Green/red emission modulation via Tb/Eu co-doping in MOF host for the ratiometric sensing of peroxyacetic acid

Abstract

As an important oxidant, peracitic acid (PAA) has found wide applications in chemical engineering, agriculture, and industry, as well as public safety. Consequently, the easy-and-fast recognition for PAA is always desired. In this work, we have introduced rare earth-based probes in a microporous host bio-MOF-1, where bio-MOF-1 denotes [Zn8(ad)4(BPDC)6O·2(Me2NH2)+]·G, ad= adenine, BPDC=4,4′-biphenyl dicarboxylic acid, G = N,N-dimetylformamide and water. Two ligands, 2,2′-bipyrimidine (bpm) and 2,2′-bipyridine (bpy), were coordinated to RE (rare-earth) ions, Tb(III) and Eu(III). The resulting RE probes were co-doped into bio-MOF-1 micropores via ionic exchange with various relative doping levels. The resulting composite samples were characterized by SEM/EDX/elemental mapping, and their doping levels were determined by ICP analysis. The interaction between PAA and ligands (bpm and bpy) adjusted ligand triplet (T1) level, leading to intensity variation of Tb(III) and Eu(III) emission lines (increased Tb(III) emission and decreased Eu(III) emission), which was modulated as a ratiometric sensing signal for PAA. Linear calibration working curves were observed for bpm-based composite samples, with maximum sensitivity of 8.01, response time of ∼36 s, LOD of 0.3 µM, and working region of 0–70 µM.