Authors: Zhao Gao | Ju-an Zhang | Zhelin Zhang | Bin Mu | Wei Tian
Source: Accounts of Chemical Research (article, 2025-12-23)
Field: Chemistry — Physical and Theoretical Chemistry

Controllable Cation-π Chemistry: Modular Monomer Design, Directed Supramolecular Assembly, and Multifunctional Applications ConspectusNoncovalent interactions serve as the molecular glue of living systems, governing the structural complexity and dynamic balance, particularly those remarkable affinities involving cations and aromatic rings, which have attracted significant attention in protein folding and were first identified by Kebarle et al. in 1981 ( <i>J. Phys. Chem.</i> 1981, 85, 1814-1820). In 1990, Dougherty ( <i>Angew. Chem., Int. Ed.</i> 1990, 29, 915-918) introduced the term cation-π interaction to denote the affinity between positively charged cations and electron-rich π units; they have subsequently attracted widespread attention across multiple disciplines due to their strong binding force, structural stability, remarkable adaptability, and inherent charge transfer characteristics. To mimic this natural cation-π system, scientists have invested considerable efforts into developing artificial cation-π interactions, including organic ammonium, alkali metal, and aromatic cation-π systems, thereby deepening the understanding of their fundamental principles and enabling the exploration of specific functions. Despite these achievements, there are still significant challenges in the controllability of cation-π interaction modes and their structure-function relationship: (1) cation-π interactions lack fixed directionality with strength and orientation highly dependent on spatial arrangement; (2) their bonding ratios are unpredictable, and precise control over molecular order and assembly pathways remains difficult; (3) the inherent difficulty in controlling molecular order and assembly directions has so far limited the rational development of cation-π-based supramolecular assemblies and further constrained the exploration of their potential functionalities. Thus, elucidating the key parameters that govern cation-π interaction modes and their corresponding structural and functional implications is essential for the effective regulation of these interactions in complex supramolecular assembly systems and advanced materials.In this Account, we introduce the concept of controllable cation-π chemistry to emphasize precise control over modular monomer design, directed supramolecular assembly, and the realization of multifunctional applications across diverse fields. First, we highlight the outstanding achievements in designing modular cation-π monomers with fine-tuned regulation of essential parameters, including spatial positioning, interaction modes, bonding ratios, and the directionality of forces. Second, by leveraging the precision of cation-π monomers, key factors governing molecular stacking during assembly can be identified, enabling the deliberate construction and fine modulation of supramolecular architectures across one-, two-, and three-dimensional space with predictable order and organization. Finally, taking advantage of both the ordered architecture and the intrinsic characteristics of cation-π interactions, we develop a wide range of multifunctional supramolecular materials for catalytic, optical and electronic, adsorption, and biological applications. We believe that this Account will advance controllable cation-π chemistry by promoting its continued development across various disciplines within the scientific community, including chemistry, biology, and materials science. Supramolecular chemistry ; Modular design ; Folding (DSP implementation) ; Rational design ; Controllability ; Molecular recognition ; Monomer ; Macromolecule ; Affinities Crystallography and molecular interactions ; Supramolecular Chemistry and Complexes ; Supramolecular Self-Assembly in Materials