[1H and 13C NMR investigation of nifedipine].

1H-13C shift-shift correlation based assignment of the 13C and 1H NMR spectra of nifedipin are presented along with some results of MM+ and PM3 conformation analysis. Both computation methods yield asymmetric low energy conformers. MM+ molecular dynamics simulations give similar results. A lower limit to the interconversion rate of the asymmetric low energy conformers is determined using magnetic shielding differences obtained by TNDO/2 calculations.