Importance of the interaction between sodium silicate and organic materials to astrobiology: Alcohol-based organo-silicates as potential biosignatures

摘要

We have found that alcohols catalyze a rapid polymerization of silicic acid to silica gel upon the addition of alcoholsLike amino acids, alcohols could be preserved in the silica gel by two mechanisms. In the first njechanism, the alcoholsbecome entombed in the silica gel In this case, only Si-O-Si bonds would be observed in the infrared (IR) spectra Inthe second mechanism, the alcohols make chemical bonds with the silicic acid, to create organo-silicates. In this case,Si-O-C bonds would be observed in the IR. We have found that steric hindrance plays a major role in the volume of analcohol required, Amino alcohols are more effective in creating a viscous gel than the alcohols, and appeared to formcovalent Si-O-C bonds in some cases. Characteristic shifts in the Si-O-Si bands of over 50 cm"1 towards lower IRj.frequencies can be observed in the alcohol gels. The hydrolysis of known organo-silicates has led to the identification of the Si-O-C band in the region of 1225-1150 cm"1, and the Si-O-Si band in the region of 1125-1000 cm"1IAlcohols play an important role in many biological pathways, and could serve as biosignatures in extreme environmentstincluding meteorites and other planets