An Isosteric Triaza Analogue of a Polycyclic Aromatic Hydrocarbon Monkey Saddle

Abstract

Since a few years, the interest in negatively‐curved fused polycyclic aromatic hydrocarbons (PAHs) has significantly increased. Recently, the first chiral negatively‐curved PAH with the topology of a monkey saddle was introduced. Herein the synthesis of its triaza congener is reported. The influence of this CH↔N exchange on photophysical and electrochemical properties is studied as well as the isomerization process of the enantiomers. The aza analogue has a significantly higher inversion barrier, which makes it easier to handle at room temperature. All experimental results are underpinned by theoretical DFT calculations.

Abstract

Monkey business: Isosteric exchange of CH↔N in a chiral monkey saddle makes the difference, N is increasing the conformational stability and significantly reduces the frequency of the bowl‐to‐bowl‐inversion.