A density functional theory study on the electronic and adsorption characteristics of cyclo M9N9 (M = B and Al)

On the basis of experimental and theoretical calculations conducted for cyclo C18, we predicted two novel inorganic cyclo M9N9 (M = B and Al) molecules. Because of the significant difference in electronegativity between M and N atoms, M–N bonds were ionic. Furthermore, the interaction of cyclo M9N9 with cyclopropylpiperazine (CPPP) was investigated. In cyclo M9N9, each M atom could adsorb one CPPP molecule. The CPPP molecules exhibited a preference to remain outside cyclo M9N9 molecules. Depending on the structural characteristics of CPPP molecules, the exciting part is that up to four CPPP molecules could be adsorbed on the exterior surface of cyclo M9N9. We calculated adsorption energies and analyzed the main structural parameters in the process. The research results indicated that adsorption on cyclo Al9N9 was energetically more favorable than that on cyclo B9N9. The cyclo M9N9 have considerable potential in the future.