Dibenzoboroles with emission from the bond-cleavage-induced ICT was reported.

Air- and moisture-stable dibenzo[b,f]gallepins with planar seven-membered rings have been designed and synthesized. From X-ray single-crystal analyses, the effects of the coordination numbers were evaluated at the gallium atom on the planarity of the seven-membered rings with a series of the synthesized complexes. Accordingly, it was shown that the seven-membered ring of dibenzogallepin involving a three-coordinated gallium atom presented the highest planarity compared to other dibenzogallepins with four- or five-coordinated gallium atoms. In addition, from theoretical calculations, it was proposed that the electronic states of the gallium atom in the complexes contributed to the energy levels of LUMOs+1.

Heterofluorenes containing group 13 atoms such as aluminum (alumafluorene) and gallium (gallafluorene) were synthesized and characterized. The synthesized heterofluorenes had five-coordinated states in their single crystals. From UV–vis absorption measurements, the heterofluorenes presented similarly shaped spectra. Interestingly, in the emission spectra at room temperature, gallafluorene presented the phosphorescence property. At 77 K, gallafluorene showed larger phosphorescence than alumafluorene did. The heavy atom effect of gallium should be responsible for the phosphorescence property of gallafluorene.