Stereoselective Chiral Molecular Carbon Imides Featuring 12‐Fold [5]helicenes Around Four Cores**

Liu, Guogang; Liu, Yujian; Zhao, Chengxi; Li, Yan; Wang, Zhaohui; Tian, He

doi:10.1002/anie.202214769

Cited by 9 publications

(4 citation statements)

References 58 publications

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“…Until now, only a limited number of molecular systems featuring multiple chiral centers has been explored. Representative examples encompass (I) planar chiral [2.2]paracyclophane oligomers, , (II) axial chiral arene-entwined double π-helices embedded by cyclooctatetraene (COT), , (III) helical nanoribbon arrays characteristic of perylene diimide (PDI) and [6]helicene substructures, − and (IV) 2D helical nanographenes incorporating PDI and [5]helicene substructures. − In these systems, gradually enhanced Cotton effects (Δε) have always been observed as the number of chiral subunits increases; in particular, the longest helicene nanoribbon has achieved an augmented Δε up to 1920 M –1 cm –1 . Nevertheless, a comprehensive understanding and unveiling of the mechanism behind chirality propagation and dissymmetry amplification in both ground and excited states at the molecular level continues to remain elusive.…”

Section: Introductionmentioning

confidence: 99%

Highly Luminescent Chiral Double π-Helical Nanoribbons

Liu,

Li,

Wang

et al. 2024

J. Am. Chem. Soc.

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Unveiling the mechanism behind chirality propagation and dissymmetry amplification at the molecular level is of significance for the development of chiral systems with comprehensively outstanding chiroptical performances. Herein, we have presented a straightforward Cu-mediated Ullmann homocoupling approach to synthesize perylene diimide-entwined double π-helical nanoribbons encompassing dimer, trimer, and tetramer while producing homochiral or heterochiral linking of chiral centers. A significant dissymmetry amplification was achieved, with absorption dissymmetry factors (|g abs |) increasing from 0.009 to 0.017 and further to 0.019, and luminescence dissymmetry factors (|g lum |) rising from 0.007 to 0.013 and eventually to 0.015 for homochiral double π-helical oligomers. The disparity of magnetic transition dipole moment (m) densities in homochiral and heterochiral tetramers by time-dependent density functional theory calculations confirmed that homochiral oligomerization can maximize the total m, which is favorable for achieving ever-increasing g factors. Notably, these double π-helices exhibited exceptional photoluminescence quantum yields (Φ PL ) ranging from 83 to 95%. The circularly polarized luminescence brightness (B CPL ) eventually reached a remarkable 575 M −1 cm −1 for the homochiral tetramer, which is among the highest values reported for chiral small molecules. This kind of linearly extended double πhelices offers a platform for a comprehensive understanding of the mechanism behind chirality propagation and dissymmetry amplification.

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Section: Introductionmentioning

confidence: 99%

Highly Luminescent Chiral Double π-Helical Nanoribbons

Liu,

Li,

Wang

et al. 2024

J. Am. Chem. Soc.

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“…12). 76 The synthetic strategy for preparation involved a series of Suzuki–Miyaura couplings and ring-closing photocyclic aromatization steps, and the final structure 62 displayed excellent solubility and air stability. Although there were 256 possible stereoisomers (or 128 possible pairs of enantiomers) that could have formed from the many overlapping PDI units, theoretical calculations and extensive NMR experiments seemed to suggest that only one pair was actually produced, specifically the (3 M ,3 M ,3 M ,3 M ) and (3 P ,3 P ,3 P ,3 P ) enantiomers (where 3 M = MMM and 3 P = PPP ).…”

Section: Helicenesmentioning

confidence: 99%

New advances in chiral nanographene chemistry

Anderson,

Gois,

Chalifoux

2023

Org. Chem. Front.

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“…Figure involves several triple helicenes including triple [5]helicene (TPH), corannulene cyclotrimer (CCT), hexabenzotriphenylene (HBT), benzannulated decacyclenes (BDCs), and triphenylene hexamide (TPHI) . Except for the CCT perturbed by bowl-shaped moieties, all other triple helicenes have C 3 - or D 3 -symmetric propeller-type structures arranged into their lowest-energy forms.…”

Section: Introductionmentioning

confidence: 99%

Highly Distorted Multiple Helicenes: Syntheses, Structural Analyses, and Properties

et al. 2023

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A series of hexapole helicenes (HHs) and nonuple helicenes (NHs) were prepared from 1,3,5-tris[2-(arylethynyl)phenyl]benzene through two steps, namely, iodocyclization and subsequent palladium-catalyzed annulation with ortho-bromoaryl carboxylic acids. The crucial advantages of this synthetic method are the facile introduction of substituents, high regioselectivity, and efficient backbone extension. Three-dimensional structures of three C 1 -symmetric HHs and one C 3 -symmetric NH were elucidated using X-ray crystallography. Unlike most conventional multiple helicenes, the HHs and NHs investigated herein possess a unique structural feature where some double helical moieties share a terminal naphthalene unit. Chiral resolution of a HH and an NH was successfully achieved, and the enantiomerization barrier (ΔH ‡ ) of the HH was experimentally determined to be 31.2 kcal/mol. A straightforward method for predicting the most stable diastereomer was developed based on density functional theory calculations and structural considerations. It was found that the relative potential energies (ΔH r s) of all diastereomers for two HHs and one NH can be obtained using minimal computational effort to analyze the types, helical configurations, numbers, and ΔH (MP−MM) s [= H(M,P/P,M) − H(M,M/P,P)] of the double helicenyl fragments.

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Stereoselective Chiral Molecular Carbon Imides Featuring 12‐Fold [5]helicenes Around Four Cores**

Cited by 9 publications

References 58 publications

Highly Luminescent Chiral Double π-Helical Nanoribbons

Highly Luminescent Chiral Double π-Helical Nanoribbons

New advances in chiral nanographene chemistry

Highly Distorted Multiple Helicenes: Syntheses, Structural Analyses, and Properties

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