A core-expanded, pyrrole-fused azacoronene analogue containing two unusual N-doped heptagons was obtained from commercially available octafluoronaphthalene and 3,4-diethylpyrrole in two steps as a heteroatom-doped nonplanar nanographene. Full fusion with the formation of the tetraazadipleiadiene framework and the longitudinally twisted structure was unambiguously confirmed by single-crystal X-ray diffraction analysis. The edge-to-edge dihedral angle along the acene moiety was 63°. This electron-rich π-system showed four reversible oxidation peaks. Despite the nonplanar structure, the Hückel aromaticity owing to a peripheral π-conjugation in the dicationic state was concluded from the bond-length alternation and nucleus-independent chemical shift (NICS) and anisotropy of the induced current density (ACID) calculations.

A hexapyrrolohexaazacoronene (HPHAC) with 12 less-bulky peripheral ethyl groups than its aryl-containing HPHAC counterpart was synthesized to investigate the innate character of HPHAC. X-ray diffraction analysis revealed that HPHAC had a planar structure and close packing because of CH−π interactions between the alkyl groups and the HPHAC core. Compared to the previously reported HPHAC decorated with 12 peripheral aryl groups, this electron-rich π-system exhibited reversible multistep oxidations at low potentials and easily formed mono- and dicationic salts and charge-transfer (CT) complexes with 7,7,8,8-tetracyano-p-quinodimethane. These oxidized species exhibited clear changes in the bond-length alternation of the pyrrole units in the crystal state, indicating charge and spin delocalization. The distinct upfield shift of the central carbon signal of the dication in the 13C NMR spectrum affirms the global aromaticity from the viewpoint of a magnetic criterion. In the UV–vis/NIR spectra, broad absorption in the NIR region was observed only for HPHAC2+ and not the structurally similar cyclo[6]­pyrrole. Magnetic circular dichroism measurements and time-dependent density functional theory calculations revealed that the broad absorption was assigned to the CT transition from the central benzene ring to the outer pyrrole rings.

Enantiopure [6]helicene containing an embedded seven‐membered ring and carbo[7]helicene (>99 % ee) with opposite helicity were simultaneously and quantitatively (>99 %) synthesized with a perfect stereospecificity through stepwise acid‐promoted intramolecular alkyne annulations of doubly axial‐chiral cyclization precursors. The helical handedness of the [6]‐ and [7]helicenes was fully stereocontrolled by the doubly axial chirality of the precursors as a result of complete axial‐to‐helical chirality transfer. The cyclizations proceeded in a stepwise manner; the first six‐membered ring formation was followed by the kinetically controlled seven‐ or six‐membered ring formation with or without helix‐inversion of a [4]helicene intermediate generated during the first cyclization step, thus quantitatively producing enantiopure circularly polarized luminescent [6]‐ and [7]helicenes with opposite helicity.

An antiaromatic cation of the expanded hexapyrrolohexaazacoronene (HPHAC) 1 + was synthesized by a Vilsmeier-type reaction of the partially unfused HPHAC 2. X-ray diffraction analysis revealed the formation of a seven-membered ring with a methyne linkage between the pyrrole moieties. Although 1 + is a monocation, upfield shifts of the peripheral ethyl protons were clearly observed in the 1 H NMR spectra, indicating 24π antiaromaticity. Global antiaromaticity was also supported by nucleus-independent chemical shift and anisotropy of the induced current density calculations. Cation 1 + displayed two reversible oxidations and one irreversible reduction in the cyclic voltammetry measurements. Treatment of 1 + with NOSbF 6 gave aromatic trication 1 3+ with 22π-electron conjugation.

Defect‐free one‐handed contracted helical tubular ladder polymers with a π‐electron‐rich cylindrical helical cavity were synthesized by alkyne benzannulations of the random‐coil precursor polymers containing 6,6′‐linked‐1,1′‐spirobiindane‐7,7′‐diol‐based chiral monomer units. The resulting tightly‐twisted helical tubular ladder polymers showed remarkably high enantioseparation abilities toward a variety of chiral hydrophobic aromatics with point, axial, and planar chiralities. The random‐coil precursor polymer and analogous rigid‐rod extended helical ribbon‐like ladder polymer with no internal helical cavity exhibited no resolution abilities. The molecular dynamics simulations suggested that the π‐electron‐rich cylindrical helical cavity formed in the tightly‐twisted tubular helical ladder structures is of key importance for producing the highly‐enantioseparation ability, by which chiral aromatics can be enantioselectively encapsulated by specific π‐π and/or hydrophobic interactions.

We report the quantitative, chemoselective, and diastereospecific formation of the defect-free C-shaped single and S-and M-shaped consecutively fused doubleand triple-expanded homochiral helicenes (all-right (P) or all-left (M) handed), in which two and three expanded helicene subunits were exclusively fused together in a helically winding manner, respectively, through the trifluoroacetic acid-promoted intramolecular multistep cascade alkyne benzannulations of anthracene-based cyclization precursors composed of a large number of complicated dynamic stereoisomers due to axial chirality. The resulting racemic expanded helicenes were all separated into enantiomers by chiral chromatography and showed intense circular dichroism and circularly polarized luminescence (CPL) with the absorption and luminescence dissymmetry factors of up to 1.5 × 10 −2 and 0.94 × 10 −2 , respectively. Moreover, the triple-expanded helicene showed the highest CPL brightness (255 M −1 ⋅cm −1 ) among all the reported CPL-active carbo-and heterohelicenes and -helicenoids. The helicity inversion barriers remarkably increased with the increasing number of incorporated helicene subunits, and the racemization of the triple-expanded helicene was completely suppressed even at 80 • C, providing the first example of an optically active expanded helicene with a static helical chirality.

Tropo(thio)ne-embedded homoHPHACs and their dications were synthesised by an electrophilic annulation of secoHPHAC and successive oxidation. 13C NMR spectra of the dications represented global 22π homoaromaticity via homoconjugation, while alkylation...

We report the unprecedented sergeants and soldiers (S&S)‐type remote control of one‐handed helicity in copolymers of chiral/achiral biphenylylacetylenes bearing amphiphilic oligo(ethylene glycol) (OEG) side chains. A small amount of chiral binaphthyl residues (≤10 mol %) introduced at the terminal of the achiral OEG spacers as many as 80 bonds away from the polymer backbones induced a complete one‐handed helix in water through preferential intramolecular encapsulation of the binaphthyl groups within a cavity of the copolymers. A fully one‐handed helix can be induced virtually independent of the OEG spacer length and concentrations. At a specific spacer length, however, its helix‐sense was inverted. The copolymers also form an excess one‐handed helix in organic solvents in an OEG spacer‐length dependent manner, yet far from the polymer backbones. We show the superiority of the present covalent‐bond driven S&S‐type remote helicity control over the corresponding noncovalent helicity induction approach.