N-Carbophenes: two-dimensional covalent organic frameworks derived from linear N-phenylenes

N-Carbophene (carbophene) is a novel class of two-dimensional covalent organic frameworks (2DCOF), based on linear N-phenylenes, that have moderate band gaps and low-mobility bands surrounding the Fermi energy; the simplest of which may have been recently synthesized. Using tight-binding density functional theory, the ground state configurations of carbophene single layers, bilayers, and bulk systems were determined. This work finds that carbophenes have formation energies per carbon atom similar to that of graphenylene. The similarity of formation energies between graphenylene and carbophene suggests that when trying to synthesize one, the other may also be synthesized. The formation energies could explain why the first reported synthesis of graphenylene also indicated that they may have synthesized 3-carbophene. Results contained in this work suggests that a carbophene was synthesized instead of graphenylene. The projected density of states (PDOS) demonstrates that the anti-aromatic nature of the cyclobutene units play a direct role in the creation of bands around the Fermi level, making this an exciting material in the theoretical understanding of the nature of aromatic bonds.