Aroyl Hydrazones Research Articles

Microwave assisted synthesis, spectroscopic and antibacterial studies of bis(cyclopentadienyl)hafnium(IV) derivatives with benzil bis(aroyl hydrazones)

The reactions of (η5-C5H5)2HfCl2 with benzil bis(hydrazones) (LH2), derived from benzil and aromatic acid hydrazides (benzoic, 2-chlorobenzoic, 4-chlorobenzoic, 2-methylbenzoic or 4-methoxybenzoic) have been studied in anhydrous tetrahydrofuran in the presence of n-butylamine by both conventional methods and by microwave heating. Binuclear complexes of type [{(η5-C5H5)2HfCl}2(L)] were obtained in both cases. Tentative structural conclusions are drawn for the reaction products based upon analyses, electrical conductance, magnetic moment and spectral (UV–vis, IR, 1H NMR and 13C NMR) data. A FAB-mass spectrum of one compound was also recorded to confirm the binuclear structures. Studies were conducted to assess the growth inhibiting potential of the complexes and free ligands against various bacterial strains.

Crystal engineering with aroyl hydrazones of diacetyl monooxime – Molecular and supramolecular structures of two Ni(II) and two Zn(II) complexes

Four new Schiff bases of aroyl hydrazides with diacetyl monooxime have been prepared, and Ni(II) and Zn(II) complexes of these ligands have been synthesized. Two Ni(II) and two Zn(II) complexes have been characterized by X-ray crystallography. The aroyl hydrazone ligands were designed in such a way that there is a systematic variation in the H-bond forming abilities of their aroyl moiety, e.g. both H-bond acceptor and donor (salicyloyl), only H-bond donor (anthraniloyl), only H-bond acceptor (isonicotinoyl). It is shown in this work that such a variation in the H-bond donor acceptor properties of the ligands leads to considerable diversity in their supramolecular architecture.

Versatility of 2,6-diacetylpyridine (dap) hydrazones in generating varied molecular architectures: Synthesis and structural characterization of a binuclear double helical Zn(ii) complex and a Mn(ii) coordination polymer

A binuclear complex of Zn(ii) with formula [Zn(dap(A)(2))](2).2.25DMF (.2.25DMF) and a Mn(ii) coordination polymer with formula [Mn(3)(dap(In)(2))(3)(H(2)O)(2).2DMSO](n) (.2DMSO)(n) have been prepared and structurally characterized [dap(A)(2) = dideprotonated form of 2,6-diacetylpyridine bis(anthraniloyl hydrazone); dap(In)(2) = doubly deprotonated form of 2,6-diacetylpyridine bis(isonicotinoyl hydrazone)]. In the Zn(ii) complex the molecular units are double helical, with the Zn(ii) ions in a square pyramidal environment. The Mn(ii) complex on the other hand is a coordination polymer containing two different types of hepta-coordinated Mn(ii) ions, which differ in their axial ligands. The magnetic properties of the Mn(ii) complex, along with those of a double helical pyridine bridged binuclear Ni(ii) complex, earlier synthesized by us, are also reported. The ability of the 2,6-diacetylpyridine bis(aroyl hydrazone) ligands to form double helical complexes is analyzed in terms of the conformational flexibility of the ligands. The differences in the magnetic properties of the micro-N bridged binuclear complexes formed by 1,1 azido N-bridging ligands, and pyridine N-bridging ligands, is analyzed with the help of EHMO calculations.

N-2-Hydroxy-4-methoxyacetophenone- N′-4-nitrobenzoyl hydrazine: Synthesis and structural characterization

A new aroyl hydrazone, N-2-hydroxy-4-methoxyacetophenone- N′-4-nitrobenzoyl hydrazine was prepared by the condensation reaction of 2-hydroxy-4-methoxyacetophenone and 4-nitrobenzoyl hydrazine. Characterization of the compound was done by elemental analysis and electronic, infrared and NMR spectral analyses. The complete structural assignment of the compound was done by NMR studies by using COSY homonuclear and HSQC heteronuclear techniques. The crystal and molecular structure was determined by single crystal X-ray diffraction studies: crystallized in the monoclinic system, space group P2 1/ n, Z = 4, a = 7.3343(9) Å, b = 20.3517(9) Å, c = 10.1375(5) Å, α = 90.00°, β = 95.735(7)° and γ = 90.00°. From the crystal structure, it is concluded that the compound exists as the keto isomer in the solid state. There is a completely extended conformation in the central part of the molecule C5 C8 N1 N2 C10 O2 with an E configuration at the double bond of the hydrazinic bridge.

