Corrosion mitigation for steel in acid environment using novel p-phenylenediamine and benzidine coumarin derivatives: synthesis, electrochemical, computational and SRB biological resistivity.

Three novel p-phenylenediamine and benzidine coumarin derivatives were synthetized, namely: 4,4'-((((1,4-phenylenebis(azaneylylidene))bis(ethan-1-yl-1-ylidene))bis(2-oxo-2H-chromene-3,6-diyl))bis(diazene-2,1-diyl))dibenzenesulfonic acid (PhODB), 4,4'-(((-([1,1'-biphenyl]-4,4'-diylbis(azaneylylidene))bis(ethan-1-yl-1-ylidene))bis(2-oxo-2H-chromene-3,6-diyl))bis(diazene-2,1-diyl))dibenzenesulfonic acid (BODB) and 4,4'-(((-((3,3'-dimethoxy-[1,1'-biphenyl]-4,4'-diyl)bis(azaneylylidene))bis(ethan-1-yl-1-ylidene))bis(2-oxo-2H-chromene-3,6-iyl))bis(diazene-2,1-diyl))dibenzenesulfonic acid (DODB). Their chemical structures were proved by performing Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance and mass spectrometry analysis. The synthesized p-phenylenediamine and benzidine coumarin derivatives were tested as corrosion inhibitors for mild steel (MS) in 1 M HCl solution using weight loss, electrochemical, morphological, and theoretical studies. The compound 3,3'-dimethoxy benzidine coumarin derivative (DODB) was proved to give the highest efficiency with 94.98% obtained from weight loss measurements. These compounds are mixed inhibitors, as seen by the polarization curves. Impedance diagrams showed that when the concentration of these derivatives rose, the double-layer capacitance fell and the charge transfer resistance increased. Calculated thermodynamic parameters were computed and the mechanism of adsorption was also studied for the synthesized p-phenylenediamine and benzidine coumarin derivatives. The ability of the synthesized derivatives to protect the surface against corrosion was investigated by scanning electron microscope (SEM), UV-visible spectroscopy and energy dispersive X-ray spectroscopy (EDX). Theoretical chemical calculations (DFT) and biological resistivity (SRB) were investigated.

Insights into the adsorption and corrosion inhibition properties of newly synthesized diazinyl derivatives for mild steel in hydrochloric acid: synthesis, electrochemical, SRB biological resistivity and quantum chemical calculations.

Two azo derivatives, 4-((4-hydroxy-3-((4-oxo-2-thioxothiazolidin-5-ylidene)methyl)phenyl) diazinyl) benzenesulfonic acid (TODB) and 4-((3-((4,4-dimethyl-2,6-dioxocyclohexylidene) methyl)-4-hydroxyphenyl)diazinyl) benzenesulfonic acid (DODB) were synthesized and characterized using Fourier-transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR) and mass spectral studies. Gravimetric methods, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), electrochemical frequency modulation (EFM) techniques and inductive coupled plasma-optical emission spectroscopy were used to verify the above two compounds' ability to operate as mild steel (MS) corrosion inhibitors in 1 M HCl. Tafel data suggest that TODB and DODB have mixed-type characteristics, and EIS findings demonstrate that increasing their concentration not only alters the charge transfer (R ct) of mild steel from 6.88 Ω cm2 to 112.9 Ω cm2 but also changes the capacitance of the adsorbed double layer (C dl) from 225.36 to 348.36 µF cm-2. At 7.5 × 10-4 M concentration, the azo derivatives showed the highest corrosion inhibition of 94.9% and 93.6%. The inhibitory molecule adsorption on the metal substrate followed the Langmuir isotherm. The thermodynamic activation functions of the dissolution process were also calculated as a function of inhibitor concentration. UV-vis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) techniques were used to confirm the adsorption phenomenon. The quantum chemical parameters, inductively coupled plasma atomic emission spectroscopy (ICPE) measurements, and the anti-bacterial effect of these new derivatives against sulfate-reducing bacteria (SRB) were also investigated. Taken together, the acquired results demonstrate that these compounds can create an appropriate preventing surface and regulate the corrosion rate.

Colorimetric Chemosensor and Turn on Fluorescence Probe for pH Monitoring Based on Xanthene Dye Derivatives and its Bioimaging of Living Escherichia coli Bacteria.

A new turn on fluorescence probe based on 3',6'-dihydroxy-6-methyl-2-((pyridin-2-ylmethylene)amino)-4-(p-tolyl)spiro[benzo[f]isoindole-1,9'-xanthen]-3(2H)-one (BFFPH) derived from benzo[f]fluorescein was prepared. Full characterization of the prepared probe using spectroscopic analysis was described such as IR, NMR and MS spectra. The sensitivity of BFFPH for monitoring of pH change in alkaline medium was studied. BFFPH exhibited a high sensitivity to alkaline pH by two pKa values at 8.82 and 10.66 in UV/vis spectroscopy titration. The pH monitoring was studied in broad range of pH values (2.5-12.2) at two pKa values at 8.72 and 10.73 by recording the effect of pH on the fluorescence intensity of BFFPH. The acid-base reversibility character of the probe was investigated as well as the effect of the pH change on the fluorescence quantum yield. The application of the prepared BFFPH probe for detection of living Escherichia coli (E. coli) bacteria using confocal fluorescence microscope was investigated.

Synthesis, biological activity and molecular modeling study of new Schiff bases incorporated with indole moiety.

A new series of heterocyclic Schiff bases 2-9 containing indole moiety were synthesized by facile and efficient condensation of indole-3/2/5-carboxaldehyde (1a/1b/1c) with different aromatic and heterocyclic primary amines using conventional and/or microwave irradiation methods. The structures of the obtained compounds were assigned by sophisticated spectroscopic and spectrometric techniques (1D-NMR, 2D-NMR and MS). The synthesized compounds were screened for their cytotoxicity and antibacterial activities. In vitro cytotoxicity screening revealed that compound 5 exhibited moderate activity against KB-3-1 cell line (IC50=57.7 µM) while 5-indolylimino derivative 7 indicated close to the activity (IC50=19.6 µM) in comparison with the positive control (+)-Griseofulvin (IC50=19.2 µM), while the tested compounds 5, 6b, 7 and 9 revealed good or moderate antibacterial activity. In addition, molecular docking study of Schiff bases 2-9 was performed by Molecular Operating Environment (MOE 2014.09) program on the matrix metalloproteinase-8 (MMP-8) (Protein Data Bank (PDB) ID: 1MNC) in an attempt to explore their mode of action as anticancer drugs.

Preparation and characterization of humic acid-carbon hybrid materials as adsorbents for organic micro-pollutants.

The present work involves the preparation of novel adsorbent materials by the insolubilization and hybridization of humic acid (HA) with carbon. The prepared materials were characterized by N2 adsorption, elemental analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, solid-state (13)C cross polarization magic angle spinning nuclear magnetic resonance, and low-field nuclear magnetic resonance (NMR) relaxometry on wetted samples. The water solubility of these materials and the lack of effect of oxidants were also confirmed. With this background, the adsorption capacities toward phenol, 2,4,6-tricholrophenol, and atrazine were evaluated, using these as model compounds for organic micropollutants of concern in water. Experimental results show that the prepared materials are mesoporous and have