Theoretical Investigation of the Defect Position Effect on the Aromaticity of N and B Doped Graphene

The NICS index is a simple, easy and reference independent method to evaluate thearomaticity of molecules. When cyclic compounds with delocalized π-electrons are subjected tothe external magnetic field perpendicular to the ring, the π-electrons in the closed-circuit providea ring current. This circular ring current produces an induced magnetic field, opposite theexternal one. Shielding of the external magnetic field will be intensified by the nuclear magneticresonance chemical shift[1]. Schleyer et al.[2] efforts lead to a method to calculate the chemicalshift not only at every nucleus but also at any point in the space in the vicinity of molecules.NICS is the negative of the isotropic component of the chemical shielding tensor. It is very oftento calculate NICS at the geometric center of the ring. To avoid the shielding effects of theframework of electrons, calculations usually are carried out at points 1Å above the center ofrings. The magnetic shielding tensor (NICS(1)zz) is considered as a better descriptor ofaromaticity[3].In this research, the effect of defection position on the aromaticity of N and B dopedgraphene diradicals has been investigated. Such a study helps to understand, control and improvethe unique features of graphene-based materials. Considering the (NICS(1)zz ) values of theconstituting rings of studied species improves that, defection in the marginal area has the leasteffect on the aromaticity of graphene.

کلیدواژه ها:

Doped Graphene ، NICS Aromaticity Iindex ، Defect Position ، Graphene Diradical