A computational investigation of B-11 and N-15 chemical shielding tensors as well as local aromaticity based on NICS characterization in the N/B doped triangular graphene quantum dots

作者：Anafcheh Maryam; Ghafouri Reza^*

来源：Superlattices and Microstructures, 2013, 62: 207-216.

DOI：10.1016/j.spmi.2013.07.018

• Triangular graphene quantum dots
• NMR
• NICS
• DFT

We have performed density functional theory calculations on a representative set of N/B doped triangular graphene quantum dots (GQDs) to investigate the effect of N/B doping on the chemical shielding (CS) parameters of nitrogen and boron nuclei, and local aromaticity based on NICS characterization. The results show that CS parameters are so sensitive to the doping position. The hexagonal lattice of the triangular GQDs consists of two sets of sublattices, in each of which the CS parameters of N/B sites appear in two layers (for sites at the edges or in the inner area of sublattice). Our results also show distinct aromaticity distribution inside these molecules such that NICS(1) at the ring centers of six hexagons has maximum values (from -8.9 to -10.2 ppm), which can be explained within the framework of the Clar's Sextet Theory. When N dopant is located in the inner area, NICS(1) index shows antiaromaticity (9.1-12.5) for the three fused hexagons around the nitrogen dopant while the substituted N dopants at the edges of GQDs diminish aromaticity in the pyridine and aza naphthalene like rings. In all the B-doped GQDs, NICS shows antiaromaticity for hexagons with B dopants (9.0-12.0 ppm) and nonaromaticity for the other hexagons.

• 出版日期2013-10