Draginja Mrvoš-Sermek

Hydrogen Bonding in the 2,2'-Bipyridinium Salt of 1,2,4,5-Benzenetetracarboxylic Acid (Pyromellitic Acid)

The 2,2′-bipyridinium salt of pyromellitic acid (PMA) (1,2,4,5-benzenetetracarboxylic acid), 2,2′-bipyridinium hemi[1,2,4,5-benzenetetracarboxylate(2-)] hemi(1,2,4,5-benzenetetracarboxylic acid), C10H8N2H+.1/2[C6H2(COO)4H2O]2-.1/2[C6H2(COO)4H4], has been prepared and studied by X-ray diffraction and IR spectroscopy. 2,2′-Bipyridine acts as a proton sponge by accepting a proton from pyromellitic acid. The transfer of protons results in strong asymmetric intramolecular hydrogen bonds: H(N)⋯N 2.603 (2) A in the bipyridinium cation which has syn conformation and H(O)⋯O 2.396 (2) A in the pyromellitate anion. The N-H⋯N hydrogen bond is part of a three-centred hydrogen bond with a carbonyl group of the neutral pyromellitic acid: N—H⋯N,O with H(N)⋯O 2.805 (2) A. Each neutral PMA molecule is connected by hydrogen bonds with two cations and four anions forming a two-dimensional network with plane indices (112). The IR spectrum also suggests the presence of strong hydrogen bonds.

Synthesis, structural studies, and biological evaluation of some purine substituted 1-aminocyclopropane-1-carboxylic acids and 1-amino-1-hydroxymethylcyclopropanes

Abstract The novel purine derivatives of 1-aminocyclopropane-1-carboxylic acid (8 and 9) and 1-amino-1-hydroxymethylcyclopropane (12 and 13) with methylene spacer between the base and the cyclopropane ring were prepared by multistep synthetic route involving alkylation of adenine and 6-(N-pyrrolyl)purine with 2-hydroxymethyl-1-aminocyclopropane-1-carboxylic acid derivative 3 as a key reaction. All novel compounds were racemic. The N-9 substitution of the purine ring and the Z-configuration of the cyclopropane ring in 4–13 were deduced from their 1H and 13C NMR spectra by analyses of chemical shifts, H-H coupling constants and connectivities in two-dimensional homo- and heteronuclear correlation spectra. An unequivocal proof of the stereostructure of 1, 4 and 5 was obtained by their X-ray structure analysis. The novel compounds were evaluated on cytostatic and antiviral activities in several cell lines. The 6-(N-pyrrolyl)purine derivative of 1,2-aminocyclopropane alcohol 12 exhibited a more pronounced inhibitory activity against the proliferation of cervical carcinoma (HeLa) and human fibroblast (WI-38) cells than other types of tumor cell lines. None of the compounds showed inhibitory activities against cytomegalovirus, varicella-zoster virus or other viruses.

catena-Poly­[[(2-methyl-1,3-benzo­thia­zole-N)­mercury(II)]-di-μ-chloro]

The reaction of 2-methyl-1,3-benzothiazole (mebta) with mercury(II) chloride in methanol in a 1:1 molar ratio resulted in the formation of single crystals of the title compound, [HgCl 2 (C 8 H 7 NS)] n . The molecules exist as continuous chlorine-bridged chains in which Hg atoms lie in distorted trigonal bipyramidal environments. The equatorial positions are occupied by an N atom from the ligand [2.236 (8) A and two Cl atoms [2.428 (3) and 2.459 (3) A]. The two axial Hg-Cl contacts to two neighbouring molecules [2.874 (3) and 2.964 (3) A] are significantly shorter than the sum of the respective van der Waals radii, and form close to linear Cl-Hg-Cl sequences [177.80 (7)].

Methyl (E)-3-(5-cyano-2-fur­yl)-2-phenyl­acrylate

In the title compound, C_15H_11NO_3, the dihedral angle between the mean planes of the furan and phenyl rings is 64.7 (1)degrees. The molecules are linked into infinite chains by C— H...O and C— H...pi interactions.

Crystal structure of 9-methyl-(6-N-pyrrolyl)purine, C10H9N5

C10H9N5, monclinic, C12/c1 (No. 15), a=11.053(1)A, b=10.231(1)A, c=16.639(2)A, beta=91.009(7)o, V=1881.3A3, Z=8, Rgt(F)=0.050, wRref(F2)=0.138, T=295.

(±)-6,7-Dihydro-1,6,11-trimethyl-5H-dibenz[c,e]azepine

In the title compound, C 17 H 19 N, the central seven-membered azepine ring adopts a twisted-boat conformation. The molecule exhibits a huge deviation from planarity by rotation of the two fused ortho-methyl-substituted phenyl rings around the central C12-C14 single bond. The dihedral angle between the planes of these two rings amounts to 56.05(4)°, with a cisoid arrangement around the C12-C14 bond. Because of this non-planarity, the molecule is axially chiral.

3,4-Bis(1,3-benzothiazol-2-yl)furan

The title compound, C 18 H 10 N 2 OS 2 , was prepared and characterized on the basis of its 1 H NMR and UV spectra, and X-ray diffraction analysis. The five-membered heterocyclic rings are flat and coplanar with their fused benzene rings. The furan ring is planar, with the 2-benzothiazolyl groups rotated out of plane by 6.3 (1) and 32.7 (1)°. The S atoms of the 2-benzothiazolyl groups are positioned anti with respect to one another.