Deep‐Blue Narrowband Hetero[6]helicenes Showing Circularly Polarized Thermally Activated Delayed Fluorescence Toward High‐Performance OLEDs

Advanced Materials, Год журнала: 2023, Номер 36(1)

Опубликована: Ноя. 14, 2023

Abstract Helicenes exhibit substantial potential as circularly polarized luminescence (CPL) active molecules. However, their application in organic light‐emitting diodes (CP‐OLEDs) is typically hindered by the challenge of integrating both high color purity and efficient triplet‐harvesting capability, particularly blue spectral region. Herein, a series hetero[6]helicene‐based emitters that strategically engineered through helical extension deep‐blue double‐boron‐based multiple resonance thermally activated delayed fluorescence (MR‐TADF) motif, introduced. Importantly, does not cause apparent structural deformation or perturb frontier molecular orbitals; thus, preserving emission MR‐TADF characteristics parent molecule. This approach also leads to reduced reorganization energy, resulting with narrower linewidth higher photoluminescence quantum yield. Further, motif enhances racemization barrier improved CPL performance dissymmetry factor values up 1.5 × 10 −3 . Exploiting these merits, devices incorporating chiral dopants demonstrate within Broadcast Service Television 2020 color‐gamut range, record external efficiencies (EQEs) 29.3%, have distinctive electroluminescence (CPEL) signals. Overall, authors’ findings underscore promising strategy for designing narrowband chiroptical materials advancing high‐definition displays.

Язык: Английский

---

B‐N Covalent Bond Embedded Double Hetero‐[n]helicenes for Pure Red Narrowband Circularly Polarized Electroluminescence with High Efficiency and Stability

Advanced Materials, Год журнала: 2023, Номер 36(5)

Опубликована: Сен. 12, 2023

Chiral B/N embedded multi-resonance (MR) emitters open a new paradigm of circularly polarized (CP) organic light-emitting diodes (OLEDs) owing to their unique narrowband spectra. However, pure-red CP-MR and devices remain exclusive in literature. Herein, by introducing B-N covalent bond lower the electron-withdrawing ability para-positioned B-π-B motif, first pair double hetero-[n]helicenes (n = 6 7) emitter peaking 617 nm with small full-width at half-maximum 38 high photoluminescence quantum yield ≈100% toluene is developed. The intense mirror-image CP light produced enantiomers characterized dissymmetry factors (g

Язык: Английский

---

A chiral spirofluorene‐embedded multiple‐resonance thermally activated delayed fluorescence emitter for efficient pure‐green circularly polarized electroluminescence

Aggregate, Год журнала: 2023, Номер 5(2)

Опубликована: Окт. 15, 2023

Abstract The simultaneous achievement of chiral multiple‐resonance thermally activated delayed fluorescence (MR‐TADF) emitters with narrowband and circularly polarized electroluminescence (CPEL) poses a challenge. Herein, MR‐TADF emitter, Spiro‐BNCz, embedding spirofluorene structure was developed separated, whose emission peaks at 528 nm in toluene Commission Internationale de L'Eclairage coordinates (0.26, 0.69). conjugation extension caused by sulfur substituted on B/N framework shortens the singlet‐triplet energy gap increases spin‐orbital coupling matrix element. Therefore, fast reverse intersystem crossing rate constant 2.8 × 10 6 s −1 high photoluminescence efficiency 92% film were achieved. organic light‐emitting diode (OLED) exhibits maximum external quantum 32.3%. Particularly, OLEDs based Spiro‐BNCz enantiomers show symmetric CPEL dissymmetry factors (| g EL |) ≈ −3 .

Язык: Английский

---

π-Extended Helical Multilayer Nanographenes with Layer-Dependent Chiroptical Properties

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(49), С. 26824 - 26832

Опубликована: Дек. 4, 2023

Helical nanographenes (NGs) have attracted increasing attention recently because of their intrinsic chirality and exotic chiroptical properties. However, the efficient synthesis extended helical NGs featuring a multilayer topology is still underdeveloped, layer-dependent properties remain elusive. In this study, we demonstrate modular synthetic strategy to construct series novel (1-3) with through consecutive Diels-Alder reaction regioselective cyclodehydrogenation from readily accessible phenanthrene-based precursors bearing ethynyl groups. The resultant exhibit bilayer, trilayer, tetralayer structures elongated π extension rigid backbones, as unambiguously confirmed by single-crystal X-ray or electron diffraction analysis. We find that photophysical these are notably influenced degree extension, which varies number layers, leading obvious redshifted absorption, fast rising molar extinction coefficient (ε), markedly boosted fluorescence quantum yield (Φf). Moreover, embedded [7]helicene subunits in result stable chirality, enabling both chiral resolution exploration Profiting good alignment electric magnetic dipole moments determined structure, excellent circular dichroism circularly polarized luminescence response unprecedented high CPL brightness up 168 M-1 cm-1, rendering them promising candidates for emitters.

Язык: Английский

---

Enhancing Chiroptical Responses in Helical Nanographenes via Geometric Engineering of Double [7]Helicenes

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(19)

Опубликована: Фев. 19, 2024

Helical nanographenes with high quantum yields and strong chiroptical responses are pivotal for developing circularly polarized luminescence (CPL) materials. Here, we present the successful synthesis of novel π-extended double [7]helicenes (ED7Hs) where two helicene units fused at meta- or para-position middle benzene ring, respectively, as structural isomers reported ortho-fused ED7H. The geometry these ED7Hs is clearly characterized by single-crystal X-ray analysis. Notably, this class exhibits bright exceeding 40 %. Through geometric regulation embedded [7]helicene from ortho-, to para-position, display exceptional amplification in responses. This enhancement evident a remarkable approximate fivefold increase absorbance dissymmetry factors (g

Язык: Английский

---

Boron‐ and Oxygen‐Doped π‐Extended Helical Nanographene with Circularly Polarised Thermally Activated Delayed Fluorescence

Chemistry - A European Journal, Год журнала: 2024, Номер 30(19)

Опубликована: Янв. 25, 2024

Abstract Helical nanographenes have garnered substantial attention owing to their finely adjustable optical and semiconducting properties. The strategic integration of both helicity heteroatoms into the nanographene structure, facilitated by a boron‐oxygen‐based multiple resonance (MR) thermally activated delayed fluorescence (TADF), elevates its photophysical chiroptical features. This signifies introduction an elegant category helical that combines (TADF) (CPL) In this direction, we report synthesis, optical, properties boron, oxygen‐doped Π‐extended nanographene. π‐extension induces distortion in DOBNA‐incorporated nanographene, endowing pair helicenes, ( P)‐ B2NG , M)‐ exhibiting circularly polarized luminescence with g lum −2.3×10 −3 +2.5×10 respectively. exhibited MR‐TADF lifetime below 5 μs, reasonably high quantum yield (50 %). Our molecular design enriches opens up new opportunities multidisciplinary fields.

Язык: Английский

---

Type‐I Photodynamic Therapy Induced by Pt‐Coordination of Type‐II Photosensitizers into Supramolecular Complexes

Chemistry - A European Journal, Год журнала: 2024, Номер 30(17)

Опубликована: Янв. 6, 2024

Platinum supramolecular complexes based on photosensitizers have garnered great interest in photodynamic therapy (PDT) due to Pt (II) centers as chemotherapeutic agents eliminate tumor cells completely, which greatly improve the antitumor efficacy of PDT. However, comparison precursor photosensitizer ligand, formed platinum typically exhibit inferior outcomes terms reactive oxygen species (ROS) generation. How boost ROS generation for enhanced PDT is an enticing yet highly challenging task. Here we report a Pt-coordination-based dimeric complex (Cz-BTZ-Py)

Язык: Английский

---

Supramolecular Polymerization as a Tool to Reveal the Magnetic Transition Dipole Moment of Heptazines

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(23), С. 15843 - 15849

Опубликована: Май 30, 2024

Heptazine derivatives have attracted significant interest due to their small S1-T1 gap, which contributes unique electronic and optical properties. However, the nature of lowest excited state remains ambiguous. In present study, we characterize transition heptazine by its magnetic dipole moment. To measure moment, flat must be chiroptically active, is difficult achieve for single molecules. Therefore, used supramolecular polymerization as an approach make homochiral stacks derivatives. Upon formation polymers, preferred helical stacking introduces circular polarization absorption fluorescence. The moments S1 ← S0 → are determined 0.35 0.36 Bohr magneton, respectively. These high values support intramolecular charge transfer from nitrogen carbon in further confirm degeneracy T1.

Язык: Английский

---

Crystallization-Induced Chirality Transfer in Conformationally Flexible Azahelicene Au(I) Complexes with Circularly Polarized Luminescence Activation

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(18), С. 12463 - 12472

Опубликована: Апрель 16, 2024

Flexible and twisted annulated π-systems exhibit numerous unique desirable features, owing to their ability display chirality. However, preventing racemization due the dynamic nature of chirality remains a challenge. One promising approach stabilize homochirality in such systems is transfer from chiral auxiliary moiety displaying Herein, we introduce new for stabilization conformationally flexible azahelicene species via crystallization-induced intermolecular Au(I) complexes featuring (dibenzo[

Язык: Английский

---

S-Shaped Helical Singlet Diradicaloid and Its Transformation to Circumchrysene via a Two-Stage Cyclization

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(15), С. 10321 - 10330

Опубликована: Апрель 3, 2024

Polycyclic hydrocarbons with diradical and polyradical characters usually display unique reactivities in ring-cyclization reactions. However, such reactions are rarely used to construct π-extended polycyclic aromatic hydrocarbons. Here, we describe the synthesis of an S-shaped doubly helical singlet diradicaloid compound its facile transformation into unprecedented circumchrysene via a two-stage ring cyclization, which includes: (1) eletrocylization from precursor (2) Scholl reaction. The reaction mechanism was investigated through

Язык: Английский

---