Novel synthetic approaches towards hexaazatriphenylene (HAT) derivatives
Large two-dimensional molecules with extended ¿-systems are subject of increasing interest as a consequence of their technological applications. In particular, hexaazatriphenylene (HAT) derivatives, present a great interest due to the influence of heteroatoms on the electronic nature without modifying the structure. HAT derivatives have recently attracted attention as materials for organic electronic applications1 and depending on the choice of substituent can have a variety of applications (discotic liquid-crystals, n-type semiconducting, magnetic materials or fluorescent dyes).2 Whereas HATs carrying six identical substituents are well known following different synthetic approaches, the synthesis of non-centrosymmetric HAT derivatives is still quite rare. In our working group we are centered in two main routes for affording HAT derivatives. One route affords a variety of symmetrical HAT derivatives including HAT condensed systems. On the other hand, we have also synthesized non-centrosymetric ¿-conjugated donor-acceptor molecules bearing a HAT core and donor groups in the periphery.3 In this communication we present a new soluble ¿-deficcient derivative which consists of three HAT molecules condensed around a central aromatic core so we have named it triHAT. We have found triHAT to be 0.75 V better acceptor than HAT in itself. We also present a new synthetic route in order to obtain non-centrosymetric ¿-conjugated donor-acceptor molecules bearing a HAT core and donnor groups in the periphery. This synthesis paves the way for further conjugated donnor-acceptor derivatives of HAT.
This work has been supported by the MCyT of Spain (Project CTQ2007-60459), a Comunidad de Madrid-Universidad Complutense joint project (CCG07-UCM/PPQ-2126, Group Nr.: 910759). R. Juárez is indebted to Universidad Rey Juan Carlos for a doctoral fellowship.