Scalable synthesis of soluble crystalline ionic-graphdiyne by controlled ion expansion

Graphdiyne (GDY) is a promising material possessing extensive electronic tunability, high π conjugacy, and ordered porosity at a molecular level for the sp/sp²-hybridized periodic structures. Despite these advantages, the preparation of soluble and crystalline graphdiyne is limited by the relatively compact stacking interactions, mostly existing in thick-layer and insoluble solids. Herein, we proposed a strategy of "framework charge-induced intercalation (FCII)" for the synthesis of a soluble (4.3 mg ml^-1) and yet interlayer-expanded (∼0.6 Å) crystalline ionic graphdiyne, named as N⁺-GDY, through regulating the interlayer interactions. The skeleton of such a sample is positively charged, and then the negative ions migrate to the interlayer to expand the space, endowing the N⁺-GDY with solution processability. The crystal structure of N⁺-GDY is proved through analysis of HR-TEM images under different axes of observation and theoretical simulations. The resulting N⁺-GDY possesses high dispersity in organic solvents to produce a pure-solution phase which is conducive to the formation of oriented N⁺-GDY films, accompanied by exfoliation-nanosheet restacking. The film exhibits a conductivity of 0.014 S m^-1, enabling its applications in electronic devices.