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

Azuperylene: The Nonalternant Isomer of Perylene

The isoelectronic isomer of perylene, hereafter called as azuperylene, has been prepared. Electronic structure analysis reveals that the new isomer can be described as a union of two antiparallel azulenes in which the azulene-type aromatic character of the starting azulene is partially retained. Four 2,8-dialkoxy (i.e., ethoxy, n-butoxy, n-hexyloxy, and n-octyloxy) functionalized derivatives of the new isomer core have been prepared. The solid-state structures of the new compounds have been resolved showing exceptional herringbone π-π stacking ideal for charge transport. Organic field-effect transistors on sublimated substrates display an excellent hole transport mobility up to 1.03 cm2 V-1 s-1 that largely surpasses that of perylene and reveals the great potential for charge transport of this new class of nonbenzenoid compounds.

Development of Aromatic Organic Materials for High-Performance Lithium-Ion Batteries: Strategies, Advances and Future Perspectives

Ever since lithium-ion batteries (LIBs) were successfully commercialized, aromatic compounds have attended every turning point in optimizing electrolytes, separators, and even electrode materials. However, the contribution of aromatic compounds has always been neglected compared to other advanced materials. At the same time, designing next-generation LIBs with higher flexibility, solid-state electrolytes, high energy density, and better Coulombic Efficiency (CE) has imposed stricter duties on aromatic components. In this review, we first systematically introduce the history of aromatic compounds that promote the development of LIBs. Typical applications of aromatic compounds in LIBs (e.g., separators, electrolytes, binders, and electrodes) are discussed in detail, and corresponding design characteristics are systematically analyzed. Finally, we suppose conjectures and prospects orientally designing aromatic compounds in the next generation LIBs.

One-Pot Transition-Metal-Free Synthesis of π-Extended Bipolar Polyaromatic Hydrocarbons

The development of straightforward synthetic methods for photoactive polycyclic aromatic hydrocarbons (PAHs) that avoid Pd-catalyzed or radical-based processes remains a challenge. Such methods are essential to reducing the cost and environmental impact of organic photodevices. In this work, we present a one-pot synthetic approach for creating novel bipolar PAHs with extended π-conjugation, which are not accessible via conventional Pd-catalyzed routes. Our cascade process operates exclusively under basic conditions, utilizing cesium carbonate and molecular sieves to facilitate the coupling of electron-deficient 4-fluoronaphthalene-1,8-dicarboximide with halogenated electron-rich moieties. This results in the regio- and chemoselective formation of new 6- and/or 5-membered conjugated rings via consecutive SNAr reactions, as confirmed through experimental and computational studies. The resulting PAHs exhibit strong emissive properties, with quantum yields ranging from 34 % to 99 %. This work provides a simple and efficient synthetic strategy for producing novel semiconducting materials, offering a new framework for designing bipolar PAHs with distinct optical characteristics.

Synthesis and characterizations of highly luminescent 5-isopropoxybenzo[rst]pentaphene

A benzo[rst]pentaphene (BPP) substituted by an isopropoxy group (BPP-OiPr) was synthesized in a facile manner. Its photophysical properties were investigated by UV-vis absorption and fluorescence spectroscopy in compassion to pristine BPP and its oxidation product, benzo[rst]pentaphene-5,8-dione (BPP-dione). BPP-OiPr exhibited a significantly enhanced photoluminescence quantum yield (PLQY), reaching 73% in comparison to pristine BPP (13%). BPP-dione, when compared to the parent BPP, also displayed improved absorption and emission from the first excited singlet (S1) state with a PLQY of 62% and an intramolecular charge-transfer character. The rod-like nano- to microcrystals as well as longer wires of these BPPs were also revealed by scanning electron microscopy. The intriguing optical properties of BPP and its derivatives may lead to their application as fluorophores.

Non-Covalent Self-Assembly Behaviors Based on Racemic Binaphthol Scaffolds

Understanding the fundamental mechanisms involved in the construction and organization of multi-scale structures is crucial for the design and manufacture of complex functional systems with long-range molecular arrangements. In this paper, a series of compounds have been synthesized using racemic binaphthols as the skeleton and a Suzuki coupling reaction for derivatization at the 6,6' positions, which resulted in various structures bearing different functional groups. Control over the self-assembly of these racemic binaphthol derivatives was successfully achieved by adjusting the types and positions of the substituents in the parent binaphthol compound, which revealed the key factors influencing the types of the non-covalent interactions and the self-assembly process. For example, the single-crystal structures of the resulting compounds indicated that assembly structures such as single helix and double helix based on non-traditional hydrogen bond motifs could be obtained, and fascinating non-covalent self-assembly structures such as molecular ladders and catenane discovered.

