Regarding the DCA based on the conventional PIBSI chemistry, it is found that the adsorption strength increases with the length of the polyamine chain, i.e. the TEPA interactions are stronger than the DETA ones, which roughly exceed the iso-octane tendency to adsorb. Our DFT results align with calculations carried out at higher level of theory with a more accurate treatment of the correlation effects behind the non-covalent amine-π mechanisms. Although previous calculations have suggested that the adsorption is not favourable for ammonia, 110 the dispersion effects of alkyl-substituted compounds (namely, amines) exceed the repulsive electrostatics and the overall interaction becomes attractive.