Living supramolecular polymerization of an AIE-active Ir(iii) complex with irregular emission

Abstract

Aggregation-induced emission (AIE) has been widely developed and successfully applied to many fields over the past two decades. Although efforts to develop excellent AIE molecules (AIEgens) are increasing, the relationship between aggregation and supramolecular self-assembly is usually elusive, which hinders the understanding of the aggregation process. Herein, we report the aggregation mechanism of an AIE-active complex 1 with irregular emission from the perspective of supramolecular self-assembly. Monitoring different emission and absorption wavelengths as fingerprints for each species of nanoparticles (1NP) and nanosheets (1NS), allows visualization of the self-assembly process in real time. Concentration-dependent and temperature-dependent spectrum studies have shown that 1NP needs to disassemble into monomers and undergo the nucleation–elongation process to form 1NS. The living and cyclic supramolecular polymerization of the complex 1 has been successfully performed for the first time and crystalline supramolecular polymers with highly controllable sizes were obtained. Finally, through an in-depth study of intermolecular interactions of complex 1, it is clear that the [010] direction relies on electrostatic interactions and the [100] direction relies on abundant intermolecular non-covalent interactions, allowing the formation of the final two-dimensional nanosheets. This work provides ideas and references for studying the self-assembly of AIEgens and the precise preparation of AIE aggregates.