Skip to main content

Ahmet Bulut

Followers

0

Following

1

Public Views

Samsun Ondokuz Mayis University

Abolghasem Moghimi

Middle East Technical University

Hacali Necefoglu

Kafkas University

FATÜMETÜZZEHRA KÜÇÜKBAY

Canakkale Onsekiz Mart University

Muharrem Dinçer

Samsun Ondokuz Mayis University

Uploads

Papers by Ahmet Bulut

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

Acta crystallographica. Section C, Crystal structure communications, 2005

The copper(II) centre in the mononuclear title complex, [Cu(C(7)H(3)NO(4))(C(14)H(12)N(2))].3H(2)... more 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.

SWAT: hierarchical stream summarization in large networks

Proceedings 19th International Conference on Data Engineering (Cat. No.03CH37405)

The problem of statistics and aggregate maintenance over data streams has gained popularity in re... more The problem of statistics and aggregate maintenance over data streams has gained popularity in recent years especially in telecommunications network monitoring, trendrelated analysis, web-click streams, stock tickers, and other time-variant data. The amount of data generated in such applications can become too large to store, or if stored too large to scan multiple times. We consider queries over data streams that are biased towards the more recent values. We develop a technique that summarizes a dynamic stream incrementally at multiple resolutions. This approximation can be used to answer point queries, range queries, and inner product queries. Moreover, the precision of answers can be changed adaptively by a client. Later, we extend the above technique to work in a distributed setting, specifically in a large network where a central site summarizes the stream and clients ask queries. We minimize the message overhead by deciding what and where to replicate by using an adaptive replication scheme. We maintain a hierarchy of approximations that change adaptively based on the query and update rates. We show experimentally that our technique performs better than existing techniques: up to £ ¥ ¤ times better in terms of approximation quality, up to four orders of magnitude times better in response time, and up to five times better in terms of message complexity.

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

Acta crystallographica. Section C, Crystal structure communications, 2005

The asymmetric unit of the title compound, {[Cu(C4O4)(C6H6N2O)2(H2O)2].2H2O}n, consists of one py... more 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.

Structural characterization and EPR spectral studies on mononuclear copper(II) complex of saccharin with ethylnicotinate

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2009

Mononuclear copper(II) saccharinate (sac) complex containing ethylnicotinate (enc), [Cu(enc)(2)(s... more Mononuclear copper(II) saccharinate (sac) complex containing ethylnicotinate (enc), [Cu(enc)(2)(sac)(2)(H(2)O)].1.4H(2)O has been synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. It crystallizes in the tetragonal crystal systems with space group I4(1)cd and Z=8. The copper(II) ion presents a CuN(4)O distorted square pyramidal coordination. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110K), indicate the presence of the unpaired electron in the d(x)(2)-(y)(2) orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sigma and in-plane pi-bonding. Some comparisons with related structures are made and the most important features of its IR spectrum were also discussed. The cyclic voltammogram of the title complex investigated in DMF (dimet...

Bis(acesulfamato)tetraaquacobalt(II)

Acta Crystallographica Section C Crystal Structure Communications, 2004

The crystal structure of the first acesulfame-metal complex, namely tetraaquabis[6-methyl-1,2,3-o... more 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.

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

Acta Crystallographica Section C Crystal Structure Communications, 2005

The title compound, alternatively known as 3-acetoxy-2-(acetylamino)pyridinium betaine of squaric... more 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.

Picolinamidium squarate and di-p-toluidinium squarate dihydrate

Acta Crystallographica Section C Crystal Structure Communications, 2004

The crystal structure determinations of picolinamidium squarate, C 6 H 7 N 2 O + ·C 4 O 4 - , (I)... more

Synthesis, structure, spectroscopic and redox properties of complexes: Crystal and molecular structure of

