Synthesis of Triptycene‐Substituted Azapentacene and Azahexacene Derivatives

Abstract

We describe the synthesis and characterization of novel iptycene-substituted azaacenes by using either a classic condensation route (diamine plus ortho-quinone) and/or a Pd-catalyzed coupling of an aromatic diamine with an aromatic dihalide. The attachment of an iptycene unit leads to a significant blueshift (15 nm) in the UV/Vis spectra of these azaacenes. The iptycene unit stabilizes a hexaazahexacene with a λ of 833 nm. By employing 5,6-diamino(benzothiadiazole) as a synthon for tetraaminobenzene, we could prepare the symmetrical bis-triptycene-substituted tetraazapentacene in high yields.

N-Heteroacenes as a New Class of Non-Fullerene Electron Acceptors for Organic Bulk-Heterojunction Photovoltaic Devices

“…By fitting the absorption onset in the PDS measurements, we find the band gap of TIPS‐TAP to be 1.55 eV, slightly lower than that of TIPS‐TAP‐1T at 1.6 eV and TIPS‐TAP‐2T at 1.7 eV. The increase in bandgap with the incorporation of triptycenyl units is in agreement with previous DFT calculations . Using these bandgaps we estimate the electron affinity of TIPS‐TAP to be 4.5 eV, which suggests it exhibits a significantly lower LUMO than that of TIPS‐TAP‐1T (at 4.2 eV) and TIPS‐TAP‐2T (at 4.1 eV).…”

“…The ionization potential (IP) was determined by fitting the low binding energy edge and was found to be 6.05 eV for TIPS‐TAP and 5.8 eV for TIPS‐TAP‐1T and TIPS‐TAP‐2T. The small decrease in the ionization potential upon the addition of the triptycenyl moiety/moieties is in agreement with the previous cyclic voltammetry measurements and density functional theory (DFT) calculations …”

“…GIWAXS measurements show that TIPS‐TAP‐1T and TIPS‐TAP‐2T show no clear crystalline features both in the pristine films and in blends with PTB7. While a crystal structure for TIPS‐TAP‐2T has been reported previously for solution grown single crystals, no crystals can be observed in thin films. It is likely that without the driving force of crystallization, the TIPS‐TAP‐1T and TIPS‐TAP‐2T blends have a more finely intermixed morphology.…”

“…Three derivatives of tetraazapentacene were synthesized based on the previously reported procedures and their molecular structures are shown in Figure . All three materials are soluble in common solvents, such as chloroform, chlorobenzene, or toluene, and were purified by column chromatography and recrystallized in hexane.…”

“…6,13‐bis(triisopropylsilylethynyl)tetraazapentacene (TIPS‐TAP), 6,17‐Bis((triisopropylsilyl)ethynyl)‐9,14‐dihydro‐9,14[1’,2’]‐benzeno‐5,7,16,18‐tetraazaheptacene (TIPS‐TAP‐1T) and 8,19‐Bis((triisopropylsilyl)ethynyl)‐5,11,16,22‐tetrahydro‐5,22[1’,2 ’],11,16[1’,2’]‐dibenzeno‐7,9,18,20‐tetraazanonacene (TIPS‐TAP‐2T) were synthesized following previously reported procedures …”