Living Supramolecular Polymerization of Ultrastable Kinetic Species of Ir(III) Complexes in Aqueous Media

Living supramolecular polymerization (LSP) has become a key technology for the progress of materials science. However, under the influence of hydrophobic interaction, the precise kinetic control of LSP in aqueous media is still challenging. In this work, we report a strategy to realize the LSP of ultrastable kinetic species that is nearly impossible to assemble spontaneously. Due to the strong hydrophobic interaction, the kinetic species of Ir(III) complex 2 (nanoparticles, 2NP) at 90 and 95% water contents can exist stably for more than 50 days at room temperature. By mixing the seeds at an 85% water content and the suspension of kinetic species at a 95% water content in equal volume, LSP can be carried out at a 90% water content, and multicycle LSP at a 90% water content can be performed successfully. This LSP strategy broadens the practicality of LSP and is implemented by structurally simple Ir(III) complexes, which provides ideas for broadening the monomer scope of LSP. Time-, temperature-, and concentration-dependent spectroscopic results show that the formation of kinetic species 2NP and thermodynamic species 2NS (nanosheets) follows the isodesmic model and the cooperative (nucleation-elongation) model, respectively, and 2NP are the off-pathway intermediates of 2NS. This study illustrates an ingenious and precise kinetic control on the LSP in aqueous media.