Azo Nitrogen Atoms Research Articles

Synthesis of metal(II) acetate complexes with a heterocyclic azo dye ligand: Characterization, geometrical molecular structures, antioxidant, biological activities, DNA binding and molecular docking studies

A series of Cu(II), Co(II), Ni(II), Mn(II), and UO2(II) complexes have been prepared from the ligand 4-(2’,4’-dihydroxybenzaldehyde phenylazo)antipyrine (H2L). FT-IR spectra demonstrated that the ligand under investigation behaves as a bi-and tridentate centre ligand through the phenolic oxygen of aldehydic, azo nitrogen atoms and carbonyl oxygen of antipyrine and forms a stable five- and six-membered chelating ring. From the X-ray crystallographic analysis (XRD) patterns of the ligand and complexes showed the polycrystalline phases are indicated by the multiple diffraction peaks in the 1igand and its complex (5). The HOMO‒LUMO energy gaps (∆E) were used to create theoretical models for the structure and confirmation barriers in molecular systems for the ligand (H2L) and metal complexes. It was found that the Cu(II), Co(II), Ni(II), and Mn(II) complexes have lower values for HOMO‒LUMO energy gaps (∆E), indicating that they are more stable than the 1igand. The biological activities of ligand (H2L) and its metal complexes showed that ligand was stronger antimicrobial and antioxidant agent than its metal complexes. 50 µg/ml H2L caused inhibition zones ranged from 13 to 20 mm against the tested bacteria and 13 to 16 against fungi. In addition, the present study tested metal (II) acetate complexes with a heterocyclic azodye ligand for their application in the textile industry as antimicrobial dyed fabrics. All obtained results confirmed the possibility of using the prepared compounds in different industrial applications. The 1igand (H2L) and its metal complexes showed moderate to strong antimicrobial activities in agar well diffusion, MIC, and antioxidant tests. Ligand and its metal complexes revealed inhibition zones against all tested microbes ranged between 6 to 24 mm. The MIC values of ligand and its metal complexes were recorded at 20 to 30 μg/ml and 30 to 145 μg/ml, respectively. 50 µg/ml of 1igand and its metal complexes was enough to complete inhibit Gram negative E. coli moreover they could inhibit the multidrug resistant bacteria K. pneumoniae and Pseudomonas sp. By molecular docking study, it was found that the complex (1) showed the highest and better binding affinity (-8.38874 and -7.74442 kcal/mol) than other 1igand (H2L) and complexes (2–5) for the breast cancer (3HB5) protein central activity and the colon cancer (2HQ6) protein central activity.

Synthesis and Characterization Some Complexes of Mixed Ligand and Study Its Effects as Antioxidant and Anticancer

A series of mixed ligand complexes of Co(II), Ni(II), Cu(II), Zn (II),Cd(II), Fe (III ) andAu(III) were prepared and characterized. A new azo ligand derived from 4-methylimidazole with sulfadiazine and Schiff base derived from 4-(dimethylamino)-2-hydroxobenzaldehyde and 4-amino-3-hydroxy benzene sulfonamide. Ligands structures and their transitional metal mix-ligand complexes were characterized using various analytical techniques, including molar conductance, elemental analysis (C.H.N), electronic spectral, magnetic measurements, 1HNMR, IR spectral studies and mass spectra. The data shows that these complexes have composition of [ML1L2H2O] where M = Co(II), Ni(II), Cu(II), Zn(II) ,Cd(II) and Hg(II). [ML1L2Cl] where M=Fe(III). [ML1L2]Cl2 where M=Au(III). The magnetic susceptibility and electronic spectral data of the complexes indicate that the octahedral geometry of all complexes, except the complex of Au(III) indicates a square plane geometry. The IR results demonstrate that the co-ordination sites are imidazole nitrogen atom and the farthest azo nitrogen atom of L1 as natural bidentate with nitrogen the azomethine and oxygen atoms of Schiff base L4. Azo ligand and Schiff base behave as tridentate manner. All the compounds showed DPPH radical scavenging activity. In general, the results indicated that the complexes have potential and promising anti-oxidant activities.

