Synthesis, spectral characterization and crystal structure of N-2-hydroxy-4-methoxybenzaldehyde-N'-4-nitrobenzoyl hydrazone and its square planar Cu(II) complex

Synthesis of Novel Cu(II), Co(II), Fe(II), and Ni(II) Hydrazone Metal Complexes as Potent Anticancer Agents: Spectroscopic, DFT, Molecular Docking, and MD Simulation Studies

Metal complexes [FeL], [NiL]·H2O, [CuL], and [CoL]·H2O were formed by the ligand (L, 4-fluoro-N'-(2-hydroxybenzylidene)benzohydrazide) reacting with Fe(OAc)2, Ni(OAc)2·4H2O, Cu(OAc)2·H2O, and Co(OAc)2·4H2O. The produced compounds were characterized using a variety of methods, such as NMR, UV-vis, FT-IR, magnetic susceptibility, elemental analysis, and molar conductivity. The spectrum of the data indicates that the geometry of the complex molecular structures is octahedral with six coordination sites. The ligand and its different metal complexes were tested in a human lung cancer cell line and a normal embryonic kidney cell line. A cytotoxic assay revealed that L-Cu is the most potent chelate against cancer cell lines. A computational study was performed to rationalize this finding. The binding potential of relatively active compounds to a suitable target was analyzed. For this purpose, a target that is known to be inhibited by small compounds with a scaffold similar to that of the synthesized compounds, lysine-specific demethylase 1 (LSD1), was first determined. Molecular docking studies demonstrated that L-Cu has a high binding potential to LSD1 at a level comparable to that of a standard ligand. Molecular dynamics (MD) simulations revealed that L-Cu and L form stable complexes with the enzyme. Furthermore, the MD simulation study showed that L-Cu remained inside the binding pocket of the enzyme during the 200 ns simulation period. Density functional theory (DFT) studies demonstrated that the chemical stability of L was higher than that of its chelate form, L-Cu.

Formation of Tetranuclear Nickel(II) Complexes with Schiff-Bases: Crystal Structures and Magnetic Properties

The cubane-type structure is a typical representative of tetranuclear coordination compounds. In this work, two anionic Schiff-base ligands, (L1)2− and (L2)2−, each offering an O^N^O coordination pocket, ligate four NiII ions into a [Ni4O4] cubane core. The ligands are H2L1 = 2−[[(3-ethoxy-2−hydroxyphenyl) methylene]amino]benzenemethanol and H2L2 = 2−[[(5-fluoro-2−hydroxyphenyl)methylene]amino]benzenemethanol. In both compounds, [Ni4(L1)4(EtOH)4] (1) and [Ni4(L2)4(MeOH)4] (2), alkoxy oxygens of the ligands act in a bridging μ3-O binding mode. Magnetic susceptibility and magnetization data for compounds 1 and 2 are presented. The Ni–O–Ni bond angles of the cubane core determined from single crystal X-ray diffraction data play a key role for a magneto-structural correlation. Dominant intracube ferromagnetic behavior is observed, and the coupling parameters were determined for both compounds, leading to nonzero spin ground states in accordance with the broadly accepted bond angle guideline.

Synthesis, Structural Characterization, Molecular Modeling and DNA Binding Ability of CoII, NiII, CuII, ZnII, PdII and CdII Complexes of Benzocycloheptenone Thiosemicarbazone Ligand

Background & Objective:

Six novel complexes of transition metal namely, [CoLCl2(H2O)2]0.5H2O, [NiLCl2(H2O)2]0.5H2O, [CuLCl2]0.5H2O, [ZnLCl2], [PdLCl2]H2O and [CdLCl2]H2O, where L is benzocycloheptenone thiosemicarbazone ligand, have been obtained. The confirmation of the structures of the obtained metal chelates depends on the different spectral and physicochemical techniques including CHN analysis, infrared spectra, molar conductivity measurement, UV-vis, thermogravimetric analysis and magnetic moment. The infrared spectral results ascertained that the ligand behaved as neutral bidentate connecting the metal centers via N and S atoms of C=N and C=S groups, respectively.

Methods:

The UV-Vis, molar conductivity and magnetic susceptibility results implied that the geometrical structures of the metal chelates are octahedral for Co(II) & Ni(II) complexes, tetrahedral for Zn(II) & Cd(II) complexes and square planar for Cu(II) & Pd(II) complexes which have been confirmed by molecular modeling studies.

