Synthesis and Properties of Hybrid Organic-Inorganic Materials Containing Covalently Bonded Luminescent Polygermanes
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- 作者：Yisong Huo and Donald H. Berry
- 刊名：Chemistry of Materials
- 出版年：2005
- 出版时间：January 11, 2005
- 年：2005
- 卷：17
- 期：1
- 页码：157 - 163
- 全文大小：122K
- 年卷期：v.17,no.1(January 11, 2005)
- ISSN：1520-5002
文摘
Covalent binding of arylmethylpolygermanes into hybrid silica materials leads to substantial increasesin thermal stability without degrading Ge-Ge 
-conjugation, as determined by UV-vis absorption andfluorescent emission spectroscopy. Poly(methyltrimethoxysilylphenylgermane) was prepared by ruthenium-catalyzed demethanative coupling of dimethyl(trimethoxysilylphenyl)germane, and then hydrolyzed andcured in the presence of either tetraethoxysilane (TEOS) or 
-acetoxyethylsilsesquioxane (BAESSQ) toyield hybrid materials containing the polygermane linked to the matrix at every repeat unit. Thermalstability of the bulk hybrid materials was examined by TGA, and films were examined by UV-visspectroscopy following thermal treatment and photochemical irradiation. Conjugation of the Ge-Ge chainsis maintained to 380 
C under nitrogen in the case of the BAESSQ-derived hybrids, but only 200 C inair. The photolytic stability of the hybrid films is greater than the parent poly(methylphenylgermane),but the gains are less dramatic. A model is proposed in which anchoring each germanium in the polymerchain to the silica matrix reduces mobility of germyl radicals produced by both thermolysis and photolysis,leading to efficient recombination to restore the Ge-Ge chains under nitrogen. On the other hand,germylene intermediates generated only during photolysis are more reactive and can combine irreversiblywith Si-O-Si bonds or residual SiOH groups in the silica matrix, leading to faster photolytic degradationof the conjugated Ge-Ge chains, even under nitrogen.
-conjugation, as determined by UV-vis absorption andfluorescent emission spectroscopy. Poly(methyltrimethoxysilylphenylgermane) was prepared by ruthenium-catalyzed demethanative coupling of dimethyl(trimethoxysilylphenyl)germane, and then hydrolyzed andcured in the presence of either tetraethoxysilane (TEOS) or -acetoxyethylsilsesquioxane (BAESSQ) toyield hybrid materials containing the polygermane linked to the matrix at every repeat unit. Thermalstability of the bulk hybrid materials was examined by TGA, and films were examined by UV-visspectroscopy following thermal treatment and photochemical irradiation. Conjugation of the Ge-Ge chainsis maintained to 380 C under nitrogen in the case of the BAESSQ-derived hybrids, but only 200 C inair. The photolytic stability of the hybrid films is greater than the parent poly(methylphenylgermane),but the gains are less dramatic. A model is proposed in which anchoring each germanium in the polymerchain to the silica matrix reduces mobility of germyl radicals produced by both thermolysis and photolysis,leading to efficient recombination to restore the Ge-Ge chains under nitrogen. On the other hand,germylene intermediates generated only during photolysis are more reactive and can combine irreversiblywith Si-O-Si bonds or residual SiOH groups in the silica matrix, leading to faster photolytic degradationof the conjugated Ge-Ge chains, even under nitrogen.