From three-dimensional polyphenylene dendrimers to large graphite subunits Original Research Article

Here we present a new approach to extremely large polycyclic aromatic hydrocarbons (PAHS) based on a cyclodehydrogenation method for polyphenylene dendrimers. These polyphenylene dendrimers are synthesized by repeated Diels-Alder reactions of ethynyl-substituted tetraphenylcyclopentadienones (1b) to the tetraethynylbiphenyl (2) core. Molecular mechanics and molecular dynamics calculations revealed that the dendrimers are shape-persistent due to the steric “overcrowding” of the benzene rings. The chemical and physical properties of the dendrimers can be controlled by varying the cyclopentadienones used in the last growth step.