NN Double Bond Research Articles

Sustainable and cost-effective metastable white cast iron powder for the degradation of textile dyes

The textile industry is one of the main consumers of dyes. The treatment of wastewater containing dyes is a major challenge worldwide for a sustainable and environmental friendly goods production. Therefore, it is necessary to develop an effective method for removing the dyes from wastewater. In this study, an economical and efficient white cast iron powder was reported to degrade reactive red 195A azo dye in an aqueous solution. The white cast iron powder was obtained by ball-milling a rapidly solidified cast iron ribbon, exhibiting unique metastable properties and a large surface area. These metastable phases are particularly effective in providing electrons for the dye degradation of NN double bonds, thereby improving the catalytic process, and enhancing the overall bond degradation efficiency. The influence of different parameters such as temperature, dye concentration, and reusability of metallic iron powder on the degradation efficiency was investigated. The experimental analysis revealed rapid and efficient dye degradation that was achieved within 15 min using 0.1 g of white cast iron powder. The study also demonstrated the effectiveness of the degradation rate improved significantly with an increase in temperature. Even after seven recycling experiments, the Fe82C15Si3 powders maintained high degradation efficiency toward the reactive red 195A solutions. This research will contribute to developing a new, highly efficient, and low-cost method for treating organic dye wastewater.

Recent Advances in the Microwave and Ultrasound-Assisted Synthesis of Pyrazole Scaffolds

Abstract: Pyrazoles are well-known five-membered heterocyclic compounds and are found in a wide variety of synthetic and natural compounds. Compounds carrying pyrazole scaffolds exhibit a wide range of biological activities such as anticancer, antimicrobial, anticonvulsant, antioxidant, analgesic and anti-inflammatory effects. Pharmaceuticals with many different activities in the pyrazole structure are currently on the market (e.g., celecoxib, lonazolac, tepoxalin, rimonabant, pyrazofurin, epirizole). The pyrazole ring contains the N-N double bond, which is thought to have a key role in biological activity, and compounds with this bond are difficult to produce by organisms, so their relative abundance is very low in nature. For this reason, many studies have been carried out on this structure and it has been revealed that the structure has a unique effect spectrum. Microwave-assisted synthesis has opened up some new opportunities compared to conventional synthesis. It is possible to use less solvent and reduce processing time with microwave synthesis. In addition, better selectivity and thermal stability are provided by microwave synthesis. Ultrasound-assisted synthesis is often used to enhance conventional solvent extraction, while microwaves reveal bioactive compounds by heating without any solvent. In the traditional method of pyrazole synthesis; polar solvents, acidic and basic catalysts are needed in large quantities in the synthesis of pyrazole scaffolds. This review aims to summarize the recent advancements in the synthesis methods of a pyrazole ring with non-traditional methods. Therefore this article will provide readers with a new perspective on the synthesis of pyrazole scaffolds as an environmentally friendly alternative.

NiO coupled SnS2 nanoparticles with improved magnetic and photocatalytic performance against the degradation of organic dyes without N[dbnd]N double bond

SnS2 exhibits lower photocatalytic activity against organic dyes without NN double bonds due to the SnIV/SnII transition which decreases its degradation efficiency due to the decreased formation of O2∗− and OH∗ radicals. To upgrade the photocatalytic ability of SnS2 against dyes without NN bonds, NiO coupling has been adopted and the results obtained are furnished in this paper. By adopting precipitation method, SnS2, NiO and SnS2NiO nanocomposite was synthesized. Structural, morphological, compositional, functional group analyses of SnS2, NiO and SnS2NiO nanocomposite were performed by adopting techniques such as XRD, SEM, TEM, XPS, FTIR and PL. The magnetic property of pure SnS2 got enhanced by coupling with NiO thereby making it suited for magnetic devices. Photocatalytic activities were performed against MB and RhB dyes under visible light. The enhanced degradation ability of the SnS2NiO composite may be due to its enhanced oxidation/reduction ability of the electrons and holes generated under the effect of visible light.