Nano‐sized Co(II), Ni(II), and Zr(IV) complexes of quinaldine‐based azo dye for promising therapeutic and catalytic applications: Synthesis, characterization, density functional theory studies and molecular docking

Novel azo dye containing the heterocyclic quinaldine nucleus, 3‐((2‐methylquinolin‐4‐yl)diazenyl)naphthalen‐2‐ol HL, and its Co(II), Ni(II) and Zr(IV) nano‐sized metal chelates have been synthesized and fully characterized by alternative analytical and spectral techniques. The finding indicated that the ligand coordinated as a monobasic bidentate via azo nitrogen and hydroxyl oxygen atom, resulting in octahedral geometry towards Co(II) and Zr(IV) complexes, and square planer geometry towards Ni(II) metal ion. Theoretical studies by DFT/B3LYP/6‐311+G(d,p)/LANLDZ including energetic parameters, geometrical optimization, dipole moment, and HOMO–LUMO energy gap were applied to support the geometrical arrangement of the complexes. The produced complexes were generated at the nanoscale, as evidenced by the average particle size from TEM. The average particle size calculated from TEM images for Co(II), Ni(II), and Zr(IV) complexes is 6.0, 12.0, and 5.5 nm, respectively. The antibacterial activity of the ligand compared with its metal complexes shows enhanced activity over the metal complexes against different types of bacteria. Antitumor efficacy of the compounds was tested against A‐549 and PANC‐1 cells, compared with the vinblastine standard. The cytotoxic efficiency of both Co(II) and Ni(II) complexes exceeded that of vinblastine. The anticancer activity of the Zr complex was then studied using molecular docking to determine the interactions between this molecule and PANC‐1. Docking studies revealed that the Zr complex produces four hydrogen bond contacts with the active amino acid residues Arg 136 and Asp 140, two hydrophobic interactions with Val 50 and Leu 147, and two electrostatic interactions with Arg 136. Also, the catalytic property of the free ligand and nanocomplexes were tested on the oxidative degradation of methyl violet 2B dye in the presence of H2O2. The following arrangement was observed for the pseudo‐first‐order rate constants: Co(II) complex (0.068 min−1) > Ni(II) complex (0.066 min−1) > Zr(IV) complex (0.061 min−1) > HL (0.037 min−1).

Synthesis and characterization of novel heterocyclic diazenyl pyridinone copper(II) complexes with antimicrobial, antioxidant, and anticancer properties

The novel diazenyl pyridinone heterocyclic ligands and their Cu(II) complexes have been prepared and characterized utilizing miscellaneous analytical tools, thermogravimetric analysis (TGA), and nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), electron paramagnetic resonance (EPR), and ultraviolet–visible spectroscopies. The investigated ligands are coordinated in a bidentate fashion through the azo nitrogen atom and the hydroxyl oxygen atom to the Cu(II) center. The EPR spectra indicated that the obtained complexes were monomeric, and density functional theory (DFT) calculations confirmed that the Cu(II) atom adopted a six‐coordinated octahedral geometry. The ligands and their complexes were investigated for their in vitro antimicrobial activity against some types of bacteria and fungi. The antioxidant and anticancer activities of the complexes were also assessed. The results show that these complexes exhibit higher antitumor efficiency and selectivity index against the models of human breast adenocarcinoma cells MCF‐7 and human primary hepatocytes THLE‐2 than the reference standard material doxorubicin. The results were supported by DFT calculations, molecular docking, and Hirshfeld surface analysis.

