Polyamines. I. Spectroscopic properties of N,N-bis-(phthalimidopropyl)-N-propylamine and supramolecular interactions in its crystals

A new derivative of polyamine, N,N-bis-(phthalimidopropyl)-N-propylamine (1) has been synthesized and its structure studied by X-ray diffraction, FTIR, Raman, 1H and 13C NMR spectroscopies. The B3LYP and DFT calculations have been carried out. The molecular structure of N,N-bis-(phthalimidopropyl)-N-propylamine (1) presents the first case of a folded conformation for this group of compounds which is stabilized by an intramolecular hydrogen bond C–H⋯O. Neither C–H⋯π, π⋯π or CO⋯CO interactions operate in this case. Also the supramolecular structure is stabilized by weak C–H⋯O and C–H⋯π hydrogen bonds. The optimized bond lengths as well as bond angles for 1 calculated by B3LYP/6-31G(d,p) approach are compared with the X-ray data. The screening constants for 13C and 1H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1H and 13C chemical shifts and the computed screening constants have been obtained.