Temperature- and Mechanical-Force-Responsive Self-Assembled Rhomboidal Metallacycle

The dianthracene-based rhomboidal organoplatinum(II) metallacycle 1 was successfully obtained via coordination-driven self-assembly involving the combination of diplatinum(II) acceptor 2 and dipyridyl donor 3. A dilute acetone solution of the prepared metallacycle exhibited temperature-responsive fluorescence involving a gradual red-shifted fluorescent change from cryan to yellow over a wide temperature range from 77 to 297 K. Notably, a linear correlation was observed between the emission maximum and temperature in the low-temperature region from 77 to 137 K. Additionally, the supramolecular coordination complex in the solid state showed reversible mechanochromic fluorescence behavior with an obvious color change between green and yellow. Further investigation revealed that a morphology change before and after grinding was responsible for the observed mechanofluorochromic phenomenon. These studies provide new insight into the preparation of well-defined supramolecular organoplatinum(II) metallacycles capble of responding to multiple stimuli.