Multiple Stimulus\nResponse Material Based on Sr-tcbpe\nMOF for Mechanochromism, Visualization Labeling, and Etching Toward\nTNP

The abuse and excessive discharge of organic pollutants\nsuch as\nnitroaromatic compounds (NACs) have become a hot topic of concern\nfor all humanity and society, and the development of fast, effective,\nand targeted technical means for detecting NACs also faces many challenges.\nHere, we reported a strontium-based metal–organic framework\n(MOF) {[Sr<sub>2</sub>(tcbpe)(H<sub>2</sub>O)<sub>4</sub>]}<sub><i>n</i></sub> (<b>Sr-tcbpe</b>), in which tcbpe represents\ndeprotonated 4′,4‴,4″‴,4‴‴-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1′biphenyl]-4-carboxylic\nacid)). In <b>Sr-tcbpe</b>, Sr–O polyhedron and deprotonated\ntcbpe<sup>4–</sup> ligand have a staggered connection to form\na self-assembled three-dimensional network structure. In addition,\nit is found that <b>Sr-tcbpe</b> undergoes no luminescent color\nchange when grinding under solvent protection, while mechanochromic\nfluorescence behavior is observed when grinding directly, leading\nto 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\nof detection as low as 2.25 μM. Moreover, during the detection\nprocess, unexpectedly, TNP exhibits a selective etching effect on <b>Sr-tcbpe</b>, which could drill nano holes with different sizes\non the surface area of MOF materials to a certain extent, achieving\nthe conversion of chemical energy to mechanical energy. In addition,\nthe successful preparation of a portable sensor <b>Sr-tcbpe</b>@gypsum block provides a platform for the perfect combination of\nmechanochromic fluorescence behavior and visualization detection toward\nTNP. It lays the foundation for the practical application of MOF materials\nin daily life.