Metal complexes of azo compounds: Synthesis, characterization, molecular modeling and degradation study by gamma radiation

The Fe(III), Co(II) and Cu(II) complexes of three azo compounds namely, 2-(phenylazo)-1-naphtllol (Sudan I) (HL1) a, 4-(phenylazo)-1-naphthol (HL2) b and 2,4-bis(phenylazo)-1-naphthol (HL3) c were prepared and characterized on the basis of their elemental analysis, molar conductance, UV–VIS and FT IR spectroscopic studies. Besides, density functional theory (DFT) computations were conducted to study structures and energetics of the ligands and their complexes. Molecular Electrostatic Potential was also calculated by the DFT method and predicts the most reactive part in the molecule. The isolated complexes are found to have the formulas [Cu(L1)2] a1, [Co(L1)2] a2, [Fe(L1)3] a3, [Cu(HL2)2Cl2].H2O b1, [Co(HL2)(NO3)2].H2O b2, [Fe(HL2)Cl3].H2O b3, [Cu(HL3)Cl2].H2O c1, [Co(HL3)(NO3)2].H2O c2 and [Fe(HL3)Cl3].H2O c3. The IR result showed that the ligand a was chelated with the metal ions in a monobasic bidentate manner, with NO donor sites of the azo nitrogen and the deprotonated phenolic oxygen. While the ligand c was chelated with the metal centers in a neutral bidentate manner and the ligand b was bound with the metal ions as a neutral monodentate donor by azo nitrogen atom. The molecular docking results indicated that the ligands HL1a, HL2b and HL3c may possess significant anti-inflammatory activity. Gamma irradiation of variable concentrations of the ligand solutions HL1a and its complexes [Cu(L1)2] a1, [Co(L1)2] a2 and [Fe(L1)3] a3 was investigated. The color bleaching of the dyes solutions was increase gradually with increasing absorbed dose in the dose range of 3, 5 and 10 kGy.

Preparation, Characterization of Some Metal Complexes of New Mixed Ligands Derived from 5-Methyl Imidazole and Study the Biological Activity of Palladium (II) Complex as Anticance

A new series of mixed ligand complexes synthesized and characterized using of azo ligand derived from (5-methyl— imidazole) with (8-hydroxy quinolone). New mix-ligand structures and their transitional metal complexes were fully characterized using several techniques, including molar conductance, elemental analysis (C.H.N), electronic spectral, magnetic measurements, 1HNMR, spectral studies, and mass spectra. The data shows that these complexes have a composition of [ML(8-HQ) Cl2] H2O where M = Co(II), Zn(II), Cu(II), X=0, and Ni(II), X=1, [ML(8-HQ)] Cl. where M=Pd. The electronic spectral data and magnetic susceptibility calculations of the complexes indicate that the octahedral geometry of all complexes, except for the Pd(II) complex, indicates a planar-square geometry. The results demonstrate that the nitrogen of the imidazole ring and azo nitrogen atom of the primary ligand are coordination sites with a nitrogen atom and oxygen atom of a secondary ligand of the (8-HQ) in the basic medium. Biological effects of the palladium (II) complex are screening against human breast cancer (MCF-7 and AMJ-13) and normal cells (HBL) were examined, which indicated colon cancer cell line LS-174. The results show the highest activity effect for the complex.

Synthesis and Identification and Biological Studies of New Azo Dyes Derived from Imidazole and their Chelate Complexes

Anew azo ligand (E)-2-((4- fluoro phenyl)diazenyl)-4,5-bis(4-methoxy phenyl)-1H-imidazolehas beensynthesized from coupling 4,5-bis(4-methoxyphenyl)imidazole with para-chloro-anline. The structures ofthe new ligand and their transition metal complexes ware investigated and characterized using differentphysicochemical studies as elemental analysis, IR spectra, 1HNMR,, UV-Vis spectra, mass spectra, Molarconductance ,and magnetic susceptibility .The complexes were found to have the general formula [ML2Cl2].H2O where M = Co(II), Ni(II), Cu(II) ,Mn(II),and Fe(II), [MLCl2].H2Owhere M=Zn(II),Cd(II),Hg(II), andPd(II). The IR results demonstrate that the co-ordination sites are the azomethine nitrogen of the imidazolering and azo nitrogen atom of the azo ligand. The electronic spectral and magnetic measurement dataindicate that the complexes exhibit octahedral geometry,except the Zn(II),Cd(II),andHg(II) complexessuggest tetrahedral and Pd(II) a square planar geometry.The cytotoxicity of Pd(II) complex on human LungCancer (SCLC) and normal cells.