Polyhedron, 2006

New bulky bisðN-3; 5-Bu t 2 phenyl-R-salicyaldiminatoÞcopperðIIÞ complexes X were synthesized and... more New bulky bisðN-3; 5-Bu t 2 phenyl-R-salicyaldiminatoÞcopperðIIÞ complexes X were synthesized and characterized by analytical, spectroscopic (IR, UV/Vis, EPR), electrochemical methods, and their chemical redox reactivity were studied. X-ray structural analysis of 1 revealed that the CuN 2 O 2 coordination core forms a distorted square-planar geometry with a cis-N 2 O 2 donor set which is not expected for analogous complexes. The UV/Vis and EPR results indicate that X complexes have a tetrahedrally distorted square-planar structure in the solid state and in solution. In the chemical oxidation of X by (NH 4) 2 Ce(NO 3) 6 along with disappearance of their EPR spectra, the appearance of new Cu(II) patterns at g = 2.169-2.189 for all X and radical signals in the cases of 5 and 6 were detected. The chemical reduction of some X complexes was accompanied by the disappearance of their EPR signals. The separation in peak potentials (DE p) for complexes X are in order 4 < 3 < 2 < 1 < 6. The electrochemical results suggested that the complex 4 has the highest electrochemical rate assuming both the Cu(II) and Cu(I) forms appear in a similar geometrical configuration, so the electron transfer does not require larger reorganization of the complex in complex 4.

mer-Diaquabis(1H-imidazole-κN3)(orotato-κ2N3,O4)nickel(II)

Acta Crystallographica Section C Crystal Structure Communications, 2004

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)(... more 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.

A capped trigonal prismatic cadmium complex with tetra- and tridentate ligands: bis(triethanolamine)-κ3N,O,O′;κ4N,O,O′,O′′-cadmium(II) squarate monohydrate

Acta Crystallographica Section C Crystal Structure Communications, 2004

In the crystal structure of the title compound, [Cd(C 6 H 15 -NO 3 ) 2 ](C 4 O 4 ).H 2 O, a supra... more

Structural, spectroscopic and voltammetric studies of bis(acetazolamido)bis(aquo)bis(nicotinamide)copper(II)

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012

Polymeric copper(II) complex, [Cu(Hacm)(2)(na)(2)(H(2)O)(2)] [H(2)acm; acetazolamide, na; nicotin... more Polymeric copper(II) complex, [Cu(Hacm)(2)(na)(2)(H(2)O)(2)] [H(2)acm; acetazolamide, na; nicotinamide] was synthesized and characterized by spectroscopic (IR; infrared spectroscopy, EPR; electron paramagnetic resonance), structural (XRD) and voltammetric structural (CV) methods. The copper(II) compound crystallizes in the triclinic space group P1¯, Z=1, with the unit-cell dimensions: a=7.672 (5)Å, b=8.681 (5)Å, c=11.938 (5)Å, α=90.807 (7)°, β=98.616 (5)° and γ=110.647 (5)°. The Cu(II) ion has a distorted octahedral coordination geometry. The crystal packing of the complex is stabilized by intermolecular O-H…O and N-H…O hydrogen bonds. The powder EPR spectrum of copper(II) complex have indicate that the paramagnetic center is in a tetragonal symmetry with the Cu(2+) ion having a distorted octahedral geometry. The vibrational investigation has been carried out on the basis of some characteristic IR bands of acetazolamide and nicotinamide molecules.

Syntheses, IR spectra, thermal properties and crystal structures of novel cyano-bridged polymeric complexes of zincII and cadmiumII with tetracyanoplatinateII

Polyhedron, 2008

Cyano-bridged complexes, which have been of interest since the XVIIth century, have been shown to... more

Synthesis, crystal structure, EPR and electrochemical studies of copper(II) dipicolinate complex with 2,2′-dipyridylamine ligand

Journal of Physics and Chemistry of Solids, 2007

The (2,2 0-dipyridylamine)(pyridine-2,6-dicarboxylato)copper(II) trihydrate complex was synthesiz... more The (2,2 0-dipyridylamine)(pyridine-2,6-dicarboxylato)copper(II) trihydrate complex was synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. The copper(II) center is surrounded by one bidentate 2,2 0-dipyridylamine (dpa) and one tridentate dipicolinate (dpc) ligand, and exhibits a distorted square-pyramidal geometry. The crystal packing involves both hydrogen-bonding and p-p interactions. The solvent water molecules link monomers to one another through hydrogen-bonding interactions, forming ladder-type chains in the ab plane. p-p interactions also occur between the dpa rings of neighboring molecules and are responsible for interchain packing. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110 K), indicate the presence of the unpaired electron in the d x 2 Ày 2 orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sand p-bonding. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centered electroactivity in the potential range 71.25 V versus Ag/AgCl reference electrode.

