# N‐Doped Nonalternant Molecular Bowl/Saddle Hybrids

## TL;DR

Scientists created new N-doped carbon molecules with unique bowl and saddle shapes that show interesting properties like fluorescence and guest binding.

## Contribution

A new synthetic strategy for creating N-doped nonalternant molecular bowl/saddle hybrids with unique structural and photophysical properties.

## Key findings

- The molecules show unique molecular dynamics and photophysical properties, including moderate fluorescence and narrowband emissions.
- They can bind multiple fullerene guests in a 1:3 stoichiometry, a rare feature in nonplanar molecular carbons.
- X-ray and NMR analyses confirmed structural evolution and shape adaptability during the synthesis process.

## Abstract

Herein, we report the straightforward synthesis and properties of N‐doped molecular bowl/saddle hybrids with nonalternant topologies via successive palladium‐catalyzed annulations. Structural evolutions from twisted, bowl‐shaped to bowl/saddle‐hybridized structures are involved during the core‐expansion process, as confirmed by X‐ray crystallographic analyses. Notably, this resultant bowl/saddle‐hybridized molecular carbon shows unique molecular dynamics, as revealed by 1H NMR, chiral HPLC analyses and theoretical calculations. These molecules exhibit interesting photophysical properties, including moderate fluorescence quantum yields and narrowband emissions. Steady‐state and transient spectroscopy reveal the different photophysical properties in these molecular bowl and bowl/saddle hybrids. Moreover, the molecular bowl/saddle hybrid exhibits the shape‐adaptive character, and allow for multiple bindings with fullerene guests in a stoichiometry ratio of 1:3, which is seldomly observed in most nonplanar molecular carbons. This study not only presents an efficient strategy to construct a new family of N‐doped nonalternant molecular bowl/saddle hybrids, but also provides insights into molecular design of topological nanocarbons with potential applications of chiral materials and organic electronics.

N‐Doped molecular bowl/saddle hybrids were developed via core‐expansion synthetic strategy. Owing to the structural features containing both positive and negative curvatures, these molecules exhibit unique molecular dynamics, photophysical properties and multiple guest bindings.