Nano-Azo Ligand and Its Superhydrophobic Complexes: Synthesis, Characterization, DFT, Contact Angle, Molecular Docking, and Antimicrobial Studies

Metal complexes of the 2,2'-(1,3-phenylenebis(diazene-2,1-diyl))bis(4-aminobenzoic acid) diazo ligand (H2L) derived from m-phenylenediamine and p-aminobenzoic acid were synthesized and characterized by different spectral, thermal, and analytical tools. The H2L ligand reacted with the metal ions Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II) as 1 : 1 stoichiometry. All complexes displayed an octahedral geometry according to the electronic and magnetic moment measurements. The IR spectra revealed the binding of the azo ligand to the metal ions via two azo nitrogen atoms and protonated carboxylate O in a neutral tetradentate manner. Both IR and 1H NMR spectra documented the involvement of the carboxylate group without proton displacement. The thermal studies pointed out that the complexes had higher thermal stability comparable with that of the free ligand. SEM images revealed the presence of the diazo ligand and its Cd(II) complex in a nanostructure form. The contact angle measurements proved that the Cd(II) complex can be considered as a superhydrophobic material. The molecular and electronic structure of H2L and [Cd(H2L)Cl2].H2O were optimized theoretically, and the quantum chemical parameters were calculated. The biological activities of the ligand, as well as its metal complexes, have been tested in vitro against some bacteria and fungi species. The results showed that all the tested compounds have significant biological activities with different sensitivity levels. The binding between H2L and its Cd(II) complex with receptors of the crystal structure of S. aureus (PDB ID: 3Q8U), crystal structure of protein phosphatase (PPZ1) of Candida albicans (PDB ID: 5JPE), receptors of breast cancer mutant oxidoreductase (PDB ID: 3HB5), and crystal structure of Escherichia coli (PDB ID: 3T88) was predicted and given in detail using molecular docking.

Preparation and Characterization of Some Complexes with New (Azo-Schiff base) Ligand and Study of Complex as Anticancer

Anew series of transition metal complexes of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Au(III) and Pt(II) have been preparation and characterization using anew azo-Schiff base ligand derived from schiff base (N1Z,N2Z)-N1,N2-bis(4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-ylidene)benzene-1,2-diamine with 5-methyl-imidazole.The structures of the new ligand azo-schiff base and their transition metal complexes are characterized using several techniques,including analysis(C.H.N),molar conductance,magnetic measurements, electronic spectral,IR spectral studies,13CNMR,1HNMR and mass spectra The data show that these complexes have composition of[MLCl2] where M=Co(II),Ni(II), Cu(II),Zn(II),Cd(II) and Hg(II),[ML] Cl3 where M=Au(III) and[ML]Cl2 ,where M=Pt(II).The electronic spectral, and magnetic susceptibility data of the complexes suggest octahedral geometry of all complexes,except the Au(III) and Pt(II) complex suggest a square planar geometry.The IR results demonstrate that the co-ordination sites are the azomethine nitrogen and azo nitrogen atoms of the ligand.The ligand behaves natural tetra dentate manner.The biological screening effect of the Pt(II) complex are tested against human breast cancer cell line MCF-7and normal cells( cell line WRL68).The results show the highest inhibitory effect for complex.

