Influences of Structural Properties on Stability of Fullerenols

Influences of structural properties on the stability of fullerenols are studied using experimental techniques including laser-induced dissociation associated with a time-of-flight measurement, synchrotron radiation XPS, and FT-IR spectroscopy. Stabilities of a family of fullerenols (C₆₀(OH)₄₂, C₆₀(OH)₄₄, C₆₀(OH)₃₀, C₆₀(OH)₃₀, C₆₀(OH)₃₂, and C₆₀(OH)₃₆) as functions of structural parameters-the hydroxyl number, intensity of the impure group, and the ratio of the carbonyl to hydroxyl groups-are investigated. It is found that the molecular stability largely depends on the quantity of impure groups, especially the highly oxygenated carbons in fullerenols, but less on the hydroxyl number. This is different from the previous consideration that the stability of fullerenols largely depends on the hydroxyl number. Previously, to gain the larger solubility required by practical applications, it was suggested to increase the number of the hydroxyl groups. This idea needs to be restudied, because in highly hydroxylated fullerenol molecules, the coinstantaneous formation of a large amount of impure groups is observed. The use of C₆₀(OH) _n>36 in practical applications should proceed with caution, since these could lead to unstable open-cage structures. The results reveal a way of controlling the formation of impure groups to gain fullerenols of high stability.