Conclusion:

Moreover, the mode of interaction between some chosen metal complexes towards SSDNA has been thoughtful by UV-Vis spectra and viscosity measurements. The value of the intrinsic binding constant (Kb) for the examined compounds has been found to be lower than the binding affinity of the classical intercalator ethedium bromide. Also, the viscosity measurements of the complexes proved that they bind to DNA, most likely, by a non-intercalative mode like H-bonding or electrostatic interactions.

Copper(ii) complexes with benzhydrazone-related ligands: synthesis, structural studies and cytotoxicity assay

The present study reports the synthesis and characterization of copper(ii) complexes with benzhydrazone-related ligands. They were screened for their cytotoxic activityin vitroin THP-1 and HepG2 human cancer cell lines.

Vibrational spectroscopic and molecular docking study of (2E)-N-(4-chloro-2-oxo-1,2-dihydroquinolin-3-yl)-3-phenylprop-2-enamide

FT-IR and FT-Raman spectra of (2E)-N-(4-chloro-2-oxo-1,2-dihydroquinolin-3-yl)-3-phenylprop-2-enamide were recorded and analyzed experimentally and theoretically. The synthesis, (1)H NMR and PES scan results are also discussed. Nonlinear optical behavior of the examined molecule was investigated by the determination of first hyperpolarizability. The calculated HOMO and LUMO energies show the chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. From the MEP it is evident that the negative charge covers the carbonyl group and the positive region is over the NH group. The calculated geometrical parameters (SDD) are in agreement with that of similar derivatives. Molecular docking simulations against targets from Mycobacterium tuberculosis are reported and the results suggest that the compound might exhibit inhibitory activity against PknB.

Synthesis, characterization, structural analysis of metal(II) complexes of N'-[(E)-3-Bromo-5-Chloro-2-hydroxybenzidene]-4-hydroxybenzohydrazide-Multisubstituted Schiff base as a F(-) and Cu(2+) ions selective chemosensor

New colorimetric chemosensor, N'-[(E)-3-Bromo-5-Chloro-2-hydroxybenzidene]-4-hydroxybenzohydrazide, containing OH and NH groups as binding sites have been synthesized and characterized by spectral UV, IR, NMR and ESR. The molecular structure of ligand is determined by X-ray crystallography and it has the monoclinic space group P21/c with cell parameters a=15.1058(6), b=14.3433(6), c=17.5800(8)Å and Z=8. The electronic spectral measurements show that Co(2+), Ni(2+) and Zn(2+) complexes have tetrahedral geometry, while Cu(2+) complex has square planar geometry. Magnetic measurements show that Cu(2+), Co(2+) and Ni(2+) complexes have paramagnetic behavior and Zn(2+) complex has diamagnetic behavior. Anion binding studies carried out using (1)H NMR and UV-visible spectrophotometric titrations revealed that these receptors exhibit selective recognition towards F(-) over other halide anions. The selectivity for F(-) among the halides is attributed mainly to the hydrogen-bond interaction of the receptor with F(-). Receptor (5 × 10(-5)M) shows color change from colorless to yellow in the presence of tetrabutylammonium fluoride (TBAF, 1.5 × 10(-3)M). Moreover, F(-)-induced color changes remain the same even in the presence of large excess of Cl(-), Br(-) and I(-). The binding constant is found to be higher towards F(-) ion and this may be due to presence of OH group, which offers extra binding site. Chromogenic receptor undergoes distinct color changes from colorless to green on gradual addition of Cu(2+) can be used as colorimetric probes for spectrophotometric and visual analysis of Cu(2+) in the presence of other transition metal ions such as Co(2+), Ni(2+) and Zn(2+).

Structural investigations of aroylhydrazones derived from nicotinic acid hydrazide in solid state and in solution