Synthesis, crystal structure, Cu2+ doped EPR, thermal and voltammetric studies of [Ni(isonicotinamide)2(H2O)4]·(sac)2 single crystal

Journal of Physics and Chemistry of Solids, 2007

The single crystal of [Ni(ina) 2 (H 2 O) 4 ] Á (sac) 2 , (NINS), (ina is isonicotinamide and sac ... more The single crystal of [Ni(ina) 2 (H 2 O) 4 ] Á (sac) 2 , (NINS), (ina is isonicotinamide and sac is saccharinate) complex has been prepared and its structural, spectroscopic and thermal properties have been determined. The title complex crystallizes in monoclinic system with space group P2 1 /c, Z ¼ 2. The octahedral Ni(II) ion, which rides on a crystallographic centre of symmetry, is coordinated by two monodentate ina ligands through the ring nitrogen and four aqua ligands to form discrete [Ni(ina) 2 (H 2 O) 4 ] unit, which captures two saccharinate ions in up and down positions, each through intermolecular hydrogen bands. The magnetic environment of copper(II) doped NINS crystal has also been identified by electron paramagnetic resonance (EPR) technique. The g and A values of Cu 2+ doped NINS single crystal were calculated from the EPR spectra recorded in three mutually perpendicular planes. These values indicated that the paramagnetic centre has a rhombic symmetry with the Cu 2+ ion having distorted octahedral environment. The complex exhibits only metal centred electroactivity in the potential range of À2.00, 1.25 V versus Ag/AgCl reference electrode.

Synthesis, crystal structure, Cu2+ doped EPR and voltammetric studies of bis[N-(2-hydroxyethyl)ethylenediamine]zinc(II) squarate monohydrate

Journal of Physics and Chemistry of Solids, 2007

Crystal structure of [Zn(hydet-en) 2 ] Á C 4 O 4 Á H 2 O (ZHES) (hydet-en is N-(2-hydroxyethyl)et... more Crystal structure of [Zn(hydet-en) 2 ] Á C 4 O 4 Á H 2 O (ZHES) (hydet-en is N-(2-hydroxyethyl)ethylenediamine) complex has been synthesized and characterized by analytical, spectroscopic (IR, UV/Vis) and voltammetric techniques. After doping Cu 2+ ion, its magnetic environment has been identified by electron paramagnetic resonance (EPR) technique. The title complex crystalizes in monoclinic system with space group P2 1 /c and with Z ¼ 4. Each hydet-en ligand acts as a tridentate ligand through the two N atoms and the hydroxyl O atom, resulting in a six coordinate Zn(II) ion. The EPR spectra were recorded in three perpendicular planes of Cu 2+ doped ZHES single crystal. The calculated g and A values indicated that the paramagnetic center is rhombic symmetry with the Cu 2+ ion having distorted octahedral environment. The molecular orbital bond coefficients of the Cu(II) ion in d 9 state is also calculated by using EPR and optical absorption parameters. The dianion SQ 2À is oxidized reversibly in two consecutive steps to the corresponding radical monoanion and neutral form.

X-ray crystal structure and Cu2+ doped EPR studies of tetraaquabis(isonicotinamide)zinc(II) and -cobalt(II) disaccharinate 1.5 hydrate single crystals

Journal of Molecular Structure, 2006

Crystal structure of [M(ina) 2 (H 2 O) 4 ](sac) 2 1.5H 2 O (MZZn 2C (1), Co 2C (2); ina for isoni... more Crystal structure of [M(ina) 2 (H 2 O) 4 ](sac) 2 1.5H 2 O (MZZn 2C (1), Co 2C (2); ina for isonicotinamide or pyridine-4-carboxyamide and sac for saccharine) complexes have been determined by X-ray diffraction analyses and their magnetic environments have been identified by electron paramagnetic resonance (EPR). The isostructural complexes of 1 and 2 both crystallize in the monoclinic system. In both complexes, the octahedral metal atom, which rides on a crystallographic center of symmetry, is coordinated by two monodentate isonicotinamide ligands through the ring nitrogens and four aqua ligands to form a discrete [M(ina) 2 (H 2 O) 4 ] 2C unit, which captures up and down two saccharinate ions, each through intermolecular hydrogen bonds. The EPR analyses of Cu 2C doped 1 and 2 single crystals indicate that there is one magnetic centre with two magnetically inequivalent sites for the paramagnetic Cu 2C ion in 1, whereas two magnetic centres with each having two magnetically inequivalent sites are observed in 2. The spin Hamiltonian parameters together with the molecular orbital coefficients for each crystal of 1 and 2 were derived from the EPR spectra and these were used to construct the ground state wave function of Cu 2C ion in each crystal.

