Anita M. Owczarzak

Silver(I) compounds of the anti-inflammatory agents salicylic acid and p-hydroxyl-benzoic acid which modulate cell function

Silver nitrate reacts with salicylic acid (salH2) or p-hydroxy-benzoic acid (p-HbzaH2) and equimolar amount of NaOH to yield a white precipitations which are then treated with tri(p-tolyl)phosphine (tptp) or tri(m-tolyl)phosphine (tmtp) to yield the complexes [Ag(tptp)2(salH)] (1), [Ag(tptp)2(p-Hbza)] (2) and [Ag(tmtp)2(salH)] (3). Complexes 1 and 3 are also obtained when aspirin (aspH) is used. The acetic ester of salicylic acid is hydrolyzed to form the complexes 1 and 3. However, when aspirin and tptp are used, a mixture of products was obtained which contains both 1 and an ionic complex of formula {[Ag(tptp)4](+)[(salH)(-)]∙[(CH3)2NCHO)]∙(H2O)} (1a). The complexes were characterized by m.p., e.a., mid-FT-IR, (1)H-,(31)P-NMR, HRMS, UV-vis spectroscopic techniques and X-ray crystallography. Two phosphorus and one carboxylic oxygen atoms form a trigonal planar geometry around Ag(I) ions in complexes 1-3. Complex 1a consists of a [Ag(tptp)4](+) cation and a deprotonated salH(-) counter anion. The influence of 1-3 on the viability of MCF-7 (breast) and HeLa (cervix) adenocarcinoma cells, is evaluated. DNA binding tests indicate the ability of 1-3 to modify the activity of cells. The binding constants of 1-3 towards calf-thymus DNA, reveal stronger interaction of 2. Changes in fluorescent emission light of ethidium bromide (EB) in the presence of DNA suggest intercalation or electrostatic interactions into DNA for 1 and 3. Docking studies on DNA-complex interactions confirm the binding of 1-3 in the minor groove of B-DNA. Moreover, the influence of 1-3 on the peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase (LOX) was kinetically and theoretically studied.

New antibacterial, non-genotoxic materials, derived from the functionalization of the anti-thyroid drug methimazole with silver ions

The new silver(I) compound {[AgBr(μ2-S-MMI)(TPP))]2} (1) and the known one [AgCl(TPP)2(MMI)] (2) were obtained by refluxing toluene solutions of silver(I) halide with triphenylphosphine (TPP) and the anti-thyroid drug 2-mercapto-1-methyl-imidazole or methimazole (MMI). The complexes were characterized by m.p., vibrational spectroscopy (mid-FT-IR), (1)H, (31)P-NMR, UV-Vis spectroscopic techniques and X-ray crystallography. The antibacterial effect of 1 and 2 against the bacterial species Pseudomonas aeruginosa (PAO) and Escherichia coli was evaluated. Compound 1 exhibits comparable activity to the corresponding one of the silver nitrate which is an antibacterial drug in use. The in vivo genotoxicity of 1-2 by the mean of Allium cepa test shows no alterations in the mitotic index values due to the absence of chromosomal aberrations. The mechanism of action of the title compounds is evaluated. The DNA binding tests indicate the ability of the complexes 1-2 to modify the activity of the bacteria. The binding constants of 1-2 towards CT-DNA indicate interaction through opening of the hydrogen bonds of DNA. Docking studies on DNA-complexes interactions confirm the binding of both complexes 1-2 in the major groove of the CT-DNA. In conclusion the silver complex 1 is an anti-bacterial and non-genotoxic material, which can be applied to antibacterial drug in the future.

