Stimuli‐Responsive Dual‐Color Photon Upconversion: A Singlet‐to‐Triplet Absorption Sensitizer in a Soft Luminescent Cyclophane |
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Authors: | Kazuma Mase Yoichi Sasaki Dr Yoshimitsu Sagara Prof?Dr Nobuyuki Tamaoki Prof?Dr Christoph Weder Dr Nobuhiro Yanai Prof?Dr Nobuo Kimizuka |
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Affiliation: | 1. Department of Chemistry and Biochemistry, Graduate School of Engineering, Center for Molecular Systems (CMS), Kyushu University, Nishi-ku, Fukuoka, Japan;2. Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido, Japan;3. JST-PRESTO, Kawaguchi, Saitama, Japan;4. Adolphe Merkle Institute, University of Fribourg, Fribourg, Switzerland |
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Abstract: | Reversible emission color switching of triplet–triplet annihilation‐based photon upconversion (TTA‐UC) is achieved by employing an Os complex sensitizer with singlet‐to‐triplet (S‐T) absorption and an asymmetric luminescent cyclophane with switchable emission characteristics. The cyclophane contains the 9,10‐bis(phenylethynyl)anthracene unit as an emitter and can assemble into two different structures, a stable crystalline phase and a metastable supercooled nematic phase. The two structures exhibit green and yellow fluorescence, respectively, and can be accessed by distinct heating/cooling sequences. The hybridization of the cyclophane with the Os complex allows near‐infrared‐to‐visible TTA‐UC. The large anti‐Stokes shift is possible by the direct S‐T excitation, which dispenses with the use of a conventional sequence of singlet–singlet absorption and intersystem crossing. The TTA‐UC emission color is successfully switched between green and yellow by thermal stimulation. |
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Keywords: | cyclophanes photochemistry photon upconversion singlet-to-triplet absorption stimuli-responsive luminescence |
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