Synthesis and Electronic Properties of Arene-Fused <i>o</i>-Carborane

A transition-metal-free, base-mediated intramolecular C-arylation of o-carborane provides facile access to arene-fused o-carboranes. The new naphthyl-fused o-carborane 2, as a fluoranthene analogue, was obtained with the reaction of 1-(8-Br-1-naphthyl)-o-carborane under basic conditions. This method is also applicable to the synthesis of biaryl-fused o-carboranes. The corresponding arene-fused nido-carborane was further obtained after deboronation with nBu4NF. The fluorescence quantum efficiency of 5 has shown significant improvement compared to fluoranthene (ΦPL: 0.79 vs 0.2). In addition, the aromaticity of the o-carborane-annulated ring systems in these new compounds was studied and found to be enhanced compared to the corresponding rings of fluoranthene.