Naphthalene-based oligothiophene-stacked polymers

Abstract

We report the synthesis and properties of p-stacked polymers consisting of oligothiophene and naphthalene as the stacked p-system and the scaffold, respectively. The titled polymers were obtained by the Suzuki-Miyaura coupling reaction. Oligothiophene units were layered in proximity, B3.0 Å from each other. Contribution of the quinoidal structure of the oligothiophene units involving the naphthalene scaffolds in the excited state resulted in relatively high photoluminescence quantum efficiencies. The polymers have potential application to optoelectronic devices such as hole-transporting materials. Polymer Journal (2010) 42, 928-934; doi:10.1038/pj.2010.101; published online 27 October 2010Keywords: conjugated polymers; p-stacked polymers; oligothiophene; redox polymers; synthesis INTRODUCTIONCommon conjugated polymers generally consist of sp-and/or sp 2 -carbon frameworks, and p-electrons are delocalized throughout the polymer backbone. Such conjugated polymers have attracted considerable attention because of their good processability and their readily tunable electronic and optical properties. [1][2][3] Recently, a new type of conjugated polymer that exhibits through-space interactions of pelectron systems has been developed. 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; 39-53 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.Cofacially aligned p-electron systems have an important role in biochemistry and material chemistry; DNA has face-to-face base pairs stacked in the double-stranded main chains, 54 and the performance of organic optoelectronic devices strongly depends on the arrangement of the p-electron systems. 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 . 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.

π-Conjugated polymer-layered structures: synthesis and self-assembly

“…[26][27][28][29][30] We have recently reported the synthesis of polymers with layered aromatic rings using a xanthene scaffold as a hairpin-shaped linker; these polymers exhibit intramolecular π-stacked structures with multiple aromatic rings stacked along a single polymer chain. [31][32][33][34][35][36] They can be regarded as the assembly of several small π-conjugated units. However, owing to the small size of the π-conjugated moieties and to the bulkiness of the xanthene scaffold, their intermolecular interactions were relatively weak.…”

Photoswitching and Thermoresponsive Properties of Conjugated Multi‐chromophore Nanostructured Materials

“…Their thermo­responsive optical behavior has been illustrated previously, which highlights the importance of this kind of materials for different optoelectronic and multi‐responsive devices . The electro‐chemiluminescence properties of oligothiophene‐based nano­structures have been reported by Bard et al Furthermore, a few other reports have demonstrated the optical and electronic properties of oligothiophene nanomaterials . Diegelmann et al have discussed the possible applications of an oligothiophene‐based supramolecular nanostructure in both biological and optoelectronic devices based on their prominent photophysical change upon aggregation .…”

“…[30][31][32] The electro-chemiluminescence properties of oligothiophene-based nano structures have been reported by Bard et al [ 33 ] Furthermore, a few other reports have demonstrated the optical and electronic properties of oligothiophene nanomaterials. [34][35][36] Diegelmann et al have discussed the possible applications of an oligothiophene-based supramolecular nanostructure in both biological and optoelectronic devices based on their prominent photophysical change upon aggregation. [ 37 ] The possible applications of oligothiophene-based nanomaterials in high-performance photovoltaic devices has also been demonstrated by Chen and coworkers.…”

Theoretical study of substituent effects on the geometry and strain enthalpy in [2,2]paracyclophanes

“…Aromatic molecules are among the most important classes of the compounds having a crucial role in biochemistry and material chemistry (Morisaki et al, 2010). It is well known that the relative orientation and distance between the aromatic rings in the solid state affects the electronic delocalization and therefore important bulk properties.…”