Elif Gungor

Two tridentate Schiff base ligands and their mononuclear cobalt (III) complexes: Synthesis, characterization, antibacterial and antifungal activities

Two Schiff base ligands (HL1, HL2) and their Co(III) complexes, [Co(HL1)(L1)] (1) and [Co(HL2)(L2)] (2) [where HL1=2-((E)-(2-hydroxyethylimino)methyl)-4-chlorophenol and HL2=2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol] were synthesized and characterized using spectroscopic methods. The crystal structures of 1 and 2 have been re-determined by single crystal diffraction at 100K. The ligands and their Co(III) complexes were screened for antibacterial and antifungal activities by the disc diffusion, microdilution broth and single spore culture techniques. The antimicrobial activity of the Co(III) complexes and the free ligands exhibit antimicrobial properties and the Co(III) complexes show enhanced inhibitory activity compared with their parent ligand.

Synthesis, spectroscopic characterization, and antimicrobial activities of Ni(II) and Fe(II) complexes with N-(2-hydroxyethyl)-5- nitrosalicylaldimine

Metal complexes [Ni(HL1)2H2O] (1) and [Fe(HL1)2] (2), where HL1 is the tridentate Schiff base N-(2-hydroxyethyl)-5-nitrosalicylaldimine, were synthesized and characterized by spectroscopic methods. The crystal structures of 1 and 2 have been determined by single crystal diffraction at 100 K. Complexes 1 and 2 have a distorted octahedral geometry. The ligand and metal complexes were screened for antibacterial and antifungal activities by the disk diffusion, microdilution broth, and single spore culture techniques. Antimicrobial activities of the ligand and its complexes have been tested against 10 bacteria, two yeast, and five filamentous fungi. The ligand and metal complexes were found to be active against all tested micro-organisms.

The first 3D and trinuclear cyano-bridged FeIII–FeIII(CN)6 complexes: structure and magnetic characterizations

[Fe(SB)(H2O)]ClO4 and [NEt4]3[Fe(CN)6] react in methanol to give a cis cyano-bridged assembly, 3D [NEt4][Fe(5-ClL1)]2[Fe(CN)6] (5-ClL1H2 = N,N′-bis(5-chlorosalicylidenato)-2,2-dimethyl-1,3-diaminopropane), 1, and a trans cyano-bridged trinuclear complex, [NEt4][Fe(5-ClL2)(MeOH)]2[Fe(CN)6] (5-ClL2H2 = N,N′-bis(5-chlorosalicylidenato)-1,2-diaminopropane), 2, depending on the Schiff base used. Complexes 1 and 2 have been characterized by X-ray analyses and magnetic measurements. The four CN− in the equatorial plane of the [Fe(CN)6]3− moiety bridge four Fe ions each in the cis position, which results in a 3D neutral layered structure giving a [–Fe–NC–Fe–CN–Fe–] linkage for 1. The two CN− in the equatorial plane of the [Fe(CN)6]3− moiety bridge two Fe ions, in the trans position, which results in a hydrogen bonded 2D neutral layered structure for 2. Magnetic studies reveal that complex 1 exhibits weak intralayer ferromagnetic coupling, while complex 2 displays transition to a 3D ferromagnetic order between low-spin Fe(III) and high-spin Fe(III) through the cyanide bridges. Complex 2 further displays frequency-dependent alternating current magnetic susceptibility.

Linear trinuclear mixed valance MnIII-MnII-MnIII complex: Synthesis, crystal structure and characterization

ABSTRACT A new linear trinuclear MnIII-MnII-MnIII complex 1 has been synthesized and characterized by elemental, spectral, X-ray and magnetic analysis. X-ray diffraction studies show that the central MnII ion is located at a crystallographic inversion center and is triply bridged to the terminal MnIII ions through one methoxide, one syn-syn carboxylate and one hydroxyl oxygen bridges with the short MnIII…MnII distance that is 3.047 Å. The intermolecular C-H…O, C-H…π and ring-metal interactions are observed in the hydrogen-bonded assembly of 1. Magnetic studies reveal that the mixed-valence complex 1 has S = 3/2 ground state with antiferromagnetic exchange interactions between MnII and MnIII ions.

Synthesis, crystal structure, magnetic properties and computational study of a series of cyano-bridged MnIII-FeIII complexes

