Azo Complex Research Articles

Selective C- and N-Methylation of Secondary Alcohols and Nitroaromatics with Methanol Catalyzed by a New Ru(II)-Azo Complex

Selective <i>C</i>- and <i>N</i>-Methylation of Secondary Alcohols and Nitroaromatics with Methanol Catalyzed by a New Ru(II)-Azo Complex

Copper (II)-azo complex modified hydrogel: A sensitive colorimetric sensor for visual detection of H2S gas

Hydrogen sulfide (H2S) in human breath is important for early diagnosis of halitosis and prevention of oral diseases. The current H2S sensors suffer from poor specificity or high detection limit, restricting their widespread applications in daily life. In this work, a novel colorimetric sensor for H2S gas detection was constructed by incorporating copper(II) pyridine diazinonaphthol (Cu-PAN) complex into agarose hydrogel. H2S can react with Cu-PAN and break the ligand bond between Cu2+ and PAN, resulting in an obvious color change. Thanks to the specificity of Cu-PAN complex and excellent loading and diffusion functions provided by three-dimensional structure of hydrogel, the prepared sensor exhibited superior sensing performance in the aspects of sensitivity, selectivity, response time, simplicity, etc. A broad detection range of 1–50 ppm was achieved by this sensor. The feasibility of the Cu-PAN hydrogel sensor for the measurement of H2S level in human exhaled breath was validated. This work supplies a new way to design a green, simple, rapid, sensitive tool for the detection of other gases.

Synthesis of ZnO Nanoparticles from Azo Complexes and Study their Biological Activity

An azo complex was prepared from the reaction of Zn(II) with the ligand 8- [(4-hydroxyphenyl) azo] guanine. A reaction with Zn(II) gave a new complex Bis(8- [(4-hydroxyphenyl) azo] guanine) zinc (II) chloride at pH = 8. Spectrophotometry of the prepared complex was performed using UV-Visible and infrared spectra and micro-elemental analysis. Zinc oxide nanoparticles were then prepared from the prepared complex by thermal decomposition method. The nano particles characteristic to know its structural properties was conducted by using a scanning electron microscope, atomic force microscopy and X-ray diffraction. The biological activity of the azo-zinc complex and the zinc oxide nanoparticles was studied against E. coli, Ps. aeruginosa and S. aureus. The iso-zinc oxide nanocomplex was more effective than the iso-zinc complex against these genera of bacteria.

Amido Black 10B Dye Copper Complex�Synthesis, Characterization and Color Analysis

The present paper presents the obtaining and the characterization of a new complex acid dye by combining the transition metal Cu (II) with an azo acid dye, namely Amido Black 10B (C.I. 20.470), as ligand. The ligand and the resulted new azo complex were characterized by FT/IR spectroscopy, UV-Vis spectroscopy, AAs spectrometry, thermal analysis, and PXRD spectrometry. The structure of the ligand and the structure of the new synthesized copper complex were elucidated by all the above mentioned analysis methods. The formation of the azo metal complex with Cu(II) was confirmed by UV-Vis spectrum. Thermogravimetric and spectral analysis reveal its different stability in the air and nitrogen atmosphere, with high nitrogen stability. The PXRD analysis shows crystalline structure for the copper complex. At the same time, the color analysis was performed for the ligand and the synthesized complex in powder by means of UV-Vis CIEL*a*b* color space parameters, under the CIE recommended illuminants: D65 (natural day light), A (incandescent light) and F2 (fluorescent light) under the standard 10� observer angle. An important color phenomenon, namely metamerism, was highlighted for the complex, as well. Due to the presence of the Cu (II) ions, this azo complex presents a different color, calculated by the color differences AE*ab and AC*, a superior saturation and color strength than its ligand.

A new zinc coordination polymer constructed from 4-[(8-hydroxy-5-quinolinyl)azo]-benzenesulfonic acid: synthesis, structure, and photoelectrical property

One new supramolecular compound based on H2L (H2L = 4-[(8-hydroxy-5-quinolinyl)azo]-benzenesulfonic acid, C15H11O4N3S), [Zn3L2(OH)2(H2O)6]n (1), has been synthesized by hydrothermal technique. Compound 1 exhibits a one-dimensional (1-D) double-chain structure. Compound 1 is the first example of an azo complex used to co-sensitize TiO2 photoanode with Ru dyes (N719, N3). In the tandem structure of compound 1/N719/TiO2, compound 1 plays a significant role in the improvement of the photoelectric conversion efficiency, which works with N719 to modify the energy level. The results show that the compound 1/N719/TiO2 solar cell exhibited excellent photovoltaic performance with the photoelectric conversion efficiency of 7.1% under standard global AM 1.5 solar irradiation conditions.

