Dual-photofunctional organogermanium compound based on donor–acceptor–donor architecture

Nyga, Aleksandra; Kaihara, Takahito; Hosono, Takumi; Sipala, Massimiliano; Stachelek, Patrycja; Tohnai, Norimitsu; Minakata, Satoshi; Sousa, Leonardo Evaristo de; Silva, Piotr de; Data, Przemysław; Takeda, Yoshifumi

doi:10.1039/d2cc01568d

Cited by 15 publications

(10 citation statements)

References 23 publications

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“…The PXRD spectra of both Zn- p and Zn- o ground samples show no diffraction peaks, which indicates the amorphous structures of the ground samples. The PXRD experiments indicate that the change of intermolecular packing should account for the observed mechanochromic luminescence and modulated TADF properties upon grinding. − On the one hand, mechanical grinding destroys the ordered crystal structures, which would reduce the distances and improve the interaction between the carbazole group and the tpy ligand, red-shifting the exciplex emission. − On the other hand, the changes in distances and interactions between the carbazole groups and the tpy ligands would alter the Δ E ST values and kinetic processes of S 1 and T 1 states, changing the TADF properties of the exciplex emission.…”

Section: Resultsmentioning

confidence: 99%

Cationic Zinc(II) Complexes with Carbazole-Type Counter-Anions: Intracomplex Donor/Acceptor Pairs Affording Exciplexes with Thermally Activated Delayed Fluorescence

Zhang

Meng

2023

Inorg. Chem.

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Two cationic zinc(II) complexes with carbazole-type counter-anions, namely, [Zn(tpy)2]2+[CAZ-p-BF3 –]2 (Zn-p) and [Zn(tpy)2]2+[CAZ-o-BF3 –]2 (Zn-o), have been designed and synthesized, where tpy is 2,2′:6′,2″-terpyridine, CAZ-p-BF3 – is 4-((9H-carbazol-9-yl)phenyl)trifluoroborate, and CAZ-o-BF3 – is (2-(9H-carbazol-9-yl)phenyl)trifluoroborate. The complex cation [Zn(tpy)2]2+ (as the acceptor) and the carbazole-type counter-anion CAZ-p-BF3 – or CAZ-o-BF3 – (as the donor) form an intracomplex donor/acceptor pair. Single-crystal structures reveal that compared to Zn-p, Zn-o exhibits a stronger π–π stacking interaction between the carbazole group (as the donor unit) of the counter-anion and the tpy ligand (as the acceptor unit) of [Zn(tpy)2]2+ because of the different anchoring position of the BF3 – anion in the counter-anion. In a doped film, Zn-p and Zn-o afford an isolated exciplex formed between the carbazole group and the tpy ligand within the single complex, which gives green-yellow emission with a thermally activated delayed fluorescence (TADF) feature. In crystalline states, Zn-p and Zn-o afford exciplexes with blue emission centered at 468 nm and green-blue emission centered at 508 nm, respectively. The Zn-p crystalline sample shows a relatively large singlet–triplet energy gap (ΔE ST) (0.33 eV) and no TADF, whereas the Zn-o crystalline sample exhibits a small ΔE ST (0.06 eV) and distinct TADF, with a reverse intersystem crossing rate at 3.3 × 105 s–1. Zn-p and Zn-o both exhibit intriguing mechanochromic luminescence, with largely red-shifted (by over 70 nm) emission and modulated TADF properties upon mechanically grinding the crystalline samples. The work demonstrates that donor/acceptor pairs affording exciplexes can be formed within cationic metal complexes using counter-anions with donor nature, which opens a new avenue toward photo-active metal complexes with rich photophysical properties.

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Section: Resultsmentioning

confidence: 99%

Cationic Zinc(II) Complexes with Carbazole-Type Counter-Anions: Intracomplex Donor/Acceptor Pairs Affording Exciplexes with Thermally Activated Delayed Fluorescence

Zhang

Meng

2023

Inorg. Chem.

