How are fullerenes different from diamond and graphite?

Fullerenes, diamond, and graphite are all allotropes of carbon, but they differ significantly in their atomic structure and bonding.1

• Diamond: Consists of an infinite, three-dimensional crystalline array where each carbon atom is covalently bonded to four others in a tetrahedral arrangement. This structure creates an exceptionally hard, dense, and stable material.21
• Graphite: Composed of stacked, two-dimensional sheets of carbon atoms arranged in fused hexagonal rings (graphene). The layers are held together by weak van der Waals forces, which allow the sheets to glide easily, resulting in softness and lubricity.21
• Fullerenes: Unlike the infinite lattices of diamond and graphite, fullerenes are discrete, hollow molecules that form closed cages (buckyballs) or cylinders (nanotubes). While each carbon atom in a fullerene is bonded to three neighbors—similar to graphite—the spherical or cylindrical shape is achieved by incorporating pentagonal rings alongside hexagonal ones. Fullerenes form molecular crystals held together by weak van der Waals interactions.34