Ahmet Karadağ

Preparations, IR spectra and crystal structures of cyano-bridged bimetallic complexes of zinc(II) and cadmium(II) with tetracyanopalladate(II)

The novel heteronuclear compounds [Zn(hydet-en)2Pd(CN)4] (1) and [Cd(hydet-en)2Pd(CN)4] (2) {hydet-en: N-(2-hydroxyethyl-ethylenediamine)} have been synthesized and characterized by elemental analyses and IR spectra. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Structural analysis shows that both compounds have shown a polymeric chain, in which the Zn(II)/Pd(II) and Cd(II)/Pd(II) centres are linked by two CN groups. Both zinc and cadmium atoms are six coordinate with two trans cyanide–nitrogen and four hydet-en N atoms in a distorted octahedron arrangement; the palladium atoms in 1 and 2 are four coordinate with four cyanide-C atoms in a square planar arrangement. The chains in both compounds are connected through weak interchain hydrogen bonds, N–H ··· O, N–H ··· N and O–H ··· N, thereby forming a three-dimensional network.

Cyano-complexes and salts with tetracyanonickellateII and N,N-bis(2-hydroxyethyl)-ethylenediamine: synthesis, IR spectra, magnetic properties, thermal analyses, and crystal structures

Four cyano complexes, [Ni(N-bishydeten)Ni(CN)4] n (c1), [Cu(N-bishydeten)2][Ni(CN)4] (c2), [Zn2(N-bishydeten)2Ni(CN)4] n (c3), and [Cd(N-bishydeten)2][Ni(CN)4] (c4), have been synthesized and characterized by FT-IR, elemental, and thermal analyses. The structures of c2 and c4 were determined by single-crystal X-ray diffraction studies; both structures contain isolated cations and anions. The c2 consists of [Cu(N-bishydeten)2]2+ with octahedrally coordinated CuII and diamagnetic [Ni(CN)4]2–, but c4 consists of [Cd(N-bishydeten)2]2+, in which CdII is eight coordinate with two tetradentate N-bishydeten and diamagnetic [Ni(CN)4]2–. The value of the shape measure S (o) indicates that the coordination geometry around CdII lies along D 2d [dodecahedron; (dd)], C 2v [bicapped trigonal prism; (btp)], and D 4d [square antiprism; (sap)] but close to D 2d and D 4d. Variable temperature magnetic susceptibility measurements of c1 and c2 show the presence of little antiferromagnetic interaction below 20 K. Thermal analyses reveal that first neutral N-bishydeten and then cyano ligands were liberated from the complexes.

Synthesis and characterization of two novel dicyanidoargentate(I) complexes containing N-(2-hydroxyethyl)ethylenediamine exhibiting significant biological activity

Two novel cyanido-bridged bimetallic polymeric complexes, [Ni(hydeten)2Ag(CN)2] [Ag(CN)2]·H2O (C1) and [Cd2(hydeten)2Ag4(CN)8]·H2O (C2) (hydeten: N-(2-hydroxyethyl)ethylenediamine) were synthesized and characterized by elemental, FT-IR, X-ray (C2), thermal and variable temperature magnetic measurement (C1) techniques. Their anticancer, antibacterial and antifungal effects were also investigated. The crystallographic analyses showed that C2 crystallizes in the monoclinic space group P21/c and shows a 3D 6,4 ladder-type polymeric chain in which the CdII centers are linked by [Ag(CN)2]− units. The Ag⋯Ag distance exhibits a short value of 3.1365(9) A. It features a rare linear pentameric unit of [Ag(CN)2]− ions assembled via d10–d10 interaction as building blocks. Both complexes exhibited outstanding antibacterial, antifungal and anticancer activities against ten different bacterial strains, two plant pathogenic fungi (Alternaria solani and Rhizoctonia solani) and four tumor cell lines (HT-29, HeLa, C6 and Vero), respectively.

Five complexes containing N,N-bis(2-hydroxyethyl)-ethylenediamine with tetracyanidopalladate(II): synthesis, crystal structures, thermal, magnetic, and catalytic properties

