Jiang He, Florian Rauch, Alexandra Friedrich, Johannes Krebs, Ivo Krummenacher, Rüdiger Bertermann, Jörn Nitsch, Holger Braunschweig, Maik Finze, Todd B. Marder

• Phenylpyridyl-fused boroles [TipPBB1]\(_4\) and TipPBB2 were synthesized and their properties investigated. [TipPBB1]\(_4\) forms a tetramer in both the solid state and solution. TipPBB2 contains a 4-coordinate boron atom in the solid state but dissociates to give a 3-coordinate boron species in solution. TipPBB2 shows interesting temperature-dependent dual fluorescence in solution because of the equilibrium between 3- and 4-coordinate boron species due to weak N⋅⋅⋅B intermolecular coordination.