Characterization of functional microbial communities involved in different transformation stages in a full-scale printing and dyeing wastewater treatment plant

A simplified model employing anaerobic3-oxic2-sedimentaion reactor and multiple linear regression was proposed in this study. Four typical azo dyes were treated as model contaminants. Decolorization firstly happened by the cleavage of NN double bond, aromatic amines were yielded. Afterwards, deamination and desulphurization occurred, phenol and naphthol were formed. Then dearomatization reactions were detected by introducing the atoms of O2 into the aromatic nucleus. At last complete mineralization happened, yielding CO2 and H2O. Two types of functional microbial communities for NN double bond cleavage and aromatic rings broken were statistically identified with multiple linear regression and the results were presented in t-value biplots. The genera of Enterococcus, Acidaminococcus, Bacteroides, Megasphaera and Klebsiella played significantly important roles in cleavage of NN, while Pseudomonas, Anaerovorax and Longilinea demonstrated significantly positive relationship with breaking the aromatic rings. We must point out that species in the genera of Anaerovorax and Longilinea are usually reported as strictly anaerobic bacteria, while, in our study, they were abundant in aerobic compartments and significantly positive with aromatic compounds. The findings will provide important information for operation process optimization and treatment efficiency improvement in printing and dyeing wastewater treatment plant.

Photocatalytic decolorization of azo dyes on TiO2: Prediction of mechanism via conceptual DFT

The aim of this study is to develop a shortcut method to predict the intermediates and the mechanism of decolorization reactions of azo dyes. To this purpose, Reactive Red 195 (RR195) was chosen as the representative member of azo dyes and photocatalytic decolorization reaction of RR195 in the presence of TiO2 under UV-A light irradiation was investigated. TiO2 was synthesized by an acid-catalyzed sol-gel method from an alkoxide precursor and characterized by XRD, XPS, ESEM-EDX and BET measurements. The decolorization reaction was monitored by UV–vis, FTIR, GC–MS and ESEM-EDX techniques. Conceptual Density Functional Theory was applied to the degradation reaction of the target molecule and reactivity descriptors were calculated by means of DFT/B3LYP/6-31G* level of theory. Eventually, the reactive sites of the molecule for OH radical attack were determined and the reaction mechanism was predicted by combining the results of the DFT calculations with the experimental FTIR and GC–MS analyses. The predicted mechanism was confirmed by comparison with the experimental results on simple structures reported in the literature. The results of the study suggest that TiO2/UV photocatalysis may be used as a method for treatment of diluted wastewaters in textile industries, adsorption on TiO2 surface occurs through sulfo and carbonyl groups of the dye molecule, while decolorization by the breaking of the NN double bond of the chromophore group.

Azo dicarboxylates are not conjugated: X-ray crystal structure and theoretical calculations on di-t-butylazodicarboxylate

The X-ray crystal structure of trans-di-t-butyl azodicarboxylate (DTBAD, 2) was determined and this revealed that the torsion angle between the NN and CO double bonds is 84.0(2)°, and that between the anti-disposed CO vectors is 180°. This is the first report of the solid state structure of an azodicarboxylate ester. The molecule was subjected to Density Functional Theory geometry optimization at the B3LYP/6-31G(d) level in cyclohexane medium, and the global minimum structure agreed in principle with that determined in the solid state by crystallography. The N–C(O) torsion angle in the optimized structure is 107.7°, and the CO vectors lie in an anti relationship. Similar calculations on the unknown cis-NN isomer revealed an optimum geometry whose energy is predicted to lie only 11.9 kJ/mol higher than that of the trans isomer. M062X/6-311+G(d) model chemistry was used to determine relative electronic energies and to conduct Natural Bond Orbital (NBO) calculations. Exploration of the energetics of rotations about the N–C(O) bonds revealed a clear preference for near-orthogonality in azodicarboxylates, and suggests almost complete absence of classical conjugation between the neighbouring π bonds. Electronic transitions were simulated using the time-dependent DFT (TD-DFT) approach at the B3LYP/6-311+G(d) level, and the weak band in the near-UV for 2 in cyclohexane was reproduced in the calculations. The electronic isolation of the NN bond may be important in the numerous applications of azodicarboxylates in organic synthesis, and the small energy difference between the trans and cis isomers implies the likely involvement of the latter in the successful photochemical diaza-Diels–Alder reaction of diethyl azodicarboxylate with 1,3-cyclohexadiene.

