An organic-inorganic hybrid photoluminescent ferroelastic with high phase transition temperature

Organic-inorganic hybrid (OIH) multifunctional materials have been widely studied in recent years due to their applications in information processing, optoelectronic devices, etc. However, it is still challenging to successfully trigger both ferroelasticity and luminescence properties in OIH materials. Herein, we report an OIH luminescent compound [TMIm][MnCl4] (TMIm = 1,1,3,3-tetramethylimidazolidinium), which experiences a high-temperature ferroelastic phase transition from the mmm point group to the 2/m point group at 443/429 K. The evolution of ferroelastic domains can be clearly observed during the heating and cooling processes. Moreover, [TMIm][MnCl4] exhibits strong green emission near 520 nm with a photoluminescence quantum yield (PLQY) of 27% and a lifetime of 1.21 ms at room temperature. Distinct luminescence responses in ferroelastic and paraelastic phases are also found through variable temperature fluorescence spectroscopy. This work provides a beneficial supplement for the discovery of OIH multifunctional materials. An organic-inorganic hybrid ferroelastic [TMIm][MnCl4] with high Tc presents distinct photoluminescence responses to ferroelastic phase transitions.