Nefise Dilek

DFT calculations, spectroscopy and antioxidant activity studies on (E)-2-nitro-4-[(phenylimino)methyl]phenol

We have reported synthesis and characterization of (E)-2-nitro-4-[(phenylimino)methyl]phenol by using X-ray crystallographic method, FT-IR and UV-vis spectroscopies and density functional theory (DFT). Optimized geometry and vibrational frequencies of the title compound in the ground state have been computed by using B3LYP with the 6-311G+(d,p) basis set. HOMO-LUMO energy gap, Non-linear optical properties and NBO analysis of the compound are performed at B3LYP/6-311G+(d,p) level. Additionally, as remarkable properties, antioxidant activity of the title compound (CMPD) has been determined by using different antioxidant test methods i.e. ferric reducing antioxidant power (FRAP), hydrogen peroxide scavenging (HPSA), free radical scavenging (FRSA) and ferrous ion chelating activities (FICA). When compared with standards (BHA, BHT, and α-tocopherol), we have concluded that CPMD has effective FRAP, HPSA, FRSA and FICA.

Synthesis, structure, spectroscopic (FT-IR) and density functional modelling studies of 1-[(4-ethoxyphenylimino)methyl]napthalene-2-ol

Synthesis, crystallographic characterisation, spectroscopic (Fourier transform infrared spectroscopy [FT-IR]) and density functional modelling studies of the Schiff base 1-[(4-ethoxyphenylimino)methyl]napthalene-2-ol (C19H17NO2) have been reported. The molecular structure obtained from X-ray single-crystal analysis of the investigated compound in the ground state has been compared using Hartree–Fock and density functional theory (DFT) with the 6-311++G(d,p) basis set. In addition to the optimised geometrical structures, atomic charges, molecular electrostatic potential, natural bond orbital, non-linear optical (NLO) effects and thermodynamic properties of the compound have been investigated by using DFT. The experimental (FT-IR) and calculated vibrational frequencies (using DFT) of the title compound have been compared. The solvent effect was also investigated for obtained molecular energies and the atomic charge distributions of the compound. There exists a good correlation between experimental and theoretical data for enol-imine form of the compound. The total molecular dipole moment (µ), linear polarisability (α), and the first-order hyperpolarisability (β) were predicted by the B3LYP method with different basis sets 6-31G(d), 6-31+G(d,p), 6-31++G(d,p), 6-311+G(d) 150 and 6-311++G(d,p) for investigating the effects of basis sets on the NLO properties. Our computational results yield that βtot for the title compound is greater than those of urea.

Crystal structure, DFT and HF calculations and radical scavenging activities of (E)-4,6-dibromo-3-methoxy- 2-((3-methoxyphenylimino)methyl)phenol

In this study, (E)-4,6-dibromo-3-methoxy-2-[(3-methoxyphenylimino)methyl]phenol has been synthesized and characterized by using X-ray technique and FT-IR experimentally and using B3LYP/6-31G(d,p) and HF/6-31G(d,p) methods theoretically. The intermolecular and intramolecular interactions of the title compound have been determined according to X-ray results. The molecular geometry, vibrational frequencies of the title compound in the ground state have been calculated using the density functional B3LYP and HF method with the 6-31G(d,p) basis set and calculated bond parameters and vibrational frequencies values show good agreement with experimental values. Theoretical and experimental results show that tautomeric form of the structure is phenol-imine form. Besides HOMO-LUMO energy gap, molecular electrostatic potential map were performed at B3LYP/6-31G(d,p) level. It is worthy note of that, the free radical scavenging activities of the title compound were assessed using DPPH˙, DMPD˙(+), and ABTS˙(+) assays. The obtained results show that the title compound has effective DPPH˙ (SC50 2.61±0.09 μg/mL), DMPD˙(+) (SC50 2.82±0.14 μg/mL), and ABTS˙(+) (SC50 4.91±0.18 μg/mL) radical scavenging activities when compared with standard antioxidants (BHA, rutin, and trolox).

Synthesis, structural characterization and DNA interaction of zinc complex from 2,6-diacetylpyridine dihydrazone and {4-[(2E)-2-(hydroxyimino)acetyl]phenoxy} acetic acid.

