Construction and Function of Low-Symmetry Metallo-Supramolecules

ConspectusNatural systems often exhibit high-symmetry structures, which are vital in biological processes. Inspired by nature, chemists have focused on designing high-symmetry metallo-supramolecular architectures due to the high predictability and controllability for self-assembly. In contrast, low-symmetry structures are ubiquitous and also play a key role in living systems. Mimicking natural low-symmetry structures has proven challenging; substantial efforts have been devoted to developing low-symmetry metallo-supramolecules. However, there are still significant challenges in both construction and function of low-symmetry metallo-supramolecules: (1) unexpected structures with similar thermodynamic stability will be generated, resulting in uncontrollable self-assembly; (2) functionalized low-symmetry supramolecular systems are limited by uncontrollable self-assembly. To address the key challenges, we developed various strategies to control the assembly process and explore the functionalities. In this Account, we summarize the recent research progress achieved by our efforts in preparing low-symmetry metallo-supramolecules and exploring their functionalities. First, the efficient approaches are discussed: (1) precise configurational control by subtly modulating ligands, (2) ligand and metal-ion selectivities enabled by selective self-complementary coordination motifs, and (3) enhancing the steric effect to control coordination modes. Second, the functionality of multidecker structures with well-organized homo/hetero-chromophoric arrangements will be introduced. Finally, a low-symmetry functionalized prismatic system with high universality was developed, which realized a high photoluminescence quantum yield, tunable luminescence, mechanically interlocked structures, and selective encapsulation of low-symmetry guests.