Borospherene in the Nanohoop: Complexation and Aromaticity of Neutral and Dioxidized Cycloparaphenylene Supramolecules with B40 and C60 Fullerenes

Supramolecular complexes of carbon nanohoops with fullerenes play a key role for the design of novel nanomaterials with technological applications. Herein we investigate with density functional theory (DFT) methods the capability of neutral and dioxidized cycloparaphenylenes (CPPs) to encapsulate all-boron fullerene B₄₀. Our results show that [9]CPP and [10]CPP are feasible host candidates to encapsulate B₄₀ displaying comparable complexation energies with the all-carbon analog [10]CPP⊃C₆₀. Upon dioxidation the host-guest interactions are not affected, whereas the positive charge is delocalized on the CPPs leading to global aromatic character of the hosts. Consequently, the dicationic complexes [n]CPP²⁺⊃B₄₀ and [10]CPP²⁺⊃C₆₀ display augmented global shielding cones that strongly shield the guests, as manifested by large upfield shifts in ¹¹B-NMR and ¹³C-NMR signals. Hence, CPP complexes with carbon fullerenes can be extended borospherene B₄₀ host-guest complexes, as well as to doubly oxidized species stabilized by global host aromaticity, expanding our understanding of carbon nanohoop complexes to boron-based fullerenes.