title: Ambient Stable Radical Cations, Diradicaloid π-Dimeric Dications, Closed-Shell Dications, and Diradical Dications of Methylthio-Capped Rylenes.
abstract: Radical cations and dications of π-conjugated systems play vital roles in organic electronic devices, organic conductors, and conducting polymers. Their structures, charge and spin distribution, and mechanism of charge transport are of great interest. In this article, radical cations and dications of a series of newly synthesized methylthio-capped rylenes were synthesized and isolated. Their ground-state structures, physical properties, and solid-state packing were systematically investigated by various experimental methods, such as X-ray crystallographic analysis, UV/Vis/NIR absorption spectroscopy, (spectro-)electrochemistry, nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, superconducting quantum interference device, and Raman spectroscopy, assisted by DFT calculations. It was found that all the charged species show an exceptional stability under ambient air and light conditions due to the efficient spin and charge delocalization over the whole rylene backbone. The dication of hexarylene turned out to have an unusual open-shell singlet rather than closed-shell ground state, thus it can be described as a diradical dication. Dimerization was observed for the radical cations and even the dications in crystals due to the strong intermolecular antiferromagnetic spin-spin interaction and π-π interaction, which result in unique magnetic properties. Such intermolecular association was also observed in solution.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Qingbiao
authors.initials: Q
authors.lastname: Qi
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071, Malaga, Spain.
authors.forename: Paula Mayorga
authors.initials: PM
authors.lastname: Burrezo
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Hoa
authors.initials: H
authors.lastname: Phan
authors.affiliation: Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore.
authors.forename: Tun Seng
authors.initials: TS
authors.lastname: Herng
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Tullimilli Y
authors.initials: TY
authors.lastname: Gopalakrishna
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Wangdong
authors.initials: W
authors.lastname: Zeng
authors.affiliation: Department of Materials Science and Engineering, National University of Singapore, 119260, Singapore.
authors.forename: Jun
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071, Malaga, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Casado
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore.
authors.forename: Jishan
authors.identifier: http://orcid.org/0000-0002-8231-0437
authors.initials: J
authors.lastname: Wu
keywords: annulation; dications; open-shell; radical ions; rylenes