Biomedical subjects

Ahmet Bulut

Publications and source records attributed to Ahmet Bulut.

15 recordsLinked to original sources

PubMed2005

Proton sharing in bis(4-carbamoylpyridinium) squarate.

Reaction in aqueous solution of nickel(II) squarate with isonicotinamide yielded well formed yellow crystals of the title compound, 2C6H6N2O+.C4O4(2-), as a side product. The squarate dianion is bisected by a crystallographic twofold rotation axis, which passes through the centres of two opposite bonds of the ring. Crystal structure analysis reveals that, far from forming discrete ionic species, it is likely that there is a large degree of proton sharing between the anion and cation, with the H atom lying almost symmetrically between the donor and acceptor sites, as evidenced by the long N-H and short H...O distances [1.15 (3) and 1.39 (3) angstroms, respectively]. Other hydrogen bonding is more conventional, and there are weaker C-H...O interactions contributing additional stability to the structure.

Journal Article↗

PubMed2005

(2,9-dimethyl-1,10-phenanthroline-kappa2N,N')(pyridine-2,6-dicarboxylato-kappa3O2,N,O6)copper(II) trihydrate.

The copper(II) centre in the mononuclear title complex, [Cu(C(7)H(3)NO(4))(C(14)H(12)N(2))].3H(2)O, is surrounded by one bidentate 2,9-dimethyl-1,10-phenanthroline (dmphen) ligand and one tridentate pyridine-2,6-dicarboxylate ligand, and exhibits a distorted square-pyramidal geometry. The crystal packing involves both hydrogen-bonding and pi-pi interactions. The solvent water molecules link monomers to one another through hydrogen-bonding interactions, forming ladder-like chains in the bc plane. Face-to-face and slipped pi-pi interactions also occur between dmphen rings of neighboring molecules and are responsible for interchain packing.

Journal Article↗

PubMed2005

A bicapped trigonal-prismatic lead complex: catena-poly[[[aquabis(1,10-phenanthroline-kappa2N,N')lead(II)]-mu-squarato-kappaO1:kappa2O2,O3] dihydrate].

The asymmetric unit of the title compound, {[Pb(C4O4)(C12H8N2)2(H2O)].2H2O}n, contains one squarate dianion, two phenanthroline (phen) ligands and one aqua ligand all coordinated to Pb, and two solvent water molecules. The eight-coordinate Pb metal ion displays a distorted bicapped trigonal-prismatic coordination environment, defined by three squarate O atoms, four N atoms from two chelating phen ligands and one O atom from the coordinated water molecule. The crystal structure contains chains of squarate-1,2,3-bridged PbII ions running in the [010] direction. These polymeric chains are linked to one another via offset face-to-face pi-pi interactions between the phen ligands, which lead to a two-dimensional network extending along the (001) plane. The crystal structure is also stabilized by O-H...O intermolecular hydrogen-bond interactions, forming a three-dimensional network.

Journal Article↗

PubMed2005

Bis(2,9-dimethyl-1,10-phenanthroline-kappa(2)N,N')copper(I) hydrogen squarate hemihydrate.

In the crystal structure of the synthetically prepared title compound, [Cu(C14H12N2)2](C4HO4) x 0.5H2O or [Cu(dmphen)2](HSq) x 0.5H2O (dmphen is 2,9-dimethyl-1,10-phenanthroline or neocuproine and HSq is hydrogen squarate), the Cu(I) centre has distorted tetrahedral coordination geometry comprised of four N atoms from two bidentate dmphen ligands. The squarate monoanions form a ten-membered dimer, graph set R(2)(2)(10), linked by two strong intermolecular O-H...O hydrogen bonds. These squarate dimers are linked into chains that propagate along the [100] direction. An extensive three-dimensional network of C-H...O hydrogen bonds and pi-pi interactions is responsible for stabilization of the crystal structure.

Journal Article↗

PubMed2005

Bis(acesulfamato-kappa2N3,O4)bis(2-aminopyrimidine-kappaN1)copper(II).

