; Wang, Lu
; Ohtsuka, Yuhki
; Nagase, Shigeru] Inst Mol Sci, Dept Theoret & Computat Mol Sci, Okazaki, Aichi 4448585, Japan
; [Jiang, De-en] Oak Ridge Natl Lab, Div Chem Sci, MS6201, Oak Ridge, TN 37931 USA
; [Zhao, Yuliang] Chinese Acad Sci, Inst High Energy Phys, Key Lab Biomed Effects Nanomat & Nanosafety, Beijing 100191, Peoples R China
; [Zhao, Yuliang] Natl Ctr Nanosci & Technol China, Beijing 100080, Peoples R China
; [Chen, Zhongfang] Univ Puerto Rico, Dept Chem, Inst Funct Nanomat, San Juan, PR 00931 USA
When an all-benzenoid nanographene is linearly unzipped into oxygen-joined fragments, the oxidized benzenoid rings (aromatic sextets) selectively adopt the low-spin (Delta S = 0) or high-spin conformation (Delta S = 1) to yield the thermally most stable isomer. The selection of the conformation depends simply on the position of the aromatic sextets: the inner ones prefer the high-spin conformation, whereas the peripheral ones prefer the low-spin conformation. Therefore, the resulting most stable isomer has a total spin whose value equals the number of inner aromatic sextets (n(i)) along the oxidizing line. The nanographene fragments contained in this isomer have a ferromagnetic spin coupling. Due to the tautomerization between the high-spin and low-spin conformations, there also exist other possible isomers with higher energies and with spins at ground state ranging from 0 to (n(i) - 1). The rich geometrically correlated spins and the adjustable energy gaps indicate great potential of the graphene oxides in spintronic devices.