Helical Spin Polymer with Magneto-Electro-Optical Activity

Abstract

A chiral π-conjugated polymer bearing a stable radical side group was synthesized by electrochemical polymerization in a cholesteric liquid crystal. The polymer thus obtained shows paramagnetism as well as electro- and optical activity. The polymer exhibits a one-handed helical spin order owing to the one-handed helix of the main chain and the stable radical side groups. This helical spin order endows the polymer with magneto-optical activity. In situ optical absorption and circular dichroism (CD) measurements during cyclic voltammetry analysis were used to investigate the electroactive chirality of the polymer. Optically active polarons (radical cations) as charge carriers were observed by CD and electron-spin resonance (ESR) measurements. Furthermore, the optical ellipticity of the polarons was found to be tunable using an electric field. The ESR analysis showed that the g-value of the phenoxy radicals on the polymer is 2.00403, whereas the g-value of the polarons in the main chain is 2.0025, indicating that the phenoxy radical side groups are independent of the polarons in terms of magnetic behavior. CD spectroscopy measurements revealed that the phenoxy radicals exist in a chiral environment. Thus, we successfully obtained a chiral magnetic conjugated polymer using liquid crystal imprinting polymerization. This method is a new approach for the preparation of chiral organic magnets.

Chirality in polythiophenes: A review

“…Followed the same approach, PThs with a 3,5-di-tert-butyl-4-phenoxy and 3,5-di-tert-butyl-phenyl (44) as the side group, respectively, were electrochemical polymerized. 78 The main chain of the as-prepared PThs formed a left-handed helical π-stacking structure and showed a Cotton effect associated with the π-π* transition that was reversible in the redox process. They proved that application of potential to 44a could generate phenoxy radicals with left-handed helical spins.…”

“…Combined with electron spin resonance (ESR) study, they proposed that the polarons were delocalized on the individual main chains twisted in a one‐handed helical manner. Followed the same approach, PThs with a 3,5‐di‐ tert ‐butyl‐4‐phenoxy and 3,5‐di‐ tert ‐butyl‐phenyl ( 44 ) as the side group, respectively, were electrochemical polymerized 78 . The main chain of the as‐prepared PThs formed a left‐handed helical π‐stacking structure and showed a Cotton effect associated with the π–π* transition that was reversible in the redox process.…”

Bulky 2,6-disubstituted aryl siloxanes and a disilanamine

“…Aryl siloxanes and silanamines are important reaction intermediates, especially as protecting groups for phenols and anilines (Lucente-Schultz et al, 2009). Thus, 5-bromo-1,3-ditert-butyl-2-[(trimethylsilyl)oxy]benzene, (I), is used as a synthetic intermediate to form inter alia p-conjugated arylboron radicals (Chung et al, 2018), p-quinone methides (Wang et al, 2018) and spin-labelled polymers (Otaki & Goto, 2019). Recently a new cross-coupling reaction using the parent phenol was shown to be more effective than using protected 1,3-di-tert-butyl-2-[(trimethylsilyl)oxy]benzene, (II) (Nieves-Quinones et al, 2019).…”

A pyridinium-pended conjugated polyelectrolyte for efficient photocatalytic hydrogen evolution and organic solar cells

“…The reversible stimulation of the radical formation and quenching in DPTFBr provides a feasible tool to tune the radical properties of conjugated polymers. [59][60][61] This radical formation and quenching process in DPTFBr was further evidenced by its electrochemical redox properties. Cyclic voltammetry (CV) tests of DPTFBr with/without 25% TEOA and illumination were conducted, and the electrochemical redox properties are summarized in Table 1.…”