酸性嫩黄G与希土离子生成的化合物的结构特性

本文通过元素分析、红外、核磁、差热分析表征了酸性嫩黄G希土化合物的结构,证明希土离子同酸性嫩黄G的磺酸基作用生成离子型化合物,并讨论了其光谱性质。     

Complexation of Amino Acid Methylesters and Amino Alcohols by 18-Crown-6 and Benzo-18-crown-6 in Methanol

The complexation of protonated amino acid methylesters and amino alcohols bythe ligands 18-crown-6 (18C6) and benzo-18-crown-6 (B18C6) has been studiedin methanol using calorimetric titrations. No influence of the anions upon thestability constants and thermodynamic data for the reaction of protonated aminoacid methylesters with both ligands has been noticed, which indicates the completedissociation of the salts employed. A similar effect has been observed for thecomplexation of protonated and unprotonated amino alcohols with 18C6 andB18C6. The values obtained of the reaction enthalpies for the complexation ofprotonated amino acid methylesters with 18C6 are larger than those correspondingto the complexation with B18C6. The results demonstrate that the complex formationof unprotonated amino alcohols is favored by entropic contributions, while thecomplexation of protonated amino alcohols is favored by enthalpic contributionswith both ligands. The influence of various substituents on the complexation behaviorof amino acid and amino alcohol has also been investigated.     

Complex formation of amphiphilic polymers with azo dyes and their photoviscosity behavior

The hydrophobic interaction of amphiphilic copolymers, which contain 2-hydroxyethyl methacrylate(HEMA) and 1vinyl-2-pyrrolidone (VPy), with Methyl Orange (MO) was compared with that of HEMA-acrylamide (AAm) copolymers to deduce the correlation between their complexation ability in a photochromic azo dye and the photoviscosity effect in aqueous copolymer/dye complex solution. On the basis of the dialysis data and fluorometric analysis it appeared that the complexation dependence on HEMA content in the copolymers was due to the hydrophobic interaction between the polymer and the dye. For a comparable HEMA content AAm copolymers bound less MO than VPy copolymers. It was confiied by photoviscosity measurements that the conformation of the complex composed of photochromic azo dye and HEMA copolymer changed reversibly in response to the photo- and thermal isomerization of the dye. In HEMA-AAm copolymer systems the photoviscosity effect was small compared with that of HEMA-VPy copolymer systems. From these results it was concluded that the complexation ability of polymers due to the hydrophobic interaction was an important factor in producing a large photoinduced conformational change in water.     

“哑铃状”偶氮化合物的合成与表征

从分子设计的角度出发, 合成了末端含有两个庞大基团的哑铃状偶氮化合物. 其大的末端基团一方面可以增加顺、反两种异构体之间的能垒, 有利于两种异构体的稳定存在, 另一方面由于大的末端基团的存在, 为采用AFM或高分辨STM直接观测两种异构体分子相的相互转变降低了难度.     

Chromatographic behaviour of trace metal ions on a strong base anion exchange resin functionalized by azo ligands

A model which allows the evaluation of the elution volume V(E) and the central point V(C) of the breakthrough curve of a metal ion at trace level on a chromatographic column containing a chelating resin is presented. V(E) and V(C) mainly depend on the complexation properties of the active groups, and on the acidity and composition of the aqueous solution, according to the Gibbs-Donnan model for the resin. The model has been tested in the case of strong base anion exchange resins in chloride form functionalized with two different sulphonated azo ligands (T-azo-C, T-azo-R). The chromatographic behaviour of copper(II) and thorium(IV) is as expected from the formation of a complex with the azo dye in the resin, while that of zinc(II) and cadmium(II) is fully described by also taking into account the formation of anionic chloro complexes inside the resin.     

