)-pyrimidine. Complex 1 forms selectively as the rac diastereoisomer upon reaction of [Ir(N<^>C)(2)(mu-Cl)](2) with H2L under mild conditions, with none of the alternative meso isomer being separated. Its structure is confirmed by X-ray diffraction. Complex 1 displays deep-red luminescence in solution or in polystyrene film at room temperature (lambda(em) = 643 nm). Variable-temperature emission spectroscopy uncovers the TADF pathway, involving the thermally activated re-population of S-1 from T-1. At room temperature, TADF reduces the photoluminescence lifetime in film by a factor of around 2, to 1 mu s. The TADF pathway is associated with a small S-1-T-1 energy gap Delta E-ST of approximately 50 meV. Calculations that take into account the splitting of the T-1 sublevels through spin-orbit coupling perfectly reproduce the experimentally observed temperature-dependence of the lifetime over the range 20-300K. A solution-processed OLED comprising 1 doped into the emitting layer at 5 wt% displays red electroluminescence, lambda(EL) = 625 nm, with an EQE of 5.5% and maximum luminance of 6300 cd m(-2).
19.	Pedersen, S. K., et al. (författare) Dianthracenylazatrioxa[8]circulene : Synthesis, Characterization and Application in OLEDs 2021 Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 27:45, s. 11609-11617 Tidskriftsartikel (refereegranskat)abstract A soluble, green-blue fluorescent, π-extended azatrioxa[8]circulene was synthesized by oxidative condensation of a 3,6-dihydroxycarbazole and 1,4-anthraquinone by using benzofuran scaffolding. This is the first circulene to incorporate anthracene within its carbon framework. Solvent-dependent fluorescence and bright green electroluminescence accompanied by excimer emission are the key optical properties of this material. The presence of sliding π-stacked columns in the single crystal of dianthracenylazatrioxa[8]circulene is found to cause a very high electron-hopping rate, thus making this material a promising n-type organic semiconductor with an electron mobility predicted to be around 2.26 cm2 V−1 s−1. The best organic light-emitting diode (OLED) device based on the dianthracenylazatrioxa[8]circulene fluorescent emitter has a brightness of around 16 000 Cd m−2 and an external quantum efficiency of 3.3 %. Quantum dot-based OLEDs were fabricated by using dianthracenylazatrioxa[8]circulene as a host matrix material.
20.	Poronik, Yevgen M., et al. (författare) Deciphering the unusual fluorescence in weakly coupled bis-nitro-pyrrolo[3,2-b]pyrroles 2020 Ingår i: Communications Chemistry. - : NATURE RESEARCH. - 2399-3669. ; 3:1 Tidskriftsartikel (refereegranskat)abstract Electron-deficient pi-conjugated functional dyes lie at the heart of organic optoelectronics. Adding nitro groups to aromatic compounds usually quenches their fluorescence via inter-system crossing (ISC) or internal conversion (IC). While strong electronic coupling of the nitro groups with the dyes ensures the benefits from these electron-withdrawing substituents, it also leads to fluorescence quenching. Here, we demonstrate how such electronic coupling affects the photophysics of acceptor-donor-acceptor fluorescent dyes, with nitrophenyl acceptors and a pyrrolo[3,2-b]pyrrole donor. The position of the nitro groups and the donor-acceptor distance strongly affect the fluorescence properties of the bis-nitrotetraphenylpyrrolopyrroles. Concurrently, increasing solvent polarity quenches the emission that recovers upon solidifying the media. Intramolecular charge transfer (CT) and molecular dynamics, therefore, govern the fluorescence of these nitro-aromatics. While balanced donor-acceptor coupling ensures fast radiative deactivation and slow ISC essential for large fluorescence quantum yields, vibronic borrowing accounts for medium dependent IC via back CT. These mechanistic paradigms set important design principles for molecular photonics and electronics. Owing to their electron-withdrawing nature, nitro-groups are desirable in the design of electron-deficient light-sensitizing aromatic pi-conjugated molecules, but most nitro-aromatics are not fluorescent. Here, the authors show how balanced donor-acceptor coupling ensures fast radiative deactivation and slow intersystem crossing in bis-nitrotetraphenylpyrrolopyrroles.
