Studies on Spherically Distributed LUMO and Electron-Accepting Properties of Caged Hexakis(germasesquioxanes)

When the caged germasesquioxanes hexakis­(cyclohexylgermasesquioxane) and hexakis­(n-octylgermasesquioxane) (GT 6 Cy and GT 6 Oc) were irradiated with γ-rays in 2-methyltetrahydrofuran (2-MTHF) glass matrices at 77 K, anisotropic ESR signals ascribed to their radical anions were observed. DFT calculations of a model radical anion, [hexakis­(methylgermasilsesquioxane)]− (GT 6 Me –), indicated unsymmetrical distribution of the SOMO (singly occupied molecular orbital), in agreement with the anisotropy of the ESR signals. To better understand the electronic states of the caged germasesquioxanes, hexakis­(dimethylaminophenylgermasesquioxane) (GT 6 An) was prepared and its photoluminescence (PL) properties were investigated. Interestingly, the PL efficiency of GT 6 An was much lower than that of dimethylaniline itself, likely because of the electron transfer from the photoexcited dimethylaniline unit to the germasesquioxane cage.