Thermally Stable Organic and Inorganic Alkalides and Electrides

Michigan State University, East Lansing MI

Investigators

Abstract

This project aims to synthesize and characterize crystalline salts that contain alkali cations complexed by organic cage complexants and either alkali metal anions (alkalides) or trapped electrons (electrides) as the counter-ions. In order to enhance thermal stability, the emphasis will be on the synthesis and use of tertiary amine aza-type complexants, which are more resistant to reduction than the currently used cyclic and bicyclic polyethers. Cryptand-like or adamanzane-like molecules with cavities appropriate for selected alkali cations will be synthesized. When the rate of encapsulation of the cation is fast enough, the free complexant will be used with the alkali metal in a solvent such as methylamine or dimethyl ether to produce the alkalide or electride in solution. Addition of a less polar co-solvent such as trimethylamine or diethyl ether will permit crystallization to be initiated. Slow cooling of the saturated solution or slow removal of the more polar (and more volatile) co-solvent will be used to grow crystals suitable for structure determination by X-ray diffraction. Characterization methods and physical property studies will include chemical anaylsis, optical absorbance and reflectance, magnetic susceptibility, pulsed EPR and ENDOR and nuclear magnetic resonance differential scanning calorimetry and conductivity. Such measurements will be much easier than are now possible with alkalides and electrides if, as we anticipate, the compounds are thermally stable to at least room temperature. In an effort to synthesize a new class of inorganic electrides, alkali metal adducts to all-silica zeolites will also be prepared and characterized. These new classes of alkalides and electride compounds are of great inferent in the materials sciences community. The importance of novel conducting materials to advancing areas of solid state materials sciences, such as molecular electronics, is receiving considerable emphasis in various industries.