TriQuinoline

Abstract

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.

Triquinoline‐ versus Fullerene‐Based Cycloparaphenylene Ionic Complexes: Comparison of Photoinduced Charge‐Shift Reactions

“…The computed values correlate well with the experimentally measured association constants. [18] In addition, the association energy for TQ•H + & [12]CPP, À46.3 kcal mol À1 ,i si nagood agreement with a value of À51.5 kcal mol À1 computed using the symmetryadaptedp erturbationa pproach. [18] Singletexcited states For am ore convenient description of the excited states,l et us divide the systems into natural subunits ( Figure S4,s ee the Supporting Information).…”

“…[18] In addition, the association energy for TQ•H + & [12]CPP, À46.3 kcal mol À1 ,i si nagood agreement with a value of À51.5 kcal mol À1 computed using the symmetryadaptedp erturbationa pproach. [18] Singletexcited states For am ore convenient description of the excited states,l et us divide the systems into natural subunits ( Figure S4,s ee the Supporting Information). Twof ragments TQ•H + and COR/ [12]CPP,w ill be considered in the binary complexes,a nd three fragments, TQ•H + ,C OR, and [12]CPP, for the ternary complex.…”

“…Recently Kumagai and co-workers [18] designeda nd synthesized triquinoline (TQ) to insert pyridinic-nitrogen defects into graphene sheets. In the trimer,t he quinolineu nits are concatenated at the 2-and 8-positions in ah ead-to-tail fashion.…”

“…The suggestedp rotocol consists of as eries of Suzuki-Miyaura cross-couplingr eactionso f2 -chloro substituted derivatives of quinoline, accomplished with the inverse-electron-demand hetero-Diels-Alder reaction. [18] It leads to the formation of TQ•TFA( TQ•H + + CF 3 COO À )s alt and all attempts to removea protonc aptured at the center of TQ failed. The protona ffinity of TQ is significantly highert han that of the reference proton sponge, 1,8-bis(dimethylamino)naphthalene.K umagai and coworkerss uggested the formation of TQ•H + based supramolecular entitiest hrough noncovalent interactions.…”

“…As ar esult,t he complexes can also exist in ah ighly polar environment. [18] In 2015, Itami and co-workers [19] successfully synthesized and characterized the Li + @C 60 & [10]CPP complexw ith K a = 4.78 10 4 mol À1 •L in dichloromethane. The electrochemicala nd spectroscopic measurements revealed as trong charge-transfer interaction between [10]CPP and Li + @C 60 .I ts charge transfer (CT) absorption band demonstrates as olvent-induced blueshift due to destabilization of the charge-separateds tate by polar medium.…”