Stimuli-Responsive Interconversion between Poly-NHC-Based Organometallic Assemblies and Their Self-Aggregated Dimers

Poly-NHC-based organometallic assemblies 3-PF₆, 3-SbF₆ and 3-OTf were obtained and verified by NMR spectroscopy, ESI mass spectrometry and single-crystal X-ray diffraction analyses. Controllable structural interconversion was observed between the poly-NHC-based organometallic assemblies and their self-aggregated dimers in solution affected by concentration, solvent and metal ion. ¹H NMR spectra of assembly 3-PF₆ in CD₃CN at different concentrations demonstrated controllable structural interconversion, and ¹⁹F NMR spectrum of assembly 3-PF₆ at high concentration further evidenced the presence of the free hexafluorophosphate anion and encapsulated hexafluorophosphate anion for its two sets of signals. In addition, single-crystal X-ray diffraction analysis provided clear evidence that in the solid state, two assemblies 3-PF₆ were vertically stuck, forming a self-aggregated dimer with an encapsulated hexafluorophosphate anion. Investigating the reversible structural interconversion is beneficial for revealing the intrinsic nature on the atom level and paving the way to design the stimuli-responsive functional system.