Merging Dual Antenna Effect with Target-Insensitive Behavior in Bimetal Biligand MOFs to Form Efficient Internal Reference Signal: Color Tonality-Ratiometric Designs

The construction of a highly luminescent, stable, and target-insensitive internal reference signal is highly significant in ratiometric and color tonality applications. Improvement of the antenna effect, the efficient mechanism that enhances luminescence emission via sensitization, is an effective route to obtain bright luminescence. Additionally, manipulation of the crystal structure and morphology is the key issue to control the reactivity, especially in metal–organic frameworks (MOFs). In the present work, a novel internal reference red emitter of Eu/Zn bimetal biligand MOF (UoZ-5) was synthesized and used as an internal reference signal. A dual-antenna effect, from triplet states (T1) of the ligands to 5Do of the Eu3+ ion, was observed and explained on the basis of the energy levels. With UoZ-5 serving as the internal reference, blue-emitting carbon quantum dots (CQDs) selective for Ag+ ions and a nonfluorescent composite, CQDs@Ag+, serving as a selective probe for vitamin B1, a color tonality-based platform and ratiometric analysis were developed.