The Scholl Reaction as a Powerful Tool for Synthesis of Curved Polycyclic Aromatics

Chemical Reviews, Год журнала: 2022, Номер 122(18), С. 14554 - 14593

Опубликована: Авг. 12, 2022

The past decade has witnessed remarkable success in the synthesis of curved polycyclic aromatics through Scholl reactions which enable oxidative aryl-aryl coupling even company with introduction significant steric strain. These are not only unique objects structural organic chemistry relation to nature aromaticity but also play an important role bottom-up approaches precise nanocarbons topology. Moreover, they have received considerable attention fields supramolecular and functional materials because their interesting properties promising applications. Despite great aromatics, outcome a newly designed substrate reaction still cannot be predicted generic manner largely due limited understanding on mechanism possible rearrangement processes. This review provides overview focus applications structures aims shed light key factors that affect synthesizing sterically strained aromatics.

Язык: Английский

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Circularly polarized luminescence of helicenes: A data‐informed insight

Chirality, Год журнала: 2023, Номер 35(4), С. 192 - 210

Опубликована: Янв. 27, 2023

Abstract Helicenes are an interesting scaffold for chiroptical properties and in particular circularly polarized luminescence (CPL). In this short review, we collect the (g lum ) absorption abs dissymmetry factors associated to first Cotton effect of electronic circular dichroism (ECD) spectrum. Considering data 170 [n]‐helicenes ( n = 4–11), overall found reasonable correlations between g . Despite a few notable exceptions, would confirm similarity stereochemistry ground emitting excited states most helicenes. These results may be useful rationalizing help chemists designing new helicene structures with desired CPL properties.

Язык: Английский

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π‐Extended Diaza[7]helicenes with Dual Negatively Curved Heptagons: Extensive Synthesis and Spontaneous Resolution into Strippable Homochiral Lamellae with Helical Symmetry

Angewandte Chemie International Edition, Год журнала: 2024, Номер 63(11)

Опубликована: Янв. 17, 2024

Abstract We report a unique category of π‐extended diaza[7]helicenes with double negative curvatures. This is achieved by two‐fold regioselective heptagonal cyclization the oligoarylene‐carbazole precursors through either intramolecular C−H arylation or Scholl reaction. The fusion two rings in helical skeleton dramatically increases strain and forces terminal carbazole moieties to stack compressed fashion. presence deformable negatively curved endows resulting dynamic chiral skeletons, aggregation‐induced emission feature relatively low racemization barrier ca. 25.6 kcal mol −1 . Further π‐extension on subsequently leads more sophisticated C 2 ‐symmetric homochiral triple helicene. Notably, these show structure‐dependent stacking upon crystallization, switching from heterochiral packing intra‐layer stacking. Interestingly, helicene molecules spontaneously resolve into lamellar structure 3 1 helix symmetry. Upon ultrasonication nonsolvent, crystals can be readily exfoliated large‐area ultrathin nanosheets height 4.4 nm corresponding layers stacked thicker constituted even‐numbered molecular lamellae. Moreover, regular hexagonal thin platelets size larger than 30 μm fabricated flash aggregation.

Язык: Английский

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Recent Progress in Metal-Catalyzed [2+2+2] Cycloaddition Reactions

Synthesis, Год журнала: 2021, Номер 54(01), С. 4 - 32

Опубликована: Сен. 27, 2021

Abstract Metal-catalyzed [2+2+2] cycloaddition is a powerful tool that allows rapid construction of functionalized 6-membered carbo- and heterocycles in single step through an atom-economical process with high functional group tolerance. The reaction usually regio- chemoselective although selectivity issues can still be challenging for intermolecular reactions involving the cross-[2+2+2] two or three different alkynes various strategies have been developed to attain selectivities. Furthermore, enantioselective efficient means create central, axial, planar chirality variety chiral organometallic complexes used asymmetric transition-metal-catalyzed inter- intramolecular reactions. This review summarizes recent advances field cycloaddition. 1 Introduction 2 Formation Carbocycles 2.1 Intermolecular Reactions 2.1.1 Cyclotrimerization Alkynes 2.1.2 Cycloaddition Two Different 2.1.3 Alkynes/Alkenes Alkenes/Enamides 2.2 Partially Intramolecular 2.2.1 Rhodium-Catalyzed 2.2.2 Molybdenum-Catalyzed 2.2.3 Cobalt-Catalyzed 2.2.4 Ruthenium-Catalyzed 2.2.5 Other Metal-Catalyzed 2.3 Totally 3 Heterocycles 3.1 Nitriles 3.2 1,6-Diynes Cyanamides 3.3 Selenocyanates 3.4 Imines Allenes Alkenes 3.5 (Thio)Cyanates Isocyanates 3.6 1,3,5-Triazines 3.7 Aldehydes Enynes Allenes/Alkenes 3.8 4 Conclusion

Язык: Английский

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Highly Luminescent Chiral Double π-Helical Nanoribbons