A GSH-activatable ruthenium(ii)-azo photosensitizer for two-photon photodynamic therapy.

A glutathione (GSH)-activatable ruthenium(ii)-azo photosensitizer was prepared. The complex had low toxicity towards cells under dark conditions. It exhibited excellent phototoxicity under two-photon excitation (810 nm) and thus was developed as a two-photon photodynamic anticancer agent for cancer therapy.

New findings and the current controversies for water oxidation by a copper(ii)-azo complex: homogeneous or heterogeneous?

In this paper, new findings for the water-oxidizing activity of [(L)Cu(II)(NO3)], (L = (E)-3-(pyridin-2-yldiazenyl)naphthalen-2-ol (HL)) under both electro-water oxidation conditions and in the presence of cerium(iv) ammonium nitrate are reported.

Structure and absorption of Co(III) azo complex dyes based on pyrrolinone esters: DFT and TD DFT study

The relation between structure and absorption of three symmetrical 2:1 octahedral Co(III) azo complexes was studied. Quantum chemical calculations based on density functional theory (DFT) relate well with E-azo configuration of ligands with coordinated nitrogen atoms coming solely from phenolic residues. DFT calculations estimate the mer stereoisomer as remarkably preferred with respect to any fac arrangement. Time dependent DFT calculations using B3LYP and CAM-B3LYP functionals were successfully used to interpret the absorption spectra in a visible range.

Fabrication of size controllable polymeric hollow nanospheres containing azo functional groups via ionic self-assembly

Fabrication of size controllable polymeric hollow nanospheres with azo functional groups is of great interest for applications in biomedical engineering, electronics, optics, and diagnostics. We report here a facile and economic way of fabricating polymeric hollow nanospheres with azo functional groups using ionic self-assembly of random copolymers poly(acrylonitrile)-stat-poly(4-vinyl-pyridine) and azobenzene dye metanil yellow (MY). The size of the hollow nanospheres is homogeneous and can be conveniently controlled by varying molar ratios of the copolymers to MY and molar ratios of monomers of the copolymers. The composition of the polymeric nanospheres and the self-assembly behaviors were characterized by 1H-NMR, FTIR, UV-Vis spectrophotometry, TEM, dynamic light scattering and elemental analysis. The formation process of hollow nanospheres was considered based on the results from UV-Vis spectrophotometry and TEM. Finally, the effects of azo complex composition on the morphology of the nanospheres were discussed, and the formation mechanism of polymeric hollow nanospheres was proposed.

Colorimetric and luminescent dual-signaling responsive probing of thiols by a ruthenium(II)-azo complex

A dinuclear ruthenium(II) complex linked via a reducible azo group [Ru(bpy)2(azobpy)Ru(bpy)2]Cl4 (Ru2azo, bpy=2,2′-bipyridine, azobpy=4,4″-azobis (2,2′-bipyridine)) was adopted as a probe for thiols. Results showed that Ru2azo could selectively and effectively react with biological thiols (such as cysteine, homocysteine and glutathione) with a 10−7M detection limit. After it reacted with thiols, the original gray color of Ru2azo solution immediately turned yellow and the luminescence significantly enhanced, showing “naked-eye” colorimetric and “off–on” luminescent dual-signaling response for thiols. Mechanism studies demonstrated that Ru2azo reacted with thiols undergoing a two-electron transfer process, forming the azo2− anion product.

Visible Light Switching of a BF2-Coordinated Azo Compound

Here we report the synthesis and characterization of a BF(2)-azo complex that can be induced to isomerize without the need of deleterious UV light. The complexation of the azo group with BF(2), coupled with the extended conjugation of the N═N π-electrons, increases the energy of the n-π* transitions and introduces new π-nonbonding (π(nb)) to π* transitions that dominate the visible region. The well separated π(nb)-π* transitions of the trans and cis isomers enable the efficient switching of the system by using only visible light. The complexation also leads to a slow cis → trans thermal relaxation rate (t(1/2) = 12.5 h). Theoretical calculations indicate that the absorption bands in the visible range can be tuned using different Lewis acids, opening the way to a conceptually new strategy for the manipulation of azo compounds using only visible light.

Hydroquinoid Chromium Complexes Bearing an Acyclic Conjugated Bridge: Chromium-Templated Synthesis, Molecular Structure, and Haptotropic Metal Migration

The naphthohydroquinoid tricarbonyl chromium complexes 3 and 6, bearing a styryl or phenylazo moiety, have been synthesized and studied for the haptotropic metal migration along the extended π-system. Quantum chemical calculations suggested a feasible stepwise rearrangement of the Cr(CO)3 fragment from the hydroquinoid to the other terminal phenyl ring for the azo- rather than for the ethene-bridged system. An experimental and kinetic study of the ethene-bridged complex 3 revealed a haptotropic metal shift onto the adjacent naphthalene ring to give isomer 7 and suggested a competing intermolecular decomplexation−recomplexation pathway for the coordination of the terminal phenyl ring, affording bismetalated complexes 8 and 9. Attempts of a controlled metal migration in the azo complex analogue 6 under similar conditions were unsuccessful and resulted in partial decomposition.

