Alkyl-Substituted N,S-Embedded Heterocycloarenes with a Planar Aromatic Configuration for Hosting Fullerenes and Organic Field-Effect Transistors

Abstract

Cycloarenes and heterocycloarenes display unique physical structures and hold great potential as organic semiconductors. However, the synthesis of (hetero)­cycloarenes remains a big challenge, and there are limited reports on their applications. Herein, a series of nitrogen- and sulfur-codoped cycloarenes NS-Octulene-n (n = 2, 3, 4) with branched alkyl substituents containing linear spacer groups from C2 to C4 have been conveniently synthesized. Compared with their isoelectronic analogues Octulene and S-Octulene, both having a saddle-shaped configuration, the coincorporation of two nitrogen atoms and two sulfur atoms leads to a fully coplanar aromatic backbone structure. Each of these three planar heterocycloarenes acts as a supramolecular host for encapsulation of both fullerenes C60 and C70 with a stronger donor–acceptor interaction for the complexation between the heterocycloarene and C70 due to the unique molecular geometry and defined cavity. Meanwhile, the electron-rich nitrogen atoms also slightly increase the energies of both highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) in this series of planar heterocycloarenes, indicating that they can be used as p-type semiconductors. Most importantly, benefitting from the planar π-conjugated backbone structure accompanied by excellent crystallinity and ordered molecular packing, as well as upon the engineering of the alkyl chain branching position, thin-film field-effect transistors of NS-Octulene-3 with moderate alkyl branching point exhibit the maximum hole mobility of 0.86 cm2 V–1 s–1, which is the highest for (hetero)­cycloarene-based organic semiconductors. This study will shed new light on designing novel high-performance macrocyclic polycyclic aromatic hydrocarbon (PAH) semiconductors.

Infinitenes as the Most Stable Form of Cycloarenes: The Interplay among π Delocalization, Strain, and π–π Stacking

“…As for future prospects, generalized infinitenes provide an abundant variety of structures and sizes for this fascinating new type of nanocarbons. They can serve as scaffolds for further functionalization and heteroatom derivatization. ,− Most generalized infinitenes are expected to have superior thermodynamic stability, making them ideal synthetic targets for ambitious organic chemists. With recent advances in the synthesis of looped polyarenes and in expanding kekulene and helicenes, we are confident to anticipate the expansion from the known [12] or [20]­infinitene to larger infinitenes in the foreseeable future.…”

BN-Embedded Cycloarenes: One-Pot Borylation Synthesis, Photoelectric Properties, and Application in Perovskite Solar Cells

“…22 Recently, N-and S-embedded octulenes (Figure 1a) were designed and synthesized by Lu and Liu. 23,24 Based on the systematic engineering of the molecular geometry and the alkyl chain branched position, the solution-processed thin-film organic field-effect transistors (OFETs) of NS-octulene exhibited a hole mobility as high as 0.86 cm 2 V −1 s −1 . 24 Over the past few years, the introduction of a boron−nitrogen (B−N) covalent bond into polycyclic aromatic hydrocarbons (PAHs) has provided a novel molecular design strategy for organic semiconductors.…”

“…23,24 Based on the systematic engineering of the molecular geometry and the alkyl chain branched position, the solution-processed thin-film organic field-effect transistors (OFETs) of NS-octulene exhibited a hole mobility as high as 0.86 cm 2 V −1 s −1 . 24 Over the past few years, the introduction of a boron−nitrogen (B−N) covalent bond into polycyclic aromatic hydrocarbons (PAHs) has provided a novel molecular design strategy for organic semiconductors. 15,16,25−30 As isoelectronicity to the C�C bond, the polar B−N bond could affect the distribution of molecular orbitals, which also improves the stability of higher acenes, as previously demonstrated.…”

“…In 2018, the Miao group constructed one S-doped cycloarene (Figure a) by postfunctionalizing phenanthrylene ethynylene macrocycle via diyne cyclocondensation and Scholl reaction . Recently, N- and S-embedded octulenes (Figure a) were designed and synthesized by Lu and Liu. , Based on the systematic engineering of the molecular geometry and the alkyl chain branched position, the solution-processed thin-film organic field-effect transistors (OFETs) of NS-octulene exhibited a hole mobility as high as 0.86 cm 2 V –1 s –1 …”

From closed-shell edge-extended kekulenes to open-shell carbonylated cycloarene diradicaloid

“…Then, treatment of 5 with Bi(OTf) 3 catalyzed cyclization in 1,2-dichloroethane (DCE) at room temperature gave the fully fused product K1 in 63% yield. 8,14,15 By the replacement of benzene units with naphthalene and anthracene units, the higher homologues K2 and K3 were synthesized as yellow and orange solids, respectively. All new products were characterized by NMR spectroscopy and high-resolution mass spectroscopy.…”