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

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(19)

Published: Feb. 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

Language: Английский

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Axially Chiral Nonbenzenoid Nanographene with Second Harmonic Generation Property

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(17), P. 12206 - 12214

Published: April 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.

Language: Английский

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Tunable 1D–2D Carbon Nanomaterials for Broadband and High-Performance Microwave Absorption via Ultrasonic Spray Ice Template

ACS Applied Materials & Interfaces, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 3, 2025

Polymer-based one- and two-dimensional (1D-2D) carbon nanomaterials are considered promising microwave-absorbing materials (MAMs) due to their high atomic utilization efficiency tunable microscopic/macroscopic morphology. The design of 1D-2D through a facile method meet the requirements advanced MAMs remains challenge. In this work, environmentally friendly processing ultrasonic spray ice template (USIT) is employed fabricate porous based on Kapton-type polyimide, which exhibit intriguing morphology both 1D nanowires 2D nanosheets. Under subsequent carbonization at 700 800 °C, obtained inherit original Furthermore, or nanomorphology can be readily controlled by adjusting concentration precursor solution. For samples fabricated with lower concentrations (0.1%), nanowire structures predominant. Interconnected conductive networks heterogeneous interfaces formed intertwining stacking nanowires, thereby enhancing conductivity loss. Additionally, abundant structure provides an effective channel for electromagnetic wave entrance, significantly improving impedance matching ability. results show that nanowire-dominated (700 °C carbonization) excellent microwave absorption performance. reflection loss minimum (RLmin) -67.2 dB 8.1 GHz 4.65 mm, maximum bandwidth (<-10 dB) 7.7 3.03 mm. Exemplified MAMs, USIT strategy has broad prospects, providing enormous potential various practical applications bridging gap between polymer precursors 1D/2D nanomaterials.

Language: Английский

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Helically twisted nanoribbons via stereospecific annulative π-extension reaction employing [7]helicene as a molecular wrench

Chemical Science, Journal Year: 2024, Volume and Issue: 15(30), P. 11737 - 11747

Published: Jan. 1, 2024

Enantiopure [7]helicenes were utilized as molecular wrenches at the terminal K-regions of conjugated pyrene nanoribbon to achieve a 99.9% conformational population single-handed helical ribbon with an end-to-end twist 171°.

Language: Английский

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Chiral twisted molecular carbons: Synthesis, properties, and applications

Interdisciplinary materials, Journal Year: 2024, Volume and Issue: 3(4), P. 453 - 479

Published: May 11, 2024

Abstract In recent years, the precisely controlled synthesis of chiral twisted molecular carbons has emerged as a forefront topic in research carbon materials. Molecular refer to nanomaterials synthesized with precision at atomic level. Through rational design, rigid and stable structures can be synthesized. The exploration field is key fully understanding various configurations materials delving into relationship between structure design functionality. This review explores such nanographene, nanobelts, nanosheets, graphdiyne, etc. It emphasizes role photocyclization, Scholl reaction, Diels–Alder reactions achieving precise control discusses range innovative strategies. These strategies have led development structures, helical, propeller, Möbius strip configurations. introduction chirality, combined inherent exceptional optical properties nanocarbon materials, facilitated creation superior chiroptical performances. advancement driving applications fields optoelectronics optics.

Language: Английский

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Noncovalent Assembly Strategy for Efficient Synthesis of Dual‐Atom Catalysts

Advanced Functional Materials, Journal Year: 2024, Volume and Issue: 34(44)

Published: July 2, 2024

Abstract Diatomic catalysts (DACs), as a frontier of research on atomically dispersed catalysts, have drawn great attention, especially in electrocatalysis. However, most the current synthetic strategies for DACs suffer from poor efficiency and high cost. In this work, novel noncovalent assembly strategy is reported efficient synthesis DACs. By aid two kinds intermolecular force, π–π stacking Coulomb forces, pair metal complex ions with opposite electrical charges spontaneously loaded onto carbon substrate transformed into diatomic sites via thermal treatment. This approach shows universal feasibility broad spectrum (Ir–Fe, Pt–Fe, Pt–Co, Pt–Ni). To prove practical utility, as‐prepared PtFe‐DAC deployed oxygen reduction reaction catalyst, performing excellent activity half‐wave potential 0.935 V (vs RHE) 2.3 times higher turnover frequency than that single‐atomic Fe‐SAC. situ characterization theoretical calculation indicate adjacent Pt could endow moderate activation molecule Fe by lowering electron pairing energy well modulation d‐band center spin states centers propelling desorption intermediates.

