Synthesis and Degradation of Schiff Bases Containing Heterocyclic Pharmacophore

This paper reports on the synthesis and characterization of two Schiff bases bearing 1,2,4-triazolic moieties, namely 4H-4-(2-hydroxy-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole and 4H-4-(4-nitro-benzylidene-amino)-5-benzyl-3-mercapto-1,2,4-triazole using thin layer chromatography, melting interval, elemental analysis, spectroscopy and thermal stability studies.     

Fatty acid triazoles: Novel corrosion inhibitors for oil well steel (N-80) and mild steel

Three fatty acid triazoles, namely, 3-undecane-4-aryl-5-mercapto-1,2,4-triazole (triazole 1), 3(heptadeca-8-ene)-4-aryl-5-mercapto-1,2,4-triazole (triazole 2), and 3(deca-9-ene)-4-aryl-5-mercapto-1,2-4-triazole (triazole 3) were synthesized and their corrosion-inhibiting action in 15% hydrochloric acid was evaluated by weight-loss method and electrochemical techniques. Electrochemical polarization studies at room temperature indicated that all the triazoles are mixed-type inhibitors, i.e., they inhibit both anodic and cathodic reactions. The adsorption of these compounds onto mild steel from 15% HCl followed Temkin's adsorption isotherm.     

Synthesis and Evaluation of Some Triazole Derivatives as Corrosion Inhibitors and Biocides

Three compounds namely; 5-(phenyl)-4H-1,2,4-triazole-3-thiol, 3-(decylthio)-5-phenyl-1H-1,2,4-triazole and 3-(benzylthio)-5-phenyl-1H-1,2,4-triazole) were synthesized. The chemical structure of the prepared compounds was confirmed using FTIR and ¹H-NMR analysis. The compounds were tested as corrosion inhibitors against the corrosion of carbon steel in 1 M HCl using weight loss, polarization and electrochemical impedance methods. The results revealed that these compounds have significant inhibiting effects on the corrosion of carbon steel. Polarization studies showed that the compounds act as mixed-type inhibitors which retard the anodic and the cathodic reactions with a predominant effect towards the cathodic reaction. The prepared compounds were evaluated as antimicrobial agents against sulfate-reducing bacteria using the serial dilution method, which showed good biocidal action.     

Synthesis and Characterization of a Novel Series of Amphiphilic Mercapto-1,2,4-Triazole Schiff Base Ligands: Investigation of their Behavior in Hydro-Organic Solutions

A novel series of four Schiff base amphiphiles derived from 3-mercapto-1,2,4-triazole and different alkyl chains were successfully prepared by a new synthetic three-step method. The chemical structures of the different ligands were characterized by elemental analysis, FT-IR spectroscopy, ¹H-NMR and ¹³C-NMR spectra. The effect of the chain length on the solution behavior of the amphiphilic ligands were studied, in both homogeneous and heterogeneous systems, using pH-metric and spectrophotometric methods. Based on the electronic spectroscopy data, some parameters governing their surfactant properties, such as the critical micelle concentration (CMC), the micellization free energy (ΔG _mic) and the hydrophilic-lipophilic balance (HLB) were evaluated in chloroform and discussed. The behavior of the four Schiff bases in the heterogeneous chloroform-water mixture was then explored through the establishment of their acidity (pK_A) and distribution (Log K _d) constants in 1 M chloride medium and the acidity constants in aqueous medium (pK_a) were deduced. Results showed that an increase of the alkyl chain decreases the distribution of the ligands and increases their acidity. The extractive performance of the Schiff base amphiphiles were investigated towards Ni(II) from a chloride medium at 30 °C. The analysis of extraction data revealed that the synthesized Schiff bases exhibit a better and faster extractability than many ligands reported in the literature.     

Marine coatings based on metal complexes of 4-amino-3-hydrazino-5-thio-1,2,4-triazole

Copper, cobalt, nickel and tin metal complexes of 4-amino-3-hydrazino-5-thio-1,2,4-triazole (I) have been prepared and their structure identified through IR and electronic spectra measurements. The cobalt and nickel have been found to be octahedral; on the other hand, a mixed structure is proposed for the copper complex. The complexes are incorporated in marine paint formulations in the presenceo of 4-(p-chlorobenzylideneamino)-3-(p-chlorobenzylidenehydrazino)-5-thio-1,2,4-triazole, 4-(3,4-dichlorobenzylideneamino)-3-(3,4-dichlorobenzyl idenehydrazino)-5-thio-1,2,4-triazole and 4-(p-nitrobenzylideneamino)-3-(p-nitrobenzylidenehydrazino)-5-thio-1,2,4-triazole. Each paint was applied to PVC and mild steel substrate and the panels were tested in Alexandria eastern harbour water. Paints containing copper, cobalt and nickel complexes of (I) in the presence of its chlorinated or nitro derivatives showed antifouling properties till about 4 months, while they protect steel substrate from marine corrosion for 1 month.     

