M. Emin Günay

Silane‐Modified Magnetic Beads: Application to Immunoglobulin G Separation

The magnetic poly(2‐hydroxyethyl methacrylate ethylene glycol dimethacrylate) [m‐poly(HEMA‐EGDMA)] beads (150–250‐μm diameter in spherical form) were prepared by a radical suspension polymerization technique. The pseudo‐specific ligand, reactive imidazole containing 3–(2‐imidazoline‐1‐yl)propyl (triethoxysilane) (IMEO) was selected as a silanization agent. IMEO was covalently immobilized onto the magnetic beads. IMEO‐immobilized m‐poly(HEMA‐EGDMA) beads were used for the affinity adsorption of immunoglobulin‐G (IgG) from aqueous solutions and human plasma. To evaluate the degree of IMEO attachment, the m‐poly(HEMA‐EGDMA) beads were subjected to Si analysis by using flame atomizer atomic absorption spectrometer, and it was estimated as 36.6 mg IMEO/g of polymer. The nonspecific IgG adsorption onto the plain m‐poly(HEMA‐EGDMA) beads was very low (about 0.4 mg/g). Higher adsorption values (up to 55 mg/g) were obtained when the m‐poly(HEMA‐EGDMA)/IMEO beads were used from both aqueous solutions and human plasma. The maximum IgG adsorption on the m‐poly(HEMA‐EGDMA)‐IMEO beads was observed at pH 7.0. The IgG molecules could be repeatedly adsorbed and desorbed with m‐poly(HEMA‐EGDMA)‐IMEO beads without noticeable loss in the IgG adsorption capacity. The adsorption capacity from human plasma in magnetically stabilized fluidized bed decreased drastically from 78.9 to 19.6 mg/g with the increase of the flow rate from 0.2 to 3.5 mL/min.

The synthesis and structural characterization of a N -heterocyclic carbene-substituted palladacycle

Reaction of {[Pd(dmba)(μ-Cl)]2} (dmba = (CH3)2NCH2C6H4) with an in situ generated N-heterocyclic carbene (NHC = 1,3-dimesitylimidazolidin-2-ylidene) afforded crystals containing [chloro-(1,3-dimesitylimidazolidin-2-ylidene)(N,N-dimethylaminobenzyl-C1,N)palladium(II)] (VII). Molecular and crystal structures of the title compound have been determined by single crystal X-ray diffraction technique. Complex VII crystallizes in space group P 1, with a = 13.685(3) Å, b = 13.590(2) Å, c = 16.229(3) Å, α = 87.162(13)°, β = 70.514(15)°, γ = 84.153(16)°, Z = 4, D Calcd = 1.367 g cm−3. There are two independent molecules in the asymmetric unit.

Bicyclic N-heterocyclic carbene (NHC) ligand precursors and their palladium complexes

Abstract Eight bicyclic amidinium precursors (3), prepared from R,S-tmcp (R,S-tmcp: (1R,3S)-diamino-1,2,2-trimethylcyclopentane) were described. Only five of the precursors (3a–e) could be converted to palladium complexes, (PdX2(6,7-NHC)PEPPSI) (4) by treatment with PdCl2, K2CO3, and pyridine (additional KBr was used for (PdBr2(6,7-NHC)PEPPSI)). The salts and complexes were fully characterized by spectroscopic methods and X-ray crystallography.

[1,3-Bis(2-ethoxyphenyl)imidazolidin-2-ylidene]bromo(cycloocta-1,5-diene)rhodium(I).

The title complex, [RhBr(C8H12)(C19H22N2O2)], has a distorted square-planar geometry. There are two molecules, A and B, in the asymmetric unit. The Rh-C bond distance between the N-heterocyclic ligand and the metal atom is 2.039 (2) A in molecule A and 2.042 (2) A in molecule B. The angle between the carbene heterocycle and the coordination plane is 87.56 (12) degrees in molecule A and 87.03 (11) degrees in molecule B. It is shown that the average Rh-C(COD) (COD is cyclooctadiene) distance is linearly dependent on the Rh-C(imidazolidine) distance in this type of compound. This can be ascribed to the steric hindrance produced by the packing. The crystal structure contains intramolecular C-H...O and intermolecular C-H...Br interactions.

Cysteamine–palladium complex ([Pd(μ-OAc)(ppy)]2, ppy:2-phenylpyridine, PhMe)-modified peroxidase biosensor immobilized on a gold electrode

Abstract A new peroxidase biosensor was developed using cysteamine–palladium complex-modified gold electrode. The principle of the measurements is based on monitoring increase in the oxidation potential of palladium complex (at + 0.47 V vs Ag/AgCl) using amperometric detection. In the optimization studies of the biosensor, effects of enzyme amount, palladium complex amount, and duration of SAM formation on biosensor responses were investigated to optimize the bioactive layer. The biosensor has a fast response time of less than 10 s to hydrogen peroxide (H2O2), with a linear range of 5.0 × 10− 6 to 150 × 10− 6 M and a detection limit of 3.38 × 10− 6 M.