Polyamines. I. Spectroscopic properties of N,N-bis-(phthalimidopropyl)- N-propylamine and supramolecular interactions in its crystals Bogumil Brycki a, * , Iwona Kowalczyk a , Justyna Werner a , Teresa Borowiak b, * , Irena Wolska b a Laboratory of Microbiocides Chemistry, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6 60-780, Poznan ´, Poland b Department of Crystallography, Faculty of Chemistry, Adam Mickiewicz University, Grunwaldzka 6 60-780, Poznan ´, Poland Received 25 November 2005; received in revised form 16 January 2006; accepted 20 January 2006 Available online 3 March 2006 Abstract 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, 1 H and 13 C 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/p, p/p or CaO/CaO interactions operate in this case. Also the supramolecular structure is stabilized by weak C–H/O and C–H/p 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 13 C and 1 H atoms have been calculated by the GIAO/B3LYP/6-31G(d,p) approach and analyzed. Linear correlations between the experimental 1 H and 13 C chemical shifts and the computed screening constants have been obtained. q 2006 Elsevier B.V. All rights reserved. Keywords: N,N-bis-(phthalimidopropyl)-N-propylamine; X-ray diffraction; B3LYP calculations; FTIR; Raman and NMR spectra 1. Introduction Polymethylene polyamines occur naturally in all living species and many functions of prokaryotic and eukaryotic cells have been shown to be polyamine dependent [1,2]. On the other hand, polyamine derivatives can be used as therapeutic agents. For example, N-alkyl analogues of biogenic poly- amines exhibit strong cytotoxic activity against human tumor cell lines [3], also naphthalimide derivatives of polyamines have potential anticancer activity [4]. Some of the polyamines and their derivatives exhibit a very good antimicrobial activity [5–7]. In order to better understand the mechanism of antimicro- bial activity, we synthesized a new series of N,N-bis- (aminopropyl)-N-alkylamines and their derivatives. These compounds were obtained as a part of our program to develop synthetic routes to novel, stable polynuclear dendritic complexes with potential biotechnical applications. In the first step of this program, we obtained N, N-bis- (phthalimidopropyl)-N-propylamine, a polyamine with two terminal amine groups blocked by phthalimide moiety. Hence, the detailed structural characterization of a new phthalimide derivative is worthy of consideration. Polyamines and their derivatives in the most cases are flexible molecules; however in some examples extended conformations are observed. Crystals with phthalimide moieties have the propensity to engage in the solid state C– H/p, p/p, dipole/dipole and other supramolecular interactions, depending on the detailed nature of the proximal functional groups [8–11]. For compounds which possess tertiary amine functions located between phthalimide moieties the interactions mentioned above lead to a folded molecular conformation as observed for compounds with the CSD codes IJOKUN, REVZEX, IJOLAU [8,9,12]. For such conformation the torsion angle N(amine)–C–C–N(phthalimide) as deter- mined by X-ray diffraction, adopts value of about 608. Without the possibility for C–H/p and the other interactions indicated above as in IJOKOH or IJOKAT [8] whose amino functions have been quaternized, an extended conformation is observed with the torsion angle N C (amine)–C–C–N(phthalimide) of about 1708. In the folded conformation also the dipole/dipole interactions play a crucial stabilizing role. This kind of interaction is characterized by a short contact between OaC (dC)/O (dK)aC dipoles [8]. Journal of Molecular Structure 791 (2006) 137–143 www.elsevier.com/locate/molstruc 0022-2860/$ - see front matter q 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.molstruc.2006.01.023 * Corresponding authors. Tel.: C48 61 829 1314; fax: C48 61 865 8008. E-mail address: iwkow@amu.edu.pl (B. Brycki).