Highly emissive perylene diimide-based bowtie-shaped metallacycles

Metallacycles hold great promise for fluorescence-based sensing due to their synthetic advantages and unique physicochemical properties. However, it remains highly challenging to develop a versatile methodology for constructing highly emissive metallacycles with targeted functionalities and therefore sought-after properties. Herein, we report a general strategy to construct a series of highly emissive perylene diimide-based metallacycles via the self-assembly of perylene diimide-based tetrapyridyl ligand with different dicarboxylic ligands featuring fixed angles and cis-Pt(PEt₃)₂(OTf)₂. Single crystal X-ray diffraction analyses verify the formation of bowtie-like metallacycles with two triangular cavities. Notably, the fluorescence quantum yields of most assemblies exceed 98%, amongst the highest values for metallacycles. Additionally, such metallacycles exhibit sensitive fluorescence responses toward picric acid with a detection limit of 2.8 × 10⁻⁶ mol/L. This study not only provides a rational strategy for preparing highly emissive bowtie-shaped metallacycles, but also sheds light on their usage in the detection of picric acid and associated compounds.