Biologically active fullerene derivatives: Computations of structures, energetics, and vibrations of C60(OH)x and C60(NO2)y

Abstract

ABSTRACT:This article reports quantum-chemical semiempirical computations of selected multihydroxy and multinitro derivatives of C . Polyhydroxylated fullerenes 60 have been known for their efficient free-radical scavenging activity and promising results in reducing the concentration of free radicals in pathological blood and in inhibiting the growth of abnormal cells. Nitro-fullerenes are directly linked to hydroxy-fullerenes as polyhydroxylated fullerenes can be produced through hydrolysis of polynitro-fullerenes. In spite of this considerable biological application potential, microscopic knowledge of the systems is very limited. This study thus supplies quantum-chemical semiempirical Ž . primarily PM3 calculations of the structure and energetics for selected hydroxy-and Ž . nitro-fullerenes. The configurational sampling of C OH extends from x s 2 to x s 36. xThe computations offer a useful insight into the molecular structure, energetics, and possible stability measures. It is suggested that thermodynamic stability could be Ž . measured through a partial dissociation heat. Among the computed structures, C OH 60 6 Ž . and C OH exhibit the best value of the partial dissociation heat. With nitro-fullerenes, 60 18 tetra-nitro derivatives were computed here. The computations follow the finding for dinitro derivatives that low-energy structures have either the two nitro groups placed in Ž . the para position on one hexagon or added to one 6r6 double bond of the cage. The lowest tetra-nitro species found has the para᎐para arrangement applied to two hexagons separated by one pentagon. Hydroxy-and nitro-fullerenes do not exhibit the highest Correspondence to: Z. Slanina.

Ca @ C 82 isomers: Computed temperature dependency of relative concentrations

“…Finally, although an overwhelming majority of computational evaluations for fullerenes and metallofullerenes has been based on potential energy only, this study presents a topical example of the deeper insight offered by the Gibbs-energy based evaluation. The temperature evolution of the Ca@C 82 system exhibits two features already known 54 for the isomeric hollow fullerenes. Relative stability interchanges can occur with increasing temperature.…”

Substituent effect on structure, stability, and aromaticity of novel BnNmC20–(n+m) heterofullerenes

“…Evidently, only the lowest energy structures are investigated for the selected heterofullerenes. There are several relevant parameters, which influence relative stabilities of scrutinized structures including hybridization effect, strain effect, number and position of heteroatom(s), concentration, and solubility . We have divided our results and discussion section into the following 2 distinct parts.…”

Gas sensing properties of platinum derivatives of single-walled carbon nanotubes: A DFT analysis

“…2 and Table 1. Nevertheless, there are some experimental and computational studies revealing that the nitro derivative on fullerenes can be found [36,37]. Though, due to the chemically inert CNT system, the functionalization of NO 2 on the CNT sidewall should be more difficult than that of a fullerene surface.…”