Synthesis and evaluation of bipyrazolic derivatives as inhibitors of corrosion of C38 steel in molar hydrochloric acid

Methyl 2-(bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amino) acetate, BT36, and methyl 2-(bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)amino)-3-(1H-indol-3-yl)propanoate, BT 43, have been synthesized. Investigation by weight-loss measurement and use of electrochemical techniques revealed the compounds are very effective inhibitors of corrosion of C38 steel in 1 M HCl solutions—percentage protection exceeded 95 % for BT43 at concentrations as low as 10^?2 M. An impedance study in the absence and presence of these compounds revealed the mechanism of protection was cathodic inhibition by polarization and charge-transfer. The Langmuir adsorption isotherm was obeyed. Quantum chemical data calculated by use of DFT at the B3LYP/6-31G* level of theory revealed a good correlation between inhibition efficiency and the molecular structure of BT36 and BT43. The highest occupied molecular orbital, the lowest unoccupied molecular orbital, the separation energy (ΔE), and the dipole moment (μ) from the inhibitor to the metal surface explain the experimental data well.     

Experimental and theoretical investigation on adsorption and corrosion inhibition properties of imidazopyridine derivatives on mild steel in hydrochloric acid solution

Imidazopyridine derivatives, namely 4‐methoxy‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3‐yl)methylene)benzenamine (MMPIPB) and 4‐chloro‐N‐((2‐(4‐methoxyphenyl)H‐imidazo[1,2‐a]pyridin‐3yl)methylene)benzenamine (CMPIPB), were investigated as inhibitors for mild steel corrosion in 15% HCl solution using the weight loss and electrochemical techniques. According to electrochemical impedance spectroscopy studies, MMPIPB and CMPIPB show corrosion inhibition efficiency of 84.8 and 77.2% at 10‐ppm concentration and 98.1 and 94.8% at 80‐ppm concentration, respectively at 303 K. The corrosion inhibition efficiency of both inhibitors increased with increasing inhibitor concentration and decreased with increasing temperature. The adsorption of both inhibitor molecules on the surface of mild steel obeys Langmuir adsorption isotherm. Polarization studies showed that both studied inhibitors were of mixed type in nature. Electrochemical impedance spectroscopy studies showed that for both inhibitors, the value of charge transfer resistance increased and double‐layer capacitance decreased on increasing the concentration of inhibitors. Scanning electron microscopy, energy‐dispersive X‐ray spectroscopy (EDX), and atomic force microscopy were performed for surface study. The density functional theory was employed for theoretical calculations. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthesis of new 1,2,3-triazole linked benzimidazole molecules as anti-proliferative agents

One pot click chemistry is used to link triazole and benzimidazole pharmacophore to get N-((1-((1H-benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)aniline and its derivatives. Flexible linkages in the form of –CH₂–R or –O–R/–N–R were designed during synthesis. All the newly synthesized compounds were characterized by FT-IR and NMR spectroscopy as well as high-resolution mass spectrometry. Selected compounds were screened for in vitro anti-proliferative activity using National Cancer Institute (NCI)-60 human tumor cell line screening program. The most potent structure N-((1-((1H-benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-4-chloroaniline 7e showed 40% growth inhibition in renal cancer cell line (UO-31) at 10?µM concentration.     

Synthesis of-4-((4-trimethylsilyl-1H-1,2,3-triazol-1-yl)methyl)-2H-chromen-2-ones: A novel class of heteroaryl anionic synthon

A one-pot synthesis of some novel anionic scaffolds: the substituted-4-((4-trimethylsilyl-1H-1,2,3-triazol-1-yl)methyl)-2H-chromen-2-one is reported. Reaction of 10 different substituted bromomethylcoumarins with trimethylsilylacetylene and sodium azide in the presence of copper(I) iodide catalyst gave the corresponding heteroaryl conjugates: the substituted-4-((4-trimethylsilyl-1H-1,2,3-triazol-1-yl)methyl)-2H-chromen-2-one in 70–92% yields. The structures of the synthesized compounds have been completely characterized by spectral and elemental analyses. For the first time, the representative single-crystal X-ray structure analysis of 6-methoxy-4-((4-trimethylsilyl-1H-1,2,3-triazol-1-yl)methyl)-2H-chromen-2-one is reported which confirms the formation of anionic synthon which bears the trimethylsilyl-group.     

