Stable π-Extended Thio[7]helicene-Based Diradical with Predominant Through-Space Spin-Spin Coupling

Hao Wu; Hiroki Hanayama; Max Coehlo; Yanwei Gu; Ze-Hua Wu; Satoshi Takebayashi; Gerhard Jakob; Serhii Vasylevskyi; Dieter Schollmeyer; Mathias Kläui; Grégory Pieters; Martin Baumgarten; Klaus Müllen; Akimitsu Narita; Zijie Qiu

doi:10.1021/jacs.3c12840

Stable π-Extended Thio[7]helicene-Based Diradical with Predominant Through-Space Spin-Spin Coupling

J Am Chem Soc. 2024 Mar 20;146(11):7480-7486. doi: 10.1021/jacs.3c12840. Epub 2024 Mar 6.

Authors

Hao Wu¹, Hiroki Hanayama², Max Coehlo³, Yanwei Gu^{1

4}, Ze-Hua Wu¹, Satoshi Takebayashi⁵, Gerhard Jakob⁶, Serhii Vasylevskyi⁷, Dieter Schollmeyer⁸, Mathias Kläui⁶, Grégory Pieters³, Martin Baumgarten¹, Klaus Müllen^{1

8}, Akimitsu Narita^{1

2}, Zijie Qiu^{1

9}

Affiliations

¹ Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
² Organic and Carbon Nanomaterials Unit, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
³ Université Paris-Saclay, CEA, INRAE, Département Médicaments et Technologies pour la Santé (DMTS), SCBM, F-91191 Gif-sur-Yvette, France.
⁴ Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201, P. R. China.
⁵ Science and Technology Group, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
⁶ Institute of Physics, Johannes Gutenberg University Mainz, Staudinger Weg 7, 55128 Mainz, Germany.
⁷ Engineering Section, Research Support Division, Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa 904-0495, Japan.
⁸ Department of Chemistry, Johannes Gutenberg University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany.
⁹ School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen (CUHK-Shenzhen), Guangdong 518172, P.R. China.

PMID: 38446414
DOI: 10.1021/jacs.3c12840

Abstract

In this work, a novel π-extended thio[7]helicene scaffold was synthesized, where the α-position of the thiophene unit could be functionalized with bulky phenoxy radicals after considerable synthetic attempts. This open-shell helical diradical, ET7H-R, possesses high stability in the air, nontrivial π conjugation, persistent chirality, and a high diradical character (y₀ of 0.998). The key feature is a predominant through-space spin-spin coupling (TSC) between two radicals at the helical terminals. Variable-temperature continuous-wave electron spin resonance (cw-ESR) and superconducting quantum interference device (SQUID) magnetometry in the solid state reveal a singlet ground state with a nearly degenerate triplet state of ET7H-R. These results highlight the significance of a stable helical diradicaloid as a promising platform for investigating intramolecular TSCs.