Adsorption and sensing properties of non-planar π surfaces towards high energy molecules: A density functional theory study

Using density functional theory (DFT), we have investigated the adsorption characteristics of several explosive compounds (nitromethane, nitrobenzene, nitroglycerin, pentaerythritol tetranitrate, hexogen, 2,4,6-trinitrotoluene and 1,1-diamino-2,2-dinitroethene) on the concave and convex surfaces of a variety of buckybowl materials (corannulene, sumanene, monoindenocorannulene, ortho-diindenocorannulene and 1,2,4-triindenocorannulene). Our results predict that the concave surface of the buckybowl materials shows enhanced adsorption properties for all of the explosive compounds studied. The curvature plays a vital role in the adsorption of explosives. The hydrogen bonding interactions in the complexes were studied using atoms in molecules (AIM) analysis, which confirmed the existence of closed-shell (non-covalent) interactions between the buckybowl materials and explosive compounds. Using natural bond orbital (NBO) analysis, the charge transfer within the complex was found to occur from the buckybowl materials, which act as electron acceptors, to the explosive compounds, which act as electron donors. Energy decomposition analysis showed that dispersion and electrostatic interactions stabilize the complexes. Thermochemical parameters, such as enthalpy, indicate that the adsorption process was exothermic. However, the Gibbs free energy values show that the adsorption process occurs at low temperature. The conductivity results show that concave buckybowl materials possess enhanced sensitivity towards the explosive compounds studied.