Synthesis and characterization of some new aromatic polytriazoles as proton conductive membranes

A series of new poly(1,2,4-triazole)s (PTAs) containing pyridine heterocyclic ring, bearing bulky aromatic pendent groups, were synthesized from the reaction of the corresponding polyhydrazides with aniline or 4-aminobenzenesulfonic acid in polyphosphoric acid (PPA) at 175 °C. The non-sulfonated PTAs showed glass transition temperatures (T _gs) of 220–250 °C and inherent viscosities (η _inh) equal to 0.48–0.78 dL/g, and the sulfonated poly(1,2,4-triazole)s (S-PTAs) exhibited T _gs of 235–265 °C and inherent viscosities equal to 0.50–0.83 dL/g. The former polymers were soluble in conc. H₂SO₄ and partially soluble in hot N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), and 1-methyl-2-pyrrolidone (NMP), and the latter were soluble in DMF, NMP, DMSO and DMAc at room temperature. All polymers had useful levels of thermal stability and were stable up to 450 °C in nitrogen. The proton conductivities of undoped sulfonated polytriazole membranes and the acid-doped sulfonated polytriazole membranes lie in the range of 5 × 10^?4–8.1 × 10^?3 and 5 × 10^?3–2.3 × 10^?2 S/cm, respectively, at 90 °C and 100 % relative humidity.     

微波辐射下1,2,4-三唑硫酮席夫碱的合成及表征

微波辐射条件下,以氨基均三唑硫醇与查尔酮为原料,通过亲核取代反应,制备了3-(4-氨基-5-硫基-3-苯基均三唑-1-氮代)-1,3-二苯-1-丙酮(Ⅳ),Ⅳ与系列芳香醛经缩合反应,合成了7种三唑硫酮席夫碱Ⅴa～Ⅴg。探讨了原料摩尔比、催化剂用量、反应时间、溶剂、微波辐射功率对收率的影响,得到了优化的工艺条件:n(芳香醛)∶n(氨基三唑硫酮)=1∶1.1,微波功率500 W,催化剂冰醋酸2 mL,反应时间5～7 min,溶剂为N,N-二甲基甲酰胺(DMF),收率为71%～87%。用IR、MS、1HNMR、元素分析对合成中间体和目标产物进行了结构表征。     

Equilibrium studies of ternary systems containing some selected transition metal ions, triazoles and aromatic carboxylic acids

Solution equilibria of the binary and ternary complex systems of the divalent transition metal ions Cu²⁺, Ni²⁺, Zn²⁺, and Co²⁺ with 1,2,4-triazole (TRZ), 3-mercapto-1,2,4-triazole (TRZSH), and 3-amino-1,2,4-triazole (TRZAM) and aromatic carboxylic acids (phthalic, anthranilic, salicylic, and 5-sulfosalicylic acid) have been studied pH-metrically at (25.0±0.1) °C, and a constant ionic strength I=1×10^?1 mol L^?1 NaNO₃ in an aqueous medium. The potentiometric titration curves show that binary and ternary complexes of these ligands are formed in solution. The stability constants of the different binary and ternary complexes formed were calculated on the basis of computer analysis of the titration data. The relative stability of the different ternary complex species is expressed in terms of Δ log K values, log X and R. S.% parameters. The effect of temperature of the medium on both the proton-ligand equilibria for TRZAM and phthalic acid and their metal-ligand equilibria with Cu²⁺, Ni²⁺, and Co²⁺ has been studied along with the corresponding thermodynamic parameters. The complexation behavior of ternary complexes is ascertained using conductivity measurements. In addition, the formation of ternary complexes in solution has been confirmed by using UV-visible spectrophotometry.     

Synthesen mit 1,3-Dithietanen. IX [1]. Reaktionen des 2,4-Bis-(äthoxycarbonyl-cyan-methylen)-1,3-dithietans und des 2-Cyan-3,3-bis-(methylmercapto)-acrylsäureäthylesters mit Carbonsäurehydraziden

Syntheses with 1,3-Dithietanes. IX. Reactions of 2,4-Bis(ethoxycarbonyl-cyano-methylene)-1, 3-dithietane and of Ethyl 2-cyano-3, 3-bis(methylmercapto)acrylate with Carboxylic Acid Hydrazides 2, 4-Bis(ethoxycarbonyl-cyano-methylene)-1, 3-dithietane 1 reacts with carboxylic acid hydrazides to yield ethyl 1-aroyl-5-imino-3-mercapto-Δ³-pyrazoline-4-carboxylates 4. 4 and hydrazin hydrate yield ethyl 1-aroyl-5-imino-3-hydrazino-Δ³-pyrazoline-4-carboxylates 5 which are transformed by heat to the ethyl 3(5)-amino-5(3)-(2-aroyl-hydrazino)pyrazole-4-carboxylates 6 . The reaction of ethyl 2-cyano-3,3-bis(methylmercapto)acrylate 8 with carboxylic acid hydrazides yield ethyl 1-aroyl-3-amino-5-methylmercapto-pyrazole-4-carboxylates 10 . Compounds 10 are compared with S-methyl derivatives of 4 .     

