Synthesis and Properties of Chiral Polyazobenzenes with Photoinduced Change in Optical Activity

Abstract

Azobenzene is one of the most famous photoresponsive chromophores, and it repeatedly photoisomerizes. In this study, main-chain type polyazobenzenes bearing chiral substituents in the side-chain are synthesized by the Suzuki–Miyaura coupling method. The chiral aggregation process of main-chain type polyazobenzene is investigated. Then, intermolecular interaction of these polymers allows the formation of chiral aggregates as higher order structures. Trans-to-cis photoisomerization of the polymers was confirmed with in situ UV–vis absorption spectra. Development of π-conjugation in the backbone can be an important factor in the design of main-chain type azobenzene polymers. In addition, we induced light-driven changes in the chiroptical activity. The microstructure of the polymers is examined with synchrotron radiation X-ray diffraction and a technique to define “chiral photochromism”.

Photoprogrammable Mesogenic Soft Helical Architectures: A Promising Avenue toward Future Chiro‐Optics

“…C) Reproduced with permission. [ 86 ] Copyright 2019, American Chemical Society. D‐a) Reproduced with permission.…”

“…Some researchers attempted to synthesize a photosensitive main‐chain polymer to obtain a sufficient geometry change. [ 86 ] Polyazobenzenes with left‐handed chiral substituents as the side chains were obtained via Suzuki–Miyaura coupling (Figure 7C‐a). A helical superstructure of the polymer formed by molecular π stacking was also corroborated through the grazing incidence X‐ray diffraction technique (Figure 7C‐b).…”

Electrochromism of Main‐Chain Polyazobenzenes Synthesized in Liquid Crystal Template and Its Orientation Behavior

“…Several studies have been reported using the optical behavior of such main chain azobenzene polymers [15–17] . Furthermore, main chain‐type azobenzene self‐assembles into a chiral two‐dimensional structure by imparting chirality have been reported [18–21] …”

“…[15][16][17] Furthermore, main chain-type azobenzene self-assembles into a chiral twodimensional structure by imparting chirality have been reported. [18][19][20][21] Electrochemical polymerization (EP) is one of the polymerization methods for conjugated polymers. In the past, electrochemical synthesis of polymers containing azobenzene with side chain or main chain has been carried out.…”

Synthesis of methyl‐substituted azobenzene–carbazole conjugated copolymers with photoinduced structural changes

“…Recently, we reported tuning of chiral aggregation of a mainchain-type azo-polymer using light. 26 The mechanism of chiral aggregation of the polymer was discussed with circular dichroism spectroscopy and grazing incidence X-ray diffraction (GIXD) measurements. In addition, a main-chain-type azo-polymer having a liquid-crystal substituent in the side chain was synthesized.…”