We report the synthesis and characterization of two hexapole [7]helicenes (H7Hs). Single crystal X-ray diffraction unambiguously confirms the molecular structure. H7H absorbs light, with distinct Cotton effect, from ultraviolet to the near-infrared (λ = 618 nm). Cyclic voltammetry reveals nine reversible redox states, consecutively from -2 to +6. These chiroptical and electronic properties of H7H are inaccessible from helicene's small homologues.

This work describes a synthetic chiral graphene nanoribbon, named supertwistacene 1. It has four superbenzene (HBC) units linearly fused in a helical manner. The structure of 1, 4.3 nm in length, with an end-to-end twist of 117°, was confirmed by single-crystal X-ray diffraction. In contrast to various twistacene compounds and their analogues, 1 has a very stable configuration. It resists thermal isomerization even when being heated at 200 °C for 16 h. Enantiopure 1 obtained by chiral HPLC shows distinct CD signals in a broad spectral range until 600 nm. In addition, two smaller congeners of 1, the trimer 2 and the dimer 3, were also prepared and systematically investigated. Combining theoretical and experimental studies on 1–3 presents a big picture on their (chir)­optical and electronic characteristics.

Herein we present the first hexapole [9]helicene (H9H). Co‐catalyzed [2+2+2] cyclotrimerization of a dinaphthopyrene (DNP) functionalized alkyne provides the hexaaryl benzene precursor 2, which is transformed into H9H via a dehydrocyclization reaction. Formation of each embedded [9]helicene involves forging of a new C−C bond, which stitches together two [4]helicene subunits of the neighboring DNP blades, reminiscent of the initial method Martin developed for the preparation of [9]helicene in the 1960s. Single‐crystal X‐ray analysis of both 2 and H9H discloses their extremely distorted and crowded structural features. Chiral resolution, optical and electronic properties of H9H are also presented.

This work reports the first double p-extended undecabenzo[7]helicene 1,w hich is al arge chiral nanographene,composed of 65 fused rings and 186 conjugated carbon atoms.T he molecular identity of 1 has been confirmed by single crystal X-rayd iffraction. Aw ine coloured solution of 1 in dichloromethane absorbs light from ultraviolet to the near infrared, featuring an extremely large molar absorption coefficient of 844 000 M À1 cm À1 at 573 nm. Optically pure 1 shows ar ecordh igh electronic circular dichroism intensity in the visible spectral range (j De j= 1375 M À1 cm À1 at 430 nm) knownf or any discrete polycyclic aromatic hydrocarbon. These unusual photophysical properties of 1 contrast sharply with those of amono-undecabenzo[7]helicene derivative 2.

This work presents a green chiral nanographene propeller (NP), which is built by fusing seven hexa­benzo­coronenes in a helical arrangement. It contains 258 conjugated carbon atoms and represents the largest three-dimensional conjugated polycyclic aromatic hydrocarbons ever prepared using scalable solution chemistry. Despite its unusual molecular size, single-crystal X-ray structural analysis (resolution 0.9 Å) and baseline chiral resolution are achieved. NP is soluble in various organic solvents and can be fully characterized by common spectroscopic and voltammetric techniques. It has a strong panchromatic absorption from the ultraviolet to the near-infrared (λmax = 659 nm, ε = 179 000 M–1 cm–1). For instance, more than half of the spectral range between 300 and 800 nm witnesses an extinction coefficient larger than 100 000 M–1 cm–1. Moreover, a record-high Cotton effect in the visible spectrum is observed for enantiopure NP, with |Δε| values of 1182 and 1090 M–1 cm–1 at 374 and 405 nm, respectively. These photophysical properties evolve significantly compared to those of the propeller-shaped hexapole [7]­helicene.