Studies on the relative stabilities of Mn(II) and Mn(III) in complexes with N 4O 2 donor environments: crystal structures of [Mn(pybzhz) 2] and [Mn(Ophsal)(imzH) 2] ClO 4 (pybzhz = N-(benzoyl)- N′-(picolinylidene) hydrazine, Ophsal = N,N′- o-phenylenebis(salicylideneimine), imzH = imidazole)

Manganese(II) complexes of four aroyl hydrazone ligands were prepared and characterized by different physicochemical techniques. The complexes are of the type Mn(L) 2, where L stands for the deprotonated hydrazone ligand. One of the compounds, Mn(pybzhz) 2, was also characterized by single crystal structure determination. In all these complexes, the Mn(II) is in an N 4O 2 donor environment and the Mn(II) center cannot be oxidized either chemically or electrochemically. However, when another ligand Ophsal is used to give the compound [Mn(Ophsal)(imzH) 2]ClO 4, which was also characterized by X-ray crystal structure determination, manganese can easily avail the +3 oxidation state. The relative stabilities of the +2 and +3 oxidation states of manganese were analyzed and it was concluded that the extent of distortion from the perfect octahedral geometry is the main controlling factor in these cases.

Binuclear complexes with uranyl ions in non-equivalent coordination environments – 2. Synthesis and electrochemistry of the complexes with binucleating aroyl hydrazones and 1,10-phenanthroline

The ternary binuclear complexes, [(UO2phen)2L1–5](NO3) n · S (1–3): n = 1; (4, 5): n = 2; S = solvent {H3L1–3 = 1-(2-hydroxybenzoyl)-2-(2-hydroxybenzal/2-hydroxy-3-methoxybenzal/2-hydroxynaphthal)hydrazine; H2L4,5 = 1-(2-aminobenzoyl)-2-(2-hydroxybenzal/2-hydroxy-3-methoxybenzal)hydrazine; phen = 1,10-phenanthroline} have been prepared and characterised, and their spectral and electrochemical properties studied. Complexes (4, 5) possess longer O=U=O bonds than those in complexes (1–3) as a result of the strong σ-donating phenolate group being replaced by an amino group. The i.r. spectra and electrochemical behaviour confirm the electronic non-equivalence of the coordination environments around the two uranyl ions in these complexes.

Binuclear complexes with uranyl ions in non-equivalent coordination environments: synthesis and electrochemistry of complexes with binucleating aroyl hydrazones and 2,2′-bipyridine

The binuclear complexes [(UO2bipy)2L1–3]NO3, (1–3), {H3L1–3 = 1-(2-hydroxybenzoyl)-2-(2-hydroxy-benzal/3-methoxybenzal/naphthal)hydrazine}, and [(UO2bipy)2L4–5](AcO)2, (4–5), [H2L4–5 = 1-(2-aminobenzoyl)-2-(2-hydroxy-benzal/naphthal)hydrazine], have been synthesised. Complexes (4–5) possess longer O=U=O bonds than those in the complexes (1–3) as the strong σ-donating phenolate is replaced by the amino group. The spectral data and electrochemical behaviour confirm the electronic nonequivalence of the coordination environments around the two uranyl ions in these complexes.

