Dicyano‐Substituted Diazaacenes

Abstract

Herein, we report the synthesis, spectroscopic, and structural properties of novel 2,3-dicyano-substituted azaacenes containing three to six annelated rings as a framework. The targets were prepared by Pd-catalyzed coupling of diamino-bis(tri-isopropylsilylethynyl)benzene, -naphthalene, and -anthracene with either 4,5-dibromophthalonitrile or 6,7-dibromonaphthalene-2,3-dicarbonitrile into the respective N,N'-dihydrodiazaacenes. Oxidation with MnO or PbO furnishes the dicyano-substituted diazaacenes in reasonable to good yields. An exception is the diazahexacene, where the N,N'-dihydrodiazaacene is difficult to oxidize. Most of the targets could be crystallized and pack in isolated pairs, stacks, and brick-wall motifs. The n-type behavior of these molecules was illustrated in a proof-of-concept organic field-effect transistor, showing mobilities up to 7×10 cm V s .

Cata‐Annulated Azaacene Bisimides

“…The even more electron‐poor 4 ‐ H 2 could only be oxidized by PbO 2 at 70 °C in chloroform. For 5 a , PbO 2 at rt was sufficiently oxidizing, but the reaction had to be carried out under N 2 because reduction back to 5 ‐ H 2 occurred spontaneously in air, similar to what has been previously observed for similarly electron‐poor dicyanodiazahexacene [12] and hexaazahexacene [8a] . This spontaneous reduction is a testament to the high electron affinities of 4 a and 5 a .…”

“…First reduction potentials and electron affinities (cyclic voltammetry, CV, Figure S2, Supporting Information) also increase with azaacene size and number of nitrogen atoms. Interestingly, cata ‐condensed bisimides are more powerful than CN‐substituents, as evidenced by a comparison of the first reduction potentials of 3 a (−0.62 V) to that of a dicyanodiazaacene (−0.7 V) [12] . The even more electron accepting 4 a and 5 a are reduced at −0.36 V and −0.35 V (vs. Fc/Fc + ), respectively.…”

“…[a] First reduction potentials measured by cyclic voltammetry (CV) in dichloromethane with Bu 4 NPF 6 as the electrolyte against Fc/Fc + as an internal standard at 0.2 V s −1 . The offset of the exact values is estimated by adjusting the ferrocene redox couple to −5.10 eV [14] on the Fermi scale, for azaacenes EA=−( E 0/− [vs. Fc+/Fc] +4.70 eV) gives a much better empirical fit of almost all CV data to DFT calculations [12,15] . A table referencing ferrocene as −5.10 eV can be found in the Supporting Information (Table S1).…”

Azaacenes Based Electroactive Materials: Preparation, Structure, Electrochemistry, Spectroscopy and Applications—A Critical Review

“…In this structural arrangement two intermolecular distances between molecules are observed within the stand. Similar stacking pattern was also observed for diazatetracene containing substituents in its terminal ring (2a, [69]). To the contrary, only one intermolecular distance of 0.343 nm within a stack was reported for a different isomer of 1a, i.e., 1b [69].…”

Imide‐Fused Diazatetracenes: Synthesis, Characterization, and Application in Perovskite Solar Cells

“…It is essential to lower the LUMO energy level of azatetracenes to achieve better n‐type performance. From the synthetic perspective, the introduction of electron‐withdrawing units could evidently deepen the LUMO of azatetracenes . Mark et al.…”