title: Electronic structure of the lowest excited triplet state of 5,12-naphthacenequinone.
abstract: Continuous-wave time-resolved EPR (cw-TREPR) and pulsed electron nuclear double resonance (ENDOR) studies have been carried out to clarify the electronic structure of the lowest excited triplet (Tl) state of 5,12-naphthacenequinone (5,12-NpQ) as well as 1,4-anthraquinone (1,4-AQ) and 6,13-pentacenequinone (6,13-PeQ). The Tl energy level and the D value of the zero-field splitting (ZFS) parameters only slightly decreased with the increasing pi-conjugated system. The Tl states of these linear para-acenequinones were assigned to the pi pi* character. In triplet 5,12-naphthacenequinone, more than 80% of the unpaired electron spins are localized on the naphthalene aromatic sub-system.
authors: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
authors: Takuji
authors: T
authors: Shimokage
authors: Tadaaki
authors: T
authors: Ikoma
authors: Kimio
authors: K
authors: Akiyama
authors: Shozo
authors: S
authors: Tero-Kubota
mesh_terms: D000880:Anthraquinones / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D004578:Electron Spin Resonance Spectroscopy; D004583:Electrons; D049449:Luminescence; D008280:Magnetics; D008956:Models, Chemical; D009279:Naphthacenes / Q000737:chemistry*; D011809:Quinones / Q000737:chemistry*; D013696:Temperature; D014050:Toluene / Q000737:chemistry
chemical_list: C468646:5,12-naphthacenequinone; C468647:6,13-pentacenequinone; D000880:Anthraquinones; D009279:Naphthacenes; D011809:Quinones; D014050:Toluene; C416442:1,4-anthraquinone