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“…[23][24][25][26] This unique feature makes TADF materials stimuli-responsive luminescent materials, which emission is sensitive to many stimuli, such as mechanical actions. The TADF materials showed MRL properties in many references in recent years, [27][28][29][30][31][32][33] which possessed high-contrast MRL switching in some cases. Nevertheless, their MRL properties are still unsatisfactory and molecular design strategy for TADF with high-contrast MRL properties is absent.…”

Section: Introductionmentioning

confidence: 99%

Y‐Shaped D‐A Type Thioxanthone Derivatives: Mechano‐Induced Thermally Activated Delayed Fluorescence and High‐Contrast Mechano‐Responsive Luminescence

Liao

et al. 2023

Chemistry A European J

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High-contrast mechano-responsive luminescence (MRL) materials with mechano-induced emission enhancement properties are fascinating candidates but few, for applications in rewritable media and recording devices.Here, an interesting design strategy of "Y-shape" donoracceptor (DÀ A) type molecules for high-contrast MRL materials was presented, based on substituted diphenylamine donor and planar acceptor. Interestingly, their DÀ A torsion angles are small in crystals but increased after ground, resulted in planar and twist intramolecular charge transfer (PICT and TICT) states, respectively. Therefore, high-contrast MRL switching between weak blue (450 nm) fluorescence and bright yellow (552 nm) thermally activated delayed fluorescence (TADF) can be achieved for compound TXDO (4,4'-dimeth-oxydiphenylamine donor), which photoluminescence quantum yield increased from 2.8 % to 54.7 % after ground. Most importantly, the two independent DÀ A conjugation dihedral angles are actually independent in the "Y-shape" molecules. Especially for compound TXDT (4,4'-di-tert-butyldiphenylamine donor), its crystal exhibited both PICT and TICT processes inside, resulted from the different dihedral angles of 11.8°and 35.5°, respectively. The TXDT crystal thus showed dual-peak emission, including both TICT fluorescence and PICT room-temperature phosphorescence. Therefore, this strategy of "Y-shape" DÀ A type molecules provide a new approach to design advanced luminescent materials with mechano-induced TADF feature, for high-contrast MRL and single-component white luminescence.

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“…21 Various nitrogen heterocycle acceptor cores have been successfully used in the design of new TADF materials, such as phenazines, quinoxalines, and pyridopyrazines, achieving high OLED efficiency. [22][23][24][25][26][27][28] The pyridopyrazine acceptor family displays high electronwithdrawing capabilities due to the presence of heterocyclic moieties containing a total of three nitrogen atoms in form of fused pyridine and pyrazine units, and can be attained with a simple synthetic approach. 29 Variation of donor moiety modifies the HOMO of the emitter, thus affecting its optical energy gap as well as the DE ST .…”

Section: Introductionmentioning

confidence: 99%

Multifunctional properties of D–A luminophores based on acenaphtopyrido[2,3-b]pyrazine core: photophysics, photochemistry, and efficient solution-processed OLEDs

Silva,

Decarli,

Espíndola

et al. 2023

J. Mater. Chem. C

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Dual-photofunctional organogermanium compound based on donor–acceptor–donor architecture

Abstract: A dual-photofunctional organogermanium compound based on a donor–acceptor–donor architecture that exhibits thermally activated delayed fluorescence and mechano-responsive luminochromism has been developed. The developed compound was successfully applied as an emitter...

Cited by 15 publications

References 23 publications

Cationic Zinc(II) Complexes with Carbazole-Type Counter-Anions: Intracomplex Donor/Acceptor Pairs Affording Exciplexes with Thermally Activated Delayed Fluorescence

Cationic Zinc(II) Complexes with Carbazole-Type Counter-Anions: Intracomplex Donor/Acceptor Pairs Affording Exciplexes with Thermally Activated Delayed Fluorescence

Y‐Shaped D‐A Type Thioxanthone Derivatives: Mechano‐Induced Thermally Activated Delayed Fluorescence and High‐Contrast Mechano‐Responsive Luminescence

Multifunctional properties of D–A luminophores based on acenaphtopyrido[2,3-b]pyrazine core: photophysics, photochemistry, and efficient solution-processed OLEDs

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