TriQuinoline

The bottom-up synthesis of structurally well-defined motifs of graphitic materials is crucial to understanding their physicochemical properties and to elicit new functions. Herein, we report the design and synthesis of TriQuinoline (TQ) as a molecular model for pyridinic-nitrogen defects in graphene sheets. TQ is a trimer of quinoline units concatenated at the 2- and 8-positions in a head-to-tail fashion, whose structure leads to unusual aromatisation behaviour at the final stage of the synthesis. The central atomic-sized void endows TQ with high proton affinity, which was confirmed empirically and computationally. TQ•H + is a two-dimensional cationic molecule that displays both π–π and CH–π contact modes, culminating in the formation of the ternary complex ([12]cycloparaphenylene(CPP) ⊃ (TQ•H + /coronene)) that consists of TQ•H + , coronene (flat), and [12]cycloparaphenylene ([12]CPP) (ring). The water-miscibility of TQ•H + allows it to serve as an efficient DNA intercalator for e.g. the inhibition of topoisomerase I activity. In this paper, the authors introduce a structurally elegant 2D triquinoline molecule as a discrete model for graphitic materials with atom-sized voids. The compound has unusual chemical properties, including high proton affinity and rich supramolecular behavior, forming complexes via both π-π and CH-π contact modes.