Aroyl Hydrazones Containing Triazole and Their Divalent Nickel Complexes

Three new aroyl hydrazones containing a triazole ring, α-N-benzoyl-β-N-2-phenyl-1,2,3-triazolylidenehydrazide, α-N-isonicotinoyl-β-N-2-phenyl-1,2,3-triazolylidenehydrazide and α-N-salicyloyl-β-N-2-phenyl-1,2,3-triazolylidenehydrazide and their Ni(II) complexes have been synthesized. These compounds were characterized by elemental analyses, IR, UV, XPS and thermal analyses. The ligands act as a bidentate donor in the complexes and are coordinated to Ni2+ via the azomethine nitrogen and enolic oxygen. Referee I: S. Utsuno Referee II: K. Sakata

Oxovanadium binuclear (IV) Schiff base complexes derived from aroyl hydrazones having subnormal magnetic moments

Oxovanadium(IV) complexes of aroyl hydrazone Schiff bases, viz. salicyloyl, nicotinoyl and benzoyl hydrazones, have been synthesized and characterized by elemental analysis, spectroscopy (IR and UV-vis) methods, magnetic susceptibility, EPR measurements, molar conductance and cyclic voltammetry studies. The room-temperature magnetic moments of the complexes are in the range 0.97–1.03 B.M. and are indicative of the presence of anti-ferromagnetic exchange. A binuclear structure has been proposed for the complexes.

Norbornenyl Aroylhydrazones and Their Copper (I) and Mercury (I) Complexes

Abstract Seven new aroyl hydrazones containing the norbornene group and their copper (I) and mercury (I) complexes have been synthesized and characterized by elemental analyses, electrolytic conductance, IR spectra, 1H NMR spectra and TGA analyses. These ligands coordinate to metal ions in the enolic form and act as bidentate ligands. All complexes are non-electrolytes in methanol — N,N-dimethylformamide (3 : 1 in volume).

Non-transferrin donors of iron for heme synthesis in immature erythroid cells

The mechanism of iron uptake from several iron-containing compounds by transferrin-depleted rabbit reticulocytes and mouse spleen erythroid cells was investigated. Iron complexes of dl-penicillamine, citrate and six different aroyl hydrazones may be utilized by immature erythroid cells for hemoglobin synthesis, although less efficiently than iron from transferrin. HTF-14, a monoclonal antibody against human transferrin, reacts with rabbit transferrin and inhibits iron uptake and heme synthesis by rabbit reticulocytes. HTF-14 had no significant effect on iron uptake and heme synthesis when non-transferrin donors of iron were examined. Ammonium chloride (NH 4Cl) increases intracellular pH and blocks the release or utilization of iron from the internalized transferrin. NH 4Cl only slightly affected iron incorporation and heme synthesis from non-transferrin donors of iron. Hemin inhibited transferrin iron uptake and heme synthesis, but had a much lesser effect on iron incorporation and heme synthesis from non-transferrin donors of iron. These results allow us to conclude that transferrin-depleted reticulocytes take up iron from all of the examined non-transferrin iron donors without the involvement of the transferrin/transferrin receptor pathway.

ChemInform Abstract: Studies on Biologically Active Heterocycles. Part 1. Synthesis and Antifungal Activity of Some New Aroyl Hydrazones and 2,5‐Disubstituted‐ 1,3,4‐Oxadiazoles.

AbstractCondensation of the hydrazide (I) and the aldehydes (II) gives the hydrazones (III) which cyclize to the oxadiazoles (IV).

Studies on biologically active heterocycles. Part I. Synthesis and antifungal activity of some new aroyl hydrazones and 2,5‐disubstituted‐1,3,4‐oxadiazoles

AbstractA series of new 1‐(2,4‐dichlorobenzoyl) hydrazones and 2‐aryl/aralkyl‐5‐(2,4‐dichlorophenyl)‐1,3,4‐oxadiazoles have been synthesized from 2,4‐dichlorobenzoylhydrazine and different aldehydes. Subsequent ring closure of the substituted aroyl hydrazones yielded the 1,3,4‐oxadiazoles. All the compounds were characterized by their sharp melting point, microanalysis, ir, 1H nmr and mass spectra and screened for their fungitoxic properties against Alternaria tenuis and Curvularia verruciformis. A few of the compounds showed good activity.

