Synthesis and Spectroscopic Studies of Arylethynylsilanes |
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| Authors: | Guang Shao Akihiro Orita Prof?Dr Koji Nishijima Kanako Ishimaru Makoto Takezaki Prof?Dr Kan Wakamatsu Prof?Dr Rolf Gleiter Prof?Dr Junzo Otera Prof?Dr |
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| Institution: | 1. Department of Applied Chemistry, Okayama University of Science, Ridai‐cho, Okayama 700‐0005, Japan, Fax: (+81)?86‐256‐4292;2. Department of Chemistry, Okayama University of Science, Ridai‐cho, Okayama 700‐0005, Japan;3. Institute of Organic Chemistry, University of Heidelberg, Im Neuenheimer Feld 270, D‐69120 Heidelberg, Germany |
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| Abstract: | A variety of arylethynylsilanes (Ar‐C?C? C6H4? C?C)nSiMe4?n were prepared successfully by reaction of the corresponding chlorosilanes Me4?nSiCln with Ar? C?C? C6H4? C?CM (M=Li, MgBr), which was prepared by treatment of ethynyl(diarylethyne)s Ar? C?C? C6H4? C?CH with BuLi or MeMgBr. The ethynyl(diarylethyne)s were readily prepared in good yields by the double‐elimination method: addition of lithium hexamethyldisilazide to a mixture of ArCH2SO2Ph, TMS? C?C? C6H4? CHO, and ClP(O)(OEt)2, followed by desilylation. In the tetrakis(arylethynyl)silanes (Ar? C?C? C6H4? C?C)4Si thus prepared, through‐space conjugation of four triple bonds on the silicon atom emerges as a result of participation of the silicon orbitals in the acetylenic π orbitals. This participation enhances the emissive quantum yields of arylethynylsilanes with an increase in the number of arylethynyl moieties on silicon: quantum yields of emission (ΦF) of 0.72 for (MeOC6H4? C?C? C6H4? C?C)4Si, 0.53 for (MeOC6H4? C?C? C6H4? C?C)2SiMe2, and 0.47 for MeO‐C6H4? C?C? C6H4? C?CSiMe3 were obtained. Although this enhancement effect was also observed in the phenylethynylarylsilane (MeOC6H4? C?C? C6H4)2SiMe2, the bis(arylethynyl)disilane (MeOC6H4? C?C? C6H4? C?C‐SiMe2)2 exhibited non‐enhanced emission. |
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| Keywords: | alkynes conjugation fluorescence spectroscopy molecular orbitals silanes |
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