Intramolecular\nCharge Transfer Inhibition Strategy\ntoward a Desired Solvatochromic Fluorescent Platform: Visualization\nof Duple Organelles and Detection of Carbon Dioxide

Solvatochromic fluorescent probes are crucial molecular\ntools to\ninvestigate and aggregate proteins’ fold, visualize fine structures\nin biomembranes, and label different organelles in dual emission colors.\nHowever, solvatochromic fluorogens often displayed a weak emission\nat high polarity, hindering their bioimaging applications. To resolve\nthis problem, herein, we propose an intramolecular charge transfer\n(ICT) inhibition strategy. The probe was designed with a single electronic\ndonor and two acceptors in order to split and inhibit the ICT procedure.\nAs a result, the probe displayed an intense emission at both low and\nhigh polarities and showed a large emission shift (84 nm) upon polarity\nchange. Using the probe, we successfully imaged lipid droplets and\nthe endoplasmic reticulum in different fluorescence colors. Moreover,\nthe different degrees of lipid accumulation by oleic acid, stearic\nacid, and cholesterol (oleic acid > stearic acid > cholesterol)\nhave\nbeen revealed. The lipid accumulation induced by the three lipids\ncould be rapidly consumed under lipid-less conditions, and the lipids\nwith stearic acid were the most difficult to be consumed. The biological\nresults could facilitate the understanding and treatment of lipid\naccumulation and obesity. Furthermore, utilizing the polarity increase\nof diethylamine after the reaction with CO<sub>2</sub>, the ratiometric\ndetection of CO<sub>2</sub> has been achieved for the first time with\nthe probe.