1,2,4-三唑并[3,4-b]-1,3,4-噻二唑的合成、结构及生物活性

为了筛选出新的高活性化合物,以二氨基硫脲与有机羧酸为原料,回流反应生成中间体4-氨基-5-取代-1,2,4-三唑硫酮,再与羧酸在POCl3的催化下合成了3,6-双取代1,2,4-三唑并[3,4-b]-1,3,4-噻二唑新化合物。目标化合物通过IR、元素分析和1H NMR对其结构进行了表征。并初步测定了该化合物对5种植物病原菌(烟草赤星病、马铃薯干腐病、小麦赤霉病、番茄早疫病、西瓜枯萎病)的杀菌活性,结果表明此类化合物对所测菌种具有良好的杀菌、抑菌作用。     

Synthesis,structure and properties of a novel 3D pentanuclear [Zn5(OH)2]8 + cluster-based (3,4,11)-connected coordination polymer

A novel coordination polymer based on the multidentate N-donor ligand 1-((1H-1,2,4-triazol-1-yl)methyl)-3,5-bis(3-pyridyl)-1,2,4-triazole (3,3′-tmbpt) and 1,2,4,5-benzenetetracarboxylate anion (btec), namely, [Zn₅(3,3′-tmbpt)(btec)₂(OH)₂] (1), has been synthesized hydrothermally. Compound 1 displays a rare 3D (3,4,11)-connected framework based on a [Zn₅(OH)₂]^8 + cluster. The optical band gap and photoluminescent property of compound 1 have been studied.     

An efficient method for synthesis of some heterocyclic compounds containing 3-iminoisatin and 1,2,4-triazole using Fe3O4 magnetic nanoparticles

1,2,4-triazole derivatives were prepared by reaction of thiocarbohydrazide and some esters in 60% ethanol. Condensation of 1,2,4-triazole derivatives with isatin gave Schiff bases of 3-iminoisatin derivatives. Reaction of malonic or succinic acid dihydrazide with isatin lead to formation of N,N'-bis-(3-imino-1,3-dihydro-indolyl-2-one)-malonamide 8a and N,N'-bis-(3-imino-1,3-dihydro-indolyl-2-one)succinamide 8b in good yields under mild reaction conditions. These reactions are catalyzed by Fe₃O₄ MNPs. The chemical structures were confirmed by Fourier transform-infrared, ¹H-NMR, ¹³C-NMR, gas chromatography-mass spectrometry spectroscopy, and elemental analysis.     

Synthesis,characterization and corrosion protection of poly-4-methyl-3-mercapto-1,2,4-triazole/TiO2 composite on copper

The present work deals with the electrochemical synthesis of poly-4-methyl-3-mercapto-1,2,4-triazole (p-MMTA)/TiO₂ composite on metallic copper to evaluate its corrosion protection. The composite was characterized by FT-IR, cyclic voltammetry, X-ray diffraction and energy dispersive X-ray analysis. The distribution of inorganic particles in the polymeric matrix was evidenced from the scanning electron microscopic studies. The corrosion performance of composite coating was evaluated by electrochemical impedance spectroscopy and Tafel polarization measurements in 3.5 % NaCl medium. The p-MMTA/TiO₂ composite showed an excellent corrosion protection ability, which was evidenced from the results of electrochemical measurements. The enhanced ability could be due to the barrier effect of composite coatings against corrosive species and also due to the synergistic effect between organic polymer and inorganic particles.     

Facile Synthesis of CuO and Ag Nanoparticles by Thermal Decomposition of Novel Schiff Base Complexes

Journal of Inorganic and Organometallic Polymers and Materials - In this paper, a new Schiff base was synthesized via the condensation reaction between 3-methyl-4-amino-5-mercapto-1,2,4 triazole...     

