The conformational search showed that two low-energy conformers are present in dichloromethane and chloroform: conformer A and B (Figure ). The conformers A and B differ only in the position of (R)-CSA relative to each other. In the conformer A the carbonyl oxygens of upper (O5) and lower (O6) guests are pointed to the right, while in the conformer B they are pointed to the left. This corresponds to a 180° rotation of the guests with the porphyrin plane remained distorted to the same extent (Figures S7-S8 and Tables ). According to the Boltzmann distribution, both the major conformer A (54%) and the minor conformer B (46%) were found in dichloromethane, while in chloroform the situation is strikingly different with the main conformer B reaching 99% (Tables and). Main positions of the guest molecules and Gibbs free energy differences in two studied solvents. Conformers A and B were found during the manual conformational search, the lowest energy conformer C was found by CREST. Simulated ECD spectra in dichloromethane for the main conformers are presented in Figure and Table (for chloroform see Figure and Table ). In dichloromethane, due to the low content of conformer A, the averaged spectrum differs from the experimental one (Figure ). However, the difference between conformers A and B is only 0.08 kcal . mol -1 ; lower than the limits of accuracy of DFT. To improve the agreement with the experimental data we did single point calculations using several other functionals, which are more accurate in the energy predictions (Table ). Thus, B3LYP-D3BJ/cc-pVTZ predicted the conformer B to be by 0.42 kcal . mol -1 more stable than the conformer A, while M06-2x/6-311++G** showed that both conformers have the same energy. In contrast, M06/cc-pVTZ predicted that the conformer A is lower in energy by 1.91 kcal . mol - 1 than the conformer B. The B3LYP-D3BJ/6-311++G** level of theory found an energy difference of 0.51 kcal . mol -1 between the conformers A and B. The best agreement with the experimental ECD spectrum (in both energies and intensities) was achieved using the energy difference of 0.51 kcal . mol -1 for calculations of the Boltzmann distribution. However, we were not able to achieve an agreement with experimental ECD spectrum in chloroform regardless of the method used for energy single point calculations (Figure and Table ). Since it is well known that ECD spectra are extremely sensitive to the geometry, and overlooking one or more significant conformations is the main error associated with conformational searches, we repeated the conformational search with a relatively new CREST (Conformer-Rotamer Ensemble Sampling Tool) software. CREST allows using the GFN2-xTB semi-empirical method, which is capable for description of non-covalent interactions determining the geometry of studied complex. Moreover, it proved to be reliable in the search for conformational assemblies, including examples of NMR and optical rotation spectra. For CREST input the two lowest energy conformers (A and B) in both solvents were used.