Functionalized nanodiamonds: Triamantane and [121]tetramantane

The selective functionalizations of the fundamental hydrogen-terminated nanodiamonds triamantane 1, as well as the most symmetrical representative of the tetramantanes (C-2h-[121] tetramantane 2) were elaborated. Electrophilic reagents (Br-2, HNO3) predominantly attack the medial C-H positions of the cages; bromination of 2 gave the medial 2-bromo derivative almost exclusively. Highly selective apical substitution in 1 and 2 is possible either under single-electron-transfer oxidations via hydrocarbon radical cations or through photoacetylation with diacetyl. The mono-and the bis-acetyl derivatives of 1 and 2 were converted through Bayer-Villiger oxidation and subsequent hydrolysis to the respective apical mono-and dihydroxy derivatives. This exceptional synthetic specificity facilitates the transformation of 2, and perhaps larger nanodiamond molecules, into functionalized building blocks needed for a wide range of applications such as nanotechnology.