Abstract
The crystal structures of the title 1,4-bis(4-cyanobenzyl)piperazine (1) and 1,4-bis(4-amidinobenzyl)piperazine tetrahydrochloride tetrahydrate (2) are reported. Compound (1) crystallizes in the triclinic space group P\bar 1 and compound (2) in the monoclinic space group P21/n. In both (1) and (2) the asymmetric unit contains one half of the molecule because the central piperazine rings were located across a symmetry center. The packing of both molecules was dominated by hydrogen bonds. The crystal lattice of (1) was formed by weak C-H...N and C-H...π interactions. The crystal structure of (2) was completely different, with cations as well as chloride anions and water molecules taking part in intermolecular interactions. Single-crystal X-ray diffraction studies combined with density functional theory (DFT) calculations allowed the characterization of the intermolecular interactions in those two systems having different types of very strong electrophilic groups: non-ionic nitrile and ionic amidine. Chemical shift data from (13)C CP/MAS (Cross Polarization Magic Angle Spinning) NMR spectra were analyzed using the different procedures for the theoretical computation of shielding constants.
Highlights
The increasing demands of the pharmaceutical industry for rapid molecular structure determination of pharmaceutical solids have prompted the development of joint analysis methods spanning X-ray diffraction, 13C CP/MAS NMR and molecular modeling
In this investigation we analyzed and compared the solidstate structures of new pentamidine analogs containing the piperazine moiety (Fig. 1), i.e. 1,4-bis(4-cyanobenzyl)piperazine (1) and 1,4-bis(4-amidinobenzyl)piperazine tetrahydrochloride tetrahydrate (2) with particular attention paid to hydrogen bonding, using different methods: single-crystal X-ray diffraction analyses combined with molecular modeling and 13C CP/MAS NMR spectroscopy
The results show that the compounds 1,4-bis(4-cyanobenzyl)piperazine (1) and 1,4-bis(4-amidinobenzyl)piperazine tetrahydrochloride tetrahydrate (2), the piperazine-derived analogs of pentamidine, crystallize in the triclinic space group P1" and monoclinic space group P21/n, respectively
Summary
The increasing demands of the pharmaceutical industry for rapid molecular structure determination of pharmaceutical solids have prompted the development of joint analysis methods spanning X-ray diffraction, 13C CP/MAS NMR and molecular modeling. The intermolecular interactions in the solid state of piperazine-type pentamidine analogs were not examined, and the results obtained here could be useful in the future explanation of their biological features. In this investigation we analyzed and compared the solidstate structures of new pentamidine analogs containing the piperazine moiety (Fig. 1), i.e. 1,4-bis(4-cyanobenzyl)piperazine (1) and 1,4-bis(4-amidinobenzyl)piperazine tetrahydrochloride tetrahydrate (2) with particular attention paid to hydrogen bonding, using different methods: single-crystal X-ray diffraction analyses combined with molecular modeling and 13C CP/MAS NMR spectroscopy.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
