Singlet open-shell character of conjugated Kekule molecules

We have studied the properties of singlet open-shell molecules that are designed, synthesized, and isolated by us. The molecules contain p-quinodimethane or cumulene structures in the middle of their skeletons, and also equip spindelocalizing moieties, phenalenyl, in the both ends for thermodynamic stabilization. Crystal structures and electronic spectra revealed that these conjugated Kekulé molecules actually had open-shell character despite closed-shell chemical structures can be drawn for the compounds.