Multiple-State Emissions from Neat,Single-Component Molecular Solids: Suppression of Kasha's Rule |
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| Authors: | Ya-Hang Wu Prof Dr Hongyan Xiao Prof Dr Bin Chen Prof Dr Richard G Weiss Prof Dr Yu-Zhe Chen Prof Dr Chen-Ho Tung Prof Dr Li-Zhu Wu |
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| Institution: | 1. Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China
These authors contributed equally to this work.;2. Key Laboratory of Bio-inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China;3. Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100190 China;4. Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC, 20057-1227 USA |
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| Abstract: | Three rigid and structurally simple heterocyclic stilbene derivatives, (E)-3H,3′H-1,1′-biisobenzofuranylidene]-3,3′-dione, (E)-3-(3-oxobenzoc] thiophen-1(3H)-ylidene)isobenzofuran-1(3H)-one, and (E)-3H,3′H-1,1′-bibenzoc] thiophenylidene]-3,3′-dione, are found to fluoresce in their neat solid phases, from upper (S2) and lowest (S1) singlet excited states, even at room temperature in air. Photophysical studies, single-crystal structures, and theoretical calculations indicate that large energy gaps between S2 and S1 states (T2 and T1 states) as well as an abundance of intra and intermolecular hydrogen bonds suppress internal conversions of the upper excited states in the solids and make possible the fluorescence from S2 excited states (phosphorescence from T2 excited states). These results, including unprecedented fluorescence quantum yields (2.3–9.6 %) from the S2 states in the neat solids, establish a unique molecular skeleton for achieving multi-colored emissions from upper excited states by “suppressing” Kasha's rule. |
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| Keywords: | Aggregationsinduzierte Emission Kasha-Regel Mehrfarbige Emission Organische Festkörpermaterialien Obere angeregte Zustände |
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