Locking the Coplanar Conformation of π‐Conjugated Molecules and Macromolecules Using Dynamic Noncovalent Bonds

Abstract

Torsional conformation of the backbone of a π-conjugated molecule or macromolecule shapes its solubility, optoelectronic characteristics, rheological behaviors, and ultimately solid-state functions. In order to tailor these molecular, supramolecular, and materials properties, the desired coplanar conformation in π-conjugated systems can be locked by using dynamic noncovalent bonds. In this article, the syntheses, characterizations, and unique properties of conjugated molecules/polymers involving a variety of bridging noncovalent bonds are disussed in the context of coplanar backbone conformation. In addition, challenges in this specific field are identified and discussed for future breakthroughs in exploiting the promising potential of noncovalent-bond-bridged, π-conjugated organic materials.

Rigid Coplanar Polymers for Stable n‐Type Polymer Thermoelectrics

“…The polymer building blocks were connected by carbon–carbon double bonds, leading to a rigid and nearly torsion‐free backbone. The intramolecular hydrogen bonds formed between the hydrogen atoms and the carbonyl groups further lock the conformation and reduce the structure disorders . Four strong electron‐withdrawing carbonyl groups in each repeating unit provide the polymers with deep LUMO levels down to −4.49 eV, and enhance their n‐doping efficacy and air stability.…”

Efficient Charge Transport in Disordered Conjugated Polymer Microstructures

“…In fact, the role of backbone rigidity (i.e., polymer persistence length) on charge transport properties has been discussed from several viewpoints including the intramolecular conformations in amorphous polymers, intercrystallite connectivity in semicrystalline materials, and as a key variable behind the high charge mobility in conjugated polymers without long‐range order . While building blocks whose extended conjugation is attained via fused aromatic rings can lead to increased chain rigidity, a complementary strategy in polymer design relies on noncovalent interactions to promote backbone planarity and even to tune intermolecular forces . These conformational locks include a large chemical diversity of through‐space interactions with varying strengths …”

“…While building blocks whose extended conjugation is attained via fused aromatic rings can lead to increased chain rigidity, a complementary strategy in polymer design relies on noncovalent interactions to promote backbone planarity and even to tune intermolecular forces . These conformational locks include a large chemical diversity of through‐space interactions with varying strengths …”

Simple Route to Synthesize Fully Conjugated Ladder Isomer Copolymers with Carbazole Units

“…Fully conjugated ladder polymers (cLPs) have drawn extensive attention because of their rigid structure with π-conjugated systems [1,2,3,4,5,6]. The unique structure of cLPs confers favorable physical, optical, and chemical properties [7,8,9,10].…”

“…Thus, cLPs are promising candidates as organic materials [11,12,13,14,15,16], such as organic solar cells, organic thin film transistors, and organic light emitting diodes. However, there still exist some challenges to synthesize new cLPs with the desired solubility and fewer structure defects, and researchers have tried various methods to solve these difficulties [6,17,18,19,20,21], such as introducing bulky alkyl side chains to improve solubility, and introducing new reactive groups using new synthetic methods to synthesize ideal conjugated defect-free polymers.…”