Structural forms of aroylhydrazones derived from nicotinic acid hydrazide have been studied in the solid state by FT-IR spectroscopy and in solution by NMR, UV-Vis and ATR spectroscopy. The studied compounds were N'-benzylidene-3-pyridinecarbohydrazide (1), N'-(2,4-dihydroxyphenylmethylidene)-3-pyridinecarbohydrazide (2), N'-(5-chloro-2-hydroxyphenylmethylidene)-3-pyridinecarbohydrazide (3), and N'-(3,5-dichloro-2-hydroxymethoxyphenylmethylidene)-3-pyridinecarbohydrazide (4). The compound 1 adopted the most stable ketoamine form (form I, -CO-NH-N=C-) in the solid state as well as in various organic solvents. In mixtures of organic solvents with water the UV-Vis and ATR spectra implied intermolecular hydrogen bonding of 1 with water molecules. The presence of both tautomeric forms I and II (form II, -COH=N-N=C-) was proposed for the solid substance and highly concentrated solutions of 2, whereas form I was detected as the predominant one in diluted solutions. For compounds 3 and 4 a coexistence of forms I and III (form III, -CO-NH-NH-C=C-CO-) was noticed in the solid state and in polar protic organic solvents. The conversion to form III was induced by increasing the water content in the solvent mixtures. This process was the most pronounced for compound 4. When exposed to daylight, an appearance of a new band was observed during time in the UV-Vis spectrum of 4 in organic solvent/water 1/1 mixtures, which implied that tautomeric interconversion was most likely followed by E/Z isomerisation.

Coordination behavior of tetraaza [N₄] ligand towards Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes: synthesis, spectroscopic characterization and anticancer activity

Novel eight Co(II), Ni(II), Cu(II), Cu(I) and Pd(II) complexes with [N(4)] ligand (L) i.e. 2-amino-N-{2-[(2-aminobenzoyl)amino]ethyl}benzamide have been synthesized and structurally characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and molar conductivity measurements. On the basis of IR, mass, electronic and EPR spectral studies an octahedral geometry has been proposed for Co(II), Ni(II) complexes and Cu(II) chloride complex, square-pyramidal for Cu(I) bromide complex. For Cu(II) nitrate complex (6), Pd(II) complex (8) square planar geometry was proposed. The EPR data of Cu(II) complexes in powdered form indicate d(x2-y2) ground state of Cu(II) ion. The antitumor activity of the synthesized ligand and some selected metal complexes has been studied. The palladium(II) complex (8) was found to display cytotoxicity (IC(50)=25.6 and 41 μM) against human breast cancer cell line MCF-7 and human hepatocarcinoma HEPG2 cell line.

Structural investigation of aroylhydrazones in dimethylsulphoxide/water mixtures

Molecular structures of aroylhydrazones derived from salicylaldehyde, o-vanilin and nicotinic acid hydrazide in DMSO and DMSO/H(2)O mixtures have been studied by NMR, UV-Vis, ATR and Raman spectroscopy. The addition of water to the system did not induce the tautomeric conversion of the existing form constituted of the ketoamino hydrazide part and the enolimino aldehyde part, but it was involved in the formation of hydrated molecules. Vibrational spectra (ATR and Raman) clearly indicated hydrogen bonding of the studied hydrazones through the carbonyl, amino and hydroxyl groups with water molecules. Increasing the water content conversion from E to Z isomer was not observed.

Spectral studies of copper(II) complexes of tridentate acylhydrazone ligands with heterocyclic compounds as coligands: X-ray crystal structure of one acylhydrazone copper(II) complex

Six copper(II) complexes of 2-hydroxy-4-methoxybenzaldehyde nicotinoylhydrazone (H2hmbn), 2-hydroxy-4-methoxyacetophenone nicotinoylhydrazone (H2hman), 2-hydroxy-4-methoxybenzaldehyde benzoylhydrazone (H2hmbb) and 2-hydroxy-4-methoxyacetophenone benzoylhydrazone (H2hmab) have been synthesized. The complexes viz. [Cu(hmbn)](2)·2H(2)O (1), [Cu(hman)](2) (2), [Cu(hmbb)](2)·2H(2)O (3), [Cu(hmbb)phen]·1(1/2)H2O (4), [Cu(hmbb)(bipy)·H2O] (5) and [Cu(hmab)phen] (6) were characterized by different physicochemical techniques. The crystal structure of [Cu(hman)phen] is obtained and it has a distorted square pyramidal geometry with π-π stacking interactions and significant C-H π interactions.

