Browsing by Author "Çetinkaya, B"

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Investigation of strontium sorption onto Kula volcanics using Central Composite Design
    (ELSEVIER SCIENCE BV) Kütahyali, C; Çetinkaya, B; Acar, MB; Isik, NO; Cireli, I
    In performance assessment studies, the uptake of the radioactive elements by rock formations play an important role in retarding their aqueous phase migration. Sorption studies of radionuclides have been conducted to obtain data on the distribution coefficient (K-d) that is as an input parameter in the performance assessment of the geological disposal of radioactive wastes. In this work, sorption experiments were studied in a batch sorption system using Sr(NO3)(2) solution on non-treated and HCl-treated Kula volcanics. The distribution coefficient (K-d) values of Sr2+ derived from batch experiments were used to evaluate the migration behavior of Sr2+. Central Composite Design was used in the experiments. Sr sorption was studied as a function of pH, temperature, initial concentration of adsorbate and contact time. The results show that the K-d values are higher at pH 7-9 which is the pH range of the natural waters. The kinetic data conformed better to the pseudo-second-order equation. Thermodynamic parameters Delta H degrees, Delta S degrees and Delta G degrees were estimated and these parameters show that adsorption is endothermic. The correlation coefficients indicate that the Langmuir model fits better for the strontium sorption onto non-treated and HCl-treated Kula volcanics with monolayer capacities as 2.04 and 1.72 mg/g, respectively. (C) 2011 Elsevier B.V. All rights reserved.
  • No Thumbnail Available
    Item
    N-Heterocyclic carbene complexes of palladium(II) and rhodium(I) with pendant ferrocenylmethyl groups
    (SPRINGER) Demirhan, F; Yildirim, Ö; Çetinkaya, B
    1-Ferrocenylmethyl-3-benzylimidazolidinium iodide and 1-ferrocenylmethyl-3-( 2,4,6-trimethylbenzyl) imidazolidinium iodide were prepared in good yields by boiling, under reflux, a solution of (ferrocenylmethyl)trimethylammonium iodide and the appropriate N-alkyl-2-imidazoline in MeCN. From the 1-ferrocenylmethyl-3-ben-zylimidazolidinium iodide salt, N-heterocylic carbene complexes of Pd-II and Rh-I were synthesized by in situ deprotonation and subsequent trapping. The new compounds were characterized by C, H, N analyses, H-1- n. m. r., C-13-n.m.r. and by cyclic voltammetry. The n. m. r. properties of the complexes are compared with those of nonferrocenylated carbene derivatives. The c. v.'s of these compounds show a number of resolved redox processes, indicating that CH(2)Fc substituents are electronically isolated from the remaining molecular framework.
  • No Thumbnail Available
    Item
    Synthesis, structure, electrochemical and antimicrobial properties of N,N′-bis(ferrocenylmethyl)imidazolinium salts
    (ELSEVIER SCIENCE SA) Özbek, HA; Aktas, PS; Daran, JC; Oskay, M; Demirhan, F; Çetinkaya, B
    The N, N'-bis(ferrocenylmethyl)imidazolinium chloride (3) and bromide (4) were prepared by reaction of N,N'-bis(ferrocenylmethyl)ethylenediamine (2) with NH4X (X = Cl, Br). The N,N'-bis(ferrocenylmethyl)imidazolinium tetrafluoroborate (6) was obtained in two steps from compound (2). The first step involves the synthesis of N,N'-bis(ferrocenylmethyl)imidazolidine (5) by condensation of (2) with aqueous formaldehyde. Compound (5) was successfully converted to the N,N'-bis(ferrocenylmethyl)imidazolinium tetrafluoroborate (6) by treatment with tritylium tetrafluoroborate. The new compounds were characterized by H-1 and C-13 NMR, IR and elemental analysis techniques which support the proposed structures. The X-ray crystal structure of the N,N'-bis(ferrocenylmethyl)imidazolidine (5) shows two ferrocenyl moieties bridged by an imidazolidine ring. The electrochemical properties were determined by cyclic voltammetry for all compounds. The compounds were screened for their in vitro antimicrobial activities against the Gram-positive, Gram-negative bacteria and antifungal activity against a Candida albicans. (3), (4), (6) show significant antimicrobial activity and theirs MIC values ranged from 169 to 520 mu g/mL. (C) 2014 Elsevier B.V. All rights reserved.
  • No Thumbnail Available
    Item
    1-Ferrocenylmethyl-3-(2,4,6-trimethylbenzyl)-1H-imidazolidin-3-ium iodide and trans-bis(3-benzyl-1-ferrocenylmethyl-1H-imidazolidin-2-ylidene)diiodidopalladium(II)
    (INT UNION CRYSTALLOGRAPHY) Daran, JC; Demirhan, F; Yildirim, Ö; Çetinkaya, B
    Owing to increasing interest in the use of N-heterocyclic carbenes (NHCs) based on imidazolidinium ions as ligands in the design of highly efficient transition-metal-based homogeneous catalysts, the characterizations of the 1-ferrocenylmethyl-3-(2,4,6-trimethylbenzyl)imidazolidin-3-ium iodide salt, [Fe(C5H5)(C19H24N2)]I, (I), and the palladium complex trans-bis(3-benzyl-1-ferrocenylmethyl-1H-imidazolidin-2-ylidene)diiodidopalladium(II), [Fe2Pd(C5H5)(2)(C16H17N2)(2)I-2], (II), are reported. Compound (I) has two iodide anions and two imidazolidinium cations within the asymmetric unit (Z' = 2). The two cations have distinctly different conformations, with the ferrocene groups orientated exo and endo with respect to the N-heterocyclic carbene. Weak C-H donor hydrogen bonds to both the iodide anions and the pi system of the mesitylene group combine to form two-dimensional layers perpendicular to the crystallographic c direction. Only one of the formally charged imidazolidinium rings forms a near-linear hydrogen bond with an iodide anion. Complex (II) shows square-planar coordination around the Pd-II metal, which is located on an inversion centre (Z' = 0.5). The ferrocene and benzyl substituents are in a trans-anti arrangement. The Pd-C bond distance between the N-heterocyclic carbene ligands and the metal atom is 2.036 (7) angstrom. A survey of related structures shows that the lengthening of the N-C bonds and the closure of the N-C-N angle seen here on metal complexation is typical of similar NHCs and their complexes.