TY - JOUR
T1 - Photochemistry of dianthrylsilanes
T2 - A study of σ,π*-interaction
AU - Yang, Ding Djung H.
AU - Yang, Nien Chu C.
AU - Steele, Ian M.
AU - Li, Huí
AU - Ma, Ying Zhong
AU - Fleming, Graham R.
PY - 2003/4/30
Y1 - 2003/4/30
N2 - In this article, we demonstrated by the application of time-resolved spectroscopy, X-ray structural analysis and other spectroscopic techniques that 9-Anthrylsilanes exhibits σ,π*-interaction between 9-anthryl group and the Si-Si linkage in anthryl-disilanes, ASi2, ASi2A, and ASi3A which does not occur in the analogous alkyl derivatives as well as the pyrenylsilane derivatives, in spite of the fact that the 0,0-band of PSi2 is about 12.8 KJ more energetic than that of ASi2 (Figure 1). More interestingly, the X-ray structural studies reveal that ASi3A exists in a butterfly-like structure in agreement with other spectroscopic analyses that the two anthryl groups do not interact in their excited states, while those in ASi2A do. This is in contrast to the analogous pyrenylsilanes; the trisilanes exhibits a stronger excimer interaction than that of disilane.10b Our results show that the σ,π*-interactions in ASi3A has imparted rigidity to the tri-silyl linkage. Potential applications of anthrylsilanes in material sciences will be explored.5 This work provides evidence that σ,π*-interaction between the 9-anthryl group and disilyl linkage does play an important role in the properties of disilanes. We attribute this enhanced σ,π*-interaction to the nature of the lowest excited state (S1 state) of anthracenes, the La transition, which has a much higher oscillator strength than the S1Lb-transition of pyrenes (Figure 1). We define the interaction in anthracene as a σ,π*(S1.La) interaction. This interaction lends a substantial barrier to the Si-Si bond with the excited anthryl nucleus in anthrylsilanes. The scope and potential applications of this phenomenon are discussed.
AB - In this article, we demonstrated by the application of time-resolved spectroscopy, X-ray structural analysis and other spectroscopic techniques that 9-Anthrylsilanes exhibits σ,π*-interaction between 9-anthryl group and the Si-Si linkage in anthryl-disilanes, ASi2, ASi2A, and ASi3A which does not occur in the analogous alkyl derivatives as well as the pyrenylsilane derivatives, in spite of the fact that the 0,0-band of PSi2 is about 12.8 KJ more energetic than that of ASi2 (Figure 1). More interestingly, the X-ray structural studies reveal that ASi3A exists in a butterfly-like structure in agreement with other spectroscopic analyses that the two anthryl groups do not interact in their excited states, while those in ASi2A do. This is in contrast to the analogous pyrenylsilanes; the trisilanes exhibits a stronger excimer interaction than that of disilane.10b Our results show that the σ,π*-interactions in ASi3A has imparted rigidity to the tri-silyl linkage. Potential applications of anthrylsilanes in material sciences will be explored.5 This work provides evidence that σ,π*-interaction between the 9-anthryl group and disilyl linkage does play an important role in the properties of disilanes. We attribute this enhanced σ,π*-interaction to the nature of the lowest excited state (S1 state) of anthracenes, the La transition, which has a much higher oscillator strength than the S1Lb-transition of pyrenes (Figure 1). We define the interaction in anthracene as a σ,π*(S1.La) interaction. This interaction lends a substantial barrier to the Si-Si bond with the excited anthryl nucleus in anthrylsilanes. The scope and potential applications of this phenomenon are discussed.
UR - http://www.scopus.com/inward/record.url?scp=0037473530&partnerID=8YFLogxK
U2 - 10.1021/ja020403u
DO - 10.1021/ja020403u
M3 - Article
C2 - 12708861
AN - SCOPUS:0037473530
SN - 0002-7863
VL - 125
SP - 5107
EP - 5110
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 17
ER -