Tetradentate amido azo Schiff base Cu(II), Ni(II) and Pd(II) complexes: Synthesis, characterization, spectral properties, and applications to catalysis in C–C coupling and oxidation reaction

New Schiff base ligands (H2L1 &H2L2) were synthesized by the reaction of salicylaldehyde with (2-((2-aminophenyl)diazenyl)-N-alkylaniline), and were used for the preparation of complexes with Cu(II), Ni(II) and Pd(II) metal ions. The structural features of the synthesized compounds were examined by UV–Vis, IR and 1H NMR spectroscopy. The crystal structures of Schiff base (H2L1) and two metal complexes Cu(L1) and Ni(L2) were determined by single crystal X-ray diffraction. The studies revealed that the synthesized Schiff bases existed as tetradentate (N,N,N,O) ligands and bonded to the metal ions through the donor atoms of the amido nitrogen, azo nitrogen, azomethine nitrogen and phenolic oxygen atoms. The redox property of Cu(L1) and Ni(L1) and emission behavior of ligand H2L1 and complexes Cu(L1) and Ni(L1) were examined. The complex Cu(L1) shows excellent catalytic activity towards oxidation of benzyl alcohol to benzyldehyde (under solvent-free condition) using H2O2 as the oxidant. Complex Pd(L1) acts as highly efficient catalyst in the Suzuki–Miyaura cross-coupling reaction of various aryl halides with phenyl boronic acid to produce the corresponding biaryls with high yields under mild reaction conditions. Both the catalysts Cu(L1) and Pd(L1) were easily recovered by simple chromatographic separation and reused for next catalytic cycle.

Spectroscopic Studies and Thermal Analysis of New Azo Dyes Ligands and their Complexes with some Transition of Metal Ions

New Azo ligands HL1 [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1-naphth aldehyde] and HL2 [3-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl)-2-hydroxy-1-naphthaldehyde] have been synthesized from reaction (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol) for HL1 and (4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one) for HL2. Then, its metal ions complexes are synthesized with the general formula; [CrHL1Cl3(H2O)], [VOHL1(SO4)] [ML1Cl(H2O)] where M = Mn(II), Co(II), Ni(II) and Cu(II), and general formula; [Cr(L2)2 ]Cl and [M(L2)2] where M = VO(II), Mn(II), Co(II), Ni(II) and Cu(II) are reported. The ligands and their metal complexes are characterized by phisco- chemical spectroscopic techniques (FT.IR, Mass, UV-Vis, 1H and 13C-NMR, TGA, (C.H.N.), molar conductivity, Atomic Absorbance, Chloride containing magnetic susceptibility). The spectral data suggest that the (HL1) behaves as a bidentate ligand in all complexes, whereas (HL2) behaves as a tridentate ligand for all complexes; bidentate ligand in Vanadium complex is coordinated with the metal ions through azo nitrogen and oxygen atoms. Theoretical studies of these ligands and their metal complexes in gas phase using Hyper chem.8. Studies of these compounds are prepared for their bacterial activity

Enhanced azo dye decolorization through charge transmission by σ-Sb3+-azo complexes on amorphous Sb2S3 under visible light irradiation

Three types of Sb2S3 with different degrees of crystallinity were synthesized via a hydrothermal procedure by adjusting the concentration of hydrochloric acid. The amorphous Sb2S3 sample (A-Sb2S3) exhibited nearly 13 times higher photocatalytic activity for the decolorization and biodegradability improvement of MO solution compared with both crystalline samples under visible light (λ > 420 nm). It was verified that MO and Congo Red azo dyes were adsorbed onto A-Sb2S3 by displacing hydroxyl groups (OH−) to complex with Sb3+ on A-Sb2S3, which occurred via σ bonding to the lone pairs of azo nitrogen atoms with Sb3+ (σ-Sb-(NN)). Moreover, the decolorization rate of MO was positively related to its adsorption onto A-Sb2S3, and no significant degradation was observed for non-azo intermediates. The predominant photodegradation pathways of MO were reduction and oxidization to sulfanilic acid, NO3− and small-molecule acids. On the basis of photoelectron spectra, ESR (Electron spin resonance) measurements and other experimental information, it was proposed that the complexes (σ-Sb-(NN)) could transmit photogenerated electrons and holes to the azo group, breaking the NN bond, causing azo dye decolorization to improve their biodegradability; while on the surface of bare A-Sb2S3, the strong coordination interaction of OH− with Sb3+ made OH− groups become the recombination centers for photogenerated electrons and holes during the photocatalytic reaction.

