10.1021/jo061204m.s001 Yang-Ping Liu Yang-Ping Liu Lan-Fen Wang Lan-Fen Wang Zhou Nie Zhou Nie Yi-Qiong Ji Yi-Qiong Ji Yang Liu Yang Liu Ke-Jian Liu Ke-Jian Liu Qiu Tian Qiu Tian Effect of the Phosphoryl Substituent in the Linear Nitrone on the Spin Trapping of Superoxide Radical and the Stability of the Superoxide Adduct:  Combined Experimental and Theoretical Studies American Chemical Society 2006 decay superoxide phosphoryl group intramolecular Superoxide B 3LYP level HOPPN PBN adduct DFT phosphorylated calculation 2006-09-29 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Effect_of_the_Phosphoryl_Substituent_in_the_Linear_Nitrone_on_the_Spin_Trapping_of_Superoxide_Radical_and_the_Stability_of_the_Superoxide_Adduct_Combined_Experimental_and_Theoretical_Studies/3056785 A new phosphorylated linear nitrone <i>N</i>-(4-hydroxybenzyliene)-1-diethoxyphosphoryl-1-methylethylamine <i>N</i>-oxide (4-HOPPN) was synthesized, and its X-ray structure was determined. The spin trapping ability of various kinds of free radicals by 4-HOPPN was evaluated. Kinetic study of decay of the superoxide spin adduct (4-HOPPN-OOH) shows the half-life time of 8.8 min. On the basis of the X-ray structural coordinates, theoretical analyses using density functional theory (DFT) calculations at the B3LYP/6-31+G(d,p)//B3LYP/6-31G(d) level were performed on spin-trapping reactions of superoxide radical with 4-HOPPN and PBN and three possible decay routes for their corresponding superoxide adducts. The comparative calculations on the spin-trapping reactions with superoxide radical predicted that both spin traps share an identical reaction type and have comparable potency when spin trapping superoxide radical. Analysis of the optimized geometries of 4-HOPPN-OOH and PBN-OOH reveals that an introduction of the phosphoryl group can efficiently stabilize the spin adduct through the intramolecular H-bonds, the intramolecular nonbonding attractive interactions, as well as the bulky steric protection. Examination of the decomposition thermodynamics of 4-HOPPN-OOH and PBN-OOH further supports the stabilizing role of the phosphoryl group to a linear phosphorylated spin adduct.