Multiple Stimulus Response Material Based on Sr-tcbpe MOF for Mechanochromism, Visualization Labeling, and Etching Toward TNP

The abuse and excessive discharge of organic pollutants such as nitroaromatic compounds (NACs) have become a hot topic of concern for all humanity and society, and the development of fast, effective, and targeted technical means for detecting NACs also faces many challenges. Here, we reported a strontium-based metal-organic framework (MOF) {[Sr₂(tcbpe)(H₂O)₄]}_<i>n</i> (<b>Sr-tcbpe</b>), in which tcbpe represents deprotonated 4',4‴,4″‴,4‴‴-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1'biphenyl]-4-carboxylic acid)). In <b>Sr-tcbpe</b>, Sr-O polyhedron and deprotonated tcbpe^4- ligand have a staggered connection to form a self-assembled three-dimensional network structure. In addition, it is found that <b>Sr-tcbpe</b> undergoes no luminescent color change when grinding under solvent protection, while mechanochromic fluorescence behavior is observed when grinding directly, leading to luminescent color changes from cyan to green (<b>Sr-tcbpe-G</b>). Additionally, <b>Sr-tcbpe</b> and <b>Sr-tcbpe-G</b> could selectively detect PNP, DNP, and TNP, and <b>Sr-tcbpe</b> achieves visual fluorescence sensing detection toward TNP at a limit of detection as low as 2.25 μM. Moreover, during the detection process, unexpectedly, TNP exhibits a selective etching effect on <b>Sr-tcbpe</b>, which could drill nano holes with different sizes on the surface area of MOF materials to a certain extent, achieving the conversion of chemical energy to mechanical energy. In addition, the successful preparation of a portable sensor <b>Sr-tcbpe</b>@gypsum block provides a platform for the perfect combination of mechanochromic fluorescence behavior and visualization detection toward TNP. It lays the foundation for the practical application of MOF materials in daily life.