Preparation, characterization, biological activity, density functional theory calculations and molecular docking of chelates of diazo ligand derived from m‐phenylenediamine and p‐chlorophenol

A novel azo dye ligand, 2,2′‐(1,3‐phenylenebis(diazene‐2,1‐diyl))bis(4‐chlorophenol), was synthesized from the diazotization of m‐phenelyenediamine and coupling with p‐chlorophenol in alkaline medium. Mononuclear Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) complexes of the azo ligand (H2L) were prepared and characterized using elemental analyses, infrared spectroscopy, electron spin resonance, magnetic susceptibility, conductance measurements and thermal analyses. The UV–visible, 1H NMR and mass spectra of the ligand and its chelates were also recorded. The analytical data showed that the metal‐to‐ligand ratio in the mononuclear azo complexes was 1:1. Diffuse reflectance and magnetic moment measurements revealed the complexes to have octahedral geometry. The infrared spectral data showed that the chelation behaviour of the ligand towards transition metal ions was through phenolic oxygen and azo nitrogen atoms. The electronic spectral results indicated the existence of π → π* (phenyl rings) and n → π* (─N═N) and confirmed the mentioned structure. Molar conductivity revealed the non‐electrolytic nature of all chelates. The presence of water molecules in all complexes was supported by thermal studies. Molecular docking was used to predict the binding between H2L and the receptors of breast cancer mutant 3hb5‐oxidoreductase, crystal structure of Escherichia coli (3 t88) and crystal structure of Staphylococcus aureus (3q8u). The molecular and electronic structure of H2L was optimized theoretically and the quantum chemical parameters were calculated. In addition, the effects of the H2L azo ligand and its complexes on the inhibition of bacterial or fungal growth were evaluated. The prepared complexes had enhanced activity against bacterial or fungal growth compared to the H2L azo ligand.

Quantitative structure-activity relationship analysis of substituted arylazo pyridone dyes in photocatalytic system: Experimental and theoretical study

A series of arylazo pyridone dyes was synthesized by changing the type of the substituent group in the diazo moiety, ranging from strong electron-donating to strong electron-withdrawing groups. The structural and electronic properties of the investigated dyes was calculated at the M062X/6-31+G(d,p) level of theory. The observed good linear correlations between atomic charges and Hammett σp constants provided a basis to discuss the transmission of electronic substituent effects through a dye framework. The reactivity of synthesized dyes was tested through their decolorization efficiency in TiO2 photocatalytic system (Degussa P-25). Quantitative structure-activity relationship analysis revealed a strong correlation between reactivity of investigated dyes and Hammett substituent constants. The reaction was facilitated by electron-withdrawing groups, and retarded by electron-donating ones. Quantum mechanical calculations was used in order to describe the mechanism of the photocatalytic oxidation reactions of investigated dyes and interpret their reactivities within the framework of the Density Functional Theory (DFT). According to DFT based reactivity descriptors, i.e. Fukui functions and local softness, the active site moves from azo nitrogen atom linked to benzene ring to pyridone carbon atom linked to azo bond, going from dyes with electron-donating groups to dyes with electron-withdrawing groups.