Two azo pigments based on β‐naphthol

There has been much discussion in the literature of the azo–hydrazone tautomerism of pigments. All commercial azo pigments with β‐naphthol as the coupling compound adopt the hydrazone tautomeric form (Ph—NH—N=C) in the solid state. In contrast, the red pigments 1‐[4‐(dimethylamino)phenyldiazenyl]‐2‐naphthol, C₁₈H₁₇N₃O, (1a), and 1‐[4‐(diethylamino)phenyldiazenyl]‐2‐naphthol, C₂₀H₂₁N₃O, (1b), have been reported to be azo tautomers or a mixture of azo and hydrazone tautomers in the solid state. To prove these observations, both compounds were synthesized, recrystallized and their crystal structures redetermined by single‐crystal structure analysis. Difference electron‐density maps show that the H atoms of the hydroxyl groups are indeed bonded to the O atoms. Nevertheless, a small amount of the hydrazone form seems to be present. Hence, the compounds are close to being `real' azo compounds. Compound (1a) crystallizes with a herring‐bone structure and compound (1b) forms a rare double herring‐bone structure.     

Reversible Redox Chemistry of Azo Compounds for Sodium‐Ion Batteries

Sustainable sodium‐ion batteries (SSIBs) using renewable organic electrodes are promising alternatives to lithium‐ion batteries for the large‐scale renewable energy storage. However, the lack of high‐performance anode material impedes the development of SSIBs. Herein, we report a new type of organic anode material based on azo group for SSIBs. Azobenzene‐4,4′‐dicarboxylic acid sodium salt is used as a model to investigate the electrochemical behaviors and reaction mechanism of azo compound. It exhibits a reversible capacity of 170 mAh g^?1 at 0.2C. When current density is increased to 20C, the reversible capacities of 98 mAh g^?1 can be retained for 2000 cycles, demonstrating excellent cycling stability and high rate capability. The detailed characterizations reveal that azo group acts as an electrochemical active site to reversibly bond with Na⁺. The reversible redox chemistry between azo compound and Na ions offer opportunities for developing long‐cycle‐life and high‐rate SSIBs.     

Identification of metabolites of 4,4'-diaminodiphenylmethane (methylene dianiline) using liquid chromatographic and mass spectrometric techniques.

The in vitro metabolism of 4,4'-diaminodiphenylmethane (methylene dianiline, MDA) was investigated using rabbit liver microsomes. Minimal clean-up of the microsomal incubations was carried out using zinc sulphate precipitation followed by solid-phase extraction on Sep-Pak C18 cartridges. Three metabolites were detected in hepatic microsomal incubations, namely the azodiphenylmethane (azo) azoxydiphenylmethane (azoxy) and 4-nitroso-4'-aminodiphenylmethane (nitroso) compounds. The azo and azoxy metabolites were produced enzymatically whereas the nitroso compound may have been formed via a non-enzymatic process. Reversed-phase high-performance liquid chromatography-plasma spray mass spectrometry was used to initially detect these metabolites. Fast atom bombardment mass spectrometry and fast atom bombardment tandem mass spectrometry were utilized to further structurally characterise these compounds. Comparison of mass spectral data obtained from synthesised standards with data obtained on the putative metabolites substantiated the characterisation of these compounds.     

Quantum-chemical calculations of the tautomeric forms of 3-phenylazopentane-2,4-dione and the thermodynamic parameters of complexation between its isomers and some metals in aqueous ethanol

MO LCAO calculations in the Hückel approximation of the tautomeric (azo enol, oxo azo, and hydrazo) forms of 3-phenylazopentane-2,4-dione (L) revealed that the oxo azo tautomer is most reactive. The effective charges at the atoms of all the tautomers were calculated. Complexation between some metals and L in aqueous ethanol was studied by potentiometric and conductometric titration. The potentiometric data were used to calculate the standard thermodynamic functions of the complexation.     

Syntheses of novel calix[4]arene hydrazone-based receptors and their cooperative complexation with soft and hard metal ions

Four novel calix[4]arene hydrazone-based receptors 3a?Cd were prepared in yields of 69?C87% by condensating formylated calix[4]arene ester (2) with salicylyl hydrazine, 2,4-dinitrophenyl hydrazine, nicotinyl hydrazine or phenyl thiosemicarhazide, respectively. New compounds were characterized through elemental analysis, IR, ESI?CMS, ¹H NMR studies. Compounds 3a?Cd containing two binding sites had the complexation abilities for hard and soft cations concurrently. The noncompetitive extracting experiments showed compounds 3a?Cd were excellent receptors for hard and soft metal cations. The competitive extracting experiments exhibited the cooperative complexation in binding hard and soft metal cations and compound 3a possessed outstanding selectivity for Na⁺ and Hg²⁺. The IR spectra of compound 3a before and after complexation revealed that the soft metal cation was binded in the cavity composed of hydrazone groups and azo groups at the upper rims of calix[4]arene units and hard metal cations was binded in cavity composed of ester groups and phenolic hydroxyl groups at the lower rims of calix[4]arene units.     

