Yusuf Özcan

Synthesis, characterization, biological activities of dimethyltin(IV) complexes of Schiff bases with ONO-type donors

Four different dimethyltin(IV) complexes of Schiff bases derived from 2-amino-3-hydroxypyridine and different substituted salicylaldehydes have been synthesized. The compounds, with the general formula [Me(2)Sn(2-OArCH=NC(5)H(3)NO)], where Ar=-C(6)H(3)(5-CH(3)) [Me(2)SnL(1)], -C(6)H(3)(5-NO(2)) [Me(2)SnL(2)], -C(6)H(2)(3,5-Cl(2)) [Me(2)SnL(3)], and -C(6)H(2)(3,5-I(2)) [Me(2)SnL(4)], were characterized by IR, NMR ((1)H and (13)C), mass spectroscopy and elemental analysis. Me(2)SnL(3) was also characterized by X-ray diffraction analysis and shows a fivefold C(2)NO(2) coordination with distorted square pyramidal geometry. H(3)C-Sn-CH(3) angles in the complexes were calculated using Lockharts equations with the (1)J((117/119)Sn-(13)C) and (2)J((117/119)Sn-(1)H) values (from the (1)H-NMR and (13)C-NMR spectra). The in vitro antibacterial and antifungal activities of dimethyltin(IV) complexes were also investigated.

Structure and characterization of N-(2-hydroxy-1-naphthylidene)threonine

Abstract Threonine Schiff base derived 2-hydroxy-1-naphthaldehyde and threonine has been isolated and investigated. The stoichiometry of this compound was derived from the results of elemental analyses, IR, 1 H-NMR and UV spectroscopic techniques. X-ray diffraction method was also used to obtain the single-crystal structure. The compound crystallizes in the space group P 2 1 with cell dimensions a =5.109(2), b =11.334(2), c=11.155(3) A and β =91(3)° with Z =2. The molecule has phenol-imine tautomeric form in the crystal structure. Some of bond lengths and angles found in the molecular structure are distorted due to π-electron delocalization and steric effect of naphthylidene and threonine groups.

Structural and spectroscopic characteristics of two new dibenzylbutane type lignans from Taxus baccata L.

Abstract Chromatographic separation of chloroform extracts of the heartwood of Taxus baccata L. has yielded two new dibenzylbutane type lignans, together with a known lignan. Their structures were established as 3′-demethylisolariciresinol-9′-hydroxy isopropylether ( 1 ) and 3-demethylisolariciresinol ( 2 ) and isolariciresinol ( 3 ) on the basis of 1D- and 2D-NMR spectroscopic analysis. Compounds 1 and 2 were identified as new lignans of isolariciresinol derivatives. Compound 1 is the first lignan with a hydroxyisopropyl group at C-9′. Molecular mechanic calculations of these compounds were carried out by using mm3 program. Furthermore, the conformations of these three compounds were computed with the semi-empirical molecular orbital methods AM1 and PM3 by using X-ray crystal structure results of similar compounds. So, three-dimensional, the most probable structure of these compounds were obtained, compared and discussed.

Investigations of rapid thermal annealing induced structural evolution of ZnO: Ge nanocomposite thin films via GISAXS

In this work, we present in depth structural investigations of nanocomposite ZnO: Ge thin films by utilizing a state of the art grazing incidence small angle x-ray spectroscopy (GISAXS) technique. The samples have been deposited by sequential r.f. and d.c. sputtering of ZnO and Ge thin film layers, respectively, on single crystal Si(100) substrates. Transformation of Ge layers into Ge nanoparticles (Ge-np) has been initiated by ex-situ rapid thermal annealing of asprepared thin film samples at 600 °C for 30, 60, and 90 s under forming gas atmosphere. A special attention has been paid on the effects of reactive and nonreactive growth of ZnO layers on the structural evolution of Ge-np. GISAXS analyses have been performed via cylindrical and spherical form factor calculations for different nanostructure types. Variations of the size, shape, and distributions of both ZnO and Ge nanostructures have been determined. It has been realized that GISAXS results are not only remarkably consistent with the electron mi...