Narrowing Segments of Helical Carbon Nanotubes with Curved Aromatic Panels

Carbon nanotubes (CNTs) have unusual physical properties that are valuable for nanotechnology and electronics,b ut the chemical synthesis of chirality-and diameterspecific CNTs and p-conjugated CNT segments is still ag reat challenge.Reported here are the selective syntheses,isolations, characterizations,a nd photophysical properties of two novel chiral conjugated macrocycles ([4]cyclo-2,6-anthracene; [4]CAn 2,6), as (À)/(+ +)-(12,4) carbon nanotube segments. These conjugated macrocyclic molecules were obtained using ab ottom-up assembly approacha nd subsequent reductive elimination reaction. The hoop-shaped molecules can be directly viewed by aS TM technique.I na ddition, chiral enantiomers with (À)/(+ +)helicity of the [4]CAn 2,6 were successfully isolated by HPLC.T he new tubular CNT segments exhibit large absorption and photoluminescence redshifts compared to the monomer unit. The carbon enantiomers are also observed to showstrong circularly polarized luminescence (g lum % 0.1). The results reported here expand the scope of materials design for bottom-up synthesis of chiral macrocycles and enrich existing knowledge of their optoelectronic properties.

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Selective Synthesis of Conjugated Chiral Macrocycles: Sidewall Segments of (−)/(+)‐(12,4) Carbon Nanotubes with Strong Circularly Polarized Luminescence

Wang

Zhuang

Chen

et al. 2019

Angewandte Chemie

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A Macrocyclic Gold(I)–Biphenylene Complex: Triangular Molecular Structure with Twisted Au₂(diphosphine) Corners and Reductive Elimination of [6]Cycloparaphenylene

et al. 2020

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The digold(I) complex [Au 2 Cl 2 (Cy 2 PCH 2 PCy 2)] reacts with 4,4'-diphenylene diboronic acid to form a triangular macrocyclic complex with twisted Au-P-C-P-Au groups at the three corners. The synthesis of the complex and its chemical oxidation produced [6]cycloparaphenylene ([6]CPP) in 59 % overall yield. Organogold complexes have attracted attention because of both their characteristic structures and properties potentially useful in catalysis, liquid crystals, devices, bioimaging, and therapies. [1] Gold(III) complexes have common square-planar structures, but they attracted much less attention than complexes of Pt II , the other 5d 8 metal. [2] Gold(I) prefers linear two-coordinated structure, and forms dinuclear complexes with diphosphine ligands such as a,w-bis(diphenylphosphino)alkanes, which are normally used as chelating ligand. [3, 4] Aurophilicity between two Au I centers stabilizes the molecular structure and conformation with close Au I positions (Au À Au distance of about 3.0). [5] Multinuclear organogold(I) complexes with such components are expected to have unique structures. Figure 1 summarizes macrocyclic complexes having more than two Au I ÀC bonds. [6] A dinuclear arylgold(I) complex with a diphosphine ligand [Au 2 (C 6 H 4-F-4) 2 (dppm)] (dppm = bis(diphenylphosphino)methane) was recently reported to cause reductive elimination of 4,4'-difluorobiphenyl upon oxidation with PhICl 2. [7] The reaction involves the oxidative chlorination of two Au I centers, the intramolecular migration of an aryl ligand, forming a chloro(diaryl)gold(III) center, and 1,1reductive elimination of biaryl (Scheme 1). This new kind of C(sp 2)-C(sp 2) bond-forming reaction can be extensively applied to synthesis of conjugated aromatic compounds.

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Manipulations of Chiroptical Properties in Belt‐Persistent Cycloarylenes via Desymmetrization with Heteroatom Doping

et al. 2021

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A desymmetrization strategy has been devised in the design of molecular cylinders to maximize the dissymmetry factor relevant to circularly polarized light. Although the highest dissymmetry factor of organic molecules was previously achieved with a chiral belt‐persistent cycloarylene having magnetic and electric transition dipole moments in parallel, we noticed that an unbalanced magnitude of two moments was detrimental for higher dissymmetry factors. In this study, a molecular cylinder was desymmetrized by arraying doped and undoped panels via stereoselective cross‐coupling macrocyclization. The desymmetrization succeeded in balancing two moments by reducing the electric transition moment at the global minimum but failed to maximize the dissymmetry factor. Structural studies revealed that the dissymmetry factor is sensitive to subtle structural fluctuations, while the rotatory strength is not affected. This study is important for the development of chiroptical materials.

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Narrowing Segments of Helical Carbon Nanotubes with Curved Aromatic Panels

Cited by 16 publications

References 63 publications

Selective Synthesis of Conjugated Chiral Macrocycles: Sidewall Segments of (−)/(+)‐(12,4) Carbon Nanotubes with Strong Circularly Polarized Luminescence

Selective Synthesis of Conjugated Chiral Macrocycles: Sidewall Segments of (−)/(+)‐(12,4) Carbon Nanotubes with Strong Circularly Polarized Luminescence

A Macrocyclic Gold(I)–Biphenylene Complex: Triangular Molecular Structure with Twisted Au₂(diphosphine) Corners and Reductive Elimination of [6]Cycloparaphenylene

Manipulations of Chiroptical Properties in Belt‐Persistent Cycloarylenes via Desymmetrization with Heteroatom Doping

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Narrowing Segments of Helical Carbon Nanotubes with Curved Aromatic Panels

Cited by 16 publications

References 63 publications

Selective Synthesis of Conjugated Chiral Macrocycles: Sidewall Segments of (−)/(+)‐(12,4) Carbon Nanotubes with Strong Circularly Polarized Luminescence

Selective Synthesis of Conjugated Chiral Macrocycles: Sidewall Segments of (−)/(+)‐(12,4) Carbon Nanotubes with Strong Circularly Polarized Luminescence

A Macrocyclic Gold(I)–Biphenylene Complex: Triangular Molecular Structure with Twisted Au2(diphosphine) Corners and Reductive Elimination of [6]Cycloparaphenylene

Manipulations of Chiroptical Properties in Belt‐Persistent Cycloarylenes via Desymmetrization with Heteroatom Doping

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A Macrocyclic Gold(I)–Biphenylene Complex: Triangular Molecular Structure with Twisted Au₂(diphosphine) Corners and Reductive Elimination of [6]Cycloparaphenylene