21.	Valiev, Rashid R., et al. (författare) When are Antiaromatic Molecules Paramagnetic? 2020 Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 124:38, s. 21027-21035 Tidskriftsartikel (refereegranskat)abstract Magnetizabilities and magnetically induced current densities have been calculated and analyzed for a series of antiaromatic cyclo[4k]carbons (k = 2-11), iso[n]phlorins (n = 4-8), expanded porphyrinoids, and meso-meso, beta-beta,beta-beta triple-linked porphyrin and isophlorin arrays. The cyclo[4k]carbons with k = 2-6 are predicted to be closed-shell paramagnetic molecules due to the very strong paratropic ring current combined with its large radius. Larger cyclo[4k]carbons with k = 6-11 are diamagnetic because they sustain a paratropic ring current whose strength is weaker than -20 nA T-1, which seems to be the lower threshold value for closed-shell paramagnetism. This holds not only for cyclo[4k]carbons but also for other organic molecules like expanded porphyrinoids and oligomers of porphyrinoids. The present study shows that meso-meso, beta-beta, beta-beta triple-linked linear porphyrin and isophlorin arrays have a domainlike distribution of alternating diatropic and paratropic ring currents. The strength of their local paratropic ring currents is weaker than -20 nA T-1 in each domain. Therefore, linear porphyrin and isophlorin arrays become more diamagnetic with increasing length of the ribbon. For the same reason, square-shaped meso-meso, beta-beta, beta-beta triple-linked free-base porphyrin and isophlorin tetramers as well as the Zn(II) complex of the porphyrin tetramer are diamagnetic. We show that closed-shell molecules with large positive magnetizabilities can be designed by following the principle that a strong paratropic current ring combined with a large ring-current radius leads to closed-shell paramagnetism.
22.	Wang, Xinyu, et al. (författare) A hybrid molecular sensitizer for triplet fusion upconversion 2021 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 426 Tidskriftsartikel (refereegranskat)abstract Triplet fusion upconversion is useful for a broad spectrum of applications ranging from solar cells, photoredox catalysis, to biophotonics applications, especially in the near-infrared (NIR, >700Â nm) range. This upconverting system typically demands efficient conversion of spin-singlet harvested energy through intersystem crossing to spin-triplet states, accessible only in rare metallic-coordinating macrocycle compounds or heavy-metal-containing semiconductor quantum dots for triplet sensitization. Herein, we describe an organicâ€“inorganic system for NIR-to-visible triplet fusion upconversion, interfacing commonly-seen, non-metallic, infrared dyes (IR806, IR780, indyocynine green, and CarCl) and lanthanide nanocrystal (sodium ytterbium fluoride) as a hybrid molecular sensitizer, which extracts molecular spin-singlet energy to nanocrystal-enriched ytterbium dopants at 48% efficiency (IR806, photoexciation at 808Â nm). Moreover, ytterbium sub-lattice energy migration increases the interaction possibility between the nanocrystal and the freely-diffusing rubrenes in solution, resulting in 24-fold (IR806) to 1740-fold (indocyanine green) upconversion (600Â nm) increase, depending on the IR dye type, as compared to the one without ytterbium nanotransducers. Ab initio quantum chemistry calculations identify enhanced spin-orbital coupling in the ytterbium-IR806 complex and high energy transfer rate in the ytterbium-rubrene interaction (1010 sâˆ’1). Employing inorganic lanthanide nanocrystals as nanotransducers unleashes the potential use of non-metallic infrared organic dyes for triplet fusion upconversion.