Language: Английский

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A Deep‐Red Emissive Sulfur‐Doped Double [7]Helicene Photosensitizer: Synthesis, Structure and Chiral Optical Properties

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(45)

Published: Aug. 8, 2024

Doping of polycyclic conjugated hydrocarbons (PCHs) with sulfur atoms is becoming more and important as a means creating unique functional materials. Recently, thiophene-containing multiple helicenes have garnered enormous attention due to their intriguing electronic (chir)optical properties compared carbohelicenes. However, the efficient synthesis thiopyran-containing underlying doping mechanisms are rather unexplored. Herein, structural analysis double [7]helicene 3 reported. X-ray crystallographic reveals its dication C

Language: Английский

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Enantiomerically Pure Helical Bilayer Nanographenes: A Straightforward Chemical Approach

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 6, 2024

The semiconductor properties of nanosized graphene fragments, known as molecular nanographenes, position them exceptional candidates for next-generation optoelectronics. In addition to their remarkable optical and electronic features, chiral nanographenes exhibit high dissymmetry factors in circular dichroism circularly polarized luminescence measurements. However, the synthesis enantiomerically pure remains a significant challenge. Typically, these materials are synthesized racemic form, followed by separation enantiomers using high-performance liquid chromatography (HPLC). While effective, this method often requires expensive instrumentation, extensive optimization conditions, typically yields analytical quantities desired samples. An alternative approach is enantioselective nanographenes; however, date, only two examples have been documented literature. work, we present straightforward chemical resolution helical bilayer nanographenes. This enables effective scalable preparation while avoiding need HPLC. incorporation BINOL core into polyarene precursor facilitates diastereomers through esterification with camphorsulfonyl chloride. Following standard chromatographic column, hydrolysis group nanographene precursors. subsequent graphitization, achieved Scholl reaction, occurs an enantiospecific manner concomitant formation furan ring heterohelicene moiety. absolute configurations final enantiomers, P-oxa[9]HBNG M-oxa[9]HBNG, determined X-ray diffraction. Additionally, electrochemical, photophysical, chiroptical thoroughly evaluated.

Language: Английский

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Impact of helical elongation of symmetric oxa[n]helicenes on their structural, photophysical, and chiroptical characteristics

Chirality, Journal Year: 2024, Volume and Issue: 36(5)

Published: May 1, 2024

Abstract The adjustment of the main helical scaffold in helicenes is a fundamental strategy for modulating their optical features, thereby enhancing potential diverse applications. This work explores influence elongation (n = 5–9) on structural, photophysical, and chiroptical features symmetric oxa[ n ]helicenes. Crystal structure analyses revealed structural variations with extension, impacting torsion angles, pitch, packing arrangements. Through theoretical investigations using density functional theory (DFT) calculations, impact extension aromaticity, planarity distortion, heightened chiral stability were discussed. Photophysical studied through spectrophotometric analysis, insights gained time‐dependent DFT (TD‐DFT) calculations. Following resolution via high‐performance liquid chromatography (HPLC), properties both enantiomers oxa[7]helicene oxa[9]helicene investigated. A slight variation ]helicenes from [7] to [9] induced an approximately three‐fold increase dissymmetry factors biggest values of| g lum | (2.2 × 10 −3 ) compared to| |of (0.8 ), findings discussed supported by TD‐DFT

Language: Английский

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The Effects of Pore Defects in π‐Extended Pentadecabenzo[9]helicene

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(41)

Published: July 19, 2024

Abstract The introduction of precise pore defects into nanocarbon structures results in the emergence distinct physicochemical characteristics. However, there is a lack research on non‐planar chiral nanographene involving defects. Herein, we have developed two analogues to π‐extended pentadecabenzo[9]helicene ( EP9H ) containing embedded Each molecules, namely extended dodecabenzo[7]helicene ED7H ; 1 or nonabenzo[5]helicene EN5H 2 ), exhibits dual‐state emission. Significantly, value | g lum exceptionally high at 1.41×10 −2 solution and B CPL as 254 M −1 cm . In PMMA film, 8.56×10 −3 , powder it 5.00×10 This study demonstrates that molecules with exhibit emission properties while maintaining quite good luminescence properties. It was distinguished from aggregation‐caused quenching (ACQ) effect corresponding without defect. Incorporating also simplifies synthesis process enhances solubility resulting product. These findings suggest can be viable approach improve molecules.

Language: Английский

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