Thiadiazolo‐Azaacenes

Abstract

This work reports the synthesis and characterization of bis-and tetrakis(thiadiazolo)-appended di-and tetraazaacenes,d isplaying up to seven catenated benzene/pyrazine rings. The targetsa re obtained by condensation of benzo-bis(thiadiazole)-4,5-dione with aromatic di-and tetraamines. The condensation products-up to a heptacene-like species-are stable but can be insoluble. Soluble derivatives are readily processible,b ut do not show enhanced electrona ffinities, as the two or four attached benzothiadiazole units are effectively resonanceseparated from the acene body,m aximizing the number of Clar-sextets.Thiadiazoles are attractive as they can confer electronegative charactert oa cenes and N-heteroacenes. [1] Compound B (Figure 1) has been known for quite some time, [2] whilea ttempts by Müllen et al. to produce compound C were met withouts uccess as it immediatelyr eactedi nto its butterflytype dimer. [3]

N-Heteroacenes and N-Heteroarenes as N-Nanocarbon Segments

“…The concept is not limited to the introduction of hydrocarbon aprons; thiadiazolo units also stabilize the acene scaffold. 68 Over all, the stability of such materials is much improved but at a cost. In our next series of experiments, we plan to extend this concept to butterfly protected nonacenes to test the limits (of stabilizing power) of this concept.…”

“…In our benzo-stabilized species, the two added phenanthrene rings equal one benzene ring electronically. The concept is not limited to the introduction of hydrocarbon aprons; thiadiazolo units also stabilize the acene scaffold . Over all, the stability of such materials is much improved but at a cost.…”

Stable N,N’‐Diarylated Dihydrodiazaacene Radical Cations

“…From 1 + + C to 3 + + C,t he oxidation potentials increase from 0.14 V to 0.26 V, while the reductionp otentials decrease from 0.63 V to 0.34 V. The radical cations become more difficult to oxidize and easier to reduce as ac onsequence of extension of the pconjugated systems. NICS(1) zz calculations [14] were performed to study the aromaticity of the neutralc ompounds and their radicalc ations.T he NICS-values of the inner N,N'-dihydropyrazine (see Figure 2) are positive,w ith their values surpassing + 19.8, indicating local antiaromaticity. [15] This antiaromaticity decreases from 1 to 3, which might be ascribed to the differencei nb ond orders of the fused bond between the dihydropyrazine core and the outer arene groups( benzene, naphthalene andacombination of both).…”

‘2E−2N squares’: Chalcogen (E=S, Se and Te) Bonding Involving Benzochalcogenodiazoles

“…Later Bunz et al introduced thiadiazolo-azacene (BDT 4) (Figure 3d) and showed that it had natural tendency to crystalize in association with half mole of solvent (there it was dichloromethane). [51] BDT 4 participates in head-on dimerization through in SÀ N interactions with a d SÀ N of 3.35 Å (Figure 3f). Again Bunz et al introduced spiro-like thiadiazole functionalized azacene (BDT 5) and utilized that as an acceptor for bulk heterojunction (BHJ) solar cells.…”

“…[46] 74% of total structures studied showed at least one '2SÀ 2N square' interaction (Figure 6). Benzo-tail (Figure 1c [49] (c), thiadiazolo-azacene (BDT 4) and their dimolecular assemblies (d, f); [51] Benzothiadiazole based twisted acenes (BDT 5) and their dimerization through SÀ N interaction (e, g) [52] Table 1. Some SÀ N interaction distance reported in case heteroacenes.…”