Cation complexation behavior of pyrene- and anthracene-appended new crown ether derivatives

Pyrene- and anthracene-appended new crown ether derivatives have been synthesized by Schiff's base reaction, and cation complexation behavior was investigated by fluorescence spectroscopy measurements. Based on photo-induced electron transfer and intramolecular charge transfer mechanism, the host molecules emit stronger fluorescence in the presence of various cations Na(+), K(+), Rb(+), Cs(+) and NH(4)(+) since the complexation between guest cations and crown ether compounds inhibit partial electron transfer from the nitrogen atom to the chromophores and subsequently fluorescence is enhanced. The binding constants were estimated from the plots of the fraction of binding sites filled for crown ether compound as a function of free-ion concentration. Results show that 15-crown-5 derivatives exhibit higher binding ability with sodium cations while 18-crown-6 derivatives had higher affinity for potassium cations, which is consistent with the hole-size relationship of the crown ethers. Ammonium ion complexation caused largest fluorescence enhancement. It is understood that ammonium ion cannot only complex with crown ether, but also interact directly with the lone pair electrons of nitrogen atom in C=N bond so that electron transfer from the nitrogen atom to chromophores is further inhibited.     

An NMR and X-ray study of the structure of the azo coupling product of 4-dimethylaminopent-3-en-2-one and benzenediazonium-tetrafluoroborate

4-Dimethylaminopent-3-en-2-one reacts with two molecules of benzenediazonium-tetrafluoroborate to give compound 1. The structure of this compound was determined by means of X-ray analysis of its crystal and 1H, 13C and 15N NMR spectra of its solution in CDCl3. The molecule of this compound contains one azo group and one hydrazone group. The substance exists, both in crystal form and in solutions of concentrations above 0.1 mol l(-1), in the form of a dimer, in which the pair of molecules are bound by two hydrogen bonds N-H...N. On diluting the solution, the dimers decompose, the two forms being in an equilibrium that is rapid on the NMR time scale.     

Determination of hydroxypropyl-beta-cyclodextrin in plasma and urine by size-exclusion chromatography with post-column complexation

The analytical method described here provides the appropriate sensitivity and selectivity for the determination of unlabelled hydroxypropyl-beta-cyclodextrin as a parenteral carrier in pharmaceutical formulations. The method may also be used in clinical trials evaluating the fate and pharmacokinetic profile of this compound, which was isolated from the biological matrix by solid-phase extraction with Bond Elut C18 cartridges. The lack of uniformity of the product was circumvented by the use of a size-exclusion chromatographic column. An indirect colorimetric complexation method was used for detection. The detection limit was 0.1 micrograms per 2 ml of biological fluid and the extraction recovery was sufficient (78%).     

Intervalence charge transfer in mixed valence compound modified by the formation of a supramolecular complex

