Mechanistic Insights of Seeded Diamond Growth from Molecular Precursors

Abstract

We report mechanistic insights of the bottom-up synthesis of nanodiamonds (NDs) from adamantane derivatives as molecular precursors. Thermal cracking of tetracosane below the decomposition temperature of adamantane, 1-adamantylamine or 2-azaadamantane revealed the initial steps of seeded diamond growth mechanism based on pyrolysis studies.

Ultrasmall Nanodiamonds: Perspectives and Questions

“…Although this wet chemical synthesis of USNDs from preassembled molecular precursors still remains to be demonstrated, recent reports have shown that it is possible to produce USNDs from nitrated polyaromatic molecules 29 and adamantane derivatives. 58,99 Further theoretical and experimental efforts are needed to fully understand the role of electron-withdrawing (nitro-) groups of the polyaromatic precursors in their conversion to diamond. 29 The effects of the environment (or catalysis) on this conversion also need a better understanding.…”

“…Examples of proposed synthetic pathways from molecular precursors to diamond and diamond-like materials: (a) mild HTHP conditions for the growth of nanodiamond from aminoadamantane seeds were proposed to proceed via decomposition of tetracosane and intermediate formation of diamantane; (b) structures proposed for diamond nanowires formed from adamantane monomers encapsulated inside a double-walled carbon nanotube at temperatures of about 550 °C in vacuum. Reprinted from ref .…”

“…For example, one may envision simultaneous covalent bonding (cross-linking) of preassembled molecular structural units bearing desired functional groups in well-defined positions (e.g., reactive diamondoid derivatives, Figure ), leading to instantaneous formation of a diamond structure in a process somewhat similar to epoxy cross-linking. Although this wet chemical synthesis of USNDs from preassembled molecular precursors still remains to be demonstrated, recent reports have shown that it is possible to produce USNDs from nitrated polyaromatic molecules and adamantane derivatives. , Further theoretical and experimental efforts are needed to fully understand the role of electron-withdrawing (nitro-) groups of the polyaromatic precursors in their conversion to diamond . The effects of the environment (or catalysis) on this conversion also need a better understanding.…”