title: Host-guest complexation of endohedral metallofullerene with azacrown ether and its application.
abstract: Complexation of endohedral metallofullerene La@C(82)-A (1) with macrocyclic compounds, such as 1,4,7,10,13,16-hexaazacyclooctadecane (2), 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane (3), mono-aza-18-crown-6 ether (4), 18-crown-6 ether (5), and p-tert-butylcalix[n]arenes (n = 4-8, 6-10), for the first time is examined. Among them, 1 forms a complex with azacrown ethers 2-4 while accompanying the electron transfer between them. This is characteristic of endohedral metallofullerene and caused by its low reduction potential. Activation energies, DeltaG(et), for the electron transfer from 2-4 to 1 are 4.6, 2.8, and 11 kcal/mol, respectively. These small DeltaG(et) values indicate that the electron transfer from the azacrown ethers to 1 is facile in the ground state. Furthermore, the selective isolation of lanthanum endohedral metallofullerenes from the extracts of soot is accomplished by utilizing the complexation of 1 with 2.
authors.affiliation: Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Kumiko
authors.initials: K
authors.lastname: Sato
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurihara
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Wakahara
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Nakahodo
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Maeda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akasaka
authors.forename: Kei
authors.initials: K
authors.lastname: Ohkubo
authors.forename: Shunich
authors.initials: S
authors.lastname: Fukuzumi
authors.forename: Tatsuhisa
authors.initials: T
authors.lastname: Kato
authors.forename: Naomi
authors.initials: N
authors.lastname: Mizorogi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase