Adamantane core

Star polymers are a class of polymers with interesting rheological and physical properties. The tetra-functionalized adamantane cores (adamantyls) have been employed as initiators in the atom transfer radical polymerization (ATRP) method applied to styrene and various acrylate monomers (see Fig. 21). 

Figure 21. Atom transfer radical polymerization (ATRP) synthetic route to tetrafunctional initiators of a star polymer with adamantyl (adamantane core). Taken from Ref. [91] with permission.

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. 

Molecules with tetrahedral symmetry can be realized with adamantane cores or tetrasubstituted sp3 centers (Fig. 3.15). Braun et al. [92] synthesized some adamantane glasses with glass transition temperatures of 116°C for 1,3,5,7-tetrakis (biphenyl-4-carbonyloxy)adamantane (45a) and 118°C for 1,3,5,7-tetrakis (4-iodobenzoyloxy)adamantane (45b), respectively. It is interesting to note that if the direction of the ester linkage is reversed (esters of adamantanetetracar-boxylic acid), Tg is lowered by 30 K. 

Research Focus Synthetic method for preparing semiconductors containing adamantane cores with imidazole thermal barriers. 

The super-adamantoid core of the [Ag6(triphos)4(CF3SO ")4]2+ cage. The broken lines indicate one of the two adamantane cores formed by silver ions and triflate ligands, whose F atoms have been omitted for clarity. From S. L. James, D. M. P. Mingos, A. J. P. White and D. Williams, Chem Commun., 2323-4 (2000). 

The cascade name for Figure 3.5 is derived by the process described above, except that the attachments to the adamantane core (i. e., 1,3,5,7) must be noted after the core multiplicity. The repeat units are readily named via replacement nomenclature, thus ... 

Daphnezomines A and B consisting of all six-membered rings are the first natural products containing an aza-adamantane core with an amino ketal bridge. A bioge-netic pathway for daphnezomine B is proposed in Scheme 18.7. Daphnezomines A... 

Cul-catalyzed coupling reactions. An example is shown in Scheme 3.31, the synthesis of aryl azide 223 from L-phenylalanine-derived iodide 222 in 91% yield. A similar approach allows the synthesis of stable organic polyazides, based on methane and adamantane cores 225. Despite the high energetic properties, these rigid structures can be handled without special precautions. ... 

To prove that SOMs can also be used to assess the similarity of chemical libraries, a second network was trained using an additional virtual library based on the adamantane core functionalized at the four bridgehead positions Figure 8(c). As shown in Figure 9(b), the SOM again discriminated very effectively between the xanthene and cubane/adamantane derivatives, but was unable to distinguish the cubane from the adamantane library, which is consistent with the conformational constraints imposed by their rigid cores. 

Compound 3 is an example of a star polymer with benzoxazole arms. The three dimensional rigid-rod polymer was obtained from the polycondensation of 4-[5-amino-6-hydroxybenzoxazol-2-yl]benzoic acid (ABA) with l,3,5,7-tetrakis(4-carboxylatophenyl)adamantane (TCBA) in polyphosphoric acid (PPA). Polymer structures were confirmed by FTIR and elemental analysis, although the extent of attachment of PBO arms to the adamantane core was not confirmed. In addition, stir opalescence was observed indicating lyotropic-like behavior. However, the more compact star structure resulted in intrinsic viscosities that were significantly less than linear PBO s obtained under identical conditions. The onset for weight loss under TGA in air occurred at 500 C for both linear and star polymers and no transitions were observed by DSC. 

The structure of the silver(I) complex of l,3,5,7-tetra(4,4 -sulfonophenyl)-adamantane, 14, (Fig. 13) clearly showed that the structure was composed of ID columns of Ag-SOs aggregates that were cross-linked in two dimensions by LI 1. Two types of channel were defined by the adamantane cores of the ligand. The first was primarily occupied by coordinated water molecules with approximate dimensions 7.4 by 5.9 A. The second was occupied by disordered water molecules and had dimensions of 8.3 by 6.0 A. The distances between adjacent columns were 11.46(1) A and 12.49(1) A. In this structure, guest and... 

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