A new water soluble zinc complex has been prepared and structurally characterized. The Zn(II) complex was synthesized by the reaction of 2,6-diacetylpyridine dihydrazone (dph) with {4-[(2E)-2-(hydroxyimino)acetyl]phenoxy} acetic acid (H₂L) in the presence of zinc(II) acetate. Single crystal X-ray diffraction study revealed that the zinc ion is situated in distorted trigonal-bipyramidal environment where the equatorial position is occupied by the nitrogen atom of pyridine ring and the oxygen atoms of acetate groups of two oxime ligands (H₂L) whereas the axial positions of the zinc complex are occupied by the imine nitrogen atoms of dph ligand. Characterization of the complex with FTIR, (1)H and (13)C NMR, UV-vis and elemental analysis also confirmed the proposed structure. Interaction of the Zn(II) complex with calf-thymus DNA (CT-DNA) was investigated through UV-vis spectroscopy and viscosity measurements. The results suggest that the complex preferably bind to DNA through the groove binding mode. The zinc complex cleaves plasmid pBR 322 DNA in the presence and absence of an oxidative agent (H₂O₂), possibly through a hydrolytic pathway which is also supported by DNA cleave experiments in the presence of different radical scavengers. The nuclease activity of the zinc complex significantly depends on concentration of the complex and incubation time both in the presence and absence of H₂O₂. DNA cleave activity is inhibited in the presence of methyl green indicating that the zinc complex seems to bind the major groove of DNA.

Synthesis, Crystal Structure, and Spectroscopic Studies of N-(4-Bromobenzylidene)-N′-(2-Pyridyl) Hydrazine Schiff Base Molecule

A new Schiff base complex N-(4-bromobenzylidene)-N′-(2-pyridyl) hydrazine, C12H10N3Br, has been synthesized and characterized by elemental analyses, mass, 1H NMR, ultraviolet–visible (UV–VIS), and IR spectroscopy and single-crystal X-ray determination. The p-Br-benzene and pyridine rings are almost planar and the dihedral angle between the planes is 11.1(3)°. The crystal structure is stabilized by intermolecular N‒H…N‒Py hydrogen bonding interaction. X-ray diffraction analyses show that N-(4-bromobenzylidene)-N′-(2-pyridyl) hydrazine Schiff base molecule crystallizes in the monoclinic system, P21/c space group, a = 5.611(5) Å, b = 19.566(5) Å, c = 10.715(5) Å, β = 98.766(5)°, and V = 1162.60(12) Å3.

Molecular structure, quantum mechanical calculation and radical scavenging activities of (E)-4,6-dibromo-2-((3,5-dimethylphenylimino) methyl)-3-methoxyphenol and (E)-4,6-dibromo-2- ((2,6-dimethylphenylimino)methyl)-3-methoxyphenol compounds

In this study, (E)-4,6-dibromo-2-[(3,5-dimethylphenylimino)methyl]-3-methoxyphenol and (E)-4,6-dibromo-2-[(2,6-dimethylphenylimino)methyl]-3-methoxyphenol compounds have been synthesized and characterized by using X-ray crystallographic method, FT-IR and Density functional method. The molecular geometry, vibrational frequencies of the title compounds in the ground state have been calculated by using B3LYP with the 6-31G(d,p) basis set. The tautomeric form of the compounds has been demonstrated by using single crystal X-ray method, FT-IR spectrometer and DFT method. In addition, HOMO-LUMO energy gap, molecular electrostatic potential map and NBO analysis of the compounds are performed at B3LYP/6-31G(d,p) level. It may be remarked that the free radical scavenging activities of the title compounds were assessed using DPPH, DMPD+, and ABTS+ assays. The obtained results show that especially compound 2 has effective DPPH (SC50 1.52±0.14 μg/mL), DMPD+ (SC50 1.22±0.21 μg/mL), and ABTS+ (SC50 3.32±0.17 μg/mL) scavenging activities compared with standards (BHA, rutin, and trolox).

Seven-coordinated cobalt(II) complexes with 2,6-diacetylpyridine bis(4-hydroxybenzoylhydrazone): synthesis, characterisation, DNA binding and cleavage properties

Synthesis and characterisation of three seven-coordinated cobalt(II) complexes of 2,6-diacetylpyridine bis(4-hydroxybenzoylhydrazone) (H4L) ligand, [Co(H2L)(H2O)2] (1), [Co(H4L)(N3)2] (2) and [Co(H4L)(NCS)2] (3) are described. The structures of the complexes were characterised by elemental analysis, IR, UV–vis and magnetic susceptibility measurement. The molecular structure of the [Co(H4L)(NCS)2] (3) was also determined by X-ray crystallography. Single crystal X-ray revealed that the Co(II) complex (3) has a pentagonal–bipyramidal coordination geometry, with pentadentate N3O2 ligand in the equatorial plane of the bipyramid and two isothiocyanato groups in the axial area. Interaction of the cobalt(II) complexes with CT-DNA was investigated by absorption titration method and viscosity measurements. Cleavage activity of the complexes with pBR 322 plasmid DNA was evaluated by agarose gel electrophoresis in presence and absence of an oxidative agent, and the mechanism of DNA cleavage was investigated. The results suggest that the cobalt(II) complexes bind effectively and they exhibit nuclease activity, which has strong dependence on the concentration of complex and reaction time, both in presence and absence of hydrogen peroxide.

