title: Radical and Diradical Formation in Naphthalene Diimides through Simple Chemical Oxidation.
abstract: We successfully synthesized, for the first time, a naphthalene diimide (NDI) radical and diradical by simple chemical oxidation using lead(IV) dioxide. The formation of the (di)radical is confirmed by UV/Vis/NIR absorption,1H NMR, and electron paramagnetic resonance (EPR) measurements. In particular, temperature-dependent EPR, SQUID (superconducting quantum interference device) measurements, and quantum calculations demonstrated that the generated NDI diradical has a singlet diradical character of y=0.69 in the ground state. Subsequent characterization of this (di)radical revealed its stabilities, large two-photon absorption cross-section, and short excited-state lifetime.
authors.affiliation: Department of Chemistry and Spectroscopy, Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Korea.
authors.forename: Sangsu
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.
authors.forename: Fang
authors.initials: F
authors.lastname: Miao
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.
authors.forename: Hoa
authors.initials: H
authors.lastname: Phan
authors.affiliation: Department of Materials Science & Engineering, National University of Singapore, 119260, Singapore, Singapore.
authors.forename: Tun Seng
authors.initials: TS
authors.lastname: Herng
authors.affiliation: Department of Materials Science & Engineering, National University of Singapore, 119260, Singapore, Singapore.
authors.forename: Jun
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.
authors.forename: Jishan
authors.initials: J
authors.lastname: Wu
authors.affiliation: Department of Chemistry and Spectroscopy, Laboratory for Functional π-Electronic Systems, Yonsei University, Seoul, 03722, Korea.
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
keywords: naphthalene diimide; oxidation; radicals; sextet rule; singlet diradicals