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

Abstract

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.

Three‐Component Multiblock 1D Supramolecular Copolymers of Ir(III) Complexes with Controllable Sequences

“…The molecular design was inspired by Ir(III) complexes with intermolecular π-π interactions reported recently. [19] The intermolecular π-π clamp interactions were constructed by selecting 4-(N,N-diphenylamino)phenyl-substituted 2phenylpyridine derivatives and 2,2'-bipyridine with flexible conformation as ligands, respectively.…”

“…The only difference for complexes 1 – 3 is that the required H 2 O/CH 3 CN ratios are 75 : 25, 83 : 17, and 80 : 20 (v/v), respectively. Importantly, it was possible to match the H 2 O/CH 3 CN ratios of these three complexes through a previously reported LSP protocol [19b] . By choosing an intermediate H 2 O/CH 3 CN ratio of 80 : 20 (v/v), the thermodynamic species 2NF can be obtained simply and quickly.…”

Supramolecular Copolymers Under Kinetic, Thermodynamic, or Pathway‐Switching Control

“…The molecular design was inspired by the living self-assembly of Ir III complexes reported by our group. [21] The intermolecular π-π interactions of 1 and 2 were constructed by rationally selecting the position of the rotatable phenyl at 2-phenylpyridine and 2,2'-bipyridine with a flexible conformation as auxiliary ligand. The hydrophobic effect of monomers in a CH 3 CN-H 2 O system is utilized to form kinetic species to retard the spontaneous nucleation of monomers.…”

Controllable 1D, 2D and 3D supramolecular assemblies of Ir(iii) complexes

“…In 2021, our group reported the seeded self-assembly of an Ir( iii ) complex in aqueous media for the first time. 42,43 Recently, we synthesized several fluorinated Ir( iii ) complexes and successfully obtained size-controllable 2D nanosheets via multistep seeded self-assembly. 44,45 However, there is still a lack of systematic studies on the reasonable design of Ir( iii ) complexes to control the morphologies of assemblies.…”