Cyclic Diamondoid Structures with Shared Vertices, Edges, or 6-membered Rings

Abstract

Abstract. Diamondoid structures with shared vertices, edges, or 6-membered rings can theoretically be curved into toroidal structures whose calculated energy provides information about steric strain. Diamondoid hydrocarbons sharing one vertex between two adamantane units are called [n]spiromantanes, where n indicates the number of adamantane units. When a pair of adamantane units shares one CC bond, the resulting assembly is called one-edge-[n]mantane, specifying (by letters in square brackets) which bonds are shared by the adamantane units. Two adjacent edges may be shared by a pair of adamantane units, and the assembly is called two-edge-[n]mantane, again specifying by letters in square brackets the shared bonds. Catamantanes or perimantanes sharing a 6-membered ring of carbon atoms may form larger rings in an assembly which is called [n]cyclomantane; in the case of catamantanes, the structure of the diamondoid is specified by codes of the dualists. Finally, nanotubes derived from hexagonal diamond, as well as corresponding toroidal structures, are discussed.

Adamantane-Derived Carbon Nanothreads: High Structural Stability and Mechanical Strength

“…Among the number of possible ANTs reported earlier, − we start with bond-connected ANTs, ( 2a ) and ( 2b ), obtained by the formation of a C–C bond connection between the adamantane units. Sharing a single carbon atom between the adamantane units in a spiro-linkage gives the NT ( 2c ).…”

“…Thus, the possible connectivity patterns would lead to four major varieties: (i) C− C bond-connected, (ii) atom-shared, (iii) edge-shared, and (iv) face-fused NTs. 24,25 Here, we have studied these varieties and compared with the reported stable BNTs using the density functional theory (DFT). A selection is made among the many possibilities by avoiding structures with obvious strong repulsive nonbonded interactions 26 (Figure 1).…”

“…Recently, two new adamantane-derived nanothreads (ANTs) are successfully synthesized from diamantane-4,9-dicarboxylic acid and the bridgehead-halogenated diamantane molecule based on nanotemplate reaction. , Balaban et al extensively studied diamondoids from adamantane-derived molecules based on connectivity patterns. ,− Adamantane has two types of carbon atoms; six secondary carbon atoms connected to each other by four tertiary carbon atoms. Thus, the possible connectivity patterns would lead to four major varieties: (i) C–C bond-connected, (ii) atom-shared, (iii) edge-shared, and (iv) face-fused NTs. , Here, we have studied these varieties and compared with the reported stable BNTs using the density functional theory (DFT). A selection is made among the many possibilities by avoiding structures with obvious strong repulsive nonbonded interactions (Figure ).…”

Energies for cyclic and acyclic aggregations of adamantane and diamantane units sharing vertices, edges, or six‐membered rings

“…[21,22] A similar approach was also used for the IUPAC nomenclature of certain perimantanes. [22] In a recent article, [23] one of the present authors described various ways in which several hydrogen-depleted molecular graphs of adamantane may share vertices, edges or faces (shared hexagons of carbon atoms). Klein et al [24] described a construction to generate novel super-adamantane structures based on the simplest connection via CAC bonds between tertiary carbon atoms of different adamantane units.…”

“…Klein and coworkers [24] described a construction to generate novel super-adamantane structures based on the simplest connection via C-C bonds between tertiary carbon atoms of different adamantane units. In the paper mentioned above [23] various ways to connect adamantane units into acyclic or cyclic arrays of spiro-adamantanes and torus-like polyadamantanes were described. There are also various ways in which adamantane units can share one or two C-C bonds according to the topological distances between them.…”