Photochemistry of various acene based molecules

Photochemistry based on acenes and their derivatives is one of the emerging research areas in the field of polycyclic aromatic hydrocarbons (PAHs). However, due to the increased reactivity of larger acenes towards light and singlet oxygen, it is difficult to precisely control their photochemical reactions. Therefore, the unexpected reactivity of acene-based molecules brings about two challenging topics: how to design stable acenes and how to utilize the photochemistry to design new acene-based functional materials. In this review, we first focus on the mechanism of photochemistry of acenes to theoretically understand how these reactions could have happened. Next, we will give a summary on both acene-based photocyclization and photooxidation reactions.     

Rücktitelbild: A Facile and Versatile Approach to Double N‐Heterohelicenes: Tandem Oxidative C?N Couplings of N‐Heteroacenes via Cruciform Dimers (Angew. Chem. 18/2015)

Novel double N‐hetero[5]helicenes that are composed of two nitrogen‐substituted heteropentacenes are synthesized by tandem oxidative C N couplings via the cruciform heteropentacene dimers. The developed method is very facile and enables the synthesis of a double helicene in only two steps from commercially available naphthalene derivatives. These double N‐hetero[5]helicenes have larger torsion angles in the fjord regions than typical [5]helicenes, and optical/electrochemical measurements revealed a significant increase in the electronic communication between the two heteropentacene moieties of the double helicenes compared with their cruciform dimers. The optical resolution of one of the double helicenes was successfully carried out, and their stability towards racemization was remarkably higher than those of typical [5]helicenes. The synthetic strategy proposed in this paper should be versatile and widely applicable to the preparation of double helicenes from other N‐containing π‐conjugated planar molecules.