Five cyanide complexes, [Ni(N-bishydeten)Pd(CN)4] (1), [Cu(N-bishydeten)Pd(μ-CN)2(CN)2]n (2), [Cu(N-bishydeten)2][Pd(CN)4] (3), [Zn(N-bishydeten)Pd(CN)4] (4), and [Cd(N-bishydeten)2][Pd(CN)4] (5) (N-bishydeten = N,N-bis(2-hydroxyethyl)-ethylenediamine), have been synthesized and characterized using various techniques. Different structures were formed when the M : L ratio was varied in copper complexes. The single-crystal X-ray diffraction analysis reveals that 2, a 1-D cyanide-bridged complex with 2,2-CT-type zigzag chain, was obtained by using 1 : 1 M : L ratio whereas 3 was formed as a complex salt in a molar ratio of 1 : 2. The thermal stabilities determined from DTGmax values of the first decomposition stages change in the order 1 > 5 > 4 > 3 > 2. Although an EPR signal was not observed for 1, the g parameters obtained from the EPR spectra of 2 and 3 indicate that CuII ions are located in tetragonally distorted octahedral sites (D 4h), and the ground state of the unpaired electron is (2B1g). The magnetic behavior indicates a very small antiferromagnetic interaction below 10 K for 1–3. In 3, there is a temperature-independent paramagnetism (α) due to the orbital moments of the d electrons. 1–3 were tested as catalysts in Suzuki and Heck coupling reactions.

Synthesis and characterization of new heterometallic cyanido complexes based on [Co(CN)6]3− building blocks: crystal structure of [Cu2(N-bishydeten)2Co(CN)6]·3H2O having a strong antiferromagnetic exchange

A tetradentate N- and O- donor, N,N-bis(2-hydroxyethyl)-ethylenediamine, (N-bishydeten), has been employed to synthesize four new heterometallic cyanido complexes, [Ni2(N-bishydeten)2Co(CN)6]·3H2O (C1), [Cu2(N-bishydeten)2Co(CN)6]·3H2O (C2), [Zn2(N-bishydeten)2Co(CN)6]·5H2O (C3) and K[Cd(N-bishydeten)Co(CN)6]·1.5H2O (C4). Characterization of the complexes was performed using IR and EPR spectroscopy (for C2), thermal analysis and elemental analysis techniques. The crystal structure of C2 was determined by the X-ray single crystal diffraction technique. The asymmetric unit of C2 consists of cyanido-bridged trinuclear Cu1Cu2Co3 units {-CN-Cu1(N-bishydeten)-μ-O-Cu2(N-bishydeten)-NC-Co3(CN)4-CN-} and three water molecules. The water molecules are situated in the inter-fragment spaces. The [Cu2(N-bishydeten)2]2+ cations are linked to the [Co(CN)6]3− anions via two cyanido bridges to give a 1D neutral zigzag chain. One of two N-bishydeten cations bridges five coordinated Cu1 and six coordinated Cu2 through deprotonated η1-O2 and the charge of C2 is counterbalanced by this η1-O2. The IR spectrum of C2 is quite different from other complexes, three ν(CN) absorption bands were observed due to different cyanido groups in its structure. The thermal decomposition of C1–C4 is processed in multistages. Variable temperature magnetic susceptibility measurement recorded in the 10–300 K range showed the presence of a strong antiferromagnetic exchange interaction in C2 between Cu1 and Cu2 by η1-O2.

Synthesis and Structural Studies of PdII/ZnII Architecture with N,N′-Bis(2-hydroxyethyl)ethylenediamine as Capping Ligand

A new compound of the composition [-{Zn-di-μ-bishydeten(O)-Zn}-μ-(CN)2Pd(CN)2] (1) was obtained from the reaction of PdCl2, bishydeten [N,N′-bis(2-hydroxyethyl)ethylenediamine], KCN and ZnCl2 in water/ethanol mixture. This dimeric polymer was characterized by IR spectroscopy and elemental analysis, and its thermal properties were studied by TG and DTG. In addition, the crystal structure was determined by single-crystal X-ray analysis. IR spectroscopy pointed out the existence of both terminal and bridged cyano ligands in the complex structure. When it comes to thermal analysis, the complex followed usual decomposition mechanism in which neutral ligands are decomposed first and then anionic ligands left the structure. Single crystal X-ray analysis revealed that 1 exhibited polymeric structure. An interesting feature of this complex is that ancillary bishydeten ligand acted as a bridge just like cyano groups did. In the complex structure, dimeric Zn units, which were gathered by –O atoms of bishydeten ligands in an asymmetric fashion, were bridged by tetracyanopalladateII anions. 1D chain turned into 3D chains by means of intermolecular hydrogen bonds.

Five novel dicyanidoaurate(I)-based complexes exhibiting significant biological activities: synthesis, characterization and three crystal structures