Different derivatives of the Schiff base (SB) N,N′-bis(2-hydroxybenzylidene)-2,2,-dimethylpropane-1,3,-diamine, LH2, have been used to obtain a series of compounds of which we here report the synthesis, structural determination and magnetic study. [Mn(SB)(H2O)]ClO4 and [NEt4]3[Fe(CN)6] react in methanol to give the cis-cyano-bridged assemblies, 3D [NEt4][Mn(5-ClL)]2Fe(CN)6]·2(MeOH) 1, 3D [NEt4]3[Mn(5-BrL)]6[Fe(CN)6]3·11(MeOH) 2, and a trans-cyano-bridged trinuclear compound [NEt4][Mn(4-MeOL)(H2O)]2Fe(CN)6]·(EtOH)·(H2O) 3, depending on the Schiff-base used. Complexes 1, 2 and 3 have been characterized by X-ray analyses, magnetic measurements and DFT calculations. The four CN− in the equatorial plane of the [Fe(CN)6]−3 moiety bridge four Mn ions, each in the cis position, which results in a 3D neutral layered structure with a [–M–NC–Fe–CN–M–] linkage for 1 and 2. The two CN− in the equatorial plane of the [Fe(CN)6]−3 moiety bridge two Mn ions in the trans position, which results in a hydrogen bonded 2D neutral layered structure for 3. Magnetic studies reveal that complexes 1 and 2 exhibit antiferromagnetic coupling, while complex 3 displays ferromagnetic interactions between low-spin Fe(III) and high-spin Mn(III) through the cyanide bridges. Complex 3 further displays alternating current (AC) frequency dependent magnetic susceptibility, typical of the presence of slow magnetization relaxation. Density functional theory (DFT) combined with the broken symmetry state method were used to study the magnetic coupling behavior of complexes 1 and 3. DFT computations reveal that the calculated exchange coupling constants Jtheo were in good agreement with the experimental ones.

Synthesis, characterization, antibacterial, and antifungal activities of one-dimensional O−H···O hydrogen-bonded Cu(II) and Ni(II) complexes

ABSTRACT Two Schiff base complexes, [Cu(HL)2], 1 and [Ni(HL)2], 2 [H2L = 2–((E)–(2–hydroxyethylimino)methyl)–1–naptaphenol] have been synthesized and characterized by elemental analysis, 1H NMR, 13C NMR, IR spectroscopy, and X-ray diffraction. In the crystalline architecture of 1 and 2, intermolecular O−H···O hydrogen bonds link the molecules which form one-dimensional polymeric chain structure along the c axis. C−H···O and C−H···π intermolecular interaction also connect the molecules in the structures which form to 3D structures of 1 and 2. The ligand and metal complexes 1 and 2 were screened for antibacterial and antifungal activities.

A new tetranuclear distorted open-cubane copper(II) Schiff base complex: Structural, spectral and magnetic characterizations

A new tetranuclear complex [Cu4(L)4] (1) (H2L = N-(2-hydroxyethyl)-3-metoxysalicylaldimine) has been synthesized and characterized by crystal structure analysis and magnetic susceptibility. Single-crystal X-ray diffraction studies reveal that complex 1 contains three independent Cu4O4 open-cubane cores of 4+2 type (four short and two long Cu•••Cu distances), where the copper(II) centers are linked by alkoxo-bridges. Each copper(II) ion have a distorted square-pyramidal geometry. Variable-temperature magnetic susceptibility measurements on the tetranuclear complex 1 in the range 2-300 K indicate dominant antiferromagnetic coupling (J =–108.46) between copper(II) centers.

3-D polymeric structure formed by hydrogen bonds of copper (II) complex

ABSTRACT A new copper complex trans-Dichlorobis[4-methoxypyridine]copper(II) (1) was synthesized and its crystal structure determined by X-ray diffraction. The close Cu···Cl contacts between the molecular units form bi-bridged dimers. The Copper(II) ion completes its 4 + 2 coordination via interaction with the Cu···Cl close contact. The complex has a polymeric structure of infinite one-dimensional (1D) bi-bridged chains, consisting of six-coordinate copper(II) units. C–H···C l intermolecular interaction connect the 1D-chains in the structure of 1 which form to 3D structure. The π ··· π interactions between the aromatic rings are also observed in the hydrogen bonded assembly of 1.

Crystal structure and magnetic properties of dinuclear iron(III) complex with ONNO-donor ligand

A new dinuclear Fe(III) complex, [Fe(5-MeOL1)(OH)0.86(CH3O)0.14]2•2(CH3OH), [H2-5-MeOL1 = N,N′-bis(5-methoxy-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine], 1 has been synthesized and characterized by single crystal structure analysis. The structure of 1 consists of two Fe(III) centers with one tetradentate schiff base ligand (N2O2) which are bridged by dihydroxo/dimethoxo groups to yield a Fe2O2 core. Complex 1 exhibits weak antiferromagnetic exchange interaction between Fe(III) ions with J = −0.21 cm–1.

A dinuclear oxygen-bridged Schiff base iron(III) complex derived from N , N ′-bis(4-methoxy-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine

The μ-oxo-bridged Fe(III) dimer complex [{Fe(4-MeOL1)}2(μ-O)]∙HOCH3, (H2-4-MeOL1 = N,N′-bis(4-methoxy-2-hydroxybenzylidene)-2,2-dimethylpropane-1,3-diamine), 1 is synthesized and characterized by single crystal X-ray diffraction. Complex 1 contains a [{Fe(4-MeOL1)}2(μ-O)] dimeric unit with a methanol solvent molecule of crystallization. Each Fe(III) ion has a distorted square-pyramidal coordination geometry. In the basal plane, the Fe(III) atom is coordinated by two N and two O atoms of the Schiff base ligand. The apical position is occupied by a bridging O2– ion, linking another Fe(III) ion in the complex. There are intermolecular C–H…O and C–H…π interactions among the dinuclear complexes.