Design and Synthesis of an o-Hydroxyphenyl-Containing Spiropyran Thermochromic Colorant

An o-hydroxyphenyl-containing spiropyran thermochromic colorant was designed and synthesized. The prepared compound is sensitive to temperature and has a reversible color change with temperature variation. X-ray diffraction analysis and variable-temperature NMR studies suggest that the thermochromism of the compound presumably involved a ring-opening C−O bond cleavage of the spiropyran moiety followed by an intramolecular hydrogen transfer.