Rational fabrication of an anionic zinc carboxylate framework as a fluorescent probe for 2,6-pyridinedicarboxylic acid

Sensitive, rapid and convenient sensing of 2,6-pyridinedicarboxylic acid (DPA, a biomarker for Bacillus anthracis) is crucial for the screening and diagnosis of anthrax. Metal organic framework (MOF)-based sensors are very promising for sensing DPA; however, the design and construction of high-performance sensors with high specificity and sensitivity is still challenging. In this work, a novel luminescent carboxylate MOF (TTCA-Zn) was assembled and employed specifically for the recognition of DPA. We found that it has a three-dimensional anionic framework structure with sqc topology and uses [NH₂(CH₃)₂]⁺ as the counter ions. The fluorescence intensity of TTCA-Zn displays a "turn-on" response to the addition of DPA and can function as a high-performance fluorescent sensor of DPA over a wide detection range of 0 to 70 μM, with a low detection limit of 14 nM. The sensing mechanism is also systematically investigated. This work not only reports a new fluorescence sensing material for DPA, but also provides a strategy for the structural design, assembly, and application of such sensors.