Azo-coupled zinc phthalocyanines: Towards broad absorption and application in dye-sensitized solar cells

The synthesis of symmetrical azo-coupled zinc phthalocyanines (7, 8, 10 and 11) incorporating two spectrally complementary photogenerators (azo dyes and phthalocyanines) by NN double bonds in a single structure was described. The four sensitizers were fully characterized by Fourier Transform infrared spectroscopy, UV–Vis spectroscopy, proton nuclear magnetic resonance, mass spectrometry, elemental analyses, thermogravimetric analysis and cyclic voltammetry. All the azo-coupled phthalocyanines exhibited broad absorptions covering the range 300–800nm. The cyclic voltammetry studies indicated that the LUMO and HOMO energy levels of four synthesized azo-coupled phthalocyanines could ensure efficient electron injection and thermodynamically favorable dye regeneration. Thermal stability studies showed that the four sensitizers were stable above 200°C. The new compounds were tested in dye-sensitized solar cells and compound 8 showed the best photovoltaic performance, yielding 2.7% power conversion efficiency.

Comparative study on the mechanism in photocatalytic degradation of different-type organic dyes on SnS2 and CdS

The photocatalytic performances of the SnS2 and the CdS under the irradiation of visible light were investigated by using different organic dyes as reactants. The photodegradation of organic dyes containing NN double bond on the SnS2 followed a reduction mechanism with photoelectrons via the SnIV/SnII transition while the photodegradation of organic dyes containing NN double bond on the CdS and the photodegradation of organic dyes without NN double bond on either the SnS2 or the CdS followed an oxidation mechanism with O2− and OH radicals. The SnS2 exhibited much higher activity than the CdS during the photocatalytic degradation of organic dyes containing NN double bond, since the reduction of reactant molecules on the SnS2 surface was much faster than the migration of either the O2− or the OH radicals. However, the SnS2 displayed even lower activity than the CdS in the photocatalytic degradation of other organic dyes without NN double bond, since all these reactions followed the oxidation mechanism and the SnS2 displayed a lower efficiency than the CdS in producing O2− or OH radicals due to the presence of the SnIV/SnII transition.

Study of cis–trans isomerization mechanism of 3,3′-azobenzene disulphonate in the lowest singlet and triplet electronic states by density functional theory

The cis–trans isomerization pathways of 3,3′-azobenzene disulphonate in the S0 and T1 states are studied by DFT method at the B3LYP/6-31G(d,p) level. In the S0 state, the cis–trans isomerization concerns the complex pathway that is characterized by the inversion of one NNC angle combined with rotation around the NC bond, and the three sequential transition states are also found on the potential energy profile. Therefore, the cis–trans isomerization of 3,3′-azobenzene disulphonate can be understood in terms of a pathway involving successive rotation, inversion, and rotation processes. The energy barrier of the S0 state is 22.79 kcal mol−1. In the T1 state, the isomerization mainly concerns the rotational pathway around the NN double bond, and the two isomers are connected through only one transition state. The isomerization of the T1 state is related to a lower energy barrier, 5.02 kcal mol−1, but requires a change in spin-multiplicity.

First allylboration of organic compounds with the NN double bond. Synthesis of N-allylpyrazolidines and allyl-1,2-diphenylhydrazine

Abstract Triallylborane adds to the N N double bond of pyrazolines 1 and 2 at 0 °C giving after deboronation the corresponding N -allylpyrazolidines 4 and 5 . Further transformations of allylpyrazolidine 4 including the cyclopropane ring opening were studied. Allylboration of azobenzene with triallylborane gives rise to 1-allyl-1,2-diphenylhydrazine.

