A DFT Comparative Study of Cyclo[18] Nanorings: Carbon, BN and BCN

Motivated by recent experimental and theoretical results for the stable form of cyclo[18]carbon (CC-18) we propose and investigate, using Density Functional Theory (DFT) formalism, the structural and thermal stability of two new molecular structures (nanorings) which are inorganic analogues of the cyclo[18]carbon. The two proposed molecules are cyclo[18]boron nitride (BN-18), and cyclo[18]boron carbon nitride (BCN-18). We investigate also their electronic properties, vibrational spectra, thermodynamic potentials and optical absorptions comparing the results against those found for the CC-18 nanoring. It was found that the nanorings are stable, insulators and apolar. Bond order analysis reveals that these nanorings exhibit a structure of alternating triple or double, and single bonds depending on the structure with short and long bonds. Due to the obtained results of thermodynamic properties, we can suggest that two nanorings can be stable and potentially synthesized: BN-18 and BCN-18. The highlight goes to the BN-18 nanoring with a particular highest thermal stability. Further, we showed that any nanoring absorbs in different regions of UV spectra. Thus, these nanorings could be suitable for development in optoelectronic molecular devices.