Hexagonite: A Hypothetical Organic Zeolite

Abstract

Elaborating the discrete hydrocarbon molecule bicyclo[2.2.2]-2,5,7-octatriene in three-dimensions, a unique, hypothetical allotrope of carbon is produced. Such a structure possesses a principal 6-fold axis; along this axis are hexagonal, organic tunnels with about a 5.70 A outside tunnel diameter across opposite vertices, and an actual, inside diameter of 4.16 A when taking into account the covalent radius of tetrahedral carbon. Across opposite edges, the outside hexagonal tunnel diameter is 4.94 A, and the inside tunnel diameter is 3.61 A. These tunnels are lined alternately with hexagonally disposed ethane-like functions and hexagonally disposed ethene-like functions that stack along the tunnel axis. The lattice lies in space group P6/mmm, and it has the Schlafli symbol given by (6, 32/5), it is therefore topologically related to the graphite–diamond hybrids. Because of the hexagonal symmetry of the unit cell, and also due to the fact that its polygonality is six, the structure has been given the name hexagonite. There are 10 carbon atoms in the unit of pattern, and the density is 2.50 g/cm3; bordered by the densities of graphite at 2.27 g/cm3 and diamond at 3.56 g/cm3. Its large organic channels, lined with π organic functions, may make it particularly useful as an organic zeolite material, or alternatively as a host lattice for ionic conduction. The electronic band structure of the empty, hexagonal host lattice is described.