Adamantane nanostructures

Due to the ability of adamantane and its derivatives to attach to DNA, it is possible to construct well-defined nanostructures consisting of DNA fragments as linkers between adamantane cores. This could be a powerful tool to design DNA-directed nanostructured self-assemblies [149]. 

A unique feature of such DNA-directed self-assemblies is their site-selective immobilization, which makes it possible to construct well-defined nanostructures. On the other hand, the possibility of the introduction of a vast number of substitutes (like peptidic sequences, nucleoproteins, of hydrophobic hydrocarbon chains) to an adamantane core (adamantyl) makes such a process capable of designing steric colloidal and supramolecular conformations by setting hydrophobic/hydrophilic and other interactions. In addition, the rigidity of the adamantane structure can provide strength and rigidity to such self-assemblies [150]. 

Bifunctional adamantyl, as a hydrophobic central core, can be used to construct peptidic scaffolding [151], as shown in Fig. 27. This is the reason why adamantane is considered one of the best MBBs. This may be considered an effective and practical strategy to substitute different amino acids or DNA segments on the adamantane core (Fig. 28). In other words, one may exploit nucleic acid (DNA or RNA) sequences as linkers and DNA hybridization (DNA probe) to attach to these modules with an adamantane core. Thus a DNA-adamantane-amino acid nanostructure may be produced. 

Figure 5.22 Cu UPD on a Au/mica substrate network are filled with adamantane thiol modified by a hybrid nanostructure consisting of (circles), (b) STM images of network-SAM a hydrogen-bonded network and a thiol SAM. hybrid structure with inset showing the (a) Cartoon ofthe hybrid structure and molecular hexagonal thiol island at molecular resolution, structures of the components. The hydrogen- (c, d) Schematic illustrations and STM images of...

C—C bond reorganization in confined space is also possible with sp -hybridized carbon-based molecules. Adamantane was confined in DWCNTs forming linear adamantine assanbUes [188]. The annealing of the sp -hybridized nanostructures under vacuum at temperatures higher than 500°C convert the adamantine into carbon chains inside the CNTs however, the introduction of H2 during the annealing step suppressed their formation. Similarly, diamond nanowires formed inside DWCNTs from encapsulated diamantane dicarboxylic acid [189]. 

DNA-Directed Assembly and DNA-Adamantane-Amino acid Nanostructures... 

Adamantane can be used to construct peptidic scaffolding and in synthesis of artificial proteins. Adamantane has also been introduced into different types of synthetic peptidic macrocycles, which are useful nanotools for many applications including in peptide- and stereochemistry. Introduction of amino-acid-functionalized adamantane to the DNA nanosttuctures may lead to constraction of DNA-adamantane-amino acid nanostructures with desirable stiflhess and integrity. Diamondoids can be employed to construct molecular rods, nanocages, nanocapsules, and also for utilization in different methods of self-assembly. In fact, by development of self-assembly approaches and utilization of diamondoids in these processes, it should be possible to construct novel nanostructures especially to design effective and specific in vivo carriers for drugs. 

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