Luminescent metal–organic frameworks (MOFs) have garnered substantial attention owing to their applications in the anticounterfeiting and bioimaging domains. Nevertheless, numerous MOFs still face challenges, including low luminescence efficiency and short luminescence lifetimes. The unique electronic properties of fluorine (F) atoms render them highly suitable for improving the luminescence performance of MOFs. In this study, two Cd-based MOFs, namely 2F-DA-MOF and DA-MOF, are synthesized using 2-fluoroterephthalic acid (2F-DA) and terephthalic acid (DA). The results suggest that the integration of F atoms into the ligands of the MOFs facilitates intermolecular interlocking and inhibits nonradiative transitions through C–H···F and C–F···F interactions. As a result, the photoluminescence quantum yield is substantially increased from 3.6% to 37.0%. Additionally, these noncovalent interactions contribute to the multipath millisecond-level luminescence of MOFs, demonstrating excitation-dependent long persistent luminescence with a wide range of tunable emissions spanning from cyan to yellow. Density functional theory calculations confirm that F atoms enhance the material properties by modulating the electron distribution and energy band structure. This research presents a valuable strategy for developing high-performance luminescent MOF materials, expanding the potential applications of MOFs in anticounterfeiting and information encryption.
Li et al. (Thu,) studied this question.