Benchmark CCSD(T) and Density Functional Theory Calculations of Biologically Relevant Catecholic Systems

Approximate complete basis set CCSD(T), MP2, and HF calculations are performed for thirty-two catechol-containing complexes. These complexes, which include metal-coordination, hydrogen-bonding, π-stacking, and other, weaker interactions, are representative of the types of noncovalent interactions that catechols undergo when binding to proteins in the body, such as in the biosynthesis of dopamine. The catechols studied include the neutral catechol and dinitrocatechol molecules, as well as the charged dopamine and DOPAC molecules. Calculations with twenty-one density functional theory methods with triple and quadruple-ζ basis sets are evaluated against the CCSD(T) benchmarks to ascertain their accuracy. It is found that MN15, M06-2X-D3, ωB97XD, ωB97M-V, and CAM-B3LYP-D3 provide good accuracy when compared with CCSD(T)/CBS calculations for these systems and may be used for the study of relevant biological systems. The local DPLNO CCSD(T) method is also evaluated against the CCSD(T)/CBS energies for a subset of the complexes and found to agree within 1-3%, with a maximum difference of 0.26 kcal/mol.