Multistimuli-Responsive Fluorescent Organometallic Assemblies Based on Mesoionic Carbene-Decorated Tetraphenylethene Ligands and Their Applications in Cell Imaging

The controllable construction of light-emitting organometallic supramolecular materials integrating stimulus responses and biological applications is still a major challenge today. In this work, emissive organometallic assemblies based on Ag^I/Au^I and mesoionic carbene-decorated tetraphenylethene (MIC-TPE) ligands have been synthesized and characterized. Photophysical studies showed that these organometallic assemblies [M₄(2)₂](OTf)₄ not only fluoresce in various dilute solutions, resulting from the rigidification of MIC-TPE ligands upon complexation, but also show tunable fluorescence wavelengths and intensity behaviors in mixed solvent systems and at varying temperatures while in solution, and mechanical pressure stimulus-responsive fluorescent features in the solid state. Furthermore, the organometallic cages [M₄(2)₂](OTf)₄ (M = Ag and Au) were successfully employed for cell imaging and showed the potential of anticancer activity, making them promising candidates for cancer theranostics. This work provides a simple and efficient method to prepare highly emissive and stimulus-responsive organometallic materials and paves the way for related biological applications such as cancer cell imaging and targeted therapy.