In the crystal structure of the title compound, bis(2-aminopyrimidine-kappaN1)bis[6-methyl-1,2,3-oxathiazin-4(3H)-one 2,2-dioxide(1-)-kappa2N3,O4]copper(II), [Cu(C4H4NO4S)2(C4H5N3)2], the first mixed-ligand complex of acesulfame, the CuII centre resides on a centre of symmetry and has an octahedral geometry that is distorted both by the presence of four-membered chelate rings and by the Jahn-Teller effect. The equatorial plane is formed by the N atoms of two aminopyrimidine (ampym) ligands and by the weakly basic carbonyl O atoms of the acesulfamate ligands, while the more basic deprotonated N atoms of these ligands are in the elongated axial positions with a strong misdirected valence. The crystal is stabilized by pyrimidine ring stacking and by intermolecular hydrogen bonding involving the NH2 moiety of the ampym ligand and the carbonyl O atom of the acesulfamate moiety.

Journal Article↗

PubMed2005

catena-Poly[[[diaquabis(pyridine-4-carboxamide-kappaN)copper(II)]-mu2-squarato-kappaO1:O3] dihydrate].

The asymmetric unit of the title compound, {[Cu(C4O4)(C6H6N2O)2(H2O)2].2H2O}n, consists of one pyridine-4-carboxamide (isonicotinamide or ina) ligand, one-half of a squarate dianion, a coordinated aqua ligand and a solvent water molecule. Both the CuII and the squarate ions are located on inversion centers. The CuII ions are octahedrally surrounded by four O atoms of two water molecules and two squarate anions, and by two N atoms of the isonicotinamide ligands. The crystal structure contains chains of squarate-1,3-bridged CuII ions. These chains are held together by N-H...O and O-H...O intermolecular hydrogen-bond interactions, forming an extensive three-dimensional network.

Journal Article↗

PubMed2005

3-Acetoxy-2-(acetylamino)pyridinium-1-squarate.

The title compound, alternatively known as 3-acetoxy-2-(acetylamino)pyridinium betaine of squaric acid, C13H10N2O6, has been synthesized. The bond distances within the squarate ring indicate two possible resonance structures. The mean planes of the pyridinium and squarate systems are inclined at an angle of 24.0 (2) degrees with respect to one another due to a strong intramolecular hydrogen-bonding interaction between the amide NH group and a squarate O atom. In the extended structure, there are additional weak pi-pi and pi-ring interactions, which also stabilize the crystal structure.

Journal Article↗

PubMed2004

Bis(acesulfamato)tetraaquacobalt(II).

The crystal structure of the first acesulfame-metal complex, namely tetraaquabis[6-methyl-1,2,3-oxathiazin-4(3H)-onato 2,2-dioxide-kappaN]cobalt(II), [Co(C4H4NO4S)2(H2O)4], is reported. The Co(II) ion resides on a twofold axis and is coordinated by four aqua ligands defining the basal plane and by two monodentate acesulfamate ligands, via their ring N atoms, in the axial positions. Two intra- and three intermolecular hydrogen-bonding interactions stabilize the crystal structure and form an infinite three-dimensional lattice.

Cobalt↗

PubMed2004

mer-Diaquabis(1H-imidazole-kappaN3)(orotato-kappa2N3,O4nickel(II).

The title mononuclear complex, [Ni(C(5)H(2)N(2)O(4))(C(3)H(4)N(2))(2)(H(2)O)(2)] or [Ni(HOr)(im)(2)(H(2)O)(2)] (im is imidazole and H(3)Or is orotic acid, or 2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid), has been synthesized and the crystal structure determination is reported. The Ni(II) ion in the complex has a distorted octahedral coordination geometry comprised of one deprotonated pyrimidine N atom and the adjacent carboxylate O atom of the orotate ligand, two tertiary imidazole N atoms and two aqua ligands. An extensive three-dimensional network of OW-H...O and N-H...O hydrogen bonds, and pi-pi and pi-ring interactions are responsible for crystal stabilization.

Journal Article↗

PubMed2004