Pseudosymmetry, polymorphism and weak interactions: 4,4′′-difluoro-5′-hydroxy-1,1′:3′,1′′-terphenyl-4′-carboxylic acid and its derivatives

The crystal structures of three derivatives of 4,4′′-difluoro-5′-hydroxy-1,1′:3′,1′′-terphenyl-4′-carboxylic acid are discussed. The acid itself (1), its ethyl ester (2)and hydrazide (3) have been chosen to study the influence of the hydrogen bonding potential on the crystal packing. In 1 and 2 short intramolecular O–H⋯O hydrogen bonds between the hydroxyl and carbonyl groups engage the strong hydrogen bond donors and acceptors, and both these compounds show the effects of packing conflicts. In 1 almost centrosymmetric, stable hydrogen-bonded dimers form between symmetry independent molecules, but the crystal structure is non-centrosymmetric and contains altogether four symmetry-independent molecules (two independent dimers), which show different pseudo-symmetries. In 2 dimer formation is impossible but two different crystal forms of this compound have been found. Both polymorphs crystallize in the P space group and differ mainly in the orientation of the OEt group. In turn in 3 there are no intramolecular hydrogen bonds and the crystal structure is determined mainly by the open motifs created by classical hydrogen bonds and by the complementarity of the respective hydrophilic and hydrophobic parts of the molecule.

The impact of the anion size on the crystal packing in 2-mercaptopyrimidine halides; isostructurality and polymorphism

The crystal structures of 2-mercaptopyrimidine (pyrimidine-2-thione) and its halides (Cl, Br and I) have been determined and the interactions important to the crystal packing are studied. The bromide complex crystallizes in two polymorphic forms, one of which is isostructural with the iodide compound, while the other shows some similarity with the chloride compound. This may suggest that the crystal packing is influenced by the anion size. Although we found that the size of the anion does not affect the type of interactions of the halogen atom, it significantly changes their geometry. The increase of the anion size causes jostling of the surrounding molecules and therefore the larger the size of the anion, the less regular the geometry of the halogen atom contacts. Moreover, the weakest interactions (pseudo anion–π and CH⋯halogen) are the first to be pushed out by larger halide anions. Pseudo anion–π interactions between the aromatic charged ring and the different anions were studied using the NICS method and a positive correlation between the distance and a possible interaction was confirmed.

4-Phenyl-1H-imidazole-2(3H)-thione.

In the asymmetric unit of the title compound, C9H8N2S, there are four symmetry-independent molecules (Z′ = 4). The geometrical features of these molecules are quite similar: in the normal probability plots the R 2 correlation factors for bond lengths and angles are generally around 0.95. The twist angles between the imidazole and phenyl rings (which are planar within 3σ) range from 9.0 (6) to 13.1 (5)°. In the crystal, pairs of independent molecules are joined by linear N—H⋯S and weak C—H⋯S hydrogen bonds, forming infinite ribbons, of the type ∼ABABAB∼ and ∼CDCDCD∼, propagating along [110]. Second-order hydrogen-bonded R 2 2(8) rings are formed via interweaving infinite C 2 2(8) chains.

Bromidotris(triphenyl-phosphane)silver acetonitrile monosolvate monohydrate.

In the title compound, [AgBr(C18H15P)3]·C2H3N·H2O, the coordination of the Ag atom is close to ideal tetrahedral, with the three Ag—P bond lengths almost equal [2.5441 (10), 2.5523 (9) and 2.5647 (10) ° A] and the Ag—Br bond slightly longer [2.7242 (5) Å]. The coordination tetrahedron is slightly flattened, the Ag atom is closer to the PPP plane; the P—Ag—P angles are wider than the Br—Ag—P angles. The voids in the crystal structure are filled with ordered acetonitrile solvent molecules. The remaining electron density was interpreted as a water molecule, disordered over three alternative positions. Neither of the solvent molecules is connected by any directional specific interactions with the complex.

N-Methyl-2-thio­cytisine

The rings of the three-ring cytisine system in the title compound [systematic name: (1R,5S)-1,2,3,4,5,6-hexahydro-1,5-methano-8H-pyrido[1,2-a][1,5]diazocine-8-thione], C12H16N2S, have planar [maximum deviation 0.0170 (7) Å], half-chair and chair conformations. In the crystal structure, relatively short and directional C—H⋯π interactions and weaker secondary C—H⋯S contacts join the molecules into helical chains along the [001] direction.