Syntheses of iron(III) aroyl hydrazones containing pyridoxal and salicylaldehyde. The crystal and molecular structure of two iron(III)-pyridoxal isonicotinoyl hydrazone complexes

Iron(III) complexes of three aroyl hydrazones, pyridoxal isonicotinoyl hydrazone (H 2pih), pyridoxal benzoyl hydrazone (H 2pbh), and salicylaldehyde benzoyl hydrazone (H 2sbh), were synthesized and characterized. In aqueous medium at pH 7, [Fe(pih)(Hpih)]·3H 2O is formed. In acidic methanol, a 1:1 ligand-to-metal complex is formed, [FeCl 2(H 2pih)]Cl ( 1), whereas in aqueous medium at low pH cis-[FeCl 2(H 2pih)(H 2O)]Cl·H 2O ( 2) is formed. Compounds 1 and 2 are high-spin d 5 with μ eff = 5.88 μ B and 5.93 μ B (298 K). The crystal structures of 1 and 2 show that H 2pih acts as a tridentate neutral ligand in which the phenolic and hydrazidic protons have shifted to the pyridine nitrogen atoms. The co- ordination polyhedron of 1 is ‘square’ pyramidal, whereas that of 2 is pseudo-octahedral. Compound 1 is triclinic, space group P l , with a = 12.704(2) Å, b = 8.655(2) Å, c = 8.820(2) Å, α = 105.42(1)°, β = 89.87(1)°, γ = 107.60(1)°, V = 888 Å 3, and Z = 2; 2 is monoclinic, space group P2 1/ c, with a = 15.358(4) Å, b = 7.304(3) Å, c = 17.442(4) Å, β = 101.00(2)°, V = 1921 Å 3, and Z = 4.

Complexes of Uranium(IV) Acetate with Hydrazones

Abstract A few uranium(IV) acetate complexes with aroyl hydrazones have been synthesized and characterized by infrared, conductivity and magnetic measurements. All the complexes are colored, amorphous, soluble in DMF and DMSO and are insoluble in common organic solvents. Conductivity data indicated that the complexes behave as non-electrolytes in solution.

Fluorometric measurement of furfural and 5-hydroxymethylfurfural

Zine(II) forms highly fluorescent chelates with the aroyl hydrazones of furfural and 5-hydroxymethylfurfural, with the latter being more fluorescent than the former. The choice of aromatic acid hydrazide (aroyl hydrazine) as analytical reagents for furfurals was examined; 4-toluenesulfonic acid hydrazine was the most sensitive reagent examined, giving a uv fluorescence 10 times as sensitive as 4-hydroxygenzoic acid hydrazide (PAHBAH). More convenient visible fluorescence was given by PAHBAH and related compounds, and these are capable of detecting less than 500 pmol 5-hydroxymethylfurfural. The condensation reaction is complete in 30 m m ethanolic hydrochloric acid within 2 min at 60°C, and the stable product forms the fluorescent chelate on mixing with a zinc-diethanolamine solution in ethanol.

Some ferrocenyl aroyl hydrazones and their copper(II) complexes

Ferrocenylidene derivatives of benzoyl-, p-chlorobenzoyl-, o-nitrobenzoyl-, salicyloyl- and isonicotinoyl hydrazines have been synthesised by condensing acetylferrocene and/or formylferrocene with the respective aroyl hydrazine. These organometallic compounds act as ligands for metal complexation and copper(II) complexes of some of these have been isolated and characterized.

Cobalt(II) and copper(II) complexes of some α-(o-hydroxy-phenyl)ethylidene acyl and aroyl hydrazones

Cobalt(II) and copper(II) complexes of some α-(o-hydroxy-phenyl)ethylidene acyl and aroyl hydrazones

Dimeric square planar complexes of Cu(II) with aroyl hydrazones

Cu(II) complexes with aroyl hydrazones have been prepared in ethanol medium and characterised by elemental analysis. They have 1:1 stoichiometry. I. R. results show that the hydrazones exist in the enol form in the complexes. These Cu(II) complexes show subnormal magnetic moments and the electronic spectra agree with the square planar configuration. In view of the magnetic and electronic spectral evidence, the dimeric square planar configuration is suggested in which CuCu interaction exists.

Hexakoordinierte Komplexe von Mangan(III) mit Hydrazonen

A few complexes of Mn(III) have been prepared by reacting manganese acetate with aroyl hydrazones in methanolic medium. The elemental analyses indicate 1∶2 or 1∶3 stoichiometry depending on the ligands. On the basis of the physicochemical investigations, coordination number six has been suggested for all these complexes.