Large-Size Linear and Star-Shaped Dihydropyrazine Fused Pyrazinacenes

Naphthalene diimide-Annulated Heterocyclic Acenes: Synthesis, Electrochemical and Semiconductor Properties and their Multifaceted Applications

Acenes and Naphthalene Diimides (NDIs) stand as distinguished classes of organic compounds, each possessing unique and intriguing properties that have garnered significant attention across various scientific disciplines. Acenes, characterized by linearly fused aromatic rings, have captivated researchers due to their diverse electronic structures and promising applications in materials science. On the other hand, NDIs, known for their distinctive electron-accepting properties, exhibit remarkable versatility in fields ranging from organic electronics, supramolecular to spin chemistry. In this review, we navigate through the fascinating realms of both acenes and NDIs before converging our focus on the highly diverse and distinctive subgroup of NDI-annulated heterocyclic acenes. This potentially important subgroup, has emerged as a subject of intense investigation, encapsulating their fascinating synthesis, optical and electrochemical characteristics, and multifaceted applications that span the realms of chemistry, physics, and biology. Through the exploration of their synthetic strategies, unique properties, and diverse applications, this review aims to offer a comprehensive understanding of the pivotal role played by NDI-based heterocyclic acenes in contemporary multidisciplinary research and technological innovation.

Azaarenes: 13 Rings in a Row by Cyclopentannulation

Cyclopentannulation was explored as a strategy to access large, stable azaarenes. Buchwald-Hartwig coupling of previously reported di- and tetrabrominated cyclopentannulated N,N'-dihydrotetraazapentacenes furnished stable azaarenes with up to 13 six-membered rings in a row and a length of 3.1 nm. Their optoelectronic and semi-conducting properties as well as their aromaticity were investigated.

π-Extended S-Heterocyclic Naphthoquinodimethane with Dual Diradical and Dipolar Character

The 2,6-naphthoquinodimethane (2,6-NQDM) containing S-heterocyclic molecule 6-S was synthesized, and its dual open-shell diradical and dipolar characters were revealed via both experimental and theoretical studies. Unlike the shorter p-quinodimethane (p-QDM)-containing analogue 5-S, which possesses a closed-shell ground state (y₀ = 0%) with small dipolar character, 6-S possesses enhanced dipolar character with a singlet diradical ground state (y₀ = 23.3%) and a thermally accessible triplet excited state (ΔE_ST = -4.13 kcal/mol). Despite this, it displays good stability (t_1/2 = 41days) under ambient air and light conditions due to its distinctive dipolar character and kinetic blocking of reactive sites.

Azaacenes Based Electroactive Materials: Preparation, Structure, Electrochemistry, Spectroscopy and Applications-A Critical Review

This short critical review is devoted to the synthesis and functionalization of various types of azaacenes, organic semiconducting compounds which can be considered as promising materials for the fabrication of n-channel or ambipolar field effect transistors (FETs), components of active layers in light emitting diodes (LEDs), components of organic memory devices and others. Emphasis is put on the diversity of azaacenes preparation methods and the possibility of tuning their redox and spectroscopic properties by changing the C/N ratio, modifying the nitrogen atoms distribution mode, functionalization with electroaccepting or electrodonating groups and changing their molecular shape. Processability, structural features and degradation pathways of these compounds are also discussed. A unique feature of this review concerns the listed redox potentials of all discussed compounds which were normalized vs. Fc/Fc⁺. This required, in frequent cases, recalculation of the originally reported data in which these potentials were determined against different types of reference electrodes. The same applied to all reported electron affinities (EAs). EA values calculated using different methods were recalculated by applying the method of Sworakowski and co-workers (Org. Electron. 2016, 33, 300-310) to yield, for the first time, a set of normalized data, which could be directly compared.

A Tetraindeno-Fused Bis(anthraoxa)quinodimethane with Nine Consecutively Fused Six-Membered Rings

A tetraindeno-fused bis(anthraoxa)quinodimethane RBR with nine consecutively fused six-membered rings in a row was synthesized. Its structure was confirmed by X-ray crystallographic analysis and NMR measurement. Compared with an unfused analogue ABA, the indeno fusion onto the zigzag edges not only enhanced the photostability but also dramatically tuned the electronic properties. Due to the existence of two rubicene units, RBR can also be readily reduced to form a radical anion and dianion.

Synthesis and Electronic Properties of Novel 5,7-Diazapentacene Derivatives

A route to the synthesis of novel 5,7-diazapentacenes and some preliminary studies on their properties is reported. A single crystal X-ray diffraction study of the dihexyl derivative showed it had formed a dimer during the analysis. The materials possess lower lying frontier orbitals than pentacene and may have potential applications in organic electronic devices. This synthetic method may be applicable to the synthesis of other azaacenes.