Synthesis, structural and electrochemical properties of LiNi0.79Co0.1Mn0.1Cr0.01O2 via fast co-precipitation

Journal of Alloys and Compounds, 2010

A novel layered material of LiNi0.79Co0.1Mn0.1Cr0.01O2 is synthesized by fast co-precipitation me... more A novel layered material of LiNi0.79Co0.1Mn0.1Cr0.01O2 is synthesized by fast co-precipitation method. Transmission electron microscope (TEM) and energy dispersive analysis of X-rays (EDAX) exhibit that Cr is successfully incorporating into LiNi0.8Co0.1Mn0.1O2. X-ray diffraction (XRD) and Rietveld refinement show that cation mixing is reduced by Cr substitution. Cyclic voltammerty (CV) indicates that the Cr substitution could decrease Jahn–Teller distortion, and improve

Structural, spectroscopic, magnetic and electrical characterization of Ca-doped polycrystalline bismuth ferrite, Bi(1-x)Ca(x)FeO(3-x/2) (x ≤ 0.1)

Journal of physics. Condensed matter : an Institute of Physics journal, 2012

The crystal structure and physical properties of multiferroic polycrystalline Ca(2+)-doped BiFeO(... more The crystal structure and physical properties of multiferroic polycrystalline Ca(2+)-doped BiFeO(3) samples have been investigated. The present experimental investigation suggests that Bi(1-x)Ca(x)FeO(3-x/2) (x ≤ 0.1) can be considered as a solid solution between BiFeO(3) and CaFeO(2.5). The oxidation state of Fe in these materials is + 3 and charge balance occurs through the creation of oxygen vacancies. For each composition, two structural phase transitions are revealed as anomalies in the variable-temperature in situ x-ray diffraction data which is consistent with the well-established high-temperature structural transformation in pure BiFeO(3). All compositions studied show antiferromagnetic behaviour along with a ferromagnetic component that increases with Ca(2+) doping. The resistivities of the Bi(1-x)Ca(x)FeO(3-x/2) samples at room temperature are of the order of 10(9) Ω cm and decrease with increasing Ca(2+) content. Arrhenius plots of the resistivity show two distinct linear...

Stardust: Fast stream indexing using incremental wavelet approximations

Proceedings of the 29th VLDB Conference, 2003

Monitoring thousands of data streams onlineposes a challenge in many data-centric applicationssuc... more Monitoring thousands of data streams onlineposes a challenge in many data-centric applicationssuch as telecommunications networks, traffic management, trend-related analysis, web-click streams, intrusion detection, andsensor networks. Stream mining techniquesemployed in these applications have to be efficientin terms of space and per-item processingtime, while providing a high quality of answersto queries such as finding similar patterns, monitoring specified conditions, detectingcorrelations, and computing ...

Tris(1,10-phenanthroline)nickel(II) squarate octahydrate

Acta Crystallographica Section E Structure Reports Online, 2005

distorted octahedral coordination geometry composed of six N atoms from the chelating phen ligand... more distorted octahedral coordination geometry composed of six N atoms from the chelating phen ligands. The Ni1-N bond distances range from 2.0814 (16) to 2.0954 (17) Å , and are in agreement with those observed in other [Ni(phen) 3 ] 2+ complexes (Suescun et al., 1999; Skoulika et al., 1995). The angles subtended at the Ni atom by the phen ligands are 80.01 (7), 79.86 (7) and 79.77 (6) , which are in agreement with those previously reported for other phen-containing Ni II complexes (Cherni et al., 1999; Lin et al., 2003). All the N-Ni-N bond angles deviate significantly from the ideal values of 90 or 180 because of the constrained geometry of the phen ring systems (Table 1). The molecular packing in (I) is controlled by intermolecular hydrogen bonding interactions (Fig. 2). The eight solvent water molecules link the squarate dianions to each other through hydrogen-bonding interactions (see Table 2 for details). The complex cation and squarate dianion are also linked to each other via C-HÁ Á ÁO hydrogen bonding. These interactions are responsible for constructing a three-dimensional network in the crystal structure of (I). metal-organic papers Acta Cryst. (2005). E61, m947-m949 Uçar et al. [Ni(C 12 H 8 N 2) 3 ](C 4 O 4)Á8H 2 O m949

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

Acta crystallographica. Section C, Crystal structure communications, 2005

The copper(II) centre in the mononuclear title complex, [Cu(C(7)H(3)NO(4))(C(14)H(12)N(2))].3H(2)... more 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.

SWAT: hierarchical stream summarization in large networks

Proceedings 19th International Conference on Data Engineering (Cat. No.03CH37405)

The problem of statistics and aggregate maintenance over data streams has gained popularity in re... more The problem of statistics and aggregate maintenance over data streams has gained popularity in recent years especially in telecommunications network monitoring, trendrelated analysis, web-click streams, stock tickers, and other time-variant data. The amount of data generated in such applications can become too large to store, or if stored too large to scan multiple times. We consider queries over data streams that are biased towards the more recent values. We develop a technique that summarizes a dynamic stream incrementally at multiple resolutions. This approximation can be used to answer point queries, range queries, and inner product queries. Moreover, the precision of answers can be changed adaptively by a client. Later, we extend the above technique to work in a distributed setting, specifically in a large network where a central site summarizes the stream and clients ask queries. We minimize the message overhead by deciding what and where to replicate by using an adaptive replication scheme. We maintain a hierarchy of approximations that change adaptively based on the query and update rates. We show experimentally that our technique performs better than existing techniques: up to £ ¥ ¤ times better in terms of approximation quality, up to four orders of magnitude times better in response time, and up to five times better in terms of message complexity.

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

Acta crystallographica. Section C, Crystal structure communications, 2005

The asymmetric unit of the title compound, {[Cu(C4O4)(C6H6N2O)2(H2O)2].2H2O}n, consists of one py... more 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.

Structural characterization and EPR spectral studies on mononuclear copper(II) complex of saccharin with ethylnicotinate

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy, 2009

Mononuclear copper(II) saccharinate (sac) complex containing ethylnicotinate (enc), [Cu(enc)(2)(s... more Mononuclear copper(II) saccharinate (sac) complex containing ethylnicotinate (enc), [Cu(enc)(2)(sac)(2)(H(2)O)].1.4H(2)O has been synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. It crystallizes in the tetragonal crystal systems with space group I4(1)cd and Z=8. The copper(II) ion presents a CuN(4)O distorted square pyramidal coordination. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110K), indicate the presence of the unpaired electron in the d(x)(2)-(y)(2) orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sigma and in-plane pi-bonding. Some comparisons with related structures are made and the most important features of its IR spectrum were also discussed. The cyclic voltammogram of the title complex investigated in DMF (dimet...

Bis(acesulfamato)tetraaquacobalt(II)

Acta Crystallographica Section C Crystal Structure Communications, 2004

The crystal structure of the first acesulfame-metal complex, namely tetraaquabis[6-methyl-1,2,3-o... more 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.

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

Acta Crystallographica Section C Crystal Structure Communications, 2005

The title compound, alternatively known as 3-acetoxy-2-(acetylamino)pyridinium betaine of squaric... more 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.

Picolinamidium squarate and di-p-toluidinium squarate dihydrate

Acta Crystallographica Section C Crystal Structure Communications, 2004

The crystal structure determinations of picolinamidium squarate, C 6 H 7 N 2 O + ·C 4 O 4 - , (I)... more

Synthesis, structure, spectroscopic and redox properties of complexes: Crystal and molecular structure of

Polyhedron, 2006

New bulky bisðN-3; 5-Bu t 2 phenyl-R-salicyaldiminatoÞcopperðIIÞ complexes X were synthesized and... more New bulky bisðN-3; 5-Bu t 2 phenyl-R-salicyaldiminatoÞcopperðIIÞ complexes X were synthesized and characterized by analytical, spectroscopic (IR, UV/Vis, EPR), electrochemical methods, and their chemical redox reactivity were studied. X-ray structural analysis of 1 revealed that the CuN 2 O 2 coordination core forms a distorted square-planar geometry with a cis-N 2 O 2 donor set which is not expected for analogous complexes. The UV/Vis and EPR results indicate that X complexes have a tetrahedrally distorted square-planar structure in the solid state and in solution. In the chemical oxidation of X by (NH 4) 2 Ce(NO 3) 6 along with disappearance of their EPR spectra, the appearance of new Cu(II) patterns at g = 2.169-2.189 for all X and radical signals in the cases of 5 and 6 were detected. The chemical reduction of some X complexes was accompanied by the disappearance of their EPR signals. The separation in peak potentials (DE p) for complexes X are in order 4 < 3 < 2 < 1 < 6. The electrochemical results suggested that the complex 4 has the highest electrochemical rate assuming both the Cu(II) and Cu(I) forms appear in a similar geometrical configuration, so the electron transfer does not require larger reorganization of the complex in complex 4.

mer-Diaquabis(1H-imidazole-κN3)(orotato-κ2N3,O4)nickel(II)

Acta Crystallographica Section C Crystal Structure Communications, 2004

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)(... more 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.

