ABSTRACT
A new synthetic route to 5,6,11,12-tetrakis(arylethynyl)tetracenes, π-extended rubrenes, was developed via [4 + 2] cycloadditions of dialkynylisobenzofuran and 1,4-naphthoquinone. Introduction of arylethynyl groups by double nucleophilic additions to tetracenequinone gave sterically congested (arylethynyl)tetracenes after reductive aromatization. The photophysical properties of the newly prepared π-conjugated molecules are also evaluated.
ABSTRACT
An efficient synthetic route to 5,6,11,12-tetrakis(arylethynyl)tetracenes, new π-extended rubrene derivatives, was developed by means of [2+4] cycloaddition of dialkynylnaphthalyne and dialkynylisobenzofuran. Importantly, two alkynyl groups introduced into the aryne exerts a significant effect in lowering the LUMO energy, allowing practical access to sterically overcrowded polycyclic structures through an efficient HOMO-LUMO interaction. Study on the potential reactivity inherent in the peri-ethynyl-substituted tetracenes revealed several interesting reactivities. X-ray analysis of these new π-extended derivatives showed distorted structures to reduce steric repulsion due to the existence of the substituents at the peri-positions.