Spectroscopic Studies and Thermal Analysis of New Azo Dyes Ligands and their Complexes with some Transition of Metal Ions

New Azo ligands HL1 [2-Hydroxy-3-((5-mercapto-1,3,4-thiadiazol-2-yl)diazenyl)-1-naphth aldehyde] and HL2 [3-((1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)diazenyl)-2-hydroxy-1-naphthaldehyde] have been synthesized from reaction (2-hydroxy-1-naphthaldehyde) and (5-amino-1,3,4-thiadiazole-2-thiol) for HL1 and (4-amino-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one) for HL2. Then, its metal ions complexes are synthesized with the general formula; [CrHL1Cl3(H2O)], [VOHL1(SO4)] [ML1Cl(H2O)] where M = Mn(II), Co(II), Ni(II) and Cu(II), and general formula; [Cr(L2)2 ]Cl and [M(L2)2] where M = VO(II), Mn(II), Co(II), Ni(II) and Cu(II) are reported. The ligands and their metal complexes are characterized by phisco- chemical spectroscopic techniques (FT.IR, Mass, UV-Vis, 1H and 13C-NMR, TGA, (C.H.N.), molar conductivity, Atomic Absorbance, Chloride containing magnetic susceptibility). The spectral data suggest that the (HL1) behaves as a bidentate ligand in all complexes, whereas (HL2) behaves as a tridentate ligand for all complexes; bidentate ligand in Vanadium complex is coordinated with the metal ions through azo nitrogen and oxygen atoms. Theoretical studies of these ligands and their metal complexes in gas phase using Hyper chem.8. Studies of these compounds are prepared for their bacterial activity

Synthesis, Spectral Characterization, and Fungicidal Activity of Transition Metal Complexes With Benzimidazolyl-2-hydrazones of Glyoxal, Diacetyl, and Benzil

A series of complexes of the type [ML2].nH2O, where L = 2- (benzimidazolyl-2′-amino) imino ethanone (HBAIE), 2-(benzi midazolyl–2′-amino) imino-1,2-dimethyl ethanone (HBAIME), 2-(benzimidazolyl-2′-amino) imino-1,2-diphenyl ethanone (HBAIPE), M = Cu(II), Co(II), Ni(II), and Zn(II), have been synthesized and characterized. The results are in consistent with tridentate chelation of ligand with azo nitrogen, ring nitrogen, and oxygen atom of glyoxal, diacetyl, and benzil. The fungi toxicity of the ligands and their complexes against some fungal pathogen has been studied.

Redox Noninnocence in Coordinated 2-(Arylazo)pyridines: Steric Control of Ligand-Based Redox Processes in Cobalt Complexes

A series of cobalt complexes of ligands based on the 2-(arylazo)pyridine architecture have been synthesized, and the precise structure and stoichiometry of the complexes depend critically on the identity of substituents in the 2, 4, and 6 positions of the phenyl ring. The 2-(arylazo)pyridine motif can support either Co(II) complexes with neutral ligands, Co(II)Cl2(L(a))2 (1), Co(II)Cl2(L(c))2 (3), [Co(II)Cl(L(b))2]2(PF6)2 (5[PF6]2), or Co(III) complexes of reduced 2-(arylazo)pyridine ligand radical anions, L(•-), Co(III)Cl(L(b•-))2 (2), Co(III)Cl(L(c•-))2 (4), and Co(III)Me(L(b•-))2 (6). All three members of the latter class are based on approximately trigonal-bipyramidal CoX(L(•-))2 architectures [L = 2-(arylazo)pyridine] with two azo nitrogen atoms and the X ligand (X = Cl or Me) in the equatorial plane and two pyridine nitrogen atoms occupying axial positions. Density functional theory suggests that the electronic structure of the Co(III) complexes is also dependent on the identity of X: the strong σ-donor methyl gives a low-spin (S = 0) configuration, while the σ/π-donor chloro gives an intermediate-spin (S = 1) local configuration. In certain cases, one-electron reduction of the Co(II)X2L2 complex leads to the formation of Co(III)X(L(•-))2; i.e., reduction of one ligand induces a further one-electron oxidation of the metal center with concomitant reduction of the second ligand.

