One-Pot Divergent Synthesis of a 13-Ring Triquinone and its Facile Conversion to a [4.4.4]Tridecastarphene.

Abstract

Acenes are notable for their optoelectronic properties and applications in organic electronics. Starphenes are structurally related molecules possessing three acene arms that radiate linearly from a central benzene ring (i. e., linearly annellated triphenylenes). Large starphenes have been prepared using convergent syntheses involving transition metal catalyzed cyclotrimerizations of either preformed acenes or arynes. Here, we report a one-pot divergent synthesis of a 13-ring triquinone that is readily converted to a [4.4.4]tridecastarphene derivative. The one-pot procedure involves the sequential reactions of three 1,4-anthraquinones with o-quinodimethane derivatives that are generated sequentially from a stable, trisulfone precursor. The resulting [4.4.4]tridecastarphene derivative bearing p-(t-butyl)phenyl substituents was characterized by ¹H NMR, ¹³C NMR and UV-vis spectroscopies, as well as mass spectrometry, cyclic voltammetry and differential pulse voltammetry. Theoretical and experimental studies reveal a relatively high-lying HOMO orbital (about -4.70 to -4.86 eV) and a relatively small HOMO-LUMO gap (2.1 eV), suggesting utility as a p-type organic semiconductor. Our [4.4.4]tridecastarphene derivative photooxidizes in a CH₂Cl₂ solution exposed to ambient light and air with a half-life of 150 minutes at room temperature, but shows no sign of degradation after 12 months in the solid-state. Our [4.4.4]tridecastarphene derivative also shows excellent solubility in a number of organic solvents including dichloromethane, chloroform and toluene, potentially enabling printed electronic applications.