Isolation and Electrochemical Property of Ho₂O@C₉₀ Isomers

Abstract

Four oxide clusterfullerenes Ho2O@C90 (I-IV) were prepared by a modified arc discharge method and isolated by a multistage high-performance liquid chromatography procedure. Based on their vis-NIR spectra, the carbon cage symmetries in Ho2O@C90 (I, III, IV) are confirmed to be C2(43)-C90, C2(40)-C90 and C2(41)-C90, respectively. Electrochemical studies display that the first and second reduction potentials of Ho2O@C90 isomers are close to those of Er2C2@C90 ones, but much lower than those of Sm@C90 ones. Moreover, it is found that the electrochemical band gaps of Ho2O@C90 isomers are also very close to those of Er2C2@C90 isomers. A detailed investigation on the redox potentials of C90 based EMFs reveals that endohedral clusters/atoms have much greater effect than carbon cage symmetries on the electrochemical properties of EMFs.

Carbon cage isomers and magnetic Dy⋯Dy interactions in Dy2O@C88 and Dy2C2@C88 metallofullerenes

“…10,11 The exploration of oxide clusterfullerenes started with a discovery of Sc 4 O 2,3 @C 80 by Stevenson et al 12,13 and then continued with a series of Sc 2 O@C 2n EMFs with cage sizes from C 70 to C 82 . [14][15][16][17][18][19][20] More recently, the focus was shifted to lanthanides, resulting in several M 2 O@C 2n EMFs with Ho (C 2n = C 74 , 21 C 84 , 22 4 isomers of C 90 , 23 and 2 isomers of C 92 24 ), Dy (C 2n = C 72 , 25 C 74 , 25 C 80 , 26 three isomers of C 82 27 ), and two isomers of Lu 2 O@C 80 . 28 In M 2 O@C 2n clusterfullerenes, two rare-earth metal ions (M 3+ ) are bridged by the µ 2 -O 2− ion; the whole M 2 O cluster has a formal charge of +4 and is encapsulated in fullerene cages preferring the C 2n 4− state.…”