23.	Wang, Zhengxi, et al. (författare) Platinum group nanoparticles doped BCN matrix : Efficient catalysts for the electrocatalytic reduction of nitrate to ammonia 2024 Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 664, s. 84-95 Tidskriftsartikel (refereegranskat)abstract The effective treatment of nitrate (NO3- ) in water as a nitrogen source and electrocatalytic NO3- reduction to ammonia (NH3 ) (NRA) have become preferred methods for NO3--to-NH3 conversion. Achieving efficient NO3--to-NH3 conversion requires the design and development of electrode materials with high activity and efficiency for the electrocatalytic NRA reaction. Herein, based on the special properties of dodecahydro- closo -dodecaborate anions, a BCN matrix, loaded with platinum -group nanoparticles (namely, Pd/BCN, Pt/BCN, and Ru/BCN), was prepared using a simple method for the electrocatalytic NRA reaction. Results showed that Pd/BCN exerts the best catalytic effect on the NRA reaction. The NH3 production rate reached 12.71 mg h- mgcat.-1 at -1.0 V vs. RHE. Faraday efficiency reached 91.79 %, which can be attributed to the more uniform distribution of the nanoparticles. Furthermore, Pd/BCN exhibited high cycling stability and resistance to ionic interference. Moreover, the density functional theory calculations indicated that small and well -distributed Pd nanoclusters in the BCN matrix have a large active surface area and promote the catalytic process. This study provides a new strategy to design catalysts for green ammonia synthesis.
24.	Weng, Taoyu, et al. (författare) Enhancing the Operability of Photoexcitation-Controlled Aggregation-Induced Emissive Molecules in the Organic Phase 2021 Ingår i: The Journal of Physical Chemistry Letters. - : American Chemical Society. - 1948-7185. ; 12:26, s. 6182-6189 Tidskriftsartikel (refereegranskat)abstract Controllable aggregation-induced emission luminogens (AIEgens) by photoexcitation can be conducted within a single solvent, thus opening new opportunities for preparing and processing smart materials. However, undesired side-reactions like photooxidation that can easily occur in the organic phase remain, limiting their applications. To enhance the operability of photoexcitation-controlled AIEgens (to specifically produce a phosphorescence characteristic) in the organic phase, in this work, we employ a typical prototype, hexathiobenzene, usually as the specific phosphorescent group, and investigate a series of physical and chemical factors, such as light intensity, dissolved oxygen content, and solvent polarity, to explore ways to control the photoexcitation-controllable AIEgens against the impurities from side-reactions. An organogel strategy was also developed to minimize interference factors and improve the practical application ability. We believe that the presented results provide new insights into the further development of the photoexcitation-based functional materials and the promotion of their practical usage.
25.	Xu, Xiaoran, et al. (författare) Applications of Boron Cluster Supramolecular Frameworks as Metal-Free Chemodynamic Therapy Agents for Melanoma 2024 Ingår i: Small. - : John Wiley & Sons. - 1613-6810 .- 1613-6829. ; 20:4 Tidskriftsartikel (refereegranskat)abstract Chemodynamic therapy (CDT) is a highly targeted approach to treat cancer since it converts hydrogen peroxide into harmful hydroxyl radicals (OH & BULL;) through Fenton or Fenton-like reactions. However, the systemic toxicity of metal-based CDT agents has limited their clinical applications. Herein, a metal-free CDT agent: 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT)/ [closo-B12H12]2-(TPT@ B12H12) is reported. Compared to the traditional metal-based CDT agents, TPT@B12H12 is free of metal avoiding cumulative toxicity during long-term therapy. Density functional theory (DFT) calculation revealed that TPT@B12H12 decreased the activation barrier more than 3.5 times being a more effective catalyst than the Fe2+ ion (the Fenton reaction), which decreases the barrier about twice. Mechanismly, the theory calculation indicated that both [B12H12]-& BULL; and [TPT-H]2+ have the capacity to decompose hydrogen into 1O2, OH & BULL;, and O2-& BULL;. With electron paramagnetic resonance and fluorescent probes, it is confirmed that TPT@B12H12 increases the levels of 1O2, OH & BULL;, and O2-& BULL;. More importantly, TPT@B12H12 effectively suppress the melanoma growth both in vitro and in vivo through 1O2, OH & BULL;, and O2-& BULL; generation. This study specifically highlights the great clinical translational potential of TPT@B12H12 as a CDT reagent. 2,4,6-Tri(4-pyridyl)-1,3,5-triazine (TPT)/ [closo-B12H12]2-(TPT@B12H12), a metal-free chemodynamic therapy (CDT) agent, decreases the activation barrier more than 3.5 times being a more effective catalyst than the Fe2+ ion (the Fenton reaction), which decreases the barrier about twice. More importantly, TPT@B12H12 effectively suppress the melanoma growth both in vitro and in vivo through 1O2, OH & BULL;, and O2-& BULL; generation. image
26.	Xu, Xiaoran, et al. (författare) Synthesis of iron-boride/carbon-nitride composites and their applications in chemodynamic therapy 2024 Ingår i: Journal of Colloid and Interface Science. - : Elsevier. - 0021-9797 .- 1095-7103. ; 658, s. 276-285 Tidskriftsartikel (refereegranskat)abstract Chemodynamic therapy (CDT) is an emerging treatment strategy that inhibits tumor growth by catalyzing the generation of reactive oxygen species (ROS), such as hydroxyl radicals (center dot OH), using specific nanomaterials. Herein, we have developed a new class of iron-based nanomaterials, i.e., iron-based borides (FeB), using the superchaotropic effect of a boron cluster (closo-[B12H1212-) and organic ligands, followed by high-temperature calcination. Experimental data and theoretical calculations revealed that FeB nanoparticles exhibit a Fentonlike effect, efficiently decomposing hydrogen peroxide into center dot OH and thus increasing the concentration of ROS. FeB nanomaterials demonstrate excellent catalytic performance, efficiently generate ROS, and exert significant antitumor effects in cell experiments and animal models. Therefore, FeB nanomaterials have
27.	Zhao, Xue, et al. (författare) Copper confined in vesicle-like BCN cavities promotes electrochemical reduction of nitrate to ammonia in water 2021 Ingår i: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 9:41, s. 23675-23686 Tidskriftsartikel (refereegranskat)abstract Electrochemical methods to convert high-concentration nitrates present in sewage into high-value-added ammonia do not just alleviate the problem of environmental pollution but also provide less energy-intensive alternatives to the Haber-Bosch process. In this work, a metal-boron organic polymer precursor was annealed at high temperature to obtain copper nanoparticles encapsulated in a vesicle-like BCN matrix (BCN@Cu). In the electrochemical reduction of nitrate (E-NIRR), this species exhibited excellent catalytic activity. Specifically, the ammonia yields of BCN@Cu under applied potentials of -0.3 V, -0.4 V, -0.5 V, and -0.6 V versus the reversible hydrogen electrode were 271.1 mu mol h(-1) mg(cat.)(-1), 354.8 mu mol h(-1) mg(cat.)(-1), 435.6 mu mol h(-1) mg(cat.)(-1), and 576.2 mu mol h(-1) mg(cat.)(-1), respectively, and the corresponding Faraday efficiencies were 86.3%, 88.0%, 89.3%, and 88.9%. Isotope labeling experiments with (NO3-)-N-15 confirmed that the detected ammonia had originated from the electrochemical reduction of NO3- on the catalyst surface. Moreover, the E-NIRR activity of BCN@Cu remained high even after using it ten consecutive times or 20 h of continuous operation, suggesting the practicality of the industrial application of BCN@Cu. The presence of copper was key in determining BCN@Cus E-NIRR activity, while the presence of boron greatly improved its catalytic performance. Furthermore, density functional theory calculations indicated that BCN does not itself promote the reaction but rather assists the dispersion of Cu nanoparticles, thereby expanding the catalysts active surface area.
28.	Zhao, X., et al. (författare) Persistent radical pairs trigger nano-gold to highly efficiently and highly selectively drive the value-added conversion of nitroaromatics 2021 Ingår i: Chem Catalysis. - : Elsevier BV. - 2667-1107 .- 2667-1093. ; 1:5, s. 1118-1132 Tidskriftsartikel (refereegranskat)abstract The development of advanced catalyst materials capable of efficiently capturing solar energy to drive the beneficial conversion of chemicals is a key part of the blueprint for “liquid sunlight.” Here, highly dispersed ultrafine nano-Au (B/TPTH3@Au) was anchored in situ on B/TPTH3 formed by alternate cross-linking of closo-[B12H12]2− and protonated 2,4,6-tris(4-pyridyl)-1,3,5-triazine. B/TPTH3@Au is an outstanding heterogeneous photocatalyst that converts low-value-added nitroaromatics into high-value-added azoaromatics. Compared with the slow kinetics of previous catalysts, the time required for the conversion of nitroaromatics to azoaromatics driven by B/TPTH3@Au is reduced by at least 10 times. These improvements could be derived from the synergy between the carrier B/TPTH3 (as a stable radical pair) and the nano-gold, including continuous electron transport in the functional carrier B/TPTH3 and the anchoring of highly dispersed ultrafine nano-Au with a strong localized surface plasmon resonance effect.
