Atom-economical Synthesis and Characterization of Poly(oxindolidene thienylene vinylene) Based on Aldol Polycondensation Reaction

Abstract

It is known that π-conjugated polymers can be easily synthesized using monomers which possess metals or halogen atoms as well as transition-metal catalysts. However, in the polymer materials synthesized by such reactions, small amounts of halogens and transition-metal-catalysts remain, often negatively affecting their optoelectronic device performances. Herein, we report a new polycondensation method based on the aldol condensation reaction utilizing the intramolecular resonance effect of the anionic monomer through π-conjugation. We have designed a novel AB type monomer to synthesize the semiconducting poly(oxindolidene thienylene vinylene) (POTV) using the proposed system. Indeed, the polymerization readily proceeded by adding 5-nitro-2-thiophenecarbaldehyde as an initiator after the α-proton abstraction of the oxindole group by the reaction of the monomer precursor with lithium hexamethylsilazide (LiHMDS)/12-crown-4. As a result, the objective POTV with Mn = 3700 and ÐM = 1.47 could be obtained with a good yield (65%). In addition, an organic field effect transistor (OFET) was based on POTV exhibited p-type characteristics, with a hole mobility of 2.24 × 10−4 cm2 V−1 s−1.

Linear Block Copolymer Synthesis

“…As the mechanistic understandings have unfolded, the focus in the field perhaps lies in catalyst design to achieve more desirable materials. Another direction that has opened up recently is transition metal-free synthesis of conjugated polymers, which offer a “greener” alternative to current polymerization methods. − …”

Aldol Condensation for the Construction of Organic Functional Materials

“…Generally, the Brønsted acids and bases as well as Lewis acids and bases utilized are p ‐toluenesulfonic acid (PTSA), acetic acid, n ‐butyric acid and LiHMDS/12‐crown‐4 [7] . Concurrently, toluene and tetrahydrofuran are the common solvents used during the reaction process [7d,8] . These structures exhibit significant rigidity due to the conjugation of π‐electrons along the carbon backbone.…”

“…successfully synthesized an oxindole‐based polymer known as poly(oxindolidene thienylene vinylene) (POTV, Figure 2b). [7d] Despite having a relatively low molecular weight ( M n =5.3k), POTV, resembling isoindigo (IID)‐like polymers, exhibits a remarkable hole mobility of 2.24×10 −4 cm 2 V −1 s −1 , highlighting the immense potential of oxindole‐based structures as organic semiconductors. Further optimization of the polymerization conditions by switching the base and reaction temperature could potentially lead to the production of POTV with controllable and relatively higher molecular weights, paving the way for its future application as organic semiconductors.…”

Synthesis of Azine-Based Conjugated Polymers by Metal-Free Dehydration Polycondensation and Characterization of Their Physical Properties

“…33,34 Recently, Higashihara et al reported a controlled aldol polymerization of an AB-type monomer. 35 In this study, we focused on conjugated polymers containing azine bonds in their main chains, 36,37 which are formed by the dehydration condensation of dialdehyde monomers and hydrazine without the need for transition-metal catalysts. 38−40 In 2012, Li et al reported the synthesis of an azine-based polymer with a diketopyrrolopyrrole (DPP) skeleton and ambipolar OFET properties with high carrier mobilities.…”

“…Zhang et al reported aldol polycondensation for synthesizing isoindigo-based conjugated polymers without using transition-metal catalysts such as Pd . The metal-free aldol polycondensation gave ladder-like polymers that serve as n-type semiconducting materials in OFETs. , Recently, Higashihara et al reported a controlled aldol polymerization of an AB-type monomer . In this study, we focused on conjugated polymers containing azine bonds in their main chains, , which are formed by the dehydration condensation of dialdehyde monomers and hydrazine without the need for transition-metal catalysts. − In 2012, Li et al reported the synthesis of an azine-based polymer with a diketopyrrolopyrrole (DPP) skeleton and ambipolar OFET properties with high carrier mobilities .…”