Stoichiometric and Homogeneous-Catalytic Diboration of the NN Double Bond of Azobenzene

The diboration of the N=N double bond of azobenzene was achieved by reaction of the [3]diboraplatinametalloarenophanes derived from ferrocene, [Fe(eta5-C5H4)B(NMe2)Pt(PEt3)2B(NMe2)(eta5-C5H4)], and bis(benzene)chromium, [Cr(eta6-C6H5)B(NMe2)Pt(PEt3)2B(NMe2)(eta6-C6H5)], with an excess of azobenzene in toluene at elevated temperature. The formation of the anticipated ansa-bis(boryl)hydrazines was substantiated by the determination of the molecular structure of the chromium derivative by X-ray diffraction. The synthesis of the ansa-bis(boryl)hydrazine derivative of ferrocene could also be accomplished under homogeneous catalysis conditions. Hence, reaction of the well-known [2]boraferrocenophane, [Fe(eta5-C5H4)2B2(NMe2)2], and azobenzene in the presence of 5 mol % [Pt(PEt3)3] afforded the bis-borylated hydrazine derivative in good yields.

Synthetic and Mechanistic Studies of the Four-Electron Reduction of Dioxygen, NN, and NO Double Bonds by Tungsten(II) Aryloxide Compounds

Reduction of the cyclometalation-resistant aryloxide compounds [W(OC6HPh2-2,6-R2-3,5)2Cl4] (1, R = Ph; 2, R = Me; 3, R = But) in the presence of a variety of phosphine ligands generates the W(II) s...

Scandium ion-promoted reduction of heterocyclic N=N double bond. Hydride transfer vs electron transfer.

Hydride transfer from 10-methyl-9,10-dihydroacridine (AcrH(2)) to 3,6-diphenyl-1,2,4,5-tetrazine (Ph(2)Tz), which contains a N=N double bond, occurs efficiently in the presence of Sc(OTf)(3) (OTf = OSO(2)CF(3)) in deaerated acetonitrile (MeCN) at 298 K, whereas no reaction occurs in the absence of Sc(3+). The observed second-order rate constant (k(obs)) increases with increasing Sc(3+) concentration to approach a limited value. When AcrH(2) is replaced by the dideuterated compound (AcrD(2)), the rate of Sc(3+)-promoted hydride transfer exhibits the same primary kinetic isotope effect (k(H)/k(D) = 5.2+/-0.2), irrespective of Sc(3+) concentration. Scandium ion also promotes an electron transfer from CoTPP (TPP(2)(-) = tetraphenylporphyrin dianion) and 10,10'-dimethyl-9,9'-biacridine [(AcrH)(2)] to Ph(2)Tz, whereas no electron transfer from CoTPP or (AcrH)(2) to Ph(2)Tz occurs in the absence of Sc(3+). In each case, the observed second-order rate constant of electron transfer (k(et)) shows a first-order dependence on [Sc(3+)] at low concentrations and a second-order dependence at higher concentrations. Such dependence of k(et) on [Sc(3+)] is ascribed to formation of 1:1 and 1:2 complexes between Ph(2)Tz(*)(-) and Sc(3+) at the low and high concentrations of Sc(3+), respectively, which results in acceleration of the rate of electron transfer. The formation of 1:2 complex has been confirmed by the ESR spectrum in which the hyperfine structure is different from that of free Ph(2)Tz(*)(-). The 1:2 complex formation results in the saturated kinetic dependence of k(obs) on [Sc(3+)] for the Sc(3+)-promoted hydride transfer, which proceeds via Sc(3+)-promoted electron transfer from AcrH(2) to Ph(2)Tz, followed by proton transfer from AcrH(2)(*)(+) to the 1:1 Ph(2)Tz(*)(-)-Sc(3+) complex and the subsequent facile electron transfer from AcrH(*) to Ph(2)TzH(*). The effects of counteranions on the Sc(3+)-promoted electron transfer and hydride transfer reactions are also reported.

