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 (Br2, 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.

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A series of subphthalocyanine-phthalocyanine dyads has been prepared by means of palladium-catalyzed cross-coupling reactions between a monoalkynylphthalocyanine and different monoiodosubphthalocyanines. Electronic coupling between the two photoactive units is ensured by a rigid and pi-conjugated alkynyl spacer. In addition, the electronic characteristics of the subphthalocyanine moiety were modulated by the introduction of different peripheral substituents. Cyclic and Osteryoung square-wave voltammetry experiments revealed that the reduction potential of this subunit can be decreased by about 400 mV on going from thioether or no substituents to nitro groups. As a consequence, the energy level of the charge-transfer state could be fine-tuned so as to gain control over the fate of the photoexcitation energy in each subunit. The diverse steady-state and time-resolved photophysical techniques employed demonstrated that, when the charge-transfer state lies high in energy, a quantitative singlet-singlet energy-transfer mechanism from the excited subphthalocyanine to the phthalocyanine takes place. On the contrary, stabilization of the radical pair by lowering the redox gap between electron donor and acceptor results in a highly efficient photoinduced electron-transfer process, even in solvents of low polarity such as toluene (Phi(ET) approximately 0.9). These features, together with the extraordinary absorptive cross section that these molecular ensembles display across the whole UV/Vis spectrum, make them model candidates for application in situations where broadband light sources are needed.

[reaction: see text] Treatment of acyclic as well as polycyclic tertiary mono- and dihydroxy hydrocarbon derivatives with thiourea in the presence of hydrobromic and acetic acid represents a convenient one-step route to the respective tertiary thiols and dithiols. This procedure was used for the preparation of diamondoid thiols of diamantane, triamantane, [121]tetramantane, and others that are prospective nanoelectronic materials.

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