Ümmühan Özdemir

Redox characteristics of Schiff base manganese and cobalt complexes related to water-oxidizing complex of photosynthesis

In an effort to obtain synthetic analogues of water-oxidizing complex (WOC) of photosystem II (PS II) of plant photosynthesis, a Schiff base manganese and a cobalt complex, employing Niten, a SALEN type ligand, have been prepared. Cyclic and square wave voltammetric measurements have been performed to assess their redox characteristics. Both complexes undergo several reduction processes in cathodic negative potential region at more or less similar potentials. In view of these reductions being independent of the nature of the metal, they are thought to be ligand-localized. Although similar in negative region, a marked difference in the behavior of the complexes is observed in anodic region. While the cobalt complex is electrochemically inactive in the positive potentials up to +1.0 V vs. Ag/AgCl, the manganese complex displays two oxidation waves at +0.25 and +0.5 V vs. Ag/AgCl. The presence of oxidation wave in manganese complex at +0.5 V vs. Ag/AgCl or +0.7 V vs. NHE suggests that this complex can catalyze the oxidation of water and can, thus, simulate the WOC of PS II.

SYNTHESIS AND CHARACTERIZATION OF THE PRODUCTS FROM REACTION OF METAL CARBONYLS (M(CO)6 (M ¼ Cr, Mo, W), Re(CO)5Br, Mn(CO)3Cp) WITH SALICYLALDEHYDE METHANESULFONYLHYDRAZONE

Five new complexes, [M(CO)5(salmsh)] (M = Cr; 1, Mo; 2, W; 3), [Re(CO)4Br(salmsh)], 4, and [Mn(CO)3 (salmsh)], 5, have been synthesized by the photochemical reaction of metal carbonyls with salicylaldehyde methanesulfonylhydrazone (salmsh). The complexes have been characterized by elemental analyses, EI mass spectrometry, FT-IR and 1H NMR spectroscopy. The spectroscopic studies show that salmsh behaves as a monodentate ligand coordinating via the imine N donor atom in 1–4 and as a tridentate ligand in 5.

Synthesis, characterization, antibacterial activities and carbonic anhydrase enzyme inhibitor effects of new arylsulfonylhydrazone and their Ni(II), Co(II) complexes

Ethane sulfonic acide hydrazide (esh: CH(3)CH(2)SO(2)NHNH(2)) derivatives as 5-methylsalicyl-aldehydeethanesulfonylhydrazone (5msalesh), 5-methyl-2-hydroxyacetophenoneethane sulfonylhydrazone (5mafesh) and their Ni(II), Co(II) complexes have been synthesized for the first time. The structure of these compounds has been investigated by elemental analysis, FT-IR, (1)H NMR, (13)C NMR, LC/MS, UV-vis spectrophotometric method, magnetic susceptibility, thermal studies and conductivity measurements. The antibacterial activities of synthesized compounds were studied against Gram positive bacteria; Staphylococcus aureus, Bacillus subtilis, Bacillus magaterium and Gram negative bacteria; Salmonella enteritidis, Escherichia coli by using the microdilution broth method. The biological activity screening showed that ligands have more activity than complexes against the tested bacteria. The inhibition activities of these compounds on carbonic anhydrase II (CA II) have been investigated by comparing IC(50) and K(i) values and it has been found that 5msalesh and its complexes have more enzyme inhibition efficiency than other compounds.

Reaction of metal carbonyls with 2-hydroxy-1-naphthaldeyde methanesulfonylhydrazone and characterization of the substitution products

Five new complexes, [M(CO)5(nafmsh)] [M = Cr, 1; Mo, 2; W, 3], [Re(CO)4Br(nafmsh)], 4 and [Mn(CO)3(nafmsh)], 5 have been synthesized by the photochemical reaction of metal carbonyls [M(CO)6] (M = Cr, Mo, W), [Re(CO)5Br], and [Mn(CO)3Cp] with 2-hydroxy-1-naphthaldehyde methanesulfonylhydrazone (nafmsh). The complexes have been characterized by elemental analysis, EI mass spectrometry, FT-IR, and 1H NMR spectroscopy. The spectroscopic studies show nafmsh is a monodentate ligand coordinating via the imine N donor atom in 1–4 and as a tridentate ligand in 5.

Photochemical reactions of metal carbonyls [M(CO)6 (M=Cr, Mo, W), Re(CO)5Br, Mn(CO)3Cp] with salicylaldehyde ethanesulfonylhydrazone (Hsalesh)

The new complexes, M(CO)5(Hsalesh) (M = Cr (1), Mo (2), W (3)), Re(CO)4Br(Hsalesh) (4) and Mn(CO)3(Hsalesh) (5) have been synthesized by the photochemical reaction of metal carbonyls M(CO)6 (M = Cr, Mo, W), Re(CO)5Br, and Mn(CO)3Cp with salicylaldehyde ethanesulfonyl hydrazone (Hsalesh). The complexes have been characterized by elemental analysis, EI mass spectrometry, FT-IR and 1H NMR spectroscopy. The spectroscopic studies show that Hsalesh behaves as a monodentate ligand coordinating via imine N donor atom in M(CO)5(Hsalesh) (M = Cr, Mo, W) and Re(CO)4Br(Hsalesh) and as a tridentate ligand in Mn(CO)3(salesh).