Molybdenum(IV)-d2 Reactivity in a Quasiplanar Oxo-Environment Modeled by Calix[4]arene: The Reductive Cleavage of NN Double Bond and the Formation of 1-Metallacyclopropene from the Corresponding Alkyne Complexes

[p-But-calix[4]-(O)4-MoIV], generated in situ from [MoCl4·THF2] and the alkali salts of p-But-calix[4]arene, displays the reactivity expected for a d2-carbenoid metal. The reaction carried out in the presence of azobenzene led to the cleavage of the NN bond and the formation of a dimeric MoVI-phenylimido derivative, [{μ-p-But-calix[4]-(O)4}2{MoVI⋮NPh}2], while the reaction with acetylenes led to 2-metallacyclopropene complexes [{p-But-calix[4]-(O)4-Mo}(η2-C2R2)], which converted to 1-metallacyclopropenes, the precursor of alkylidene and alkylidyne functionalities, in the reaction with a hydride source.

New Isomers of N8 without Double Bonds

Quantum mechanical methods have been used to examine isomers of N8. In addition to the previously studied octaazacubane structure (Oh symmetry, 1), we have investigated two new structures, of D2h (2) and C2v (3) symmetry, without NN double bonds. The C2v structure may be designated octaazacuneane. The following basis sets and methods have been employed to optimize geometries: (1) (SCF, CISD, CCSD)/DZP; (2) (SCF, MP2, B3LYP, B3P86, BHLYP)/6-31G*; (3) B3LYP/6-311+G*. The single-point energies have also been estimated at the CISD+Q/DZP level of theory with CISD/DZP geometries and at the CCSD(T)/DZP level with CCSD/DZP geometries. The harmonic vibrational frequencies and their infrared intensities have also been predicted with the SCF, MP2, and DFT methods. The results show that the two new isomers are both minima on the N8 potential energy hypersurface and of higher energy than isomers containing NN double bonds. Among the three isomers with only single bonds, the ones with the higher symmetry have higher energies.

Strain Energies in Homoatomic Nitrogen Clusters N(4), N(6), and N(8).

Strain energies and resonance energies can be obtained as the energy changes for appropriate homodesmotic reactions using ab initio calculated total energies as the energies of the reactants and products involved. Homodesmotic reactions conserve bond types and preserve valence environments at all atoms, requirements that favor the cancellation of basis set and electron correlation errors in the ab initio energies. In this paper we calculate strain energies and resonance energies for N(4), N(6), and N(8) clusters in a number of chemically significant but, for nitrogen, hypothetical structural forms. The nitrogen cluster strain energies are generally of the same order of magnitude as those of isostructural hydrocarbon clusters, and individual differences can be explained by using the ring strain additivity rule and recognizing the effect of the presence of lone pairs of electrons on nitrogen clusters but not on the hydrocarbons. Resonance energies of the nitrogen clusters are much smaller than those of the comparable aromatic hydrocarbons. The differences can be rationalized by considering the relative strengths of CC and NN single and double bonds. Strain and resonance energies of nitrogen clusters are compared with those previously reported for homoatomic clusters of phosphorus and arsenic. Trends through the series are remarkably similar, but strain energies for clusters from lower periods are progressively smaller. Strain and resonance have been important organizing concepts in organic chemistry for many years. Estimates of corresponding parameters for inorganic analogs are only now becoming available.

Reactions of Bifunctional Sulfur Compounds with Dihydrazido Phosphoric Acid Derivatives—Five- and Six-Membered Rings with Four N-Atoms

Abstract Thionylchloride and sulfurdichloride react with N-substituted phosphoric acid or thiophosphoric acid dihydrazides in the presence of triethylamine to yield six-membered rings containing sulfur if the substituents at N adjacent to the sulfur are electron-withdrawing groups such as -C(=O)Et. These groups lacking redox reactions are observed, resulting in the formation of a five-membered ring with an NN double bond that contains no sulfur. The X-ray structure of this “λ5-phosphatetrazolin” has been investigated: the ring is planar, PN 1.665(6), 1.680(6), N-N 1.372(9), 1.385(10), N=N 1.275(10)A.

