Diamondoid, in the context of building materials for nanotechnology components, most generally refers to structures that resemble diamond in a broad sense: namely, strong, stiff structures containing dense, 3-D networks of covalent bonds, formed chiefly from first and second row atoms with a valence of three or more. Examples of diamondoid structures would include crystalline diamond, sapphire, and other stiff structures similar to diamond but with various atom substitutions which might include N, O, Si, S, and so forth. Graphite consisting of carbon atoms arranged in planar sheets ("graphene" sheets), carbon nanotubes consisting of sheets of carbon atoms rolled into tubes, and other graphene structures are sometimes also included in the class of diamondoid materials for nanotechnology.

In the context of classical chemistry, "diamondoid" refers to variants of the carbon cage molecule known as adamantane (C₁₀H₁₆), the smallest unit cage structure of the diamond crystal lattice. Diamondoids may include one or more cages (adamantane, diamantane, triamantane, and higher polymantanes) as well as numerous isomeric and structural variants of adamantanes and polymantanes. These diamondoids occur naturally in petroleum deposits and have been extracted and purified into large pure crystals of polymantane molecules having more than a dozen adamantane cages per molecule. Examples include:

• Adamantane (C₁₀H₁₆)
• Iceane (C₁₂H₁₈)
• BC-8 (C₁₄H₂₀)
• Diadamantane (C₁₄H₂₀)
• Triadamantane (C₁₈H₂₄)
• Isotetramantane (C₂₂H₂₈)
• Cyclohexamantane (C₂₆H₃₀)
• Super-adamantane (C₃₅H₃₆)

See also

• Boron nitride