The cation-π cloud interaction and the zeolite basicity concept

Two adsorption complexes between pyrrole and alkaline T6 zeolite clusters were studied theoretically using DFT method. Results show that at B3LYP/6-311+G**//B3LYP/6-31G* the oxygen atoms in LiT6 are, in average, more charged than in CsT6. The cation-π complex is more stable than the complex possessing a hydrogen bond between T6 clusters and pyrrole. Correlations between alkaline cation hardness and ΔHadsorption (kcal/mol) showed a linear correlation for both complexes, indicating that the driving force for pyrrole adsorption is cation hardness.