Theoretical study of putrescine and X12Y12 (X=Al, B and Y=N, P) nanocage interactions

A theoretical study on the interactions between X12Y12 nanocages (Al12N12, Al12P12, B12N12, and B12P12) and putrescine molecule (Put) is presented, using density functional theory (DFT) B3LYP/6-31+G(d) methodology. Structural, energetic, and electronic variations were observed for putrescine molecules adsorbed in nanocages, and results showed that (1) the highest transferred charges (0.37 e-) of Put on nanocages found were of B12N12 and B12P12, as well as the lowest bond length interaction with putrescine X12Y12-Put (1.62 angstrom and 1.64 angstrom, respectively); (2) X12Y12-Put adsorption interaction is chemical in nature, and adsorption energy is in the order of Al12N12 > B12N12 > Al12P12 > B12P12; however, only the B12P12 presented low recovery time (113 s), showing that it is well suited to avoid spontaneous desorption at room temperature; and (3) the electronic properties of nanocages were affected by their interaction with putrescine, with a significant decrease in band gap (E-g) of frontier molecular orbitals (9.46 %) for B12P12 and in work function (phi) (19.53% and 13.69%) for Al12N12 and B12P12, causing an increase in the electrical conductivity and an increase in the density of electron current. Based on calculated results, B12P12 nanocage has potential applications as conductometric and work function-type sensors for the determination of putrescine molecule.