title: Unusual role of oxygen in electron-transfer processes.
abstract: Molecular oxygen's unique involvement in electron-transfer processes is demonstrated on a series of dyads between porphyrin derivatives and fullerene C60. It has been shown for the first time that oxygen can serve as an inhibitor of back electron transfer by enhancing intersystem crossing of a singlet radical ion pair into its triplet state. The effect is observed only when energy of the charge-separated state is lower than that of the locally excited triplet states. Due to the spin statistics, the reverse intersystem crossing is less efficient, allowing use of oxygen and other paramagnetic species for impeding charge recombination in various electron-transfer systems.
authors.affiliation: Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico, USA. snsm@nmsu.edu
authors.forename: Sergei
authors.initials: S
authors.lastname: Smirnov
authors.forename: Ivan
authors.initials: I
authors.lastname: Vlassiouk
authors.forename: Olaf
authors.initials: O
authors.lastname: Kutzki
authors.forename: Michael
authors.initials: M
authors.lastname: Wedel
authors.forename: Franz-Peter
authors.initials: FP
authors.lastname: Montforts
mesh_terms: D002244:Carbon / Q000737:chemistry*; D004583:Electrons; D037741:Fullerenes; D008665:Metalloporphyrins / Q000737:chemistry*; D018716:Molecular Mimicry; D010100:Oxygen / Q000737:chemistry*; D010777:Photochemistry; D010788:Photosynthesis; D011166:Porphyrins / Q000737:chemistry*
chemical_list: D037741:Fullerenes; D008665:Metalloporphyrins; D011166:Porphyrins; C017802:zinc hematoporphyrin; C006969:chlorin; D002244:Carbon; C069837:fullerene C60; D010100:Oxygen