Ahmet Nedim Ay

Layered double hydroxides — multifunctional nanomaterials

Layered double hydroxides (LDH’s), also known as anionic clays, are lamellar inorganic solids. The structure of most of them corresponds to that of mineral hydrotalcite, consisting of brucite-like hydroxide sheets, where partial substitution of trivalent or divalent cations results in a positive sheet charge compensated by reversibly exchangeable anions within interlayer galleries. These layered materials have good intercalation properties capturing inorganic and organic ions and they are promising materials for a large number of practical applications, both for direct preparation and for after thermal treatment.Over the past decade, significant interest has been devoted to the synthesis of LDHs with new compositions allowing improved applications in many areas. This contribution reviews the recent advances in water treatment, nuclear waste treatment/storage, catalytic, industrial, and advanced applications and biomedical applications of LDH-based nanomaterials.

Bioinorganic Magnetic Core−Shell Nanocomposites Carrying Antiarthritic Agents: Intercalation of Ibuprofen and Glucuronic Acid into Mg−Al−Layered Double Hydroxides Supported on Magnesium Ferrite

This paper describes the synthesis and characterization of a composite constituted by an antiarthritic agent (AA) intercalated into a layered double hydroxide (LDH) supported on magnesium ferrite. Core-shell nanocomposites were prepared by depositing Mg-Al-NO(3)-LDH on a MgFe(2)O(4) core prepared by calcination of a nonstoichiometric Mg-Fe-CO(3)-LDH. Intercalation of ibuprofen and glucuronate anions was performed by ion-exchange with nitrate ions. The structural characteristics of the obtained products were investigated by powder X-ray diffraction, element chemical analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Morphologies of the nanocomposite particles were examined by scanning electron microscopy and transmission electron microscopy. The products were shown to intercalate substantial amounts of AA with enhanced thermal stabilities. Room-temperature magnetic measurements by vibrating sample magnetometry revealed that the products show soft ferromagnetic properties suitable for potential utilization in magnetic arthritis therapy.

Monodentate chromium(III) ascorbate complexes prepared via chromate reduction in THF

ABSTRACT Two new Cr(III)-ascorbate complexes, K[Cr(C6H7O6)2(OH)2-(H2O2)2]·3H2O (1) and K2[Cr(C6H7O6)3(OH)2(H2O)]·2H2O (2), have been prepared by reducing chromate with L-ascorbic acid in aqueous THF. The complexes have been characterized by various analytical and spectroscopic methods (UV/Vis, FTIR, 13C NMR and EI MS) and by thermal and magnetic measurements. Experimental results indicated a distorted octahedral environment around the Cr(III) centers and the coordination mode of ascorbic acid has been shown to be monodentate through its O(3) atom by NMR studies. The analytical and spectroscopic data available allowed the proposal of structural formulae for (1) and (2).

5-Fluorouracil intercalated iron oxide@layered double hydroxide core-shell nano-composites with isotropic and anisotropic architectures for shape-selective drug delivery applications.

We report the synthesis, characterization and in vitro release behavior of anti-cancer drug carrying iron oxide@layered double hydroxide core-shell nanocomposites with sizes ranging from 40 to 300 nm, good drug loading capacities and soft ferromagnetic properties. HRTEM analyses verified that nearly spherical isotropic carriers were obtained by coating spherical magnetite particles while anisotropic carriers were obtained by coating spindle-shaped hematite particles. They both displayed a fluctuating in vitro release profile with a higher release percentage for the anisotropic carrier.

