CH Activation as a Shortcut to Conjugated Polymer Synthesis

Abstract

Direct (hetero)arylation polymerization exploits the palladium-catalyzed activation of aromatic CH bonds for the atom-economical synthesis of conjugated polymers for a wide range of applications. This account outlines how direct arylation methodologies overcome many of the limitations of contemporary polymerization techniques at both the research and production scale, and explains how monomer design and reaction conditions must be tailored to ensure high polymer molecular weight, yield, and structural integrity. Current research aims to improve further this reaction's profile as a sustainable methodology while at the same time making it competitive with the Migita-Stille and Miyaura-Suzuki polymerizations both in scope of accessible structures and synthetic efficiency. This feature article charts the recent developments and future directions of CH activation research as it moves toward becoming at once an industrially feasible, environmentally friendly, and synthetically powerful polymerization technique.

Synthesis and Characterization of a 2,3-Dialkoxynaphthalene-Based Conjugated Copolymer via Direct Arylation Polymerization (DAP) for Organic Electronics

“…Contrary to Livi et al [ 43 ], our results show that pathway B is more efficient than pathway A to synthesize dialkoxynaphthalene-based CPs. The literature on BT-based polymers synthesized through DAP supports our results [ 13 , 55 , 56 ], where the use of the BT monomer as the dibromo derivative leads to polymers with higher molecular weights and less structural defects. The theoretical calculations in Section 3.2 .…”

“…However, they require multiple synthetic steps, using expensive and toxic organometallic precursors. These disadvantages, including the residual impurities produced by organometallic compounds during synthesis, have a negative impact on the optoelectronic devices [ 12 , 13 , 14 , 15 , 16 ]. Palladium-catalyzed direct arylation polymerization (DAP), based on the C–H bond activation strategy, has recently emerged as a simple, eco-friendly, and long-term sustainable alternative to build carbon-carbon bonds between arenes [ 17 , 18 , 19 , 20 , 21 ].…”

Synthesis and properties of fluorinated benzotriazole‐based donor‐acceptor‐type conjugated polymers via Pd‐catalyzed direct CH/CH coupling polymerization

“…Although it is reliable, such a process involves the use of highly toxic stannanes that require multistep organometallic processes and is difficult to purify 18 . Recently, direct (hetero)arylation polymerization (DArP) has been utilized as an alternative approach for the synthesis of such polymers 19,20 . DArP displays some features of fewer synthetic steps and easier handle of monomers, but it still requires halogenateion step of one of aromatic comonomers.…”

“…18 Recently, direct (hetero)arylation polymerization (DArP) has been utilized as an alternative approach for the synthesis of such polymers. 19,20 DArP displays some features of fewer synthetic steps and easier handle of monomers, but it still requires halogenateion step of one of aromatic comonomers. Moreover, two DArP routes (i.e., X-Ar 1 -X/H-Ar 2 -H or H-Ar 1 -H/X-Ar 2 -X) for the synthesis of the same targeting D-A copolymer often lead to significant difference of the polymerization reaction, thus yielding copolymers with different molecular weights and structural defects depending on the reaction conditions.…”

Single‐Material OECT‐Based Flexible Complementary Circuits Featuring Polyaniline in Both Conducting Channels

“…[ 10 ] Furthermore, current synthetic techniques are complex and purification of the polymer is very challenging with trace metals occasionally detected in the product. [ 17,18 ] Thus, a major quest in the field of bioelectronics has been to find high performing n ‐type or ambipolar OECT materials with well‐matched charge transport, ideally with streamlined synthesis and favorable device processing properties, to further develop OECT‐based circuits for applications in neural sensing, [ 19 ] ion‐logic and “iontronics,” [ 20 ] and biosymbiotic systems, e.g., electronic plants. [ 21 ] Here, we demonstrate the design of electrochemically driven OECT‐based complementary circuits made using a pair of transistors containing the same channel material (Figure 1B).…”