Synthesis and Redox Properties of Pyrrole- and Azulene-Fused Azacoronene

Sasaki, Yoshiki; Takase, Masayoshi; Okujima, Tetsuo; Mori, Shigeki; Uno, Hidemitsu

doi:10.1021/acs.orglett.9b00515

Cited by 62 publications

(33 citation statements)

References 40 publications

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“…Based on the unique electronic and optical properties, azulene has recently been utilized as a building unit to synthesize functional πconjugated compounds. [33] The helicene 15 showed two reversible oxidation waves in the cyclic voltammogram. By oneelectron chemical oxidation with AgPF 6 , the PF 6 À salt of 15…”

Section: Cation Radicals Of Helicenesmentioning

confidence: 98%

Helicene Radicals: Molecules Bearing a Combination of Helical Chirality and Unpaired Electron Spin

2020

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Chiral helicenes that have helical π-conjugated frameworks comprised of ortho-fused aromatic rings have been intensively investigated for several decades owing to their attractive properties and high potential for a variety of applications. In contrast, studies concerning helicene radicals (open-shell helicenes) formed by redox reactions have been severely limited due to inherent high reactivity of organic radicals. However, open-shell helicenes possessing a combination of chirality and unpaired electron spin(s) delocalized on helical π-conjugated orbital(s) are promising for novel synergic magnetic functions. Recently, several kinds of isolable air-stable helicene radicals have been prepared to enable their detailed analysis of the crystal structures and physicochemical properties. This Minireview describes the recent advances and future prospects of organic-based helicene radicals categorized into three groups: 1) ionic radicals, 2) neutral radicals, and 3) diradicals.

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Section: Cation Radicals Of Helicenesmentioning

confidence: 98%

Helicene Radicals: Molecules Bearing a Combination of Helical Chirality and Unpaired Electron Spin

2020

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“…Sasaki et al. [ 85 ] designed azulene‐fused azacoronene ( 38 ) through oxidative coupling between pyrrole and the five‐carbon ring of azulene, which exhibited multistep reversible oxidations. They proved that the polymer possesses 22‐π‐electron conjugation.…”

Section: Fused Azulenes and Nanoribbonsmentioning

confidence: 99%

Azulene‐Based Molecules, Polymers, and Frameworks for Optoelectronic and Energy Applications

Huang

Zhao

et al. 2020

Small Methods

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has a large dipole moment of 1.08 D. [2] By contrast, naphthalene, which only contains two fused six-membered rings, has a dipole moment of 0 D. Azulene, which was discovered and named by Piesse in 1863, has attracted considerable interest since its discovery in petroleum exploitation. [3] In 1937, Plattner and Pfau published their pioneering report on the synthesis of azulene. [4] However, their method was not practical due to its low azulene yield. In the 1950s, Ziegler and Hafner formulated a highly efficient and practical method for synthesizing azulene and its derivatives. [5] Because azulene is difficult to synthesize and has a low natural abundance, research on azulene-based molecules and materials is less advanced relative to research on its isomer. Direct functionalization of 1-and/ or 3-positions is a common and effective method of producing azulene derivatives. However, direct functionalization of other positions is much harder, e.g., bromination of 6-and 1,3-positions, [6] nucleophilic addition to obtain 6-subsituted azulene, [7] borylation at 2-position, [8] arylation at the 2-position, [9] and so on. The electron distribution in the front-line molecular orbitals (MOs) must usually be considered when functionalizing azulene. Because of resonance delocalization, the oddnumbered position of azulene, which is electron-rich, easily reacts with electrophilic compounds. Among the odd-numbered azulene varieties, 1-and 3-azulene have the highest activity. [10] By Azulene has a considerably larger dipole moment than its isomer naphthalene; it also has unique physicochemical properties, including different reactivities on five-and seven-membered rings, a dark color, a narrow gap between the highest occupied molecular orbital and lowest unoccupied molecular orbital, and stimulus response. Although azulene was discovered more than 100 years ago, the use of azulene-based derivatives can be traced back to five centuries ago. Due to its unusual structure, azulene-based molecules and materials are widely used in various fields. However, studies on azulene-based materials have long been hindered by difficulties in the synthesis. Considerably fewer studies have been conducted on azulene-based derivatives than on naphthalene-based derivatives. This perspective paper mainly introduces recent reports on the synthesis of azulene-based aromatic molecules, conjugated polymers, and coordination polymers, in addition to azulene-based frameworks. The structure-property relationship, optoelectronic applications, and energy-related applications of azulene-based derivatives are reviewed, including their use in near-infrared absorption, organic field-effect transistors, organic solar cells, and microsupercapacitors.

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“…In 2019, Takase, Uno, and co-workers reported azulene-fused azacoronene analogue 190 ( Scheme 63 ) [ 100 ]. Suzuki–Miyaura cross-coupling reaction of bromopentafluorobenzene with the corresponding azulenylboronate, followed by the nucleophilic aromatic substitution with 3,4-diethylpyrrole, gave 2-azulenylpentapyrrolylbenzene 189 .…”

Section: Synthesis Of Azulene Derivatives Incorporated With Porphymentioning

confidence: 99%

Development of Heterocycle-Substituted and Fused Azulenes in the Last Decade (2010–2020)

Shoji

Okujima

Ito

2020

IJMS

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Azulene derivatives with heterocyclic moieties in the molecule have been synthesized for applications in materials science by taking advantage of their unique properties. These derivatives have been prepared by various methods, involving electrophilic substitution, condensation, cyclization, and transition metal-catalyzed cross-coupling reactions. Herein, we present the development of the synthetic methods, reactivities, and physical properties for the heterocycle-substituted and heterocycle-fused azulenes reported in the last decade.

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Synthesis and Redox Properties of Pyrrole- and Azulene-Fused Azacoronene

Cited by 62 publications

References 40 publications

Helicene Radicals: Molecules Bearing a Combination of Helical Chirality and Unpaired Electron Spin

Helicene Radicals: Molecules Bearing a Combination of Helical Chirality and Unpaired Electron Spin

Azulene‐Based Molecules, Polymers, and Frameworks for Optoelectronic and Energy Applications

Development of Heterocycle-Substituted and Fused Azulenes in the Last Decade (2010–2020)

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