Facile Access to Phosphorus Ylide-fused Heteroarenes Possessing Tunable Optoelectronic Properties and High Nonlinear Optical Performances

We report here a novel family of ylidic P-heteroarenes (P1-P6), structurally featuring unique phosphonium cyclopentadienylide (P-Cp)-fused π-skeletons and synthetically prepared via an unexpected one-pot [2+3]/[3+3] phospha-annulation reaction. While the facile and modular synthesis allows the fine-tuning of their optical absorptions and redox properties, single-crystallographic and theoretical analysis of these P-heteroarenes further reveal that the fusion of P-Cp moiety leads to substantial intramolecular charge-separated features with high ylidic character values of up to 84 %. Benefitted from such dipolar structures, these P-heteroarenes not only allows stepwise electrophilic substitution reaction for further structural π-expansions, but also exhibit excellent nonlinear optical (NLO) responses and optical limiting (OL) performances comparable to or exceed those of C60. As a model compound, the persistent radical-anion salt of P5a was also prepared through chemical reduction, thus offering valuable insights into the electronic structures of reduced P-ylidic species. Our work not only established a highly efficient synthetic method toward new P-heteroarenes, but also provide fundamental understanding of those fused-ring ylidic P-heterocycles with promising NLO/OL applications.

Non-alternant Benzodifluoranthene Tetraimides from 7,8,9,10-Fluoranthene Diimides: Synthesis, Structure, and Optical-Limiting Properties

A novel tetraimide-functionalized non-alternant π-conjugated system, namely, benzodifluoranthene tetraimides (BDFTI), has been designed and synthesized through highly efficient UV-photocyclization of a vinyl-bridged fluoranthene diimide dimer (i. e., FDI-V). The synthesis of FDI-V starts from a straightforward three-step route to produce novel 7,8,9,10-fluoranthene diimide (FDIs) building-blocks, followed by nearly complete bromination and then Stille-coupling reaction to give the desired dimer. The analysis by X-ray crystallography confirms a near-coplanar geometry for FDIs, while BDFTI shows a U-shaped and distorted backbone configuration proven by theoretical optimizations. The tetraimide BDFTI exhibits several advantages over the FDI cores, including an extended absorption band and a red-shift in photoluminescence spectra. This enhancement can be attributed to the presence of additional electron-deficient imide units, which promotes increased intramolecular charge transfer and improved electron affinity. All the imides show a local aromatic characteristic owing to the incorporation of pentagon rings in the π-frameworks. The fully fused BDFTI exhibits nonlinear optical properties as analyzed by the open-aperture Z-scan technique, demonstrating superior optical-limiting performance compared to vinyl-bridged FDI-V. The versatile UV-photocyclization chemistries provide a pathway for developing complex and unique multiimide-functionalized π-conjugated systems, paving the way for creating high-performance optical-limiting materials.

Direct Synthesis of K-Region Functionalized Polycyclic Aromatic Hydrocarbons via Twofold Intramolecular C-H/C-H Arylation

Functionalized polycyclic aromatic hydrocarbons (PAHs) are essential building blocks for the bottom-up fabrication of structurally uniform nanocarbons. Herein we report a simple and efficient synthetic method toward K-region hydroxy-functionalized PAHs via TEMPO-mediated twofold intramolecular C-H/C-H arylations of 1-biphenyl-2-yl-2-aryl-ethanone derivatives. This method achieves high yields and selectivity, synthesizing a variety of PAH frameworks, including pyrenes, chrysenes, benzo[c]phenanthrenes, and benzo[k]tetraphenes. Our results also demonstrate the potential of these compounds as valuable candidates for the selective construction of larger PAH structures.

Palladium-Catalyzed Annulation Reaction of Bay-Diiodinated Arenes with o-Chloroaromatic Carboxylic Acids to Access Polycyclic Aromatic Compounds

A palladium-catalyzed annulation reaction of bay-diiodinated arenes with o-chloroaromatic carboxylic acids was established. This approach enables the synthesis of a variety of polycyclic aromatic compounds, especially polyalkoxy-substituted polycyclic aromatic compounds, frequently found in discotic liquid-crystalline materials. The investigations indicate that the product 2,3,8,9,12,13-hexakis(hexyloxy)-5-azadibenzo[fg,op]tetracene demonstrates favorable room-temperature liquid-crystalline properties.

Dithio-Fused Boron Dipyrromethenes: Synthesis and Impact of S-Heteroaromatic Annulation Mode

Three dithio-fused boron dipyrromethenes (BODIPYs), DTFB-1, DTFB-2, and DTFB-3, in which symmetrically S-heteroaromatic ring units fused at [a], zigzag, and [b] bonds of the parent BODIPY core, respectively, were prepared from the facile and efficient post-functionalization of tetra-halogenated BODIPYs through Pd-catalyzed cyclization. Dithio-fusion at various positions of BODIPY effectively tunes their photophysical properties and single-crystal structural packing arrangements. The single-crystalline microribbons of DTFB-2 exhibit commendable hole mobilities in air, reaching up to 0.03 cm2 V-1 s-1.

Regio- and Diastereoselective Radical Dimerization Reactions for the Construction of Benzo[f]isoindole Dimers

This study presents a novel approach for synthesizing benzo[f]isoindole dimers, which involves cascade cyclization and oxidative radical dimerization. Our method allows for the formation of up to five carbon-carbon bonds in a single reaction, exhibiting remarkable diastereoselectivity and regioselectivity. The mechanism and regioselectivity were investigated through a combination of experiments and calculations.