A new family of two-dimensional carbon allotropes is presented, based on graphene stripes linked to each other by acetylenic connections. The large amount of allowed connectivities demands for a family name to them: Grazynes. The present study reports the energetic, structural, elastic, and electronic physicochemical properties of a set of simple grazynes by means of density functional theory based calculations, suggesting also possible synthetic routes. The main results conclude that these are exotic yet stable materials, stiffer than graphene in the acetylenic direction, highly anisotropic, and with the presence of Dirac points in the reciprocal space along the graphene stripes direction resistant to strain, regardless of its direction. Thus, grazynes infer directionality in electron conductivity and resilience to the materials stretching/compression, quite important, for instance, in the nanoelectronics applicability point of view.

The structural, electronic, and nonlinear optical (NLO) properties of pristine dodecadehydrotribenzo[18]annulene ([18]DBA) functionalizing with the alkali metal atom (Li and Na), NH2 and NO2 functional groups and its location are inspected through density functional theory (DFT) calculations. The NBO analysis indicates that functionalizing [18]DBA caused increasing charge transfer (CT) and introduced a new acceptor–donor model for NLO materials due to the structure with of π-electron of [18]DBA. The results demonstrate that the functional groups notably narrow the energy gap of [18]DBA, and the electronic character of [18]DBA is sensitive to the functional groups. Furthermore the considered functional groups enhance the static first and second hyperpolarizability of [18]DBA. Interestingly, replacement of H atom by Na and NO2 in [18]DBA leads to large static first hyperpolarizability (β0) values of 3977.40 and 3722.56 au and very great static second hyperpolarizability (γtot) 980380.40 and 752886.20 au, respectively, which is the largest among the considered functionalizing structures. Also transition energies (ΔE) decrease due to functionalizing, and the best location for functionalizing is position 2.

No abstract

No abstract