A Facile Access to New Polymethylmethacrylate-Anchored Ferrocene Substituted Nickel(II) Unsymmetrical Schiff Base Complexes: Synthesis and Characterization

This paper discloses two new side-chain metallopolymers containing an unsymmetrical organometallic Schiff base complex of Ni(II) linked to a polymethylmethacrylate (PMMA) matrix. The neutral ferrocene substituted Schiff base complex 1, Ni{CpFe(η⁵-C₅H₄)-C(O)CH=C(CH₃)N–o-C₆H₄N=CH-(2-O,5-OH-C₆H₃)} where (Cp = η⁵-C₅H₅), was synthesized via template reaction by condensation of the tridentate half-unit metalloligand Fc-C(O)CH=C(CH₃)-N(H)-o-C₆H₄NH₂ (Fc = ferrocenyl = CpFe(η⁵-C₅H₄)) with 2,5-dihydroxybenzaldehyde in the presence of nickel(II) acetate tetrahydrate. The binuclear Schiff base complex of Ni(II) containing an aromatic free hydroxyl group was reacted under basic conditions with PMMA to afford, upon trans-esterification reaction, metallopolymers 2 (complex 1 monomeric unit/PMMA = 1/5) and 3 (complex 1 monomeric unit/PMMA = 1/3). Elemental analysis, FT-IR, ¹H and ¹³C NMR spectroscopies, and cyclic voltammetry were utilized to characterize the newly synthetized compounds. Surface morphology of the metallopolymer film of 2 was studied using atomic force microscopy.     

4-氨基-3-肼基-5-巯基-1,2,4-三唑的合成及其对醛的检验

以硫脲和水合肼合成了可用于检验醛的试剂——4-氨基-3-肼基-5-巯基-1，2，4-三唑(别名：紫醛)，其结构通过红外光谱、核磁进行了确定。试验表明，紫醛对醛的检验敏感、专一、快速、操作简单。     

6-巯基-5-三氮杂茂[4,3-b]-S-四氮杂苯的合成及在甲醛残留快速检测中的应用

采用4-氨基-3-联氨-5-巯基-1,2,4-三氮杂茂为原料合成6-巯基-5-三氮杂茂[4,3-b]-S-四氮杂苯,并配成0至1000mg/L标准色列。采用三氮杂茂快速检测方法测定食品中甲醛含量,用乙酰丙酮比色检测方法对三氮杂茂快速检测方法的检测结果进行验证,符合率在64%~95%。     

Inhibition of mild steel corrosion in hydrochloric acid solution by triazole derivatives: Part I. Polarization and EIS studies

A comparative study of 5-amino-1,2,4-triazole (5-ATA), 5-amino-3-mercapto-1,2,4-triazole (5-AMT), 5-amino-3-methylthio-1,2,4-triazole (5-AMeTT) and 1-amino-3-methylthio-1,2,4-triazole (1-AMeTT) as inhibitors for mild steel corrosion in 0.1 M HCl solution at 20 °C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behaviour in the absence and presence of different concentrations of these inhibitors under the influence of various experimental conditions. Measurements of open circuit potential (OCP) as a function of time till reaching the steady-state potentials (E_st) were also established. The studies have shown that 5-AMT was the most efficient inhibitor reaching values of inhibition efficiency (IE%) up to 96% at a concentration of 10⁻³ M. Polarization curves showed that the four studied compounds act as mixed inhibitors. The potential of zero charge (PZC) of mild steel was determined in 0.1 M HCl in the absence and presence of the studied inhibitors. The effect of chemical structure of the four tested inhibitors was discussed. Results obtained from OCP versus time, polarization and impedance measurements are in good agreement.     

Six- and four-coordinated zinc(II) complexes exhibit strong blue fluorescent properties

A new ligand, 4-(p-chlorophenyl)-1,2,4-triazole (^pCltrz), and its complexes, [Zn(^pCltrz)₆]₂(ClO₄)₂ · H₂O (1) and [Zn(^pCltrz)₂Cl₂] (2), were synthesized. The structure of 1 exhibits the first case that zinc(II) ion coordinated with six triazole ligands to form octahedral environment. Both 1 and 2 display very strong blue photoluminescence as the result of the fluorescence from the intraligand emission excited state.     

Poly(l-lactide) initiated by silver N-heterocyclic carbene complexes: synthesis, characterization and properties

Poly(l-lactide) (PLLA) was successfully synthesized by ring-opening polymerization (ROP) in bulk using silver N-heterocyclic carbene (Ag–NHC) complex. The effect of reaction time, temperature and monomer/initiator ratio on polymerization process were determined. The optimum conditions were found as 130 °C, 4 h and M/I molar ratio of about 100. The polymers were characterized by FTIR, ¹H-NMR, GPC and TG. High-molecular-weight PLLA (M _w = 3.78 × 10⁴, M _n = 1.91 × 10⁴, PDI = 1.97) was synthesized by the ROP of l-lactide (LLA) with bis-(N-methyl N′-dodecylimidazole) silver(I) di-bromo argentate (1a) in bulk. The effect of different N-substituted ligand groups on the polymerization was studied. The antimicrobial activity of the synthesized polymers were investigated by using minimum inhibitory concentration test against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli and Pseudomonas aeruginosa). It was observed that the synthesized polymers displayed moderate antimicrobial activity.