title: Nature of isomerism of solid isothiourea salts, inhibitors of nitric oxide synthases, as studied by 1H-14N nuclear quadrupole double resonance, X-ray, and density functional theory/quantum theory of atoms in molecules.
abstract: Isothioureas, inhibitors of nitric oxide synthases, have been studied experimentally in solid state by nuclear quadrupole double resonance (NQDR) and X-ray methods and theoretically by the quantum theory of atoms in molecules/density functional theory. Resonance frequencies on (14)N have been detected and assigned to particular nitrogen sites in each molecule. The crystal packings of (S)-3,4-dichlorobenzyl-N-methylisothiouronium chloride with the disordered chlorine positions in benzene ring and (S)-butyloisothiouronium bromide have been resolved in X-ray diffraction studies. (14)N NQDR spectra have been found good indicators of isomer type and strength of intra- or intermolecular N-H···X (X = Cl, Br) interactions. From among all salts studied, only for (S)-2,3,4,5,6-pentabromobenzylisothiouronium chloride are both nitrogen sites equivalent, which has been explained by the slow exchange. This unique structural feature can be a key factor in the high biological activity of (S)-2,3,4,5,6-pentabromobenzylisothiouronium salts.
authors.affiliation: Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland. Jolanta.Latosinska@amu.edu.pl
authors.forename: J N
authors.initials: JN
authors.lastname: Latosińska
authors.forename: M
authors.initials: M
authors.lastname: Latosińska
authors.forename: J
authors.initials: J
authors.lastname: Seliger
authors.forename: V
authors.initials: V
authors.lastname: Žagar
authors.forename: J K
authors.initials: JK
authors.lastname: Maurin
authors.forename: Z
authors.initials: Z
authors.lastname: Kazimierczuk
mesh_terms: D001965:Bromides / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D007536:Isomerism; D008958:Models, Molecular; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011789:Quantum Theory; D013890:Thiourea / Q000737:chemistry* / Q000494:pharmacology
chemical_list: D001965:Bromides; D002712:Chlorides; D019001:Nitric Oxide Synthase; D013890:Thiourea