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

Abstract

Diamondoids are hydrocarbons having a carbon scaffold comprised from polymer‐like composites of adamantane cages. This article describes computed total energies and “SWB‐tension” energies (often referred to as “strain” energies) for species having n adamantane or diamantane units sharing pairwise: one carbon atom (spiro‐[n]adamantane or spiro‐[n]diamantane); one CC bond (one‐bond‐sharing‐[n]adamantane or one‐bond‐sharing‐[n]diamantane); or one chair‐shaped hexagon of carbon atoms (1234‐helical‐cata‐[n]diamantanes). Each of the five investigated polymer‐like types is considered either as an acyclic or a cyclic chain of adamantane‐ or diamantane‐unit cages. With increasing n values, SWB‐tension energies for acyclic aggregates are found to increase linearly, while the net SWB‐tension energies of cyclic aggregates often go thru a minimum at a suitable value of n. In all five cases, a limiting common energy per unit ( E/n) is found to be approached by both cyclic and acyclic chains as n→∞, as revealed from plots of E/n versus 1/n for acyclic chains and of E/n versus 1/n2 for cyclic chains. © 2015 Wiley Periodicals, Inc.

Energies for Cyclic and Acyclic Aggregations of Adamantane Sharing Six-membered Rings

“…[5] The diagrams of SWB tension energy per adamantane unit versus 1/n 2 for cyclic aggregates, and versus 1/n for acyclic aggregates, respectively, manifest slopes with opposite signs, and this proved to be true for most other hexagonsharing aggregates (unpublished data). In our search, however, we have encountered two exceptions with slopes of the same signs, discussing these exceptions in the present paper -with a central part of the understanding by distinguishing between a geometric strain energy, and the SWB tension energies.…”

“…[5] In order to provide information without needing to consult Part 1, some repetition of text and figures from Part 1 is made.…”

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

“…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 ).…”

Chemistry-Mathematics-Philosophy Brew: a Personal Approach

“…In another collaboration with Douglas J. Klein and his co-workers, we studied theoretically the total energies and the strain energies of acyclic and cyclic aggregates of diamantane units that share a carbon atom, a C-C bond, or a chair-shaped hexagon of carbon atoms [21]. nets: in the former ones we find molecules (including monatomic noble gas "molecules"), whereas in atomic nets we have tightly-bonded atoms such as carbon in diamond, or silicon and oxygen in quartz.…”