Density functional calculations, utilizing the BLYP and Becke3LYP functionals, have been used to calculate the vibrational frequencies and interaction energies for a variety of intermolecular complexes modeling the interaction of weak bases with acidic hydroxyl groups in microporous materials. The interaction complexes of nitrogen, acetylene, ethene, and benzene have been studied. Comparison is made between calculated vibrational frequencies, vibrational frequency shifts, and interaction energies with experimental determinations. Good agreement is observed between calculated vibrational properties and experimental determinations for nitrogen, acetylene, and ethene interactions. Interaction energies are significantly underestimated in most cases.