Circularly Polarized Luminescence in a Möbius Helicene Carbon Nanohoop**

Malinčík, Juraj; Gaikwad, Sudhakar; Mora‐Fuentes, Juan P.; Boillat, Marc-Aurèle; Prescimone, Alessandro; Häußinger, Daniel; Campaña, Araceli G.; Šolomek, Tomáš

doi:10.1002/ange.202208591

Cited by 11 publications

(10 citation statements)

References 64 publications

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“…Such compounds are prone to decomposition, either during the purification step after their synthesis or when stored, even at low temperatures, although such negative results are rarely reported in the literature. 1k 4d 11 Because of the individual drawbacks of the methyl and TES groups, we decided to search for an alternative protecting group that would (a) be easy to introduce, (b) would undergo stereoselective addition of ArLi to ketones A , (c) would be significantly more stable than TES, and (d) would be easy to remove to allow for a mild aromatization. Such a protecting group could introduce additional orthogonality to the synthesis of topological molecular nanocarbons.…”

Section: Table 1 Optimization Of the Reaction Condition...mentioning

confidence: 99%

Exploring Silyl Protecting Groups for the Synthesis of Carbon Nanohoops

2023

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Synthesis of topological molecular nanocarbons, such as hoop-like [n]cycloparaphenylenes, requires the use of spatially prearranged, masked aromatic units to overcome a build-up of large molecular strain in their curved structures. The used cyclohexadienyl units, however, contain tertiary alcohols that need protection to prevent side-reactions until the aromatization step that affords the final curved hydrocarbon. Although alkyl and triethylsilyl groups have been successfully applied as the protecting groups for this purpose, each suffers from specific drawbacks. Here, we explore the potential of sterically more crowded silyl groups, namely, tert-butyldimethylsilyl and triisopropylsilyl, to be used as alternatives to the established protection strategies. We show that tert-butyldimethylsilyl can be easily installed and deprotected under mild conditions displaying markedly higher resistance towards acids or bases than the triethylsilyl group used to this date. Unlike in the case of the alkyl groups, tert-butyldimethylsilyl also preserves a high stereoselectivity of the nucleophilic additions of ArLi. Furthermore, we demonstrate that both tert-butyldimethylsilyl and triethylsilyl groups can be installed on the same substrate and the latter be selectively deprotected. Thus, the high stereoselectivity, improved stability, and easy deprotection make tert-butyldimethylsilyl an excellent protecting group for the synthesis of carbon nanohoops.

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Section: Table 1 Optimization Of the Reaction Condition...mentioning

confidence: 99%

Exploring Silyl Protecting Groups for the Synthesis of Carbon Nanohoops

2023

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“…Inspired by these progresses, chemists are now moving on to synthesize even more challenging carbon nanostructures such as twisted and knotted molecules containing fully conjugated units. For example, a number of CPP-based Möbius strip-like [18][19][20] or mechanically interlocked molecules [21][22] have been reported. These structures mainly contain single-stranded CPP rings and thus the π-conjugation is limited due to the significant tortional angles between the 1,4-phenylene units.…”

Section: Main Textmentioning

confidence: 99%

Synthesis and chiral resolution of a triply twisted Möbius carbon nanobelt

Fan

Fukunaga

et al. 2022

Preprint

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Atomically precise synthesis of topological molecular carbons such as Möbius carbon nanobelts (MCNBs) represents a big challenge in synthetic organic chemistry as it requires careful control of both twist and strain. So far, only one singly twisted MCNB has been reported and the MCNBs with more than two twists remain unknown. Herein, we report the facile synthesis of the first triply twisted MCNB by rational design and via a synthetic route involving Suzuki coupling-mediated macrocyclization, Bi(OTf)3-catalyzed cyclization of vinyl ethers, followed by oxidative dehydrogenation. The Möbius band-like structure was unambiguously confirmed by X-ray crystallographic analysis, which also revealed coexistence of (P,P,P)- and (M,M,M)- enantiomers. The racemic isomers were resolved by chiral HPLC and the isolated enantiomers exhibited a large absorption dissymmetry factor (|gabs| = 0.019) according to circular dichroism spectroscopy, which can be explained by the fully conjugated structure and the desirable orientation of the electric and magnetic transition moments.

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“…To date, [n]helicenes and their analogs have been the subject of various studies on topological chemistry, supramolecular chemistry, asymmetric synthesis, and chiroptical properties. Recently, helicenes that display circularly polarized luminescence (CPL) [5–18] have gained attention because of their potential application in quantum‐based computing, spintronic systems, biological probes, and optoelectronic devices [19–26] . However, molecular design that precisely controls the excited state for remarkable CPL properties is not straightforward, and limited examples of CPL dyes based on rational approaches are available.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Chiroptical Properties of Binaphthyl‐Hinged [5]Helicenes

et al. 2023

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The synthesis, structure, and circularly polarized luminescence (CPL) of two types of shape‐persistent [5]helicenes, hinged by a tethered (−OCH2CH2O−) or untethered (−OCH3) binaphthyl, are reported. The binaphthyl tethering system facilitated an effective Wittig ring‐closure reaction in the synthesis of a macrocyclic precursor, which could be easily converted to the title compound via successive photocyclization. The tethered groups were replaced with untethered −OCH3 groups by treatment with BBr3 followed by methylation. Both compounds exhibited similar spectra, and their longest wavelength absorption band with a low intensity was attributed to the transition from HOMO to LUMO+1. These compounds exhibited CPL with higher dissymmetry factors glum values than unlocked helicenes.

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Circularly Polarized Luminescence in a Möbius Helicene Carbon Nanohoop**

Cited by 11 publications

References 64 publications

Exploring Silyl Protecting Groups for the Synthesis of Carbon Nanohoops

Exploring Silyl Protecting Groups for the Synthesis of Carbon Nanohoops

Synthesis and chiral resolution of a triply twisted Möbius carbon nanobelt

Synthesis and Chiroptical Properties of Binaphthyl‐Hinged [5]Helicenes

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