Features of the reaction of 4-bromobut-2-enylphosphonium salts with monosubstituted hydrazines

(4-Bromobut-2-en-1-yl)triphenylphosphonium bromide reacted with phenylhydrazine at 2°C in the presence of sodium carbonate to form triphenyl[4-(2-phenylhydrazinylidene)but-2-en-1-yl]phosphonium bromide in 62% yield. The obtained N-phenylhydrazine derivatives cyclized into the corresponding pyrazoline derivatives of phosphonium salts. Unlike phenylhydrazine, ethylhydrazine reacted with (4-bromobut-2-ene-1-yl)triphenylphosphonium bromide under the same conditions to afford triphenyl[(1-ethyl-4,5-dihydro-1Hpyrazol-3-yl)methyl]- and -[(1-ethyl-1H-pyrazol-3-yl)methyl]phosphonium bromides in yields of 60 and 40%.     

Synthesis,anticancer, and computational studies of 1, 3, 4-oxadiazole-purine derivatives

Theophylline-7-acetic acid (acefylline) ( 3 ) and its derivatives are pharmacologically active compounds and generally recognized as bronchodilators for the treatment of respiratory diseases like acute asthma for over 70 years. In this article, synthesis of 2-((5-((1,3-dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-yl)thio)-N-arylacetamides ( 10a-j ) has been reported. All the synthesized derivatives ( 10a-j) were structurally verified by FT-IR, ¹H NMR, ¹³C NMR and evaluated for their anti-cancer (using MTT assay), hemolytic and thrombolytic potential. N-(4-Chlorophenyl)-2-(5-((1,3-dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-ylthio)acetamide ( 10g ) was found to be the most active against human liver cancer cell lines (Huh7) having cell viability 53.58 ± 1.28 using 100 μg/mL concentration of compound which was further in-silico modelled to describe the possible mechanistic insights for its anti-proliferative activity. The results of hemolytic and thrombolytic activities indicated that these derivatives were less toxic and hold considerable potential as a drug candidate. 2-(5-((1,3-Dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-ylthio)-N-(2-fluorophenyl)acetamide ( 10c ) of the series was found to be least toxic with 0.1% hemolysis relative to ABTS (95.5%) as positive control. 2-(5-((1,3-Dimethyl-2,6-dioxo-2,3-dihydro-1H-purin-7(6H)-yl)methyl)-1,3,4-oxadiazol-2-ylthio)-N-(tetrahydro-2H-pyran-4-yl)acetamide ( 10j ) exhibited potent clot lysis activity (90%) as compared to negative control DMSO (0.57%).     

Synthesis,X-ray structure and theoretical study of benzazole thioether and its zinc complex as corrosion inhibitors for steel in acidic medium

A ligand, 2-((benzo[d]thiazol-2-ylthio)methyl)-1H-benzo[d]imidazole, and its zinc complex have been synthesized. The structure of these compounds have been determined by spectroscopic techniques and single crystal X-ray diffraction. The corrosion inhibition study of these compounds for steel in 0.5 M H₂SO₄ medium has also been investigated using potentiodynamic polarization and EIS techniques. The quantum calculations were applied to investigate the relationship between the electronic properties and the corrosion inhibition efficiency of the two benzazoles derivatives. Surface analysis (XRF) indicated that the rust layer formed on the Cu-containing steels was enriched with Cu compounds. Polarization curves revealed that both inhibitors acted as a mixed-type inhibitor.     

A novel method for the synthesis of coumarin laser dyes derived from 3-(1H-benzoimidazol-2-yl) coumarin-2-one under microwave irradiation

We want to achieve the synthesis of 3-(1H-benzoimidazol-2-yl)-7-(diethylamino) coumarin-2-one (1), 3-(1H-benzoimidazol-2-yl)-7-(dimethylamino) coumarin-2-one (2), 3-(1H-benzoimidazol-2-yl) coumarin-2-one (3) that are important dyes in industries (Soko owska et al., 2001). Methods for the synthesis of some of these compounds have been the title in some pervious patents, but enough information about separation and purification of them was not clearly indicated. We carried out several methods for the synthesis of the mentioned compound and purification with different yields. Now, we can synthesise these dyes under microwave irradiation in solid phase and solvent free methods with 80% yield, which is a high and remarkable percentage.     

