[<i>n</i>]Cyclodibenzopentalenes as Antiaromatic Curved Nanocarbons with High Strain and Strong Fullerene Binding
Jan S. Wössner, Daniel Wassy, Andrej Weber, Marcel Bovenkerk, Mathias Hermann, Maximilian Schmidt, Birgit Esser
Abstract
Conjugated nanohoops provide a platform to study structure–property relationships; they are attractive hosts for supramolecular chemistry as well as promising candidates as new organic materials. We herein present [n]cyclodibenzopentalenes ([n]CDBPs) as antiaromatic analogues of [n]cycloparaphenylenes. Platinum-mediated macrocyclization of dibenzopentalene boronic esters provided the trimer and tetramer with strain energies of up to 80 kcal mol–1. In the solid state, the cylindrical [4]CDBP molecules align to form columnar structures. The larger hoop [4]CDBP binds both fullerenes C60 and C70 with temperature-dependent exchange behavior, providing higher activation energies for the exchange compared to [10]CPP. The antiaromatic character of the [n]CDBPs paired with the cyclic conjugation leads to high HOMO energies and lowered LUMO energies with band gaps below 2 eV. This work presents a new class of the antiaromatic and nonalternant curved nanocarbons with intriguing supramolecular and ambipolar optoelectronic properties.