Tateishi, Kenichiro, Makoto Negoro, Hiroshi Nonaka, Akinori Kagawa, Shinsuke Sando, Satoshi Wada, Masahiro Kitagawa, and Tomohiro Uesaka. “Dynamic Nuclear Polarization with Photo-Excited Triplet Electrons Using 6,13-Diphenylpentacene.” Physical Chemistry Chemical Physics 21, no. 36 (2019): 19737–41.
Dynamic nuclear polarization with photo-excited triplet electrons (Triplet-DNP) is demonstrated using 6,13-diphenylpentacene (DPPentacene). DPPentacene is soluble in various organic solvents, while pentacene, which is used in most of the triplet-DNP experiments, has limited solubility. An enhancement factor of 81 is obtained for 1H spins in the glass of ethanol-d6 : water = 80 : 20 (w/w) doped with 0.1 mM DPPentacene at 90 K in 0.67 T.