Adsorption and Corrosion Inhibition Behavior of L-Cystine and Synergistic Surfactants Additives on Mild Steel in 0.1 M H2SO4

The adsorption and corrosion inhibition behavior of mild steel in 0.1 M H₂SO₄ in presence of L-cystine and L-cystine in combination with surfactants sodium dodecyl sulfate and cetyltrimethyl ammonium bromide at 30–60°C was investigated using weight loss and potentiodynamic polarization measurements. Inhibition efficiency of L-cystine is synergistically enhanced on addition of surfactants. Surface morphology of corroded steel samples was evaluated using scanning electron microscopy and atomic force microscopy, which further confirmed the existence of an adsorbed protective film on the mild steel surface. Calculated thermodynamic parameters reveal that adsorption process is spontaneous and obey Langmuir adsorption isotherm.     

Investigation on the Adsorption and Corrosion Inhibition Behavior of Gum Acacia and Synergistic Surfactants Additives on Mild Steel in 0.1 M H2SO4

Adsorption and corrosion inhibition effect of gum acacia alone and in presence of surfactants sodium dodecyl benzene sulphonate and cetyltrimethyl ammonium bromide on mild steel in 0.1 M H₂SO₄ in temperature range of 30 to 60°C was investigated using weight loss method, chemical analysis of solution, scanning electron microscopy, atomic force microscopy and determination of thermodynamic parameters. Inhibiting action of gum acacia is synergistically enhanced on addition of small amount of surfactants. SEM and AFM results confirmed the existence of an adsorbed protective film on the mild steel surface. Thermodynamic parameters reveal that adsorption process is spontaneous and obey Freundlich adsorption isotherm.     

Influence of Molecular Weight on Mild Steel Corrosion Inhibition Effect by Polyvinyl Alcohol in Hydrochloric Acid Solution

The corrosion inhibition of mild steel in hydrochloric acid solution in the presence of three different molecular weights of polyvinyl alcohol (PVA) designated as PVA-I, PVA-II, and PVA-III corresponding to 14,000, 72,000, and 125,000 g mol^?1, respectively, was investigated using electrochemical impedance spectroscopy, linear polarization resistance (LPR), and potentiodynamic polarization techniques at 25°C. It was found that PVA of different molecular weights inhibited the corrosion of mild steel in the acid environment. Inhibition efficiency (η%) increases with increase in concentration of the polymers. LPR measurements clearly show that inhibition efficiency increases with increasing molecular weight in the order PVA-III > PVA-II > PVA-I. Polarization curves indicate that PVA functions as a mixed inhibitor affecting both the anodic metal dissolution and cathodic hydrogen evolution partial reactions of the corrosion process. The experimental data obtained fitted well into Langmuir adsorption isotherm model. Physical adsorption mechanism is proposed from the thermodynamic (free energy of adsorption) parameters obtained.     

Corrosion inhibition of mild steel in hydrochloric acid by betanin as a green inhibitor

The effect of betanin (2,6-pyridinedicarboxylic acid, 4-(2-(2-carboxy-5-(beta-D-glucopyr-anosyloxy)-2,3-dihydro-6-hydroxy-1H-indol-1-yl)ethenyl)-2,3-dihydro-(S-(R*,R*))) on the corrosion inhibition of mild steel has been investigated in 1 M HCl solution. Weight loss method, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques were applied to study the mild steel corrosion behavior in the absence and presence of different concentrations of betanin under the influence of various experimental conditions. The results obtained showed that betanin is a good “green” inhibitor for mild steel in 1 M HCl solution. Scanning electron microscopy observations of the steel surface confirmed the protective role of the inhibitor. The polarization curves showed that betanin behaves mainly as a mixed-type inhibitor. Maximum inhibition efficiency (98%) is obtained at betanin concentrations of 0.01 M. The results obtained from weight loss, polarization, and impedance measurements are in good agreement.     

Synthesis of diverse (E)-2-((1H-imidazol-1-yl)methyl)-2-((benzyloxy)methyl)-2,3-dihydro-1H-inden-1-one O-benzyl oxime derivatives as potent antileishmanial agents

A series of (E)-2-((1H-imidazol-1-yl)methyl)-2-((benzyloxy)methyl)-2,3-dihydro-1H-inden-1-one O-benzyl oximes ( 6a-j ) were prepared and evaluated for their in vitro antileishmanial potency against Leishmania donovani (in promastigote and amastigote models). At a concentration of 05-μg/mL, compounds 3a-d , 4a-d , 5a , 5b , 6a-d, and 7a-d exhibited 97% to 100% and 87% to 100% inhibition against promastigotes and amastigotes, respectively. Compounds 6a , 6d-6j and 6a , 6i , 6j exhibited equal antileishmanial potency to that of SSG and Pentamidin at lower values of IC₅₀.     

