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| Content Provider | Royal Society of Chemistry (RSC) |
|---|---|
| Author | Watanabe, Shigeru Yoshida, Katsuhira Ooyama, Yousuke Yoshikawa, Shintaro |
| Copyright Year | 2007 |
| Abstract | Novel solid-emissive indeno[1,2-b]benzo[4,5-e]pyran-11-one-type fluorophores 3a–3c having non-planar structures with sterically hindered substituents (R = butyl, phenyl, and thienyl) have been designed and conveniently synthesized. The fluorescence quantum yields of 3a–3c in 1,4-dioxane were 3a (Φ = 0.053) ≫ 3b (Φ = 0.013) > 3c (Φ = 0.003). On the other hand, the solid-state fluorescence quantum yields of the fluorophores were 3a (Φ = 0.39) > 3b (Φ = 0.15) > 3c (Φ = 0.06). To elucidate the large differences in the quantum yields in solution and in the solid state and among the fluorophores 3a–3c, we performed time-resolved fluorescence spectroscopic measurements, semi-empirical molecular orbital calculations (AM1 and INDO/S), and X-ray crystallographic analyses of 3a–3c. The comparison of the values of the radiative and non-radiative rate constants determined by the time-resolved spectroscopic measurements in solution and in the crystalline state supported that non-radiative decay is reduced by restriction of the rotation of the phenyl and thienyl rings in the solid state. In addition, the X-ray crystal structures demonstrated that, in 3a and 3b, the non-planar structure with sterically hindered substituents prevents the fluorophores from forming short π–π contacts and produces strong solid-state fluorescence. On the other hand, in the crystal of 3c, the formation of continuous intermolecular CH⋯S bonding between neighboring fluorophores was found to increase short π–π contacts and reduce the fluorescence intensity. |
| Starting Page | 1260 |
| Ending Page | 1269 |
| Page Count | 10 |
| File Format | HTM / HTML PDF |
| ISSN | 14770520 |
| Volume Number | 5 |
| Issue Number | 8 |
| Journal | Organic & Biomolecular Chemistry |
| DOI | 10.1039/b700848a |
| Language | English |
| Publisher | Royal Society of Chemistry |
| Access Restriction | Open |
| Subject Keyword | Molecular orbital X-ray crystallography INDO Austin Model 1 Quantum mechanics Butyl group Pyranose Fluorescence Phenyl group 1,4-Dioxane |
| Content Type | Text |
| Resource Type | Article |
| Subject | Organic Chemistry Biochemistry Physical and Theoretical Chemistry |
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