title: Evaluation of the β value of the phenylene ethynylene unit by probing the exchange interaction between two nitronyl nitroxides.
abstract: A series of nitronyl nitroxide radicals having different lengths of phenylene ethynylene molecular wire were synthesized to investigate the decay constant of p-phenylene ethynylene. By the measurement and simulation of the ESR spectra of the biradicals, it was found that the exchange interaction decreased with a decay constant (β) of 0.39 Å(-1) as the length of the molecule increased. This result indicates that the spin-spin exchange interaction between neutral radicals has a decay constant similar to that of the molecular conductance. This value of the decay constant indicates that a hopping mechanism does not take place in the measurement of the exchange interaction between neutral radicals even when the molecular wire has enough length to show hopping conduction of electrons.
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo-ku, Kyoto 615-8510, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Shinomiya
authors.forename: Kenji
authors.initials: K
authors.lastname: Higashiguchi
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuda
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D015394:Molecular Structure; D009589:Nitrogen Oxides / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D000480:Alkynes; D004987:Ethers; D005609:Free Radicals; D009589:Nitrogen Oxides; C436384:phenyleneethynylene