Synthesis of benzimidazole derivatives via reaction between aromatic amines and aldehydes: Structure determination and theoretical insights

The condensation reaction between primary amine and aromatic aldehyde or ketone ubiquitously synthesizes –C=N- function that appears in the Schiff bases. Presence of ortho –NH/NH₂ group may form a cyclic product which is further oxidized to generate –C=N- function. Herein, two quinoline based cyclic benzimidazole compounds, namely, 2-[1-(Phenyl-pyridin-2-yl-methyl)-1H-benzoimidazol-2-yl]-quinoline (L5) and 2-[1-(Phenyl-pyridin-2-yl-methyl)-1H-benzoimidazol-2-yl]-quinolin-8-ol (L6) are synthesized from o-phenylenediamine derivative [N¹-(phenyl(pyridin-2-yl)methyl)benzene-1,2-diamine] (L) via condensation followed by in-situ dehydrogenation. The structures of the products have been confirmed by the single crystal X-ray diffraction measurement and other physicochemical data. The intra- and intermolecular H-bonding, C–H ^… π interactions in the structures instigate supramolecular self-assembly. The DFT computation has been attempted to explain the formation of energy minimized cyclic product out of acyclic counterpart; the meticulous comparison of the present theoretical outcomes with that of previously reported o-phenylenediamine derivatives, further supports the formation of energy minimized products.     

Synthesis and in-vitro antioxidant activities of some coumarin derivatives containing 1,2,3-triazole ring

A new green protocol was developed for the S-alkylation of 2-mercapto-1,3,4-oxadiazole by the reaction of 5-substituted-2-mercapto-1,3,4-oxadiazole with propargyl bromide in sodium bicarbonate in water. The newly synthesized 5-[(substitutedphenoxy)methyl]-2-[(prop-2-yn-1-yl)sulfanyl]-1,3,4-oxadiazole when reacted with azidomethyl coumarins underwent regioselective reaction yielding 4-(((4-((5-((substitutedphenoxy)methyl)-1,3,4-oxadiazol-2-yl)sulfanylmethyl)-1H-1,2,3-triazol-1-yl)methyl)-6-methyl)-2H-chromene-2-one or 1-((4-((5-((substitutedphenoxy)methyl)-1,3,4-oxadiazol-2-yl)sulfanylmethy)-1H-1,2,3-triazol-1-yl-)methyl)-3H-benzo[f]chromene-3-one. Structures of the newly synthesized compounds were confirmed by spectral and analytical data. The compounds were screened for their in-vitro antioxidant property.     

Synthesis and antitumor activity of novel pyridazinone derivatives containing 1,3,4-thiadiazole moiety

Abstract

A series of novel pyridazinone derivatives containing the 1,3,4-thiadiazole moiety were synthesized and characterized by ¹H NMR, 13C NMR, spectroscopies HRMS and IR. Among them, the structure of compound 5c (2-(Tert-butyl)?4-chloro-5-((5-((2-ethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was unambiguously confirmed via single crystal X-ray diffraction analysis. The inhibitory activity of all the target compounds against MGC-803 and Bcap-37 was determined by MTT assay, with doxorubicin (the inhibition rates were 95.5?±?0.4% and 95.7?±?1.0% respectively) as a control. The preliminary results showed that the inhibitory activity of compound 5n (2-(Tert-butyl)?4-chloro-5-((5-((3-fluorophenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One) was superior to the others. The inhibition rates of MGC-803 and Bcap-37 cells were 86.3?±?2.2% and 92.3?±?0.6% at a concentration of 10?μmol/L, respectively. The preliminary structure-activity relationship showed that when the 2-position of the benzene ring was substituted by a methyl group, such as compound 5j (2-(Tert-butyl)?4-chloro-5-((5-((2,3-dimethylphenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), it exhibited good anticancer activity on MGC-803 cells. Besides, introducing fluorine, chlorine, or trifluoromethyl group onto the benzene ring, such as compound 5?m (2-(Tert-butyl)?4-chloro-5-((5-((4-(trifluoromethoxy)phenyl)amino)?1,3,4-thiadiazol-2-yl)thio)pyridazin-3(2H)-One), displayed good anticancer activity on MGC-803 and Bcap-37 cells.     

