Nevin Turan

Synthesis, Characterization of Poly(E)-3-amino-4-((3-bromophenyl)diazenyl)- 1H-pyrazol-5-ol: Investigation of Antibacterial Activity, Fluorescence, and Optical Properties

The oxidative polycondensation reaction conditions of (E)-3-amino-4-((3-bromophenyl)diazenyl)-1H-pyrazol-5-ol (Schiff base monomer) has been accomplished using NaOCl, and air O2 oxidants in an aqueous alkaline medium. The optical conductivity, dielectric and optical properties of synthesized poly(Schiff base) were examined. The magnitude of the refractive index decreases with increasing of photon energy up to about 2.5 eV, then refractive index of the poly(Schiff base) increases with increasing of photon energy. The E0 and Ed values of the poly(Schiff base) were found to be 5.34 and 9.22 eV, respectively. An indirect energy-gap value of the poly(Schiff base) was found to be 0.94±0.009 eV. A direct energy-gap value of the poly(Schiff base) was found to be 1.38±0.01 eV and 1.96±0.009 eV at first region and second region, respectively. Absorption coefficient K changes from 11.87 to 18.25 cm−1. In addition to fluorescence property of poly(Schiff base) was investigated. Finally, poly(Schiff base) and Schiff base monomer were tested for antibacterial activities against some bacteria.

Pro-oxidant and antiproliferative effects of the 1,3,4-thiadiazole–based Schiff base and its metal complexes

Adverse biological activities of Schiff base (SB) derivatives are well known. In this study, the ligand and its metal complexes have been synthesized and characterized by IR, 1H-NMR spectra, elemental analyses, magnetic susceptibility, UV-Vis spectra, and thermogravimetry/differential thermal analysis. From the elemental analyses data, the complexes were proposed to have the general formula [Mn(L)2(H2O)2], [Co(L)2(H2O)2], and [Ni2(L)(H2O)4(Cl)3]. From the magnetic moment and UV-Vis spectra data, it was found that the geometrical structures of these complexes are octahedral. In the in vivo experiment, adult male rats were injected subcutaneously with a new SB (L) and its [Mn(L)2(H2O)2], [Co(L)2(H2O)2], and [Ni2(L)(H2O)4(Cl)3] complexes (25 mg/kg body weight) and were then sacrificed 16 days later. Effects of these compounds on serum antioxidant vitamins (i.e., vitamins A, E, and C) and malondialdehyde (MDA) levels were measured in blood serum, liver, and kidney tissues. In an in vitro experiment, antiproliferative effects of these compounds were assessed on the human breast carcinoma MCF-7 and murine leukemia L1210 cell lines. Serum MDA and vitamins A, E, and C levels did not change by the treatments. However, in the kidney and liver tissues, MDA levels were higher, whereas vitamin levels were lower in treatment groups, compared to the control group. All compounds inhibited cell proliferation of MCF-7 and L1210 cancer cell lines in a dose- and time-dependent manner. In conclusion, SB derivatives tested in the current study induced oxidative stress in vivo and exhibited anti-proliferative effects in an in vitro culture system.

Synthesis, Structural Characterization and Biological Activity of Novel Cyclohexane-1,3-dione Ligands and Their Metal Complexes

Some new Zn(II) and Cu(II) complexes [Cu(L1)(OAc)2]∙H2O, [Cu(L1)(NO3)H2O]∙NO3∙3.5H2O, [Zn(L1)(NO3)2]∙4.5H2O, [Zn(L1)(OAc)2(H2O)2]∙3H2O, [Cu2(L2)(OAc)4]∙2H2O∙2DMF, [Cu(L2)2]∙2NO3∙1.5DMF∙H2O, [Zn(L2)2(NO3)2]∙DMF and [Zn2(L2)(OAc)4(H2O)4]∙5H2O; L1 = 2-[2-(2-methoxyphenyl)hydrazono]cyclohexane-1,3-dione and L2 = 2-[2-(3-nitrophenyl)hydrazono]cyclohexane-1,3-dione were synthesized and characterized by IR, 1H-NMR,13C-NMR and ultraviolet (UV-Vis.) spectroscopy, elemental analysis, magnetic susceptibility, mass spectrometry and thermogravimetry-differential thermal analysis (TGA-DTA). The synthesized ligands and their complexes were tested for antibacterial activity against Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Salmonella typhimurium CCM 583. Some of complexes showed medium-level antibacterial activity against the test bacteria compared with ampicillin.

Metal Complexes of Schiff Base Derived from Terephthalaldehyde and 2-Amino-5-Ethyl-1,3,4-Thiadiazole Synthesis, Spectral and Thermal Characterization

The present study deals with the preparation of Schiff base and its chelates with some transition metal ions, e.g., Co(II), Ni(II), Cu(II) and Fe(II). The structures of the ligand N-(5-ethyl-1,3,4-thiadiazole-2-yl)terephthalaldehyde imine (L) and its complexes have been synthesized and characterized by IR, 1 H-NMR spectra, elemental analyses, magnetic susceptibility, UV-vis and thermogravimetry-differential thermal analysis (TGA-DTA). From the magnetic moment and UV-vis spectra data, it is found that the geometrical structures of these complexes are octahedral.