Aliphatic C−H/π Interactions: Methane−Benzene, Methane−Phenol, and Methane−Indole Complexes

Noncovalent C−H/π interactions are prevalent in biochemistry and are important in molecular recognition.
In this work, we present potential energy curves for methane−benzene, methane−phenol, and methane−indole complexes as prototypes for interactions between C−H bonds and the aromatic components of
phenylalanine, tyrosine, and tryptophan. Second-order perturbation theory (MP2) is used in conjunction with
the aug-cc-pVDZ and aug-cc-pVTZ basis sets to determine the counterpoise-corrected interaction energy for
selected complex configurations. Using corrections for higher-order electron correlation determined with
coupled-cluster theory through perturbative triples [CCSD(T)] in the aug-cc-pVDZ basis set, we estimate,
through an additive approximation, results at the very accurate CCSD(T)/aug-cc-pVTZ level of theory.
Symmetry-adapted perturbation theory (SAPT) is employed to determine the physically significant components
of the total interaction energy for each complex.