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

When the caged germasesquioxanes hexakis­(cyclohexylgermasesquioxane) and hexakis­(n-octylgermasesquioxane) (GT6Cy and GT6Oc) 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)]− (GT6Me–), 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) (GT6An) was prepared and its photoluminescence (PL) properties were investigated. Interestingly, the PL efficiency of GT6An was much lower than that of dimethylaniline itself, likely because of the electron transfer from the photoexcited dimethylaniline unit to the germasesquioxane cage.