Twisted Arenes

Wang, Kung K.

doi:10.1007/128_2012_361

Cited by 8 publications

(5 citation statements)

References 96 publications

(134 reference statements)

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“…This demonstrated that the half-life of racemization (in toluene at 85 °C) is 24 h, and the racemization barrier was determined to be 31.0 kcal/mol at 298 K (Figures S13 and S14), which is in good agreement with the DFT calculations. Furthermore, the barrier for the helical inversion of 3c is remarkably high compared to 4,5-diphenylphenanthrene ( 1 ) (Δ G ⧧ = 22.1 kcal/mol, Figure S7), which is in line with reports that 4,5-bis(4-ethylphenyl)phenanthrene racemizes fairly rapidly in the solution above 50 °C . These results demonstrate that the twisted structure can enhance the axial chirality of the 4,5-diphenylphenanthrene subunit to create a shape-persistent macrocycle.…”

Section: Resultssupporting

confidence: 87%

Synthesis of Highly Twisted, Nonplanar Aromatic Macrocycles Enabled by an Axially Chiral 4,5-Diphenylphenanthrene Building Block

Yagi

Itami

2020

J. Am. Chem. Soc.

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The synthesis, structures, and properties of highly twisted, nonplanar aromatic macrocycles are described. These macrocycles with an approximately 90°twist angle were synthesized by an effective synthetic approach through a quadruple Suzuki− Miyaura coupling of 4,5-bisarylphenanthrene, a novel axially chiral nonplanar building block. By varying the cross-coupling partner as the spacer, a family of twisted macrocycles was synthesized, allowing for a systematic study of the effect of the spacer on macrocycle shape and photophysical properties. For example, a unique macrocyclic aggregation-induced emission (AIE) emitter with double tetraphenylethylene units as the spacers was readily synthesized. Furthermore, attributed to its conformationally restricted twisted structure, a 3,6-disubstituted-1,8-naphthalimide-incorporated macrocycle showed remarkable solvatofluorochromism with high fluorescence quantum yields. The excellent conformational stability of these macrocycles further enabled complete enantiomeric resolution and characterization. The racemization barrier of macrocycle was determined experimentally and supported by DFT calculations.

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Section: Resultssupporting

confidence: 87%

Synthesis of Highly Twisted, Nonplanar Aromatic Macrocycles Enabled by an Axially Chiral 4,5-Diphenylphenanthrene Building Block

Yagi

Itami

2020

J. Am. Chem. Soc.

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“…Bottom-up synthetic efforts toward well-defined, nanosized polycyclic aromatic hydrocarbons (PAHs) have captured the attention of chemists for many years because of their interesting optical and electronic properties, making them of interest for a host of applications . Compared to planar PAHs, nonplanar PAHs, such as circulenes, helicenes, and twisted acenes (as shown in Figure a), show a variety of fascinating molecular packing and structures due to their curved π-electron system. Helicene-like molecules are an interesting class of nonplanar PAHs that can be defined as ortho-fused PAHs, and the deviation of planarity is a result of intramolecular steric repulsion.…”

Section: Introductionmentioning

confidence: 99%

Chiral Peropyrene: Synthesis, Structure, and Properties

et al. 2017

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Herein we describe the synthesis, structure, and properties of chiral peropyrenes. Using p-terphenyl-2,2″,6,6″-tetrayne derivatives as precursors, chiral peropyrenes were formed after a 4-fold alkyne cyclization reaction promoted by triflic acid. Due to the repulsion of the two aryl substituents within the same bay region, the chiral peropyrene adopts a twisted backbone with an end-to-end twist angle of 28° that was unambiguously confirmed by X-ray crystallographic analysis. The chiral peropyrene products absorb and emit in the green region of the UV-visible spectrum. Circular dichroism spectroscopy shows strong Cotton effects (Δε = ±100 M cm at 300 nm). The Raman data shows the expected D-band along with a split G-band that is due to longitudinal and transversal G modes. This data corresponds well with the simulated Raman spectra of chiral peropyrenes. The chiral peropyrene products also display circularly polarized luminescence. The cyclization reaction mechanism and the enantiomeric composition of the peropyrene products are explained using DFT calculations. The inversion barrier for racemization was determined experimentally to be 29 kcal/mol and is supported by quantum mechanical calculations.

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“…The structure of these circulenes changes from a bowl ([5]circulene) to a plane ([6]circulene) and then finally to a saddle ([7]circulene). Theoretical studies indicated that the strain energy of these circulenes, using [6]circulene as a strain-free reference, follows the order: [7]circulene. [27] Although investigations of [4]circulene remain theoretical, tetrabenzo[4]circulene 16 has recently been acquired and identified as a bowl-shaped molecule.…”

Section: [8]circulenesmentioning

confidence: 99%

“…[1] Geometrically, planar PAs can be extended from acenes [2] via condensed arenes [3] or nanoribbons [4] to graphenes. [5] Deformation of a planar structure caused by steric crowding between substituents or an angular arrangement of the aromatic backbone generates twisted PAs [6] or helicenes, [7] respectively. Strain accumulation through the bridge connecting two nonadjacent positions on an aromatic ring makes a cyclophane containing a bent conformation.…”

Section: Introductionmentioning

confidence: 99%

Metal‐Catalyzed Cascade Reactions: Useful Synthetic Tools for the Preparation of Polycyclic Arenes

Feng

Hsieh

2014

The Chemical Record

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This account summarizes our recent efforts to synthesize numerous important and interesting polycyclic arenes under mild conditions using metal-catalyzed protocols. The palladium-catalyzed annulations of 2-iodobiphenyls or 2,2'-diiodobiphenyls with alkynes efficiently generated phenanthrene derivatives. This synthetic method was utilized as the key step when preparing phenanthrene-based alkaloids, tetrabenzopyracylenes and persubstituted [8]circulenes. Depending on whether a palladium or nickel catalytic system was used, 1-ethynyl-8-iodonaphthalenes underwent either a cyclodimerization or a nitrile-incorporated cascade reaction to produce zethrenes or pyrroloarenes, respectively. Methylene-bridged polyarenes are generated easily from 2-halo-2'-methylbiaryls through benzylic C-H bond activation and subsequent carbon-carbon bond formation, and palladium complexes promote the arylation of methylene carbons. The palladium-catalyzed annulations of 1,8-bis(arylethynyl)naphthalene derivatives with o-diiodoarenes yielded benzo[k]fluoranthene-based linear acenes, which can be applied to synthesize highly curved fragments of fullerenes. The self-reactions of diarylethynes formed either dihydrocyclopenta[a]indenes or octaaryl-1,3,5,7-octatetraenes through palladium-catalyzed cycloisomerization or nickel-catalyzed tetramerization, respectively. In the presence of palladium catalysts, the hydroalkynylation of terminal arylalkynes directly generated angular trimerization adduct dienynes.

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Twisted Arenes

Cited by 8 publications

References 96 publications

Synthesis of Highly Twisted, Nonplanar Aromatic Macrocycles Enabled by an Axially Chiral 4,5-Diphenylphenanthrene Building Block

Synthesis of Highly Twisted, Nonplanar Aromatic Macrocycles Enabled by an Axially Chiral 4,5-Diphenylphenanthrene Building Block

Chiral Peropyrene: Synthesis, Structure, and Properties

Metal‐Catalyzed Cascade Reactions: Useful Synthetic Tools for the Preparation of Polycyclic Arenes

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