Mechanical interlocking induced emission in two-dimensional covalent organic frameworks

The development of two-dimensional (2D) solid-state luminescent covalent organic frameworks (COFs) remains an intriguing challenge due to the aggregation quenching caused by π-π interactions. In this study, a novel approach utilizing mechanical interlocking was employed to construct two 2D-COFs, namely mTPE-COF-1 and mTPE-COF-2. These COFs exhibited robust solid-state emissive properties. Fully characterization and spectroscopic analysis revealed that the regular interleaving mechanical restraints was able to mitigate the π-π stacking interactions in the two 2D-COFs. As a result, this inhibition inactivates non-radiation deactivation and turns on the luminescence. Theoretical calculations support the promotion of mechanical interlocking for emissions. Furthermore, by coating mTPE-COF-1 and mTPE-COF-2 onto a blue light-emitting diode, a high purity white light can be generated. This study offers a novel approach to design 2D luminescent COFs using mechanical interlocking strategy.