One‐Step Synthesis of [16]Helicene

Mori, Kanji; Murase, Takashi; Fujita, Makoto

doi:10.1002/ange.201502436

Cited by 81 publications

(29 citation statements)

References 44 publications

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“…[5][6][7] Like regular TD-DFT, it computes excited states from a (hybrid) Kohn-Sham reference state, but is orders of magnitude faster due to a reduced matrix eigenvalue problem size and drastic integral simplifications (monopole approximation) in the TD-DFT treatment. In the present work, we apply the sTD-DFT approach to compute the electronic circular dichroism (ECD) spectrum of a recently reported [16]helicene 8…”

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confidence: 99%

Electronic Circular Dichroism of [16]Helicene With Simplified TD‐DFT: Beyond the Single Structure Approach

Bannwarth

Seibert

2016

Chirality

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The electronic circular dichroism (ECD) spectrum of the recently synthesized [16]helicene and a derivative comprising two triisopropylsilyloxy protection groups was computed by means of the very efficient simplified time-dependent density functional theory (sTD-DFT) approach. Different from many previous ECD studies of helicenes, nonequilibrium structure effects were accounted for by computing ECD spectra on "snapshots" obtained from a molecular dynamics (MD) simulation including solvent molecules. The trajectories are based on a molecule specific classical potential as obtained from the recently developed quantum chemically derived force field (QMDFF) scheme. The reduced computational cost in the MD simulation due to the use of the QMDFF (compared to ab-initio MD) as well as the sTD-DFT approach make realistic spectral simulations feasible for these compounds that comprise more than 100 atoms. While the ECD spectra of [16]helicene and its derivative computed vertically on the respective gas phase, equilibrium geometries show noticeable differences, these are "washed" out when nonequilibrium structures are taken into account. The computed spectra with two recommended density functionals (ωB97X and BHLYP) and extended basis sets compare very well with the experimental one. In addition we provide an estimate for the missing absolute intensities of the latter. The approach presented here could also be used in future studies to capture nonequilibrium effects, but also to systematically average ECD spectra over different conformations in more flexible molecules. Chirality 28:365-369, 2016. © 2016 Wiley Periodicals, Inc.

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Electronic Circular Dichroism of [16]Helicene With Simplified TD‐DFT: Beyond the Single Structure Approach

Bannwarth

Seibert

2016

Chirality

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“…Such distorted ribbons could show enhanced rigidity compared to their presumably more easily undulating flat analogues.O ne extreme hypothetical example of an onflat fully kata-condensed ribbon is polyhelicene (Scheme 1, top), the spiral analogue of polyphenacene,the simplest stable flat arene ribbon. [2] Thes ynthesis of polyhelicene is synthetically very challenging because of the strong geometric constraints that are to be expected in the build-up and cyclization of cisoid diarylethene precursors with voluminous alreadyhelicenic aryl moieties.T hus,t he longest helicene obtained to date is [16]helicene, [3] published in 2015 after a4 0-year hiatus since the report of the synthesis of [14]helicene in 1975. [4] An alternative,s terically less demanding,a pproach would be the lateral fusion of helicenic segments of limited size,such as [6]-or [7]helicene segments.…”

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A Naphtho‐Fused Double [7]Helicene from a Maleate‐Bridged Chrysene Trimer

et al. 2017

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Perkin condensation of chrysenyl-6-acetic acid with chrysenylene-6,12-diglyoxylic acid followed by in situ esterification gives a bismaleate, whose conjugated stilbene moieties are efficiently shielded against intermolecular condensations and undergo iodine-catalyzed oxidative photocyclization in toluene without the need for high dilution. The concentration is limited by the low solubility of the flexible bismaleate at room temperature. The so-obtained double [7]helicene crystallizes in a nonchiral meso form. It is notably more soluble than its flexible precursor because it cannot fold to optimize π-π stacking.

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“…X-ray diffraction analysis showed that the novel nanographene 7ha has ac haracteristic conformation and packing structure in the solid state.C ompound 7ha consists of both planar and twisted aromatic regions derived from many fused rings and the remaining [5]helicene moiety (Figures 2b and c). [9] Ther ed-filled phenanthrene moiety is Figure 2. a,h) One-step successiveAPEX reactions of chrysene (1h)a nd 3,6-di-tert-butylphenanthrene (1i), and X-ray crystallographic structures of 7ha.…”

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Rapid Access to Nanographenes and Fused Heteroaromatics by Palladium‐Catalyzed Annulative π‐Extension Reaction of Unfunctionalized Aromatics with Diiodobiaryls

2017

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Efficient and rapid access to nanographenes and pextended fused heteroaromatics is important in materials science.H erein, we report ap alladium-catalyzed efficient one-step annulative p-extension (APEX) reaction of polycyclic aromatic hydrocarbons (PAHs) and heteroaromatics, producing various p-extended aromatics.I nt he presence of ac ationic Pd complex, triflic acid, silver pivalate,a nd diiodobiaryls,d iverse unfunctionalized PAHs and heteroaromatics were directly transformed into larger PAHs,n anographenes,a nd p-extended fused heteroaromatics in as ingle step.I nt he reactions that afford[ 5]helicene substructures, simultaneous dehydrogenative ring closures occur at the fjord regions to form unprecedented larger nanographenes.T his successive APEX reaction is notable as it stiches five aryl-aryl bonds by CÀHf unctionalization in as ingle operation. Moreover,t he unique molecular structures,c rystal-packing structures,photophysical properties,and frontier molecular orbitals of the thus-formed nanographenes were elucidated. p-Extended fused aromatics have recently received much

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One‐Step Synthesis of [16]Helicene

Cited by 81 publications

References 44 publications

Electronic Circular Dichroism of [16]Helicene With Simplified TD‐DFT: Beyond the Single Structure Approach

Electronic Circular Dichroism of [16]Helicene With Simplified TD‐DFT: Beyond the Single Structure Approach

A Naphtho‐Fused Double [7]Helicene from a Maleate‐Bridged Chrysene Trimer

Rapid Access to Nanographenes and Fused Heteroaromatics by Palladium‐Catalyzed Annulative π‐Extension Reaction of Unfunctionalized Aromatics with Diiodobiaryls

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