Synthesis,chemical nuclease activity,and in vitro cytotoxicity of benzimidazole-based Cu(Ⅱ)/Co(Ⅱ) complexes

In this study, novel mono/di-nuclear Cu(p-2-bmb)(OH)(ClO₄) (1) and Co₂(p-2-bmb)₂Cl₄ (2) (p-2-bmb=1- ((2-(pyridin-2-yl)-benzoimidazol-1-yl)methyl)-1H-benzotriazole) complexes with the nitrogen heterocyclic benzimidazole-based ligand were synthesized and characterized. The two complexes showed antiproliferative effects in various carcinoma cell lines, especially complex 1 in the SMMC7721 tumor cell line. Complex 1 was also able to pass through the cell membrane and enter the nucleus and mitochondrion. An analysis of in vitro chemical nuclease activity revealed that complex 1 partially intercalated to calf thymus DNA and exhibited strong unwinding activity against pBR322 superhelical plasmid DNA. The comet assay and flow cytometry analysis confirmed that 1 caused extensive DNA damage and arrested SMMC7721 tumor cells at G2/M phase of the cell cycle, leading to loss of mitochondrial membrane potential and apoptosis. These results suggest that these benzimidazole-based metal complexes could be potential anti-cancer agents.     

Synthesis and biological evaluation of some new substituted benzoxazepine and benzothiazepine as antipsychotic as well as anticonvulsant agents

Various 2-((2-((5-benzylideneamino)-1,3,4-oxa/thiadiazol-2-yl)methyl)hydrazinyl) methyl)benzo[b][1,4]oxa/thiazepin-4(5H)-ones (4a–4l), 2-((2-((5-(4-oxo-2-substitutedphenyl thiazolidin-3-yl)-1,3,4-oxa/thiadiazol-2-yl)methyl)hydrazinyl)methyl)benzo [b] [1,4]oxa/thiazepin-4(5H)-ones (5a–5l) and 2-((2-((5-(3-chloro-2-(substitutedphenyl)-4-oxoazetidin-1-yl)-1,3,4-oxa/thia diazol-2-yl)methyl)hydrazinyl)methyl)benzo[b][1,4]oxa/thiazepin-4(5H)-ones (6a–6l) have been synthesized. The structures of these compounds have been established by elemental (C, H, N) and spectral (IR, ¹H-NMR and Mass) analysis. The synthesized compounds were screened for their antipsychotic and anticonvulsant activities. Compound 5l was found to be the most active compound of this series.     

One-potCuAAC synthesis of (1H-1,2,3-triazol-1-yl)methyl-1,3,4/1,2,4-oxadiazoles starting from available chloromethyl-1,3,4/1,2,4-oxadiazoles

The one-pot CuAAC synthesis of (1H-1,2,3-triazol-1-yl)methyl-1,3,4-oxadiazole and (1H-1,2,3-triazol-1-yl)methyl-1,2,4-oxadiazole derivatives via three-component reaction of consequent nucleophilic substitution of chlorine, with azide, and its further “click” reaction, with alkynes, in the presence of CuI was studied. The utility of newly synthesized 2-(azidomethyl)-1,3,4/1,2,4-oxadiazoles and chloromethyl-1,3,4/1,2,4-oxadiazole derivatives was explored, and their limitations were determined. Novel 5-([4-aryl-1H-1,2,3-triazol-1-yl]methyl)-3-(aryl)-1,2,4-oxadiazoles, 2-([4-aryl-1H-1,2,3-triazol-1-yl]methyl)-5-(aryl)-1,3,4-oxadiazoles were obtained in good yields.     

A 2-D tetrazole-based Zn(II) coordination polymer: crystal structure,dielectric constant,and luminescence

A tetrazole-based Zn(II) coordination polymer, [Zn(TMPT)₂] _n (1) (TMPT?=?5-(4-((1H-1,2,4-triazol-1-yl)methyl)phenyl)-2H-tetrazole), was synthesized by in situ reaction of 4-((1H-1,2,4-triazol-1-yl)methyl)benzonitrile, Zn(NO₃)_2?·?6H₂O, and NaN₃ under hydrothermal conditions and structurally characterized by single-crystal X-ray diffraction. Complex 1 contains π–π stacking interactions between tetrazole rings and phenyl rings of the 2-D ordered layered structural framework, which contribute to the dielectric response. In addition, 1 was demonstrated to display strong blue fluorescence emissions in the solid state at room temperature.