2.2 DFT calculation
Surface analysis and G solv of designed molecules were calculated by DFT calculation. All electronic structures in this work were conducted using the Gaussian 09 suite of the program29. The designed molecules investigated were fully optimized in the gas and solution phase by the B3LYP /6-31G(d)30, 31, including empirical dispersion corrections DFT-D3 method32, 33, and were performed using the tight convergence criterion, which was always followed by the calculation of harmonic vibrational modes. To utilize the SMD model consistently, we have performed calculations of G solv at the same levels of theory utilized in the parameterization of SMD. We used M05-2X exchange-correlation functionals34 along with 6-31G(d) to calculate the single point energy in gas and water, which has proved to be reliable for calculating the E ads andE sol35.G solv could calculate by the formula as follow:
where G solv is solvation free energy,E sol and E gas are the single-point energy calculated by M05-2X/6-31G(d). Based on the optimized molecular structures, the HOMO/LUMO electrostatic potential (ESP) and molecular polarity index (MPI) were analyzed by the Multiwfn program36 and visualized via the VMD package37. All basis sets are obtained from the Basis Set Exchange library.