A capped trigonal prismatic cadmium complex with tetra- and tridentate ligands: bis(triethanolamine)-κ3N,O,O′;κ4N,O,O′,O′′-cadmium(II) squarate monohydrate

Acta Crystallographica Section C Crystal Structure Communications, 2004

In the crystal structure of the title compound, [Cd(C 6 H 15 -NO 3 ) 2 ](C 4 O 4 ).H 2 O, a supra... more

Structural, spectroscopic and voltammetric studies of bis(acetazolamido)bis(aquo)bis(nicotinamide)copper(II)

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2012

Polymeric copper(II) complex, [Cu(Hacm)(2)(na)(2)(H(2)O)(2)] [H(2)acm; acetazolamide, na; nicotin... more Polymeric copper(II) complex, [Cu(Hacm)(2)(na)(2)(H(2)O)(2)] [H(2)acm; acetazolamide, na; nicotinamide] was synthesized and characterized by spectroscopic (IR; infrared spectroscopy, EPR; electron paramagnetic resonance), structural (XRD) and voltammetric structural (CV) methods. The copper(II) compound crystallizes in the triclinic space group P1¯, Z=1, with the unit-cell dimensions: a=7.672 (5)Å, b=8.681 (5)Å, c=11.938 (5)Å, α=90.807 (7)°, β=98.616 (5)° and γ=110.647 (5)°. The Cu(II) ion has a distorted octahedral coordination geometry. The crystal packing of the complex is stabilized by intermolecular O-H…O and N-H…O hydrogen bonds. The powder EPR spectrum of copper(II) complex have indicate that the paramagnetic center is in a tetragonal symmetry with the Cu(2+) ion having a distorted octahedral geometry. The vibrational investigation has been carried out on the basis of some characteristic IR bands of acetazolamide and nicotinamide molecules.

Syntheses, IR spectra, thermal properties and crystal structures of novel cyano-bridged polymeric complexes of zincII and cadmiumII with tetracyanoplatinateII

Polyhedron, 2008

Cyano-bridged complexes, which have been of interest since the XVIIth century, have been shown to... more

Synthesis, crystal structure, EPR and electrochemical studies of copper(II) dipicolinate complex with 2,2′-dipyridylamine ligand

Journal of Physics and Chemistry of Solids, 2007

The (2,2 0-dipyridylamine)(pyridine-2,6-dicarboxylato)copper(II) trihydrate complex was synthesiz... more The (2,2 0-dipyridylamine)(pyridine-2,6-dicarboxylato)copper(II) trihydrate complex was synthesized and characterized by spectroscopic (IR, UV-vis, EPR), X-ray diffraction technique and electrochemical methods. The copper(II) center is surrounded by one bidentate 2,2 0-dipyridylamine (dpa) and one tridentate dipicolinate (dpc) ligand, and exhibits a distorted square-pyramidal geometry. The crystal packing involves both hydrogen-bonding and p-p interactions. The solvent water molecules link monomers to one another through hydrogen-bonding interactions, forming ladder-type chains in the ab plane. p-p interactions also occur between the dpa rings of neighboring molecules and are responsible for interchain packing. Based on EPR and optical absorption studies, spin-Hamiltonian and bonding parameters have been calculated. The g-values, calculated for title complex in polycrystalline state at 298 K and in frozen DMF (110 K), indicate the presence of the unpaired electron in the d x 2 Ày 2 orbital. The evaluated metal-ligand bonding parameters showed strong in-plane sand p-bonding. The cyclic voltammogram of the title complex investigated in DMF (dimethylformamide) solution exhibits only metal centered electroactivity in the potential range 71.25 V versus Ag/AgCl reference electrode.

