Host-guest complexation of endohedral metallofullerene with azacrown ether and its application.
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.
Tsuchiya
Takahiro
T
Center for Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
Sato
Kumiko
K
Kurihara
Hiroki
H
Wakahara
Takatsugu
T
Nakahodo
Tsukasa
T
Maeda
Yutaka
Y
Akasaka
Takeshi
T
Ohkubo
Kei
K
Fukuzumi
Shunich
S
Kato
Tatsuhisa
T
Mizorogi
Naomi
N
Kobayashi
Kaoru
K
Nagase
Shigeru
S