B,N‐Embedded Hetero[9]helicene Toward Highly Efficient Circularly Polarized Electroluminescence

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(18)

Опубликована: Фев. 21, 2024

The intrinsic helical π-conjugated skeleton makes helicenes highly promising for circularly polarized electroluminescence (CPEL). Generally, carbon undergo low external quantum efficiency (EQE), while the incorporation of a multi-resonance thermally activated delayed fluorescence (MR-TADF) BN structure has led to an improvement. However, reported B,N-embedded all show dissymmetry factors (g

Язык: Английский

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Design and enantioselective synthesis of 3D π-extended carbohelicenes for circularly polarized luminescence

Nature Synthesis, Год журнала: 2024, Номер 3(6), С. 774 - 786

Опубликована: Апрель 19, 2024

Язык: Английский

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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

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Nonalternant Nanographenes Containing N-Centered Cyclopenta[ef]heptalene and Aza[7]Helicene Units

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(23), С. 16161 - 16172

Опубликована: Май 9, 2024

Introducing helical subunits into negatively curved π-systems has a significant effect on both the molecular geometry and photophysical properties; however, synthesis of these embedded with nonbenzenoid remains challenging due to high strain deriving from curvature helix. Here, we report family nonalternant nanographenes containing nitrogen (N)-doped cyclopenta[ef]heptalene unit. Among them, CPH-2 CPH-3 can be viewed as hybrids benzoannulated aza[7]helicene. The crystal structures revealed saddle for CPH-1, saddle-helix hybrid CPH-2, twist-helix CPH-3. Experimental measurements theoretical calculations indicate that moieties in CPHs undergo flexible conformational changes at room temperature, while aza[7]helicene subunit exhibits dramatically increased racemization energy barrier (78.2 kcal mol–1 143.2 CPH-3). combination lone electron pairs N-doped unit twisted helix fragments results rich photophysics distinctive fluorescence phosphorescence CPH-1 similar Both enantiopure display distinct circular dichroism (CD) signals UV–vis range. Notably, compared reported fully π-extended nanographenes, excellent chiroptical properties |gabs| value 1.0 × 10–2 |glum| 7.0 10–3; values are among highest nanographenes.

Язык: Английский

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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

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bay/ortho-Octa-substituted Perylene: A Versatile Building Block toward Novel Polycyclic (Hetero)Aromatic Hydrocarbons

Accounts of Chemical Research, Год журнала: 2024, Номер 57(5), С. 763 - 775

Опубликована: Фев. 22, 2024

ConspectusPolycyclic (hetero)aromatic hydrocarbons (PAHs) have emerged as a focal point in current interdisciplinary research, spanning the realms of chemistry, physics, and materials science. Possessing distinctive optical, electronic, magnetic properties, these π-functional exhibit significant potential across diverse applications, including molecular electronic devices, organic spintronics, biomedical functions, among others. Despite extensive documentation various PAHs over decades, efficient precise synthesis π-extended remains formidable challenge, hindering their broader application. This challenge is primarily attributed to intricate often elusive nature synthesis, compounded by issues related low solubility unfavored stability.The development π-building blocks that can be facilely modularly transformed into π-frameworks constitutes potent strategy for creation novel PAH materials. For instance, based on classic perylene diimide (PDI) unit, researchers such Würthner, Wang, Nuckolls successfully synthesized plethora structurally PAHs, well numerous other However, until now availability versatile building still severely limited, especially those simultaneously having facile preparation process, adequate solubilizing groups, favored material stability, critically, rich possibilities structural extension spaces.In this Account, we present an overview our invention highly bay-/ortho-octa-substituted block, designated Per-4Br, construction series scaffolds with tailor-made structures optoelectronic properties. First, starting brief discussion challenges associated bottom-up rationalize key features Per-4Br enable access new molecules its ease large-scale preparation, stability solubility, multiple flexible reaction sites, comparison PDI motif. Then, showcase rational design sophisticated body neutral or charged, closed- open-shell, curved, planar via controlled annulative π-extensions different directions peripheral, diagonal, dimensions skeleton. In part, fundamental structure–property relationships between conformations, structures, self-assembly behaviors unique physiochemical properties unusual open-shell ground states, global aromaticity, state-associated/stimuli-responsive activity, charge transport characteristics will emphatically elaborated. Finally, offer perspective continued advancement which, posit, may stimulate heightened research interest motifs typified consequently catalyzing further progress realm

Язык: Английский

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Axially Chiral Nonbenzenoid Nanographene with Second Harmonic Generation Property

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(17), С. 12206 - 12214

Опубликована: Апрель 18, 2024

Chiral nanographenes (NGs) have garnered significant interest as optoelectronic materials in recent years. While helically chiral NGs been extensively studied, axially only witnessed limited examples, with no prior reports of nonbenzenoid NGs. Herein we report an nanographene featuring six pentagons and four heptagons. This compound, denoted 2, was efficiently synthesized via efficient Pd-catalyzed aryl silane homocoupling reaction. The presence two bulky 3,5-di-tert-butylphenyl groups around the axis connecting PAH (AHR) segments endows 2 atropisomeric chirality high racemization energy barrier, effectively preventing both R- S-enantiomers at room temperature. Optically pure R-2 S-2 were obtained by HPLC separation, they exhibit circular dichroism (CD) activity wavelengths up to 660 nm, one longest CD responses reported for Interestingly, racemic forms a homoconfiguration π-dimer crystal lattice, belonging I222 space group. Consequently, this unique structure renders crystals second harmonic generation (SHG) response, distinguishing it from all benzenoid Moreover, also SHG-CD properties.

Язык: Английский

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Benzo-Extended Heli(aminoborane)s: Inner Rim BN-Doped Helical Molecular Carbons with Remarkable Chiroptical Properties

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(32), С. 22600 - 22611

Опубликована: Авг. 5, 2024

Atomically precise synthesis of three-dimensional boron-nitrogen (BN)-based helical structures constitutes an undeveloped field with challenges in synthetic chemistry. Herein, we synthesized and comprehensively characterized a new class molecular carbons, named benzo-extended [n]heli(aminoborane)s (

Язык: Английский

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Helical Nanographenes Bearing Pentagon‐Heptagon Pairs by Stepwise Dehydrocyclization

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(20)

Опубликована: Март 6, 2024

The incorporation of pentagon-heptagon pairs into helical nanographenes lacks a facile synthetic route, and the impact these on chiroptical properties remains unclear. In this study, method for stepwise construction in by dehydrogenation [6]helicene units was developed. Three containing were synthesized characterized using approach. A wide variation molecular geometries photophysical observed, with changes length structures introduction pairs. embedded reduced oxidation potential nanographenes. high isomerization energy barriers enabled chiral resolution helicene enantiomers. Chiroptical investigations revealed remarkably enhanced circularly polarized luminescence dissymmetry factors an increasing number

Язык: Английский

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Recent Advances of Chiral Isolated and Small Organic Molecules: Structure and Properties for Circularly Polarized Luminescence

Chemistry - An Asian Journal, Год журнала: 2024, Номер 19(9)

Опубликована: Март 7, 2024

Abstract This paper explores recent advancements in the field of circularly polarized luminescence (CPL) exhibited by small and isolated organic molecules. The development application CPL molecule are systematically reviewed through eight different chiral skeleton sections. Investigating intricate interplay between molecular structure properties, aims at providing enlighting novel strategies for CPL‐based applications.

Язык: Английский

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