Yu-Ma Chou

Theoretical studies of C70(OH)n (n=14, 16, 18 and 20) fullerenols

The experimental results indicated that polyhydroxylated C70 fullerene may generate water soluble C70(OH)n fullerenols with n=14, 16, 18 and 20. The plausible reaction mechanism has been proposed with the consideration of cyclosulfation and hydrolysis. According to the experimental results, the number of hydroxyl substitutes in C70(OH)n fullerenols should be even. Random subroutine in MS FORTRAN 5.0 program library and reaction-mechanism consideration were first used to generate the structure of possible isomers for C70(OH)14, C70(OH)16, C70(OH)18 and C70(OH)20 fullerenols and reaction precursors C70(SO4)7, C70(SO4)8, C70(SO4)9 and C70(SO4)10. The heats of formation, relative stability and optimized structures have been generated by semi-empirical PM3 calculation. Among the possible structures, the electronic structures of these having higher symmetry were then computed. According to the structure analysis, the relative stability of fullerenols depends on the number of hydroxy addends in the equatorial belt region. The 2D Schlegel diagrams of C70(OH)n fullerenols were presented for the geometrically optimized structure by PM3 calculations and contained exact positions of hydroxy addend in C70. These diagrams may be helpful in the investigation of the physical properties of starburst polymers or other groups substituted onto fullerenols. This theoretical computational procedure for searching possible isomers may be a helpful tool for isomer study with symmetry consideration.

Comparative theoretical study of carbon nanotubes and boron-nitride nanotubes

Abstract The structure of BN nanotube is similar to that of C-C nanotube, which has zig-zag, coiled and toroidal structure. The geometry optimized structures for BN nanotubes are generated by molecular mechanics calculations. The tubes diameter and intershell distance are obtained also.

Spherical shape of the goldberg type giant fullerenes

Abstract A method is devised to construct spherical giant fullerenes of icosahedral (C20, C60, C180, C240, C320 and C540) and tetrahedral C28, C40, C100, C228, C304 and C568) symmetries by using a triangular motif. The average radius and standard deviation of radius of these giant fullerenes are generated to verify the spherical shape.