title: Substituent effect on g-tensor: multifrequency ESR study and DFT calculation of polycrystalline phenoxyl radicals in diamagnetic crystals.
abstract: The substituent effect on the g-tensor of polycrystalline 2,6-di-tert-butyl phenoxyl radical derivatives diluted in diamagnetic crystals was investigated using multifrequency ESR spectroscopy and DFT calculations. It was revealed that the g-tensors of the series of phenoxyl radical derivatives essentially have an orthorhombic symmetry. For some radicals, the hyperfine-splitting tensors from the para groups were resolved. The interpretations and the assignments of the spin-Hamiltonian parameters were confirmed with computer simulations in all bands. The DFT-calculated g-tensors were consistent with the experimental g-tensors. Furthermore, the shifts Delta(g) from the free electron ge were analyzed in details as the sum of three contributions. The spin-orbit interactions were found to be the dominant factor with regard to the Delta(g). With a focus on the s-o term, thus, the relationship of the g-values and the electronic excited states was explained by visualizing the molecular orbitals of the phenoxyl radical derivatives. This study thus showed the very significant potential of the combination of a multi-frequency ESR approach and a DFT calculation to advanced ESR analysis, particularly, g-tensor analysis, even for a powder-sample radical.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa, Kyoto 606-8502, Japan. toshiki-y@nirvana.mbox.media.kyoto-u.ac.jp
authors.forename: Toshiki
authors.initials: T
authors.lastname: Yamaji
authors.forename: Islam S M
authors.initials: IS
authors.lastname: Saiful
authors.forename: Masaaki
authors.initials: M
authors.lastname: Baba
authors.forename: Seigo
authors.initials: S
authors.lastname: Yamauchi
authors.forename: Jun
authors.initials: J
authors.lastname: Yamauchi