Heterogeneous Suzuki and copper-free Sonogashira cross-coupling reactions catalyzed by a reusable palladium(II) complex in water medium

An efficient heterogeneous Pd(II) azo complex catalyst for Suzuki and Sonogashira cross-coupling reaction has been developed. The catalyst showed an excellent activity for these reactions in water medium under aerial conditions. A new polystyrene anchored Pd(II) azo complex has been synthesized and characterized. The present Pd(II) azo complex behaves as a very efficient heterogeneous catalyst in the Suzuki coupling and Sonogashira coupling reaction in water medium. Aryl halides, coupled with phenylboronic acids (Suzuki–Miyaura reaction) or terminal alkyne (Sonogashira reaction), smoothly afford the corresponding cross-coupling products in excellent yields (83–100% yield for Suzuki reaction and 68–96% yield for Sonogashira reaction of aryl halides) under phosphine-free reaction conditions in the presence of polystyrene anchored Pd(II) azo complex catalyst in water medium. Furthermore, the catalyst has shown good thermal stability and recyclability. This polymer-supported Pd(II) catalyst could be easily recovered by simple filtration of the reaction mixture and reused for more than six consecutive trials without a significant loss of its catalytic activity.

Spectral, thermal and optical properties of metal(ІІ)–azo complexes for optical recording media

A novel ligand, (Z)-1,5-dimethyl-4-(2-(3-methyl-5-oxo-1-phenyl-1H-pyrazol-4(5H)-ylidene)hydrazinyl)-2-phenyl-1,2-dihydropyrazol-3-one] and its metal(II)–azo complexes were synthesized and characterized using elemental analyses, proton NMR, electrospray ionization mass spectrometry, FT-IR and UV–visible absorption. Smooth thin films of the metal(II)–azo complexes were prepared using spin-coating, and the absorption spectra of the films were measured. The thermal properties of the metal(ІІ)–azo complexes were investigated using TGA and DSC. The optical constants (complex refractive index N = n + ik) of the films on single-crystal silicon were determined using variable-angle scanning ellipsometry from which the complex dielectric function ( ɛ) and absorption coefficient ( α) were calculated. The photostabilities of the metal(II)–azo complex films were also investigated.

Use of a New Polymer Anchored Cu(II) Azo Complex Catalyst for the Efficient Liquid Phase Oxidation Reactions

A new polymer anchored copper(II) azo complex has been synthesized and characterized by using scanning electron microscope (SEM), thermogravimetric analysis (TGA), elemental analysis, atomic absorption spectroscopy (AAS) and spectrometric methods like diffuse reflectance spectra of solid (DRS) and Fourier transform infrared spectroscopy (FTIR). The immobilized Cu(II) catalyst shows excellent catalytic activity in oxidation of cyclohexene, styrene, benzyl alcohol and ethylbenzene in presence of tert-butylhydroperoxide (TBHP) as an oxidant. The effects of different solvents, oxidants, temperature, substrate oxidant ratio and amount of catalyst were also studied. The catalytic results reveal that the polymer-anchored Cu(II) azo complex catalyst can be recycled more than five times without appreciable loss in the catalytic activity.

Investigation of electrochemical degradation and application of e-paper dyes in organic solvents

To avoid environmental pollution due to organic dye solutions, the electrophoresis and degradation of dye in organic solvents such as alcohol were investigated. Many dyes were tested in the Indium tin oxide (ITO) electrode driving cell, and about 15 dyes moved under voltage driving. Both the curves of ultraviolet-visible (UV-Vis) and infrared (IR) spectra of the electrophoresis samples showed that the metal complexes Red 04 and Acid Black 1 were degradable in alcohol solution by electrochemical reaction. The cyclic volt-ampere curves of the samples from the electrochemical working station proved that electrochemical reactions took place. Based on the analysis of UV-Vis and IR spectra, the electrochemical degradation products of azo and metal complex azo dyes at lower voltage driving (1-5 V) in organic solvents are oxidized azobenzene, not hydrazine, which was found in the electrochemical degradation of dye water solutions. When the ITOelectrode is modified by a polyimide (PI) film to a thickness less than 4 μm, the electrochemical degradation of the dye in alcohol solution will not appear in the cyclic volt-ampere curves. A dye electrophoresis in organic solution flexible prototype e-paper display was formed and the display picture is shown.

