Layered Thiadiazoloquinoxaline‐Containing Long Pyrene‐Fused N‐Heteroacenes

Abstract

Three thiadiazoloquinoxaline-containing long pyrene-fused N-heteroacenes with 8, 13, and 18 rings were designed and synthesized.T hey show high electron affinities (EAs) of approximately 4.1 eV,w hichw ere derived from the onset of the reduction peaks in cyclic voltammetry.C rystal structure analysis revealed in-plane extension through close contacts between thiadiazole units as well as layered packing, enabling in-plane and interlayer electron transport. Organic field-effect transistor devices provided electron mobilities, which suggest apotential way to enhance the charge transport in long N-heteroacenes.

Three-Dimensional Pyrene-FusedN-Heteroacenes

“…45,46 The first bands in the UV−vis spectra originate from the π−π transition, and the second bands can be attributed to the n−π transition of the conjugated aromatic backbones. 47 From P1 to P4, small red-shifts are observed, which are similar to our previous results in linear graphene nanoribbons 25 and agree with the computational result (Figure S33). The third bands in P1−P4 can be assigned to the 0−1 and 0−0 transitions.…”

“…7,11,21−25 We reported pyrene-fused N-heteroacenes up to 18 rings terminated by thiadiazoloquinoxaline (TQ) units stabilizing it structurally with pyrene contributing to stabilizing the structure and TQ as ending groups to ensure low LUMO energy levels. 25 More interestingly, nanoribbonlike layered structures by the adjacent thiadiazole units were observed in the crystals which enhances the charge transport. 25−28 Well soluble pyrene-fused heteroacenes up to 30 rings with a size up to 7.7 nm were reported, too, using triisobutylsilyl (TIBS) to replace triisopropylsilyl (TIPS) in the side chain and large ketal as terminal units, which block the condense packing and thus result in poor charge transport.…”

“…As shown in Figure 1, the 3D pyrene-fused heteroacenes with triptycene core with three wings, which has a length of ∼1.7 nm, are based on our previous TQ containing pyrene-fused N-heteroacene unit. 25 The average diameters of the 3D pyrene-fused heteroacenes are 3.66, 6.06, 8.48 and 10.88 nm for P1−P4, respectively. It should be noted that P4 is the largest pyrene-fused N-heteroacene reported to date.…”

“…As shown in Scheme S1, the intermediate A is synthesized by the condensation of tert-butyl pyrene tetraketone (S1) 24,25,42 with TIPS acetylene benzothiadiazole diamine (S2) 27 50 000 scans were used to gain resolved 13 C NMR spectrum at 140 °C. However, no 13 C NMR with high enough intensity was obtained due to too many atoms in P4 (1501 atoms, 69 carbons with different chemical shifts predicted theoretically), whereas the NOESY indicted a clear structure of P4 (Figures S18 and S19).…”

“…Because of the rigid 3D conjugated backbones, small Stokes shift of 23, 24, 21 and 19 nm for P1−P4 were observed, respectively, which are smaller than that of their linear counterparts, and agrees with their higher rigidity of 2.5D structures than those of their linear counterparts. 25 The cyclic voltammetry (CV) curves of P1−P4 in THF with tetrabutylammonium hexafluorophosphate (n-Bu 4 PF 6 ) as electrolyte (0.1 M) are shown in Figure 2b. In the negative direction, two quasi-reversible reduction peaks are observed.…”