The 13C-NMR spectra is a powerful tool, useful for modeling biological activity.NMR spectra reflect quantum mechanical properties which, depends on local electrostatics and geometry of the target molecule. 13c-NMR spectrum of a compound contains a pattern of frequencies that correspond directly to the quantum mechanical properties of the carbon nuclear magnetic field.the NMR chemical shift-tensor is composed of a diamagnetic term and paramagnetic term.the diamagnetic term is directly related to electrostatic potential of nucleus, whereas paramagnetic term is dependent on orbital configuration...