Multi-Stimuli-Responsive Properties of Aggregation-Enhanced Emission-Active Unsymmetrical PtII Metallomesogens through Self-Assembly

Herein, we report a series of unsymmetrical bispyrazolate-type Pt^II compounds that exhibit mesomorphism at low temperatures and photophysical multi-stimuli-responsive properties. These Pt^II compounds show a great ability to be self-assembled by intermolecular Pt⋅⋅⋅Pt interactions in the solid state, so generating a columnar stacking of molecules that is responsible for the formation of the mesophases. By controlling the nature of the molecular assembly through external stimuli such as the temperature, the pressure, or the presence of vapours or solvents, it is possible to modulate the luminescence behaviour of these materials. The Pt^II monomers emit a greenish light, whereas aggregation of molecules produces a redshifted emission. These metallomesogens also show a high stability and successive grinding/fuming cycles can be performed without degradation of the sample. The application of these materials is very attractive as rewritable luminescent platforms, and their use is already demonstrated.