29.	Zhao, Xue, et al. (författare) Simultaneous anchoring of Ni nanoparticles and single-atom Ni on BCN matrix promotes efficient conversion of nitrate in water into high-value-added ammonia 2022 Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 433:Part 2 Tidskriftsartikel (refereegranskat)abstract Electrochemical synthesis of ammonia driven by clean energy is expected to realize the supply of ammonia for distributed production of industry and agriculture. Here, nickel nanoparticles and nickel in the form of single atoms were simultaneously anchored on the electrochemically active carrier BCN matrix through a structured domain strategy, which realized a high-efficiency, high-value-added, conversion of nitrate in sewage. Specifically, the electrochemical nitrate reduction reaction (NIRR) driven by BCN@Ni in alkaline media achieves an ammonia yield rate as high as 2320.2 μg h−1 cm−2 (at −0.5 V vs RHE), and Faraday efficiency as high as 91.15% (at −0.3 V vs RHE). Even in neutral and acidic media, the ammonia yield rates of NIRR driven by BCN@Ni are as high as 1904.2 μg h−1 cm−2 and 2057.4 μg h−1 cm−2, respectively (at −0.4 V vs RHE). The 15NO3- isotope labeling experiment verified that the recorded ammonia all came from the electrochemical reduction of NO3– on BCN@Ni. Density functional theory (DFT) calculations show that both nano-Ni and single-atom Ni in BCN@Ni have the ability to electrochemically convert NO3– into NH3, and that the addition of BCN can further promote the NIRR on Ni.
30.	Zhao, Xue, et al. (författare) Two-dimensional BCN matrix inlaid with single-atom-Cu driven electrochemical nitrate reduction reaction to achieve sustainable industrial-grade production of ammonia 2021 Ingår i: APPLIED MATERIALS TODAY. - : Elsevier. - 2352-9407. ; 25 Tidskriftsartikel (refereegranskat)abstract Electrochemical methods have been proven to effectively eliminate nitrates in sewage and convert them into high value-added ammonia products. Here, after annealing treatment of metal boron cluster organic polymers formed by the combination of 1,10-phenanthroline, Cu2+ and closo-[B12H12](2)(-), a Cu single-atom doped BCN (B-doped CN) with a diamond-shaped nanosheet structure was obtained. In the electrochem-ical reduction reaction of nitrate, BCN-Cu exhibits excellent catalytic activity, specifically: 1) the ammonia yield rate reached as high as 498.85 mu g h(-1) cm(-2), 1047.14 mu g h(-1) cm(-2), 1900.07 mu g h(-1) cm(-2) and 3358.74 mu g h(-1) cm(-2) at -0.3 V, -0.4 V, -0.5 V and -0.6 V vs reversible hydrogen electrode, respectively, and Faradaic efficiency is 95.90%, 97.28%, 98.23% and 97.37%; 2) after repeated use of BCN-Cu 10 times or continuous operation for 16 h, the activity against electrochemical reduction reaction of nitrate anions is almost unchanged. The (NO3-)-N-15 isotopic labeling experiment proved that the detected NH3 comes from the reduction of NO3- on BCN-Cu. Control experiments show that the presence of Cu determines whether BCN-Cu has the possibility of catalyzing electrochemical reduction reactions of nitrate, and the presence of the B element enhances the catalytic activity of BCN-Cu. Density functional calculations indicate that in the water phase the process of reducing NO3- to NH3 on Cu-0 is an exothermic reaction, and that the adsorption process of NO3- on Cu-0 is the rate-determining step.

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