Development of pyrene-based MOFs probe for water content and investigations on their mechanochromism and acidochromism

A smart fluorescent pyrene-based MOFs (HPU-26) was synthesized by the solvothermal method, which possessed multi-stimuli-responsive properties and could detect water content in common organic solvents. The reversible multicolor fluorescent switching between yellowish green and cyan were observed under the stimulation of force, heating, and acid-base vapors. PXRD pattern, DSC curve, FI-IR spectra and the solid-state UV–vis absorption spectra were conducted to prove that the changes of π - conjugation induced the transformations between excimer and monomer formation under external stimulation, thus resulting in different fluorescent properties. In addition, HPU-26 could realize the detection of water content by remarkable change of fluorescent color from yellowish green to blue with increasing the water content in common organic solvents, which was attributed to the decomposition of crystal structure. The limit of detection (LOD) values of HPU-26 for detecting the water content in EtOH, DMA, Acetone and ACN were determined as 0.0260 %, 0.0578 %, 0.1978 %, and 0.5637 % (v/v), respectively. Furthermore, HPU-26 could be applied in advanced anti-counterfeiting and convenient visual detection of water content in common organic solvents by smartphone-based software.