α-Ketocarbenium Ions Derived from Orthoquinone-Containing Polycyclic Aromatic Compounds

α-Ketocarbenium ions derived from synthesized orthoquinone-containing polycyclic aromatic compounds were generated in the presence of Brønsted acids such as sulfuric acid, trifluoromethanesulfonic acid, and fluorosulfonic acid. The prepared α-ketocarbenium ions were stabilized by conjugation of the aromatic moiety. In addition, unique absorption properties of the α-ketocarbenium ions were observed and identified on the basis of the calculated absorption spectra. It was suggested that the zigzag-shaped architecture stabilizes the newly discovered α-ketocarbenium ions derived from orthoquinone-containing polycyclic aromatic compounds.

Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds: Synthetic Routes, Properties, and Applications

Two-dimensionally extended, polycyclic heteroaromatic molecules (heterocyclic nanographenes) are a highly versatile class of organic materials, applicable as functional chromophores and organic semiconductors. In this Review, we discuss the rich chemistry of large heteroaromatics, focusing on their synthesis, electronic properties, and applications in materials science. This Review summarizes the historical development and current state of the art in this rapidly expanding field of research, which has become one of the key exploration areas of modern heterocyclic chemistry.

Different Strategies for the Stabilization of Acenes and Acene Analogues

Acenes, a type of polycyclic aromatic hydrocarbon containing linearly fused benzene rings, have received much attention from organic chemists, physical chemists, and materials scientists, due to their intriguing properties and potential applications in organic electronics. Without doubt, acene chemistry has been one of the hottest topics among the π-conjugated systems. However, poor stability of acenes is the prominent issue that limits their applications. In this personal account, we summarize different strategies developed in our group to construct and stabilize acenes and acene analogues. In addition, the unique properties and applications of some molecules will be discussed.

Fusing N-heteroacene analogues into one "kinked" molecule with slipped two-dimensional ladder-like packing

An unexpected "kinked" N-heteroacene with a slipped two-dimensional ladder-like packing feature is produced from the conventional condensation reaction. The as-obtained compound [2,2']bi(5,12-bis(TIPS)piperazin-3-one[2,3-b]phenazine) (2BPP) consists of two identical backbones (5,12-bis(TIPS)piperazin-3-one[2,3-b]phenazine), which are fused together through a C[double bond, length as m-dash]C double bond and two intramolecular H-bonds. A study on the charge carrier transport indicates that a 2BPP single crystal has a hole mobility up to 0.3 cm2 V-1 s-1, while theoretical calculations suggest that this compound might possess potential well-balanced ambipolar charge-transport characteristics.

Hexaazatriphenylene (HAT) derivatives: from synthesis to molecular design, self-organization and device applications

The creativity and inventiveness of chemists working with the 1,4,5,8,9,12-hexaazatriphenylene (HAT) building block is highlighted in this review.

Star-shaped carbazole-based BODIPY derivatives with improved hole transportation and near-infrared absorption for small-molecule organic solar cells with high open-circuit voltages

The star-shaped carbazole-based BODIPY derivatives, realizing strong near-infrared absorption and high hole transportation, have been developed for solution-processed small-molecule organic solar cells with high open-circuit voltages.

Isoquinolino[4,3,2-de]phenanthridine: synthesis and its use in 1,3-dipolar cycloadditions to form nitrogen-containing polyaromatic hydrocarbons

The synthesis of the novel azomethine ylide, isoquinolino[4,3,2-de]phenanthridine, and its use in 1,3-dipolar cycloaddition with various alkenes and alkynes to form the corresponding fused pyrrolidines and pyrroles is reported.

A concise method to prepare novel fused heteroaromatic diones through double Friedel–Crafts acylation

Different types of fused heteroaromatic diones have been successfully prepared through the concise intramolecular double Friedel–Crafts acylation strategy.

Synthesis and nonvolatile memory behaviors of dioxatetraazapentacene derivatives

Two novel heteroacenes 2,3,9,10-tetra(furan-2-yl)-1,4,8,11-tetraaza-6,13-dioxapentacene (FAOP, 1) and 2,3,9,10-tetra(thiophen-2-yl)-1,4,8,11-tetraaza-6,13-dioxapentacene (TAOP, 2) was successfully synthesized through a one-step condensation reaction, which have been fully characterized by (1)H NMR (nuclear magnetic resonance), (13)C NMR, FT-IR (Fourier transform infrared spectroscopy), and HRMS (high-resolution mass spectrum). The sandwich-structure memory devices have been fabricated using FAOP (1) and TAOP (2) as active layers, showing a typical bipolar resistive switching (RS) behavior in positive and negative regions.