A Two‐Photon Dye with Favorable Photophysical Properties and Ultrahigh Polarity Sensitivity Designed by Utilizing the Tautomerism of β‐Diketone

The designed two-photon dye with a β-diketone moiety can undergo a keto-enol equilibrium and thus impart ultrahigh polarity sensitivity. The enol form, as the main component in aprotic environments with a long conjugated chain, displays much stronger two-photon fluorescence, while the keto form in protic environments with negligible fluorescence shows good water-solubility and cell membrane permeability. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.