[60] Fullerene - Barbituric Acid And Its Dimer Geometric Structure And Electronic Structure

Geometric and electronic properties of fullerene—barbituric acid and its dimer have been studied by density functional theory(DFT) at BLYP level with dnp basis sets.The monomer with 6,6 close-bond structure was found to be stable.The volume of the C₆₀ cage expands slightly,while the molecular orbital distribution changs a lot. Fullerene—barbituric acid ,as a result of the charge transferring from C₆₀ cage to the barbituric acid ,forms a D-A system.The results of vertical ionization protential(VIP) and vertical electron affinity(VEA) indicate that fullerene—barbituric acid remains most properties of C₆₀ , but it is less stable and higher reactive than C₆₀ . Three possible isomers of fullerene—barbituric acid dimers (i.e. 1 [6,5-6,5], 2 [6,6-6,5], 3 [6,6-6,6]) were examined at the same level. Calculations of energies revealed that 3 is the most stable . After polymerization, the C₆₀ cage deforms slightly,and the carbon atoms connected with the other cage are projecting somewhat. For dimer,the degeneracy of energy splits while the homo-lumo energy gap is smaller than that of monomer . So it has higher reactivity and could form to the linear fulleropolymer.