Discovering terpene catalysis inside nano-capsules with multiscale modeling and experiments

Stability trends in carbocation intermediates stemming from germacrene A and hedycaryol

“…It is noteworthy that optimization with ωB97M-V/6-31+G(d,p) and single point calculations performed with M06-2X and ωB97M-V using the triple-ζ def2-TZVPP basis set provide similar trends for both germacrene and hedycaryol carbocations (the energy comparison plots for the different methods are added in Supporting Information File 1 (Figure S4)). This is evidence that our original method of choice is reliable for this type of studies and in agreement with our earlier benchmark study [36]. Additionally, we carried out single point energy calculations in solvent (chloroform) [43,44] using the SMD [45] solvation model.…”

“…Additionally, to check the reliability of the energy calculations single point calculations were also performed with the larger def2-TZVPP [34] basis set for both functionals and to account for intramolecular non-covalent interactions, D3 dispersion corrections were added to the M06-2X calculations with zero damping [35]. Extensive benchmarking on different sets of classical and nonclassical carbocations have shown that M06-2X in conjunction with the 6-31+G(d,p) basis set performs well for carbocations [29,36], and here we confirm this finding for hydroxylated carbocations. All gas-phase calculations were performed using Gaussian 16 (revision A.03) [37] and Q-Chem (version 5.4.2) [38], with default tight geometry optimization convergence criteria (10 −5 au) and SCF convergence thresholds (10 −8 au).…”

Unraveling the role of prenyl side-chain interactions in stabilizing the secondary carbocation in the biosynthesis of variexenol B

“…Structure optimizations were done with the M06-2X [43] density functional theory method and the 6-31+G(d,p) basis set without any symmetry restrictions. M06-2X was selected because of its accuracy in calculating terpene-forming reactions and its proven track record being used in previous studies of reaction mechanism analysis [16,44]. Vibrational frequency calculations at the same level of theory with optimization were performed to verify that each local minimum has no imaginary frequency and that each TS has only a single imaginary frequency.…”

Understanding the competing pathways leading to hydropyrene and isoelisabethatriene

“…Optimizations and subsequent frequency calculations were performed using the Gaussian 16 program [30] at the M06-2X/6-31G+(d,p) level of theory [31,32]. This combination has been employed previously to TPS reactions [17,18,20,24,25,[33][34][35][36]. The Gibbs free energies were calculated within the standard harmonic approximation and at a pressure of 1 bar and temperature of 298 K. We note that for some reaction steps, a transition state could not be located.…”