Isomorphic graphene-like building unit

Abstract

A novel structural unit is proposed for constructing crystalline materials and molecular systems by mimicking the morphologies of carbon in its sp² allotropic forms. The new family of layered graphene-like crystals in 2D lattices exhibit crown ether-like cycles. The proposed structures are not limited to a single chemical element, carbon, and have the potential to modulate electronic properties based on their composition. Nine combinations of atomic elements of the structural unit are presented, which give rise to structures whose electronic gaps can vary from zero to 2.597 eV for a B-N-S-Si combination of the basic unit. Depending on the atomic composition, this structural unit may give rise to unstable or stable structures. The elastic constant analysis shows that three of the proposed structures are mechanically stable, while only the N-C-O-Ni configuration is both mechanically and dynamically stable, which is confirmed by the absence of negative frequencies in the dispersion calculations.