Old Bottles\nof New Wines: Dynamic Multimode Color-Tuning\nLong Afterglow and White Light Emission in Cost-Effective Metal-Organic\nFrameworks (MOFs)

Metal–organic frameworks (MOFs) with long afterglow\nluminescence\n(LAL) have gained attention for applications in light-emitting devices\nand anticounterfeiting. However, developing cost-effective and high-performance\ndynamic multicolor LAL MOFs remains challenging. Here, the rigid organic\nligand 5-fluoronicotinic acid (FL), which incorporates a F atom to\nform molecular interlocking and inhibit nonradiative transitions,\nwas chosen to self-assemble with MCl<sub>2</sub> (M = Zn and Cd) to\nfabricate long-lived phosphorescent MOFs. The synthesized MOFs, namely,\nFLCd, FLZn, and FLCd-DMF, exhibit excitation-dependent luminescence,\nranging from blue/cyan to green, with cold white light emissions under\nspecific excitations. Furthermore, all MOFs achieve dynamic color-tuning\nLAL based on excitation wavelength and temperature. Photoluminescence\nproperties and theoretical calculations indicate that the multicolor\nLAL arises from the emissions of FL and its aggregation state, while\nenhanced phosphorescence can be assigned to heavy-atom and interlocking\neffects, coordination, and noncovalent interactions. Additionally,\nby leveraging their LAL behavior, these MOFs are applied for encrypting/decrypting\ninformation.