Synthesis and characterization of Cu(II), Co(II) and Ni(II) complexes of a number of sulfadrug azodyes and their application for wastewater treatment

The azodye ligand (HL1) was synthesized from the coupling of sulfaguanidine diazonium salt with 2,4-dihydroxy-benzaldehyde while the two ligands, HL2 and HL3, were prepared by the coupling of sulfadiazine diazonium salt with salicylaldehyde (HL2) and 2,4-dihydroxy-benzaldehyde (HL3). The prepared ligands were characterized by elemental analysis, IR, 1H NMR and mass spectra. Cu(II), Co(II) and Ni(II) complexes of the prepared ligands have been synthesized and characterized by various spectroscopic techniques like IR, UV–Visible as well as magnetic and thermal (TG and DTA) measurements. It was found that all the ligands behave as a monobasic bidentate which coordinated to the metal center through the azo nitrogen and α-hydroxy oxygen atoms in the case of HL1 and HL3. HL2 coordinated to the metal center through sulfonamide oxygen and pyrimidine nitrogen. The applications of the prepared complexes in the oxidative degradation of indigo carmine dye exhibited good catalytic activity in the presence of H2O2 as an oxidant. The reactions followed first-order kinetics and the rate constants were determined. The degradation reaction involved the catalytic action of the azo-dye complexes toward H2O2 decomposition, which can lead to the generation of HO radicals as a highly efficient oxidant attacking the target dye. The detailed kinetic studies and the mechanism of these catalytic reactions are under consideration in our group.

Syntheses, structures, and properties of Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane

Ni(II) complexes with 5,5′-bis(4-halogenphenyl)diazo-dipyrromethane have been synthesized and characterized by X-ray crystallography. All the complexes have similar crystal structures in which Ni(II) is square-planar by coordinating to two pyrrole and two azo nitrogen atoms. The azo-pyrroles of the ligands can be converted to the hydrazone tautomer after complexing nickel. Moreover, the C–H ··· Ni interaction played an important role in directing self-assembly of the complexes. The UV-Vis spectra of the complexes showed great difference with the metal complexes of pyrrol-2-imine.

Synthesis, characterization and crystal structures of 2-[(E)-2-(4-hydroxy-3,5-dimethylphenyl)-1-diazenyl]benzoic acid and its polymeric and monomeric triorganotin(IV) complexes

Three triorganotin(IV) complexes of composition R 3SnLH (R = Me, Bu and Ph and LH = 2-[(E)-2-(4-hydroxy-3,5-dimethylphenyl)-1-diazenyl]benzoate) have been synthesized and characterized by 1H, 13C, 119Sn NMR, and IR spectroscopic techniques in combination with elemental analysis. The crystal structures of the carboxylate ligand HO 2CC 6H 4{N N(C 6H 2-4-OH-3,5-(CH 3) 2)}- o in its neutral form and three triorganotin(IV) complexes, viz., polymeric (R 3Sn[O 2CC 6H 4{N–N(H)(C 6H 2-4-O-3,5-(CH 3) 2)}- o]) n (R = Me ( 1) and Bu ( 2)) and monomeric Ph 3Sn[O 2CC 6H 4{N–N(H)(C 6H 2-4-O-3,5-(CH 3) 2)}- o] ( 3) complexes are reported. The polymeric complexes 1 and 2 exist as extended chains in which the LH-bridged Sn-atoms adopt a trans-R 3SnO 2 trigonal bipyramidal configuration with R groups in the equatorial positions and the axial sites occupied by an oxygen atom from the carboxylate ligand and the phenoxide O atom of the next carboxylate ligand. The Sn atom in complex 3 has a distorted tetrahedral geometry. In all three complexes, the carboxylate ligand is in the zwitterionic form with the phenolic proton moved to the nearby azo nitrogen atom, in contrast to the free carboxylic acid ligand which is in the azo form.