A Multifunctional Fluorescence Europium‐Organic Framework for Turn‐On Sensing of pH and Turn‐Off Sensing of 2‐Thiazolidinethione‐4‐carboxylic Acid and Aztreonam

Comprehensive Summary A luminescent lanthanide‐organic framework [Eu 2 (adip)(H 2 adip)(DMF) 2 ]·CH 3 OH ( 1 ) was synthesized by a solvothermal method using anthracene‐based ligand 5,5’‐(anthracene‐9,10‐diyl)diisophthalic acid (H 4 adip). 1 possesses a 3D coordination framework, which could be rationalized as a 4,8‐connected 2‐nodal (4 16 6 12 )(4 4 6 2 ) topological network. 1 shows an excellent linear increase in fluorescence intensity as the pH value rises from 4.8 to 7.1. Particularly, the fluorescence enhancement percentage reaches 588% for each increase of pH value, which is the highest value recorded for fluorescence pH sensing materials, promoting the sensitivity of pH detection within the physiological pH range. In addition, 1 can also specifically recognize carbon disulfide biomarkers 2‐thiothiazolidine‐4‐carboxylic acid (TTCA) and antibiotic aztreonam (ATM) by fluorescence quenching, with the K SV values of 1.02 × 10 5 L·mol –1 (0—10 μmol·L –1 ) and 4.67 × 10 5 L·mol –1 (0—50 μmol·L –1 ), the limit of detection (LOD) of 86 nmol·L –1 and 19 nmol·L –1 , respectively. Among only a few cases reported, the detection sensitivities of 1 for both TTCA and ATM are the highest. The sensing mechanisms of pH, TTCA, and ATM are also discussed in detail.