Diacetonitrile-tetra-kis{μ(2)-3-anilinocarbonyl-1-[(5-chloro-2-oxidophen-yl)diazen-yl]-2-naphtholato}tetra-aqua-diiron(III)disodium(I) dihydrate.

The title compound, [Fe2Na2(C23H14ClN3O3)4(C2H3N)2(H2O)4]·2H2O, is a hydrated Fe–azo complex dimer that is used as a charge-control agent in electrophotography. The mol­ecule is a centrosymmetric dimer with two octa­hedral FeIII units linked by two bridging five-coordinate NaI cations. Each FeIII atom is chelated by the N and two O atoms from two 3-anilinocarbonyl-1-[(5-chloro-2-oxidophen­yl)diazen­yl]-2-naph­tholate ligands. The Na+ cation is coordinated by a carbonyl O atom from the two ligands of each octa­hedral FeIII unit, two water mol­ecules and the N atom of an acetonitrile mol­ecule. Two solvent water mol­ecules complete the structure. In the crystal structure, the dimeric mol­ecules are bridged by a pair of discrete inter­molecular O—H⋯O hydrogen bonds, one of which involves a sodium-bound water mol­ecule and a hydrate water, and the other a 5-chloro­phenolate O atom and a water molecule to form an extended chain along b.

Optical properties of nickel(II)–azo complexes thin films for potential application as high-density recordable optical recording media

Smooth thin films of three kinds of nickel(II)–azo complexes were prepared by the spin-coating method. Absorption spectra of the thin films on K9 glass substrate in the 300–600 nm wavelength region were measured. Optical constants (complex refractive index N = n + i k ) and thickness of the thin films prepared on single-crystal silicon substrate in the 300–600 nm wavelength region were investigated on rotating analyzer–polarizer type of scanning ellipsometer, and dielectric constants ε ( ε = ε 1 + i ε 2 ) , absorption coefficients α as well as reflectance R of thin films were then calculated at 405 nm. In addition, in order to examine the possible use of nickel(II)–azo complex thin film as an optical recording medium, one of the nickel(II)–azo complex thin film prepared on K9 glass substrate with an Ag reflective layer was also studied by atomic force microscopy and static optical recording. The results show that the nickel(II)–azo complex thin film is smooth and has a root mean square surface roughness of 2.25 nm, and the recording marks on the nickel(II)–azo complex thin film are very clear and circular, and their size can reach 200 nm or less.

Studies on the Effect of Hydroxy Benzene Diazonium Salts on Physico-Mechanical Properties of Jute Fiber

ABSTRACT Jute fiber was treated with three different hydroxy benzene diazonium salts in acidic and basic media. The formation of coupling with lignin in the polymer system was observed by the infrared spectra and nitrogen content estimation. The physico-mechanical properties, viz., tensile strength, tenacity, elongation at break, moisture regain, shrinkage, and loss in weight of jute fiber were studied. The tensile strength, tenacity, and moisture regain properties of the treated fiber were found lower in comparison to those of raw (control) fiber. However, higher tensile strength and tenacity of the fiber treated with ortho hydroxy benzene diazonium salts in comparison to fiber treated with meta hydroxy benzene diazonium salts were observed. The tensile strength and tenacity of the fiber treated with meta hydroxy benzene diazonium salts were higher than those of the fiber treated with para hydroxy benzene diazonium salts. The elongation at break of the treated fiber is found greater than that of the raw fiber. The fiber treated in basic media shows higher tensile strength than that treated in acidic media. The formation of metallated azo complex compound on jute fiber was observed by infrared spectra. The nature of the shades developed on jute fiber was also reported.

Optical parameters and absorption of copper (II)-azo complexes thin films as optical recording media

Smooth thin films of three kinds of azo dyes of 2-(5′- tert-butyl-3′-azoxylisoxazole)-1, 3-diketones and their copper (II)-azo complexes were prepared by the spin-coating method. Absorption spectra of the thin films on a glass substrate in the 300–600 nm wavelength region were measured. Optical constants (complex refractive index N= n+ ik) and thickness of the thin films prepared on single-crystal silicon substrate in the 300–600 nm wavelength region were investigated on rotating analyzer–polarizer type of scanning ellipsometer, and dielectric constants ε( ε= ε 1+ iε 2), absorption coefficients α as well as reflectance R of thin films were then calculated. In addition, one of the copper (II)-azo complex thin film prepared on glass substrate with an Ag reflective layer was also studied by atomic force microscopy (AFM) and static optical recording. AFM study shows that the copper (II)-azo complex thin film is very smooth and has a root mean square surface roughness of 1.89 nm. Static optical recording shows that the recording marks on the copper (II)-azo complex thin film are very clear and circular, and the size of the minimal recording marks can reach 200 nm.