Self-adjusted aromatic cation-π binding promotes controlled self-assembly of positively charged π-electronic molecules

Self-assembly of identically charged π-electronic molecules generates unique charged assemblies with properties not observed in corresponding electronically neutral analogs. However, electrostatic attraction between opposite charges typically leads to charge-by-charge assemblies that hinder the manifestation of desired functionalities. Herein, we present a self-adjusted aromatic cation-π binding strategy to address this challenge. The described approach involves a self-complementary design featuring double-site aromatic cation-π binding interactions that govern the self-assembly direction, resulting in positively charged columnar assemblies. The obtained columnar structures are controlled by the self-adjustment process inherent in the specific aromatic cation-π binding modes. We characterize the transition from alternate overlapping to helical stacking, which ultimately yields thermodynamically favorable columnar polymorphism, including molecular crystals and liquid crystals with tunable intra-/inter-columnar correlations. These charged columnar assemblies serve as efficient intrinsic CO₂ reduction photocatalysts. The helically stacked columnar assemblies exhibit enhanced performance, thus highlighting the profound impact of molecular stacking modes on photocatalytic efficiency.