Alkoxy substituted D-π-A dimethyl-4-pyrone derivatives: Aggregation induced emission enhancement, mechanochromic and solvatochromic properties

Three series of D-π-A 2,6-dimethyl-4-pyrone-cored derivatives were designed and synthesized. Evaluation by spectroscopic methods indicated that all the compounds exhibited aggregation-induced emission enhancement (AIEE) effect and solvatochromism. The experimental results revealed that the restriction of intramolecular rotation is the key element for showcasing the AIEE phenomenon. Moreover, all of the compounds presented red-shifted mechanochromic behavior, the extent of the red-shift was mainly dependent on the position and length of alkoxyl group. The PXRD and DSC profiles demonstrated a transformation from crystalline to amorphous state upon grinding. The D-A strategy introduced in this work could facilitate the development and application of ingenious mechanochromic materials.