Photophysical Properties and Metal Ion Sensing of a Pyrene-Based Liquid Crystalline Dimer.

This study investigates the liquid crystalline behavior, photophysical properties, and metal ion sensing capabilities of a pyrene-based imine dimer (DPyH9). The compound exhibits monotropic nematic mesophase behavior, with a glass transition at 43 °C, as confirmed by polarized light microscopy (PLM) and differential scanning calorimetry (DSC). Its photophysical properties, including UV-vis absorption, solvatochromic fluorescence, and acidochromism, observed through spectral shifts upon HCl addition, were systematically analyzed. Notably, DPyH9 displayed selective metal ion sensing capabilities towards Sn and Cu with binding constants of 4.51 × 10 M and 4.03 × 10 M and detection limits of 1.61 × 10 M (Sn) and 4.73 × 10 M (Cu). Fluorescence titrations revealed distinct responses: Sn induced an initial quenching and an enhancement at higher concentrations, while Cu caused significant fluorescence quenching. These results therefore highlight DPyH9 as a potential candidate for sensing applications and optoelectronic devices.