Extending Hexaazatriphenylene with Mono-/Bithiophenes in Acceptor-Donor Diads and Acceptor-Donor-Acceptor Triads

Three new hexaazatriphenylene (HAT)-based electron-accepting molecules with octupolar disc-like symmetry that combine the HAT core with six branches of electron-donor thiophenes in two modalities have been synthesized: (i) with six donor thiophenes and bithiophenes delineating a six-donor-to-one-acceptor (6-1) profile and (ii) with six donoracceptor branches configuring a 6-6-1 acceptordonoracceptor triad. The 6-fold accumulation of donors and acceptors in the periphery of the HAT core is expected to tune the molecular electronic and optical properties. An exhaustive analysis of these properties as a function of the 6-1 and 6-6-1 stoichiometry of the molecules is described by combining a palette of experimental spectroscopic techniques such as electronic absorption (from the ground electronic and excited states), emission (fluorescence and phosphorescence), ultraviolet photoelectron spectroscopy, spectroelectrochemistry, and vibrational Raman have been implemented, all combined with electrochemistry and molecular theoretical modeling. A particular focus on the charged species and the charge distribution around the 6-1 and 6-6-1 patterns is conducted. Structureproperty relationships have been outlined. The complete understanding of all these properties might help to design improved chromophores based on the HAT structure and to anticipate new properties.