Ab initio studies of NMR chemical shifts for calix[4]arene and its derivatives

Ab initio calculations are performed for the calix[4]arene (1) and its derivatives 2 and 3), in this study. H-1 and C-13 NMR measured spectral data given in our previous work are used to elucidate the structures of the prepared calix[4]arenes (1-3). The molecular geometry and chemical shift are calculated by using ab initio calculations based on the Hartree-Fock (HF) and the density functional theory (DFT) in the ground state. The results obtained from both methods are in agreement with the experimental results. The results of molecular geometry and chemical shifts show that DFT approach is closer to the experimental data than HF method.