The electrochemical and spectroelectrochemical properties of N,N-diphenyl-1,4-phenylenediamine (PDA) were investigated in the absence and in the presence of 18-crown-6-ether (18C6) or dibenzo 24-crown-8-ether (DB24C8), in a solution of tetrabutylammonium hexafluorophosphate (TBAPF6) in acetonitrile and in the presence of trifluoroacetic acid (TFA) only for 18C6. In neutral acetonitrile, PDA undergoes two reversible oxidation processes, which lead first to the formation of the cation-radical considered as mixed valence (MV) compound, and then to the dicationic species. When 18C6 is added in the medium and depending on 18C6 concentration, cyclic voltammetry shows a marked shift to more cathodic potentials of the current waves of the second redox process only. This is attributed to a strong interaction between the PDA(+2) dication and two 18C6 molecules, leading to the formation of a supramolecular complex with an association constant value K(a) = 7.0 × 10(7) M(-2). The interaction of 18C6 with PDA(+2) dication has a direct effect on the PDA(+.) cation-radical corresponding to a decrease in the lifetime of the MV compound and of the intramolecular electron transfer rate when 18C6 is present. Indeed, it results in a large decrease in the intervalence charge transfer (IV-CT) between the two amine centers in the MV compound (k(th) = 1.35 × 10(10) s(-1) in 18C6-free neutral solution containing 5.0 × 10(-4) M PDA, and k(th) = 3.6 × 10(9) s(-1) in the same medium at [18C6]/[PDA] = 20/1). And the comproportionation constant K(co) falls from 6.0 × 10(6) in 18C6-free solution to 1.6 × 10(3) at [18C6]/[PDA] = 20/1. In acidified acetonitrile and when TFA concentration is increased, PDA still shows the two successive and reversible oxidation processes, but both are shifted to more anodic potentials. However, when 18C6 is added, the two oxidation waves shift to more cathodic potentials, indicating an interaction of all protonated PDA redox states with 18C6, resulting in the formation of supramolecular complexes. In the presence of TFA, the value of K(co) is decreased to 4.3 × 10(4), but it remains unchanged when 18C6 is added, indicating no change in the lifetime of the MV compound. In this medium, IV-CT in the MV compound is greater with 18C6 (k(th) = 2.3 × 10(10) s(-1) for [18C6]/[PDA] = 20/1) than without (k(th) = 1.4 × 10(9) s(-1)), which indicates a more important IV-CT rate when 18C6 is present. The results show for the first time that is it possible to control the IV-CT rate, through the lifetime and the potential range where the MV compound is the most important. This control is not obtained as usual by chemical modification of the structure of the starting molecule, but by varying either the acidity or the 18C6 concentration as external stimuli, which lead to reversible formation/dissociation of a supramolecular complex species. Moreover, we also studied the electrochemical properties of PDA in the presence of wider crown ether such as DB24C8. We showed that PDA undergoes the same electrochemical behavior with DB24C8 than with 18C6 in neutral organic medium (K(a) = 2.9 × 10(3) M(-1)). This result suggests that the complexation between the electrogenerated PDA(+2) dication and the crown ethers may occur through face-to-face mode rather than rotaxane mode even with DB24C8 which is supposed to form inclusion complexes.     

Microwave-assisted synthesis and characterization of phthalocyanines substituted with azo compound containing eugenol moiety

The new metallophthalocyanines (Co, Ni, Cu, and Zn) substituted with azo compound containing eugenol moiety are described. Firstly, azo compound (I) containing eugenol moiety was synthesized by treating eugenol with p-hydroxyaniline. Then phthalonitrile compound (1) was synthesized by microwave-assisted synthesis method. The purification of phthalonitrile compound (1) was carried out by column chromatographic separation. Intramolecular hydrogen bonding in the azo compound (I) prevent base-catalyzed nucleophilic aromatic substitution of OH group belongs eugenol. At the last step, metallophthalocyanines (1a, 1b, 1c, and 1d) were synthesized by the microwave irradiation. The microwave-assisted synthesis method reduces reaction times and enhances the yield of the reactions. All phthalocyanine compounds are soluble in DMF and DMSO. The structures were confirmed by elemental analysis, ¹H NMR, ¹³C NMR, UV/Vis, IR and Mass spectra.     

Spectral, thermal and electrical properties of some new azo complexes

Cobalt(ll), nickel(II) and copper(II) acetates react with thymine compound (H2L) to form complexes having the general formula [MH2L(OAC)2(H2O)2]nH2O. However, the interaction of iron(III) chloride with thymine in acetic acid-water medium yields a new complex of the type [FeH2L(OAC)2H2O]OAC.H2O. All the thymine complexes have been characterized by elemental analyses, spectral and magnetic studies where thymine acts as a neutral ligand and the acetate ion behaves as a strong nucleophile during complexation. 6-aryl and thiazolylazo thymine compounds and their metal complexes were synthesized and characterized where the ligands act as a bidentate dibasic. The azo group is not involved in the structure. Thermal decomposition studies of the azo complexes were explained to give more information on the structure of the investigated materials. The effect of some transition metal cations such as Co11, Ni11 and CuII on the electrical behaviour of 6-(2-thiazolylazo)thymine compound is studied. The data obtained obeyed the relation sigma = sigma degrees exp ( - E/2kT) over the temperature range 30-150 degrees C. The observed conductivities of the different complexes follow the order Co < Ni < Cu. It is clear that this trend is depending on the decreasing of the ionic radii and the increasing stability of metal complexes. The calculated mobility of charge carriers is ranged from 10(-5) to 10(-9)cm2/V s suggesting that the conduction of the studied complexes takes place by hopping mechanism.     