Journal of the American Chemical Society, Год журнала: 2024, Номер 146(8), С. 5295 - 5304

Опубликована: Фев. 16, 2024

Unveiling the mechanism behind chirality propagation and dissymmetry amplification at molecular level is of significance for development 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, tetramer while producing homochiral or heterochiral linking centers. A significant was achieved, absorption factors (|gabs|) increasing from 0.009 0.017 further 0.019, luminescence (|glum|) rising 0.007 0.013 eventually 0.015 oligomers. The disparity magnetic transition dipole moment (m) densities in tetramers by time-dependent density functional theory calculations confirmed that oligomerization can maximize total m, which favorable achieving ever-increasing g factors. Notably, these π-helices exhibited exceptional photoluminescence quantum yields (ΦPL) ranging 83 95%. circularly polarized brightness (BCPL) reached remarkable 575 M–1 cm–1 tetramer, among highest values reported small molecules. This kind linearly extended offers platform comprehensive understanding amplification.

Язык: Английский

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Multiple Heterohelicenes: Synthesis, Properties and Applications**

Chemistry - A European Journal, Год журнала: 2022, Номер 28(65)

Опубликована: Авг. 11, 2022

Multiple heterohelicenes are a unique class of helical nonplanar scaffolds that have attracted great attention due to their appealing shapes, optical and electronic properties, potential applications in chiral materials. This review describes the recent advances challenges design synthesis representative multiple with intriguing properties. And corresponding also covered.

Язык: Английский

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Five‐Fold Symmetric Pentaindolo‐ and Pentakis(benzoindolo)Corannulenes: Unique Structural Dynamics Derived from the Combination of Helical and Bowl Inversions

Angewandte Chemie International Edition, Год журнала: 2021, Номер 61(1)

Опубликована: Ноя. 5, 2021

Peripherally π-extended corannulenes bearing quintuple azahelicene units, 10 and 11, were prepared their dynamic behaviors studied experimentally theoretically. The fused synthesized from sym-pentabromocorannulene in three steps. X-Ray diffraction analysis for displayed a conformer possessing P(M) bowl chirality PPMPM (PMPMM) helical chirality, which was found to be the most stable conformer(s). Variable-temperature NMR measurements of 11 revealed that structural isomers can interconvertible solution, depending on steric congestion around scaffolds. Automated search conformers equilibrium transition states by Artificial Force Induced Reaction (AFIR) method interconversion networks, including bowl-inversion helical-inversion. This indicated co-existing corannulene moieties influence conformational dynamics, leads mitigation activation energy barriers isomerization.

Язык: Английский

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Furan‐Extended Helical Rylenes with Fjord Edge Topology and Tunable Optoelectronic Properties

Angewandte Chemie International Edition, Год журнала: 2022, Номер 62(5)

Опубликована: Дек. 6, 2022

Lateral furan-expansion of polycyclic aromatics, which enables multiple O-doping and peripheral edge evolution rylenes, is developed for the first time. Tetrafuranylperylene TPF-4CN octafuranylquaterrylene OFQ-8CN were prepared as model compounds bearing unique fjord topology helical conformations. Compared to TPF-4CN, higher congener displays a largely red-shifted (≈333 nm) intensified absorption band (λmax =829 well narrowed electrochemical gap (≈1.08 eV) due its pronounced π-delocalization emerging open-shell diradicaloid upon increase length. Moreover, strong circular dichroism signals in broad range until 900 nm are observed chiral OFQ-8CN, owing excellent conformational stability central bis(tetraoxa[5]helicene) fragments. Our studies provide insights into relationships between topologies (chir)optoelectronic properties this novel type O-doped PAHs.

Язык: Английский

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Impact of helical elongation of symmetric oxa[n]helicenes on their structural, photophysical, and chiroptical characteristics

Chirality, Год журнала: 2024, Номер 36(5)

Опубликована: Май 1, 2024

Abstract The adjustment of the main helical scaffold in helicenes is a fundamental strategy for modulating their optical features, thereby enhancing potential diverse applications. This work explores influence elongation (n = 5–9) on structural, photophysical, and chiroptical features symmetric oxa[ n ]helicenes. Crystal structure analyses revealed structural variations with extension, impacting torsion angles, pitch, packing arrangements. Through theoretical investigations using density functional theory (DFT) calculations, impact extension aromaticity, planarity distortion, heightened chiral stability were discussed. Photophysical studied through spectrophotometric analysis, insights gained time‐dependent DFT (TD‐DFT) calculations. Following resolution via high‐performance liquid chromatography (HPLC), properties both enantiomers oxa[7]helicene oxa[9]helicene investigated. A slight variation ]helicenes from [7] to [9] induced an approximately three‐fold increase dissymmetry factors biggest values of| g lum | (2.2 × 10 −3 ) compared to| |of (0.8 ), findings discussed supported by TD‐DFT

Язык: Английский

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[2+2+2] Cycloadditions

Elsevier eBooks, Год журнала: 2025, Номер unknown

Опубликована: Янв. 1, 2025

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