Molecular structures, spectral and computational studies on nicotinohydrazides

The FT-IR and the high resolution (1)H and (13)C NMR spectra have been recorded for N'-(2-methyl-3-phenylallylidene)nicotinohydrazide (1) and N'-(2-methyl-3-phenylallylidene)isonicotinohydrazide (2) and analyzed. (1)H-(1)H COSY spectra were also recorded for the hydrazides. The spectral studies reveal that both the hydrazides exist in the keto form. Theoretical calculations were performed for some possible conformations of the hydrazide and the minimum energy conformers are predicted to be the one in which the azomethine protons are syn to N-NH bond. From the optimized structures, HOMO-LUMO energy gap and geometrical parameters were derived and these parameters were compared with the XRD measurements of hydrazide 1. The vibrational frequencies in the ground state have been calculated using DFT and HF methods and compared with the observed frequencies. Non-linear optical (NLO) behaviour of the hydrazides was investigated by the determination of the electric dipole moment mu, the polarizability alpha and the hyperpolarizability beta using B(3)LYP method.

Spectroscopic, thermal and toxicity studies of some 2-amino — 3- cyano — 1, 5 -diphenylpyrrole containing Schiff bases copper (II) complexes

Two novel Schiff base ligands of 2-amino-3-cyano-1,5-diphenylpyrrole and salicylaldehyde (HL1) or 2- hydroxy1-naphthylaldehyde (HL2) and their copper(II) complexes have been synthesized and characterized by elemental analyses, spectral (UV-Vis, IR, EPR, Mass (for ligands)), thermal (DTA-TGA) methods, magnetic and conductance measurements. IR results demonstrate the bidentate binding of the Schiff base ligands involving azomethine nitrogen, phenolic or naphtholic oxygen and suggest the presence of HL2 and complexes (1, 2, 4 and 8) in enolimine-ketonamine tautomeric forms in the solid state. The EPR spectral data of complexes (2, 5, 6) show that the metal — ligand bonds have considerable covalent character. The thermal studies show that complexes (1, 2, 4 and 8) that are present in enolimine-ketonamine tautomeric forms exhibit lower thermal stability. The effect of synthesized ligands (HL1, HL2) and complexes (1, 5) were tested on the mortality of entomopathogenic nematodes (EPN) (Heterorhabditis bacteriophora and Steinernema carpocapsae). The study shows that the mortality of the nematodes increased with increasing concentrations of copper(II) ion, ligands and complexes. Copper(II) ion was the most toxic for EPN.

N'-(3-Methoxy-benzyl-idene)-4-nitro-benzohydrazide monohydrate

There are two independent formula units in the asymmetric unit of the title compound, C(15)H(13)N(3)O(4)·H(2)O. The C=C-N-C torsion angle of the methyl-idenehydrazide group is 174.3 (2)° in one mol-ecule and 178.6 (2)° in the other. The dihedral angles between the two benzene rings in the two mol-ecules are 4.17 (12) and 3.58 (12)°. In the crystal structure, inter-molecular O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds link the components into a two-dimensional network and additional stabilization is provided by weak inter-molecular C-H⋯O hydrogen bonds.

4-Nitro-N'-[(E)-3-pyridylmethyl-idene]benzohydrazide

In the title moleclue, C(13)H(10)N(4)O(3), the methyl-idene-hydrazide [-C(=O)-N-N=C-] fragment is essentially planar, with a maximum deviation of 0.0228 (7) Å. The mean planes of the benzene and pyridine rings make dihedral angles of 25.44 (6) and 5.47 (7)°, respectively, with the mean plane of the methyl-idene-hydrazide fragment. In the crystal structure, inter-molecular N-H⋯N hydrogen bonds link mol-ecules into chains along the b axis. Additional stabilization is provided by weak inter-molecular C-H⋯O hydrogen bonds. The O atoms of the nitro group are disordered over two sets of sites of equal occupancy.

Spectroscopic study and structure of (E)-2-[(2-chlorobenzylimino)methyl]methoxyphenol

(E)-2-[(2-chlorobenzylimino)methyl]methoxyphenol has been synthesized from the reaction of 2-hydroxy-3-methoxy-1-benzaldehyde(o-vanillin) with 2-chlorobenzylamine. The title compound has been characterized by using elemental analysis, FT-IR, (1)H NMR, (13)C NMR and UV-vis spectroscopic techniques. The crystal structure of the title compound has also been examined cyrstallographically. It crystallizes in the orthorhombic space group Pbca with unit cell parameters: a = 7.208(1) A, b = 13.726(2) A, c = 27.858(4) A, V = 2756.0(1) A(3), D(c) = 1.18 g cm(-3) and Z = 8. The crystal structure was solved by direct methods and refined by full-matrix least squares to a find R = 0.046 for 2773 observed reflections.