Anion-Radical Polymerization of Sulfur- and Selenium-Substituted N-Type Conjugated Polymers

Abstract

While controlled chain-growth polymerizations have been developed for a handful of p-type conjugated polymers, most n-type conjugated polymers are still synthesized through step-growth methods that offer little to no control over the polymerization. The anion-radical polymerization of thiophene-flanked naphthalene diimides has been shown to exhibit non-living chain-growth behavior; however, anion-radical polymerizations are limited to a few examples that exhibit varying degrees of control. Strategies to improve and expand the scope of this promising methodology have not been developed. In this study, we investigate the anion-radical polymerization of a series of oxygenated and thionated, thiophene-and selenophene-flanked naphthalene diimides. We show, through optical and spectroelectrochemical studies, that anion-radical monomers likely consist of a complex mixture of organic radicals with varying oxidation states. Surprisingly, subtle changes in monomer structure afforded by sulfur and selenium substitution result in significant changes in polymer synthesis. Notably, selenophene-flanked naphthalene diimides polymerize more rapidly to reach higher degrees of polymerization when compared to thiophene-flanked analogues. While thionated naphthalene diimides form anion-radical complexes and exhibit signs of catalyst insertion, they do not undergo polymerization. These results provide insights into the further development of anion-radical polymerization as a promising route to well-defined n-type conjugated polymers.

Copolymers Based on π-Conjugated Asymmetric Naphthalene Diimide Building Blocks: Synthesis, Crystallography, and Structure–Property–Charge Transport/Photovoltaic Correlations

“…The three symmetric NDI monomers containing furan ( 1a , NDIFu2 ), thiophene ( 1b , NDITh2 ), and selenophene ( 1c , NDISe2 ) substituents (Figures and S1) were synthesized via previously reported procedures. ,, The two new asymmetric NDI monomers 5a ( NDIThFu , furan and thiophene) and 5b ( NDIThSe , thiophene and selenophene) were synthesized in three steps. The 2-thyenyl-6-hydroxy-NDI compound 3 was obtained in a yield of 85% by Pd-catalyzed direct arylation reaction of NDIBr2 , N , N ′-disubstituted with 2-octyldecyl (2OD) chains, and an excess of thiophene .…”

Electron-Transporting Conjugated Polymers from Novel Aromatic Five-Membered Diimides: Naphtho[1,2-b:4,3-b′]-dithiophene and -Diselenophene Diimides

“…Imide-functionalized arenes 1−8 such as pyromellitic, 1,9 perylene, 2,10 and naphthalene 11,12 diimides are regarded as the important building blocks in the design and synthesis of polymeric engineering materials, 13 intense organic chromophores, 4,14 and organic/polymeric semiconductors. 15,16 For example, Kapton is a well-known imide-functionalized polymeric engineering material with excellent mechanical properties and high temperature resistance.…”

“…Imide-functionalized arenes − such as pyromellitic, , perylene, , and naphthalene , diimides are regarded as the important building blocks in the design and synthesis of polymeric engineering materials, intense organic chromophores, , and organic/polymeric semiconductors. , For example, Kapton is a well-known imide-functionalized polymeric engineering material with excellent mechanical properties and high temperature resistance . The utilization of these species in donor–acceptor (D–A)-conjugated polymers has also received increasing attention during the past few decades owing to their high electron deficiencies, desirable optoelectronic properties, high carrier mobilities, as well as fine-tunable solubility and solid-state packing via imide N -alkylation .…”

Precision Synthesis of Various Low‐Bandgap Donor–Acceptor Alternating Conjugated Polymers via Living Suzuki–Miyaura Catalyst‐Transfer Polymerization

“…succeeded in the CTP of arylenediimide‐dithiophene utilizing the same series of catalysts [46–48] . Nonetheless, undesired step‐growth polymerization occurred upon changing the monomer moiety from arylenediimide to isoindigo, [49] and from thiophene to selenophene, [50] thereby implying a significantly limited scope of this catalytic system (Figure 1a). In addition, controlled CTP of strong D‐strong A to obtain a low E g opt was not achieved so far, because of the low ring‐walking ability of conventional catalytic systems on DA units with vastly different electronic properties [51–55] .…”