A MONONUCLEAR, MIXED (SALICYLATO) (NICOTINAMIDE) COMPLEX OF ZN (II) WITH PENTA- AND HEXA-COORDINATION SITES: A NOVEL FRAMEWORK STRUCTURE

The title compound, diaqua(bissalicylato-κO)(bisnicotinamide-κN)zinc(II)][bis(triaqua (monosalicylato-κO)(mononicotinamide-κN)zinc(II)salicylate, includes three Zn(II) ions, four nicotinamide ligands, six salicylate ligands and eight coordinated aqua ligands in the asymmetric unit in complex structure. The geometry around one of the Zn(II) ions is a slightly distorted octahedron, of which the equatorial plane is formed by two carboxylate oxygens and two aqua oxygens, while the axial positions are occupied by two pyridyl nitrogen atoms. The other Zn(II) ions adopt fivefold coordinations with one carboxylate oxygen atom from salicylate ligand, one N atom from nicotinamide ligand and three oxygen atoms from aqua ligands. In addition, there are two salicylate anions in the unit cell that are not coordinated. They provide charge balance as counter-ions in the complex framework.

Prolate spheroidal hematite particles equatorially belt with drug-carrying layered double hydroxide disks: Ring Nebula-like nanocomposites

A new nanocomposite architecture is reported which combines prolate spheroidal hematite nanoparticles with drug-carrying layered double hydroxide [LDH] disks in a single structure. Spindle-shaped hematite nanoparticles with average length of 225 nm and width of 75 nm were obtained by thermal decomposition of hydrothermally synthesized hematite. The particles were first coated with Mg-Al-NO3-LDH shell and then subjected to anion exchange with salicylate ions. The resulting bio-nanohybrid displayed a close structural resemblance to that of the Ring Nebula. Scanning electron microscope and transmission electron microscopy images showed that the LDH disks are stacked around the equatorial part of the ellipsoid extending along the main axis. This geometry possesses great structural tunability as the composition of the LDH and the nature of the interlayer region can be tailored and lead to novel applications in areas ranging from functional materials to medicine by encapsulating various guest molecules.

Ascorbic acid as a potential masking agent in the tanning process. Olated chromium complexes involving ligating ascorbate and bridging sulfate groups

Two polynuclear complexes, a dimer and a tetramer, involving sulfate and hydroxo bridges and ligating ascorbate were isolated from aqueous solutions. Structural formulae are proposed on the basis of microanalytical and thermal analysis results, i.r., 13C-n.m.r., mass spectral data and magnetic measurements.

Tetra­aqua­bis(orotato-κO)cobalt(II) dihydrate

In the title CoII complex, [Co(C5H3N2O4)2(H2O)4]·2H2O, the CoII ion is located on an inversion center and is coordinated by two orotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) anions and four water molecules in a slightly distorted octahedral geometry. The dihedral angle between the carboxylate group and the attached orotate ring is 1.2 (3)°. In the crystal structure, intermolecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. π–π contacts between the orotate rings [centroid–centroid distances = 3.439 (2) and 3.438 (2) Å] further stabilize the structure.

Tetraaquabis(orotato-κO)cobalt(II) dihydrate

In the title CoII complex, [Co(C5H3N2O4)2(H2O)4]·2H2O, the CoII ion is located on an inversion center and is coordinated by two orotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) anions and four water molecules in a slightly distorted octahedral geometry. The dihedral angle between the carboxylate group and the attached orotate ring is 1.2 (3)°. In the crystal structure, intermolecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. π–π contacts between the orotate rings [centroid–centroid distances = 3.439 (2) and 3.438 (2) Å] further stabilize the structure.

Tetraaquabis(orotato-kappa O)cobalt(II) dihydrate

In the title CoII complex, [Co(C5H3N2O4)2(H2O)4]·2H2O, the CoII ion is located on an inversion center and is coordinated by two orotate (2,6-dioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylate) anions and four water molecules in a slightly distorted octahedral geometry. The dihedral angle between the carboxylate group and the attached orotate ring is 1.2 (3)°. In the crystal structure, intermolecular O—H⋯O, N—H⋯O and C—H⋯O hydrogen bonds link the molecules into a three-dimensional network. π–π contacts between the orotate rings [centroid–centroid distances = 3.439 (2) and 3.438 (2) Å] further stabilize the structure.