Metal-ion-programmed Pyridoin complexes for white-light emission and bacterial inhibition

The rational design of molecular platforms whose function can be precisely programmed remains a central goal in materials science. Herein, we report that the identity of the coordinated metal ion serves as a direct and powerful programming tool to dictate the functionality of complexes derived from a single pyridoin-based ligand (FC). Comprehensive spectroscopic analysis reveals that Al(III) coordination promotes the formation of multiple charge-transfer excited states, leading to excitation-dependent dual emission and enabling fine-tuned white-light generation with CIE coordinates of (0.32, 0.33). In stark contrast, Zn(II) coordination yields a complex with a distinct photophysical signature and potent, selective antibacterial activity against Bacillus subtilis, exhibiting a low minimum inhibitory concentration (MIC) of 128 μg/mL alongside excellent biocompatibility. This work provides clear spectroscopic evidence for a metal-ion-programmed functional switching mechanism within a unified ligand scaffold. It establishes a straightforward "one-ligand-multiple-functions" paradigm, demonstrating how simple metal-ion selection can be leveraged to design tailored materials for applications ranging from single-component white-light emitters to targeted antibacterial agents.