Five new cyanido-bridged coordination polymers having closed formulae [Ni(hydeten)Au2(CN)4] (C1), [Ni(hydeten)2Au2(CN)4]·H2O (C2), [Cu(hydeten)2Au2(CN)4]·CH3OH (C3), [Zn(hydeten)2 Au2(CN)4]·H2O (C4), and [Cd(hydeten)2Au2(CN)4]·H2O (C5) (hydeten: N-(2-hydroxyethyl)-ethylenediamine) have been prepared and characterized by elemental, thermal, FT-IR and XRD (C3, C4 and C5) measurement techniques. The anticancer, antibacterial and antifungal activities of the complexes are also investigated. The C3, C4 and C5 units according to XRD analyses are linked to each other via –CN–M(hydeten)–NC–Au(1)–CN–M(hydeten)–CN– chains (MII = Cu, Zn and Cd) and aurophilic interacted –Au(1)(CN)2–Au(2)(CN)2–Au(1)(CN)2–Au(2)(CN)2– zig-zag shaped chains along the a axis. C1, C2 and C4 show significant antifungal effects against several plant pathogenic fungi, while surprisingly C3 exhibits a considerable antibacterial effect against Gram negative E. coli. The studies of the antiproliferative activity on Hela, HT29 and C6 tumor cell lines indicated the anticancer potential of these complexes even at low doses.

Common Mistakes in the Dual-Energy X-ray Absorptiometry (DXA) in Turkey. A Retrospective Descriptive Multicenter Study

BACKGROUND Osteoporosis is a widespread metabolic bone disease representing a global public health problem currently affecting more than two hundred million people worldwide. The World Health Organization states that dual-energy X-ray absorptiometry (DXA) is the best densitometric technique for assessing bone mineral density (BMD). DXA provides an accurate diagnosis of osteoporosis, a good estimation of fracture risk, and is a useful tool for monitoring patients undergoing treatment. Common mistakes in BMD testing can be divided into four principal categories: 1) indication errors, 2) lack of quality control and calibration, 3) analysis and interpretation errors, and 4) inappropriate acquisition techniques. The aim of this retrospective multicenter descriptive study is to identify the common errors in the application of the DXA technique in Turkey. METHODS All DXA scans performed during the observation period were included in the study if the measurements of both, the lumbar spine and proximal femur were recorded. Forearm measurement, total body measurements, and measurements performed on children were excluded. Each examination was surveyed by 30 consultants from 20 different centers each informed and trained in the principles of and the standards for DXA scanning before the study. RESULTS A total of 3,212 DXA scan results from 20 different centers in 15 different Turkish cities were collected. The percentage of the discovered erroneous measurements varied from 10.5% to 65.5% in the lumbar spine and from 21.3% to 74.2% in the proximal femur. The overall error rate was found to be 31.8% (n = 1021) for the lumbar spine and 49.0% (n = 1576) for the proximal femur. CONCLUSION In Turkey, DXA measurements of BMD have been in use for over 20 years, and examination processes continue to improve. There is no educational standard for operator training, and a lack of knowledge can lead to significant errors in the acquisition, analysis, and interpretation.

Two novel cyanido-bridged polymeric complexes with suspension bridge type connections and a series of related complex salts: crystallographic and thermal characterizations

In this study, two cyanido-bridged coordination polymers and three cyanido complex salts with the general formulas [M(edbea)Ni(CN)4] {M = Zn (1) and Cd (2); edbea = 2,2′-(ethylenedioxy)bis(ethylamine)} and [Cd(edbea)2][M′(CN)4]·XH2O {M′ = Ni (3), Pd (4) and Pt (5); X = 2 (3) and 0 (4 and 5)} were synthesized and characterized using elemental analysis and FT-IR spectroscopy. X-ray studies of 1–5 exhibited two different coordination modes of the edbea ancillary ligand. While edbea acts as a suspension bridge with two nitrogen atoms positioned in an unusual way between adjacent metal ions for 1 and 2, in the remaining complexes, it behaves as a tetradentate ligand resulting in an eight coordinated CdII center. 3 showed an interesting packing of the cationic components hosted between the layers created by the anions and lattice water molecules. Thermal analysis studies showed that all of the complexes exhibited a similar mechanism in which the neutral groups were released first and then, the anionic ligands decomposed. Also, the complexes with salt structures could not retain their thermal stability as long as the polymeric ones.

A Novel Potentiometric Sensor for Determination of Neurotoxin β-N-Oxalyl-L-α, β-Diaminopropionic Acid

A novel potentiometric sensor based on ionophore (Cd(NH2CH2CH2OCH2CH2OCH2CH2NH2)Ag3(CN)5) for the determination of β-N-oxalyl-l-α, β-diaminopropionic acid (ODAP) is developed. The ODAP-selective membrane sensor demonstrates high sensitivity and short response time. The detection limit of the ODAP-selective membrane sensor is about 2 × 10−6 mol L-1 and the response time is shorter than 6 s. The linear dynamic range of the ODAP-selective membrane sensor is between ODAP concentrations of 1.0 × 10−2 and 1 × 10−6 mol L-1. The ODAP-selective membrane sensor exhibits good operational stability for at least one week in dry conditions at 4–6°C. It has a reproducible and stable response during continuous work for at least 10 h with a relative standard deviation of 0.28% (n = 18).