Abstract:

Correlations between experimental chemical shifts and GIAO-calculated isotropic shielding constants of hydrogen and carbon atoms were obtained for a series of imidazole derivatives with antiproloferative activity, in order to assess the performance of NMR spectral calculations, using both HF and DFT-B3LYP level of theory with different basis sets. The influence of the choice of the method and the basis set on the chemical shift was investigated. The theoretical values were compared with the experimental data. The experimental shifts for carbons are in better agreement with the HF/6-311 G(d) and B3LYP/6-31 G(d) calculations, whereas for protons the differences are almost negligible. The calculated root mean square values for ¹H shifts indicate that the 6-311+G(2d,p)basis set provides better fit for chemical shifts than the other basis sets. The obtained b values differ with statistical significance from zero (P < 0.001), which on the linear model used is adequate and correctly describes the dependence between the experimental and the calculated values of the corresponding chemical shifts. The analysis of the obtained pharmacological data for the newly synthesized imidazole derivatives shows that the target structures possess antiproliferative activity and they may be recognized as leading structures for future development of new anti-neoplastic agents.