Solution and solid state structure and tautomerism of azo coupled enaminone derivatives of benzoylacetone

The reaction of 4-substituted benzenediazonium tetrafluoroborates with 3-amino-1-phenylbut-2-en-1-one, 4-amino-4-phenylbut-3-en-2-one and their N-aryl derivatives 1a-1g has been used to prepare the respective azo coupling products i.e. compounds 2-5 from enaminone 1a, compounds 6-9 from enaminone 1c, compound 10 from enaminone 1d, compound 11 from enaminone 1e, compounds 12, 13 from enaminone 1f, compounds 14, 15 from enaminone 1b and compound 16 from enaminone 1g. Tautomerism of the azo coupling products prepared has been investigated in CDCl3 solutions by means of 1H, 13C and 15N NMR spectra. Crystal structures of selected products have also been investigated by means of X-ray diffraction.     

Syntheses and properties of arenediazonium and anilinium cation lariat ether complexes: an “ostrich molecule” complex and evidence for intramolecular sidearm - macroring interaction

The preparation of several novel lariat ethers (macrocyclic crown polyethers having sidearms bearing pendant donor groups) is reported, These compounds are ethers derived from known 2-hydroxymethyl-15-crown-5 or -21-crown-7. The sidearms Include 2-aminophenyl, 2,4-diaminophenyl, 2-nitrophenyl, 2-(3'-nitrobiphenyl), and 2-(3'-aminobiphenyl). In several cases, the amino groups were converted into ammonium salts which showed substantial stabilization by intramolecular hydrogen bonding. Likewise, an -NH₂^+.,BF₃^- complex showed evidence of intramolecular hydrogen bonding. Diazotization of the aminobiphenyl residue produced an arenediazonium cation which underwent intramolecular crown complexation, as judged by infrared spectroscopic studies to form what we call an “ostrich molecule” complex. Addition of N,N-dimethylaniline to the intramolecular arenediazonium cation complex afforded an azo compound, but europium shift reagent studies showed clearly that the diazonium cation reacted outside the macroring.     

In-field determination of nanomolar nitrite in seawater using a sequential injection technique combined with solid phase enrichment and colorimetric detection

A novel sequential injection method for the determination of nitrite at nanomolar level in seawater samples has been developed. The pink azo compound was formed based on the Griess reaction and quantitatively adsorbed onto a Sep-Pak C18 cartridge. The enriched azo compound was rinsed with water and ethanol (28%, v/v) in turn, and then eluted with an eluent containing 26.6% (v/v) ethanol and 0.108 mol L⁻¹ H₂SO₄. Finally the azo compound was measured using a spectrophotometer at 543 nm. Under the optimized conditions, the linear calibration ranges were 0.71–42.9 nmol L⁻¹ for a 150-mL sample and 35.7–429 nmol L⁻¹ for a 15-mL sample. The relative standard deviation of 8 measurements was 1.44% for 14.3 nmol L⁻¹ nitrite. For the 150 mL sample, the detection limit was estimated to be 0.1 nmol L⁻¹. The throughput of the method was about 4 samples per hour. The proposed method has been successfully applied to the in-field determination of nanomolar concentrations of nitrite in seawater.     

Thermochemical characteristics of complexation of some ions with 3-(4-bromophenylazo)pentane-2,4-dione in aqueous ethanol

The potentiometric and conductometric titration was used to study complexation between some metal ions and 3-(4-bromophenylazo)pentane-2,4-dione (L) in aqueous ethanol. The standard thermodynamic characteristics of the complex formation reaction were determined. The effective atomic charges in the tautomeric forms of L (azo enol, azo keto, hydrazo) were calculated by MO LCAO quantum-chemical method in the Hückel approximation.