Crystal structure of bis(isothiocyanato)[2,6-diacetylpyridine bis(4-hydroxybenzoylhydrazone)]Fe(III) Chloride bis(dimethylformamide) solvate

The crystal structure of title compound (Fe[(C25H21N7O4S2)] · 4(C3NOH7), where C3NOH7 is dimethylformamide, DMF) was determined by the X-ray diffraction method. This compound crystallizes in the monoclinic C2/c space group, Z = 4. Unit cell parameters are: a = 13.6080(5), b = 17.6375(7), c = 19.5571(6) Å, β = 108.753(2)°. The N-H...O and O-H...O interactions stabilize the molecules in the lattice. The structure contains also the solvent dimethylformamide molecules, which are connected with intermoleculer hydrogen bond. The O atoms of DMF molecules take place as acceptor atoms.

One-pot synthesis of a new 2-substituted 1,2,3-triazole 1-oxide derivative from dipyridyl ketone and isonitrosoacetophenone hydrazone: Nickel(II) complex, DNA binding and cleavage properties

An efficient and simple one-pot synthesis of a new 1,2,3-triazole-1-oxide via reaction between isonitrosoacetophenone hydrazone and dipyridyl ketone in the EtOH/AcOH at room temperature has been developed smoothly in high yield. The reaction proceeds via metal salt free, in-situ formation of asymmetric azine followed by cyclization to provide 1,2,3-triazole 1-oxide compound. It has been structurally characterized. The 1:1 ratio reaction of the 1,2,3-triazole 1-oxide ligand with nickel(II) chloride gives the mononuclear complex [Ni(L)(DMF)Cl2], hexa-coordinated within an octahedral geometry. Characterization of the 1,2,3-triazole compound and its Ni(II) complex with FTIR, 1H and 13C NMR, UV-vis and elemental analysis also confirms the proposed structures of the compounds. The interactions of the compounds with Calf thymus DNA (CT-DNA) have been investigated by UV-visible spectra and viscosity measurements. The results suggested that both ligand and Ni(II) complex bind to DNA in electrostatic interaction and/or groove binding, also with a slight partial intercalation in the case of ligand. DNA cleavage experiments have been also investigated by agarose gel electrophoresis in the presence and absence of an oxidative agent (H2O2). Both 1,2,3-triazole 1-oxide ligand and its nickel(II) complex show nuclease activity in the presence of hydrogen peroxide. DNA binding and cleavage affinities of the 1,2,3-triazole 1-oxide ligand is stronger than that of the Ni(II) complex.

Probing the effect of arm length and inter- and intramolecular interactions in the formation of Cu(II) complexes of Schiff base ligands derived from some unsymmetrical tripodal amines

The syntheses of two previously known, 2-((2-aminoethyl)(pyridin-2-ylmethyl)amino)ethanol (1) and 2-((3-aminopropyl)(pyridin-2-ylmethyl)amino)ethanol (2), and four new unsymmetrical N-capped tripodal amines, 2-((4-aminobutyl)(pyridin-2-ylmethyl)amino)ethanol (3), 3-((2-aminoethyl)(pyridin-2-ylmethyl)amino)propan-1-ol (4), 3-((3-aminopropyl)(pyridin-2-ylmethyl)amino)propan-1-ol (5) and 3-((4-aminobutyl)(pyridin-2-ylmethyl)amino)propan-1-ol (6), are reported. The ligands (3–4) feature a longer arm, 3-hydroxypropyl or butylamino, than in the analogues previously employed (2-hydroxyethyl arm, ethylamino-arm or propylamino-arm in 1 and 2). All six tripodal amines, 1–6, are equipped with a 2-methylpyridyl-arm and either an ethylamino-arm (1 and 4), propylamino-arm (2 and 5) or butylamino-arm (3 and 6). The new amines, 3–6, have been employed in one pot condensation reactions with 2-hydroxy-1-naphthaldehyde and salicylaldehyde (and its derivatives) in the presence of Cu(II) metal ions to generate a series of new mononuclear complexes, [MIILaldi](ClO4) as well as new dinuclear complexes [CuIILaldi]2(ClO4)2 of new ligands Laldi. Four monomeric complexes and one dimeric complex have been characterised by single crystal X-ray diffraction, revealing a distorted square-pyramidal copper(II) ion. A general comparison between these structures shows that the number and types of chelate ring sequences around the metal ions are important in the formation of structures. Theoretical studies show that the 3-hydroxypropyl arm in these complexes is a weak coordinating group and it can readily be removed from the coordination sphere of metal ions, resulting in a dimerised four coordinate complex. Calculations show that the interaction between the two monomeric fragments is very weak.