Schiff Bases of Methanesulfonylhydrazine. Synthesis, Spectroscopic Characterization, Conformational Analysis, and Biological Activity

Three novel Schiff bases: salicylaldehyde methanesulfonylhydrazone (1), 2-hydroxyacetophenone methanesulfonylhydrazone (2) and 2-hydroxy-1-naphthaldehyde methanesulfonylhydrazone (3) have been synthesized. Compounds 1-3, as well as acetone methanesulfonylhydrazone (4) have been characterized by TLC, 1H NMR and IR spectra. The spectroscopic results for 1-3 have revealed the presence of an intramolecular hydrogen bond between the hydroxyl group and the imine N atom. The conformational isomerism of 1-4 with respect to the rotations around the SN and NN bonds have been studied by the method of molecular mechanics. Compounds 1-4 and methanesulfonylhydrazine exhibit antibacterial and cytotoxic effects.

Photochemical reactions of metal carbonyls [M(CO)6 (M = Cr, Mo and W), Re(CO)5Br, Mn(CO)3Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh)

Five new complexes, [M(CO)5(apmsh)] [M = Cr; (1), Mo; (2), W; (3)], [Re(CO)4Br(apmsh)] (4) and [Mn(CO)3(apmsh)] (5) have been synthesized by the photochemical reaction of metal carbonyls [M(CO)6] (M = Cr, Mo and W), [Re(CO)5Br], and [Mn(CO)3Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh). The complexes have been characterized by elemental analysis, mass spectrometry, f.t.-i.r. and 1H spectroscopy. Spectroscopic studies show that apmsh behaves as a monodentate ligand coordinating via the imine N donor atom in [M(CO)5(apmsh)] (1–4) and as a tridentate ligand in (5).

Synthesis and characterization of some metal carbonyls with 2-hydroxyacetophenone ethanesulfonylhydrazone

Abstract Five new complexes, [M(CO) 5 (apesh)] [M=Cr; ( 1 ), Mo; ( 2 ), W; ( 3 )], [Re(CO) 4 Br(apesh)] ( 4 ) and [Mn(CO) 3 (apesh) ] ( 5 ) have been synthesized by the photochemical reaction of metal carbonyls [M(CO) 6 ] (M=Cr, Mo, W), [Re(CO) 5 Br], and [Mn(CO) 3 Cp] with 2-hydroxyacetophenone ethanesulfonylhydrazone (apesh). The complexes have been characterized by elemental analysis, mass spectrometry, FT-IR, 1 H NMR spectroscopy. The spectroscopic studies show that apesh behaves as a monodentate ligand coordinating via imine N donor atom in ( 1 )–( 4 ) and as tridentate ligand in ( 5 ).

New aromatic/heteroaromatic propanesulfonylhydrazone compounds: Synthesis, physical properties and inhibition studies against carbonic anhydrase II (CAII) enzyme

Some new aromatic/heteroaromatic propanesulfonylhydrazone derivatives (1-8) were synthesized and characterized by elemental analyses, FT-IR, (1)H NMR, (13)C NMR, LC/MS techniques. The geometry optimizations and spectral calculations were performed by using DFT/B3LYP/6-311G(d,p) basis set in Gaussian 09 program. The inhibition activities of the synthesized compounds on carbonic anhydrase II (CAII) isoenzyme have been investigated by comparing IC50 values. Acetazolamide (5-acetamido-1,3,4-thiadiazole-2-sulfonamide) AAZ, a clinically used in CAII inhibition has also been investigated as standard inhibitor. The best aromatic/heteroaromatic propanesulfonylhydrazone inhibitors of this isoform were o-aminobenzaldehydepropanesulfonylhydrazone (1) and thiophenecarboxyaldehyde propanesulfonylhydrazone (5) having the same IC50 (0.55 mM) value. The molecular descriptors for propanesulfonylhydrazones were obtained to develop structure activity relationship (SAR) model between experimental IC50 values and the molecular descriptors calculated by PM3-based SAR models in Hyperchem 8, respectively. The obtained models confirm the good carbonic anhydrase II (CAII) inhibition activity of the propanesulfonylhydrazone derivatives. The selected descriptors are sensitive both to the imine (CH=N) and NH2 groups that are responsible from higher activities of (1) and (5) in their series.

Synthesis and Characterization of Metal Carbonyl Complexes of M(CO)6 (M = Cr, Mo, and W), Re(CO)5Br, and Mn(CO)3Cp with Acetonemethanesulfonylhydrazone (amsh) and Methanesulfonylhydrazone (msh)

Abstract Ten new complexes, [M(CO)5(amsh)] [M = Cr; (1a), Mo; (2a), W; (3a)], [Re(CO)4Br(amsh)] (4a), and [Mn(CO)2(amsh)Cp] (5a) and [M(CO)5(msh)] [M = Cr; (1b); Mo, (2b); W, (3b)], [Re(CO)4Br(msh)], (4b), and [Mn(CO)3(msh)], (5b), have been synthesized by the photochemical reaction of the metal carbonyls [M(CO)6] (M = Cr, Mo, and W), [Re(CO)5Br], and [Mn(CO)3Cp] with acetonemethanesulfonylhydrazone (amsh) and methanesulfonyl hydrazine (msh). The complexes have been characterized by elemental analyses, mass spectrometry, FT‐IR and 1H NMR spectroscopy. The spectroscopic studies show that amsh and msh behave as a monodentate ligands coordinating via an imine N donor atom in (1a)–(5a) and a hydrazine N donor atom in (1b)–(5b).