Synthesis of Oligothiophene‐Layered Polymers

Abstract

Polymers with layered π-electron systems comprising bithiophenes and quaterthiophenes based on a xanthene skeleton have been synthesized by an iron-catalyzed oxidative coupling reaction. The polymers are well soluble in common organic solvents, and polymer thin films are readily obtained by a spin-coating or casting technique. The synthesized polymers exhibit good thermal stability, and their 10% weight loss temperatures are approximately 400 °C. These behaviors of the polymers suggest that they can be used as opto-electronic devices such as hole-transporting materials.

Naphthalene-based oligothiophene-stacked polymers

“…Such an upfield shift was not observed in the xanthene-based oligothiophene-layered polymers. 46 The shortest distance between oligothiophene units in the polymers is expected to be B3 Å based on the X-ray crystal structures of 1,8-bis(5,2¢-bithiophen-2-yl)naphthalene 61 and bithiophenophane. 64,73 We also obtained the X-ray crystal structures of 5, as shown in Figure 2 (the data are shown in Supporting Information).…”

“…55 We have recently reported the synthesis of aromatic-ring-layered polymers using xanthene compounds as scaffolds. [40][41][42][43][44][45][46][47] [2.2] Paracyclophane-layered polymers, which mimic multilayered cyclophanes, 56-59 exhibited fluorescence resonance energy transfer from the layered paracyclophanes to the end-capping groups. The use of xanthene as a scaffold enabled us to introduce various aromatic compounds, such as phenylenes, 44 carbazoles, 45 thiophenes 46 and anthracene, 47 into the polymers, with the distance between the layered aromatic units being B4.5 Å .…”

“…Poly(dibenzofulvene)s, 4-11 7,7-diarylnorbornane-containing conjugated polymers, 12,13 cyclophanecontaining polymers and face-to-face ferrocene polymers [36][37][38] have been synthesized, and their optical and electrochemical properties have been studied in detail. Polymers with layered aromatic rings and p-electron systems have also been investigated; [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] for example, Chen et al 53 recently reported the synthesis and formation of a twodimensional assembly of polymeric ladder phanes containing face-toface p-electron systems. These polymers have potential applications in optoelectronic devices and single-molecular devices such as singlemolecular wires.…”

“…[40][41][42][43][44][45][46][47] [2.2] Paracyclophane-layered polymers, which mimic multilayered cyclophanes, [56][57][58][59] exhibited fluorescence resonance energy transfer from the layered paracyclophanes to the end-capping groups. The use of xanthene as a scaffold enabled us to introduce various aromatic compounds, such as phenylenes, 44 carbazoles, 45 thiophenes 46 and anthracene, 47 into the polymers, with the distance between the layered aromatic units being B4.5 Å . Our next target is to construct layered and p-stacked aromatic systems in proximity, less than the sum of the van der Waals radius (3.40 Å ) of an sp 2 -carbon, in the polymer backbone.…”

Synthesis of Aromatic-Ring-Layered Polymers

“…The two end-capping nitrophenyl moieties in P9 effectively quenched the photoluminescence from the layered biphenylenes via throughspace interactions of the single polymer chain. Oligothiophenes were also layered on xanthenes (Morisaki et al, 2009f;Morisaki et al, 2010b); the synthetic routes for the bithiophene-layered polymer P10 by iron-mediated oxidative coupling and modified Suzuki-Miyaura coupling are shown in Scheme 5. Bis(thienyl)xanthene monomer 10 was prepared in 81% yield by Negishi coupling (Negishi et al, 1977;Negishi, 1982) of 2-thienylzinc bromide and 6 and then treated with FeCl 3 to obtain the corresponding polymer P10 in 84% isolated yield with an M n of 4500.…”