Spectroscopic and computational insight into weak noncovalent interactions in crystalline pyrimidine

► Non-uniform shifts in vibrational spectra accompany transition from liquid to solid. ► Modes associated with spectral shifts involve significant motion of H atoms. ► Polarized Raman spectra facilitate assignment of CH stretching region of pyrimidine. ► The crystalline environment was modeled with eight neighboring pyrimidines. ► DFT computations with this model include the eight nearest neighbor CH⋯N interactions and reproduce most shifts.