Laser-induced fluorescence of CNN in an Ar matrix

Fourier transform laser-induced fluorescence of CNN, A 3Π→ X 3Σ −, in an argon matrix has been investigated. Eight new vibronic transitions have been found, indicating that the ground-state asymmetric stretch is 1419 cm −1, about half the 2847 cm −1 value of earlier studies. Reanalysis of the isotopic data of Milligan and Jacox shows that CNN is similar to its isomer NCN with respect to vibrational frequencies and force constants. The new force constants indicate that CNN has CN and NN double bonds and as one of the double bonds breaks the other becomes stronger.

Reaktionen an komplexgebundenen Liganden. XXXII.: Synthese und eigenschaften von heteronuklearen mangan-chrom-komplexen mit distickstoff- diazen- und hydrazin-brükenliganden

Synthesis and properties of C 5H 5(CO) 2Mn-N 2H 4-Cr(CC) 5 (1) , C 5H 5(CO) 2Mn-N 2H 2-Cr(CO) 5 (2) and C 5H 5(CO) 2Mn-N 2-Cr(CO) 5 (3) are reported. (1) , (2) and (3) constitute the first series of heteronuclear complexes in which N 2, N 2H 2 and N 2H 4 are bound to identical metal centers. (1) and (3) are obtained by reacting C 5H 5Mn(CO) 2N 2H 4 respectively with Cr(CO) 5THF, (2) by oxidation of (1) . (2) disproportionates by addition of base yielding (3) and H 2. The IR Spectrum of (2) allows the assignment of five normal vibrations of the diazene ligand; in the IR spectrum of the deuterated analogue all six normal vibrations can be assigned. The 1H-NMR spectrum of (2) yields the coupling constant of protons on NN double bonds for the first time; the value of 3J HH  23,5 Hz points to a trans structure of (2) .

Wolfram-Carbonylkomplexe mit Stickstoff-Wasserstoff-Liganden [1] / Tungsten Carbonyl Complexes with Nitrogen Hydride Ligands [1

Abstract Synthesis, properties and reactions of [(OC)5W]2N2H2, [(OC)5W]2N2H4, (OC)5WN2H4, (OC)5WNH3, [(OC)4PØ3W]2N2H4, [(OC)4PØ3WN2H4], [(OC)5W-N2H2-W(CO)4PØ3], [(OC)5W-N2H2-W(CO)4P(CH3)3] and [(OC)5WNHCH3NHC6H5] are reported. The hydrazine complexes are synthesized by ligand exchange from the corresponding tetra-hydrofuran complexes. Oxidation by various oxidizing agents yields the diazene complexes, in most cases very low yields. Substitution of CO by phosphanes leads to reduced stability of the compounds. All complexes undergo base catalysed H-D exchange yielding the corresponding ND derivatives; the diazene complexes show a much faster exchange than the corresponding hydrazine and ammonia complexes, which is explained by the higher acidity of the N2H2 protons. The diazene complexes disproportionate under base catalysis to hydrazine and dinitrogen compounds, the latter of which loose the N2 ligand immediately. The diazene ligand of [(OC)5W]2N2H2 cannot be alkylated by reactions with (CH3)2SO4, LiCH3 or CH2N2; instead, LiCH3 as well as CH2N2 cause disproportionation to N2H4 and N2 complexes. UV irradiation of [(OC)5W]2N2H2 in THF leads to substitution of CO by THF. The THF complexes can be converted to the phosphane substituted diazene complexes. The IR, UV-VIS and 1H NMR spectra of the (OC)5W complexes are nearly identical to those of the analogous Cr and Mo compounds. The unsymmetrical phosphane diazene complexes, however, show a quartet of the N2H2 protons in the 1H NMR spectra with coupling constants of 25-26 Hz for the protons on the NN double bond. This value points to a trans configuration of the diazene ligand and its complexes respectively.