Synthesis, crystal structure, Cu2+ doped EPR, thermal and voltammetric studies of [Ni(isonicotinamide)2(H2O)4]·(sac)2 single crystal

Journal of Physics and Chemistry of Solids, 2007

The single crystal of [Ni(ina) 2 (H 2 O) 4 ] Á (sac) 2 , (NINS), (ina is isonicotinamide and sac ... more The single crystal of [Ni(ina) 2 (H 2 O) 4 ] Á (sac) 2 , (NINS), (ina is isonicotinamide and sac is saccharinate) complex has been prepared and its structural, spectroscopic and thermal properties have been determined. The title complex crystallizes in monoclinic system with space group P2 1 /c, Z ¼ 2. The octahedral Ni(II) ion, which rides on a crystallographic centre of symmetry, is coordinated by two monodentate ina ligands through the ring nitrogen and four aqua ligands to form discrete [Ni(ina) 2 (H 2 O) 4 ] unit, which captures two saccharinate ions in up and down positions, each through intermolecular hydrogen bands. The magnetic environment of copper(II) doped NINS crystal has also been identified by electron paramagnetic resonance (EPR) technique. The g and A values of Cu 2+ doped NINS single crystal were calculated from the EPR spectra recorded in three mutually perpendicular planes. These values indicated that the paramagnetic centre has a rhombic symmetry with the Cu 2+ ion having distorted octahedral environment. The complex exhibits only metal centred electroactivity in the potential range of À2.00, 1.25 V versus Ag/AgCl reference electrode.

Synthesis, crystal structure, Cu2+ doped EPR and voltammetric studies of bis[N-(2-hydroxyethyl)ethylenediamine]zinc(II) squarate monohydrate

Journal of Physics and Chemistry of Solids, 2007

Crystal structure of [Zn(hydet-en) 2 ] Á C 4 O 4 Á H 2 O (ZHES) (hydet-en is N-(2-hydroxyethyl)et... more Crystal structure of [Zn(hydet-en) 2 ] Á C 4 O 4 Á H 2 O (ZHES) (hydet-en is N-(2-hydroxyethyl)ethylenediamine) complex has been synthesized and characterized by analytical, spectroscopic (IR, UV/Vis) and voltammetric techniques. After doping Cu 2+ ion, its magnetic environment has been identified by electron paramagnetic resonance (EPR) technique. The title complex crystalizes in monoclinic system with space group P2 1 /c and with Z ¼ 4. Each hydet-en ligand acts as a tridentate ligand through the two N atoms and the hydroxyl O atom, resulting in a six coordinate Zn(II) ion. The EPR spectra were recorded in three perpendicular planes of Cu 2+ doped ZHES single crystal. The calculated g and A values indicated that the paramagnetic center is rhombic symmetry with the Cu 2+ ion having distorted octahedral environment. The molecular orbital bond coefficients of the Cu(II) ion in d 9 state is also calculated by using EPR and optical absorption parameters. The dianion SQ 2À is oxidized reversibly in two consecutive steps to the corresponding radical monoanion and neutral form.

X-ray crystal structure and Cu2+ doped EPR studies of tetraaquabis(isonicotinamide)zinc(II) and -cobalt(II) disaccharinate 1.5 hydrate single crystals

Journal of Molecular Structure, 2006

Crystal structure of [M(ina) 2 (H 2 O) 4 ](sac) 2 1.5H 2 O (MZZn 2C (1), Co 2C (2); ina for isoni... more Crystal structure of [M(ina) 2 (H 2 O) 4 ](sac) 2 1.5H 2 O (MZZn 2C (1), Co 2C (2); ina for isonicotinamide or pyridine-4-carboxyamide and sac for saccharine) complexes have been determined by X-ray diffraction analyses and their magnetic environments have been identified by electron paramagnetic resonance (EPR). The isostructural complexes of 1 and 2 both crystallize in the monoclinic system. In both complexes, the octahedral metal atom, which rides on a crystallographic center of symmetry, is coordinated by two monodentate isonicotinamide ligands through the ring nitrogens and four aqua ligands to form a discrete [M(ina) 2 (H 2 O) 4 ] 2C unit, which captures up and down two saccharinate ions, each through intermolecular hydrogen bonds. The EPR analyses of Cu 2C doped 1 and 2 single crystals indicate that there is one magnetic centre with two magnetically inequivalent sites for the paramagnetic Cu 2C ion in 1, whereas two magnetic centres with each having two magnetically inequivalent sites are observed in 2. The spin Hamiltonian parameters together with the molecular orbital coefficients for each crystal of 1 and 2 were derived from the EPR spectra and these were used to construct the ground state wave function of Cu 2C ion in each crystal.

Synthesis, structural and electrochemical properties of LiNi0.79Co0.1Mn0.1Cr0.01O2 via fast co-precipitation

Journal of Alloys and Compounds, 2010

A novel layered material of LiNi0.79Co0.1Mn0.1Cr0.01O2 is synthesized by fast co-precipitation me... more A novel layered material of LiNi0.79Co0.1Mn0.1Cr0.01O2 is synthesized by fast co-precipitation method. Transmission electron microscope (TEM) and energy dispersive analysis of X-rays (EDAX) exhibit that Cr is successfully incorporating into LiNi0.8Co0.1Mn0.1O2. X-ray diffraction (XRD) and Rietveld refinement show that cation mixing is reduced by Cr substitution. Cyclic voltammerty (CV) indicates that the Cr substitution could decrease Jahn–Teller distortion, and improve

Structural, spectroscopic, magnetic and electrical characterization of Ca-doped polycrystalline bismuth ferrite, Bi(1-x)Ca(x)FeO(3-x/2) (x ≤ 0.1)

Journal of physics. Condensed matter : an Institute of Physics journal, 2012

The crystal structure and physical properties of multiferroic polycrystalline Ca(2+)-doped BiFeO(... more The crystal structure and physical properties of multiferroic polycrystalline Ca(2+)-doped BiFeO(3) samples have been investigated. The present experimental investigation suggests that Bi(1-x)Ca(x)FeO(3-x/2) (x ≤ 0.1) can be considered as a solid solution between BiFeO(3) and CaFeO(2.5). The oxidation state of Fe in these materials is + 3 and charge balance occurs through the creation of oxygen vacancies. For each composition, two structural phase transitions are revealed as anomalies in the variable-temperature in situ x-ray diffraction data which is consistent with the well-established high-temperature structural transformation in pure BiFeO(3). All compositions studied show antiferromagnetic behaviour along with a ferromagnetic component that increases with Ca(2+) doping. The resistivities of the Bi(1-x)Ca(x)FeO(3-x/2) samples at room temperature are of the order of 10(9) Ω cm and decrease with increasing Ca(2+) content. Arrhenius plots of the resistivity show two distinct linear...

Stardust: Fast stream indexing using incremental wavelet approximations

Proceedings of the 29th VLDB Conference, 2003

Monitoring thousands of data streams onlineposes a challenge in many data-centric applicationssuc... more Monitoring thousands of data streams onlineposes a challenge in many data-centric applicationssuch as telecommunications networks, traffic management, trend-related analysis, web-click streams, intrusion detection, andsensor networks. Stream mining techniquesemployed in these applications have to be efficientin terms of space and per-item processingtime, while providing a high quality of answersto queries such as finding similar patterns, monitoring specified conditions, detectingcorrelations, and computing ...

Tris(1,10-phenanthroline)nickel(II) squarate octahydrate

Acta Crystallographica Section E Structure Reports Online, 2005

distorted octahedral coordination geometry composed of six N atoms from the chelating phen ligand... more distorted octahedral coordination geometry composed of six N atoms from the chelating phen ligands. The Ni1-N bond distances range from 2.0814 (16) to 2.0954 (17) Å , and are in agreement with those observed in other [Ni(phen) 3 ] 2+ complexes (Suescun et al., 1999; Skoulika et al., 1995). The angles subtended at the Ni atom by the phen ligands are 80.01 (7), 79.86 (7) and 79.77 (6) , which are in agreement with those previously reported for other phen-containing Ni II complexes (Cherni et al., 1999; Lin et al., 2003). All the N-Ni-N bond angles deviate significantly from the ideal values of 90 or 180 because of the constrained geometry of the phen ring systems (Table 1). The molecular packing in (I) is controlled by intermolecular hydrogen bonding interactions (Fig. 2). The eight solvent water molecules link the squarate dianions to each other through hydrogen-bonding interactions (see Table 2 for details). The complex cation and squarate dianion are also linked to each other via C-HÁ Á ÁO hydrogen bonding. These interactions are responsible for constructing a three-dimensional network in the crystal structure of (I). metal-organic papers Acta Cryst. (2005). E61, m947-m949 Uçar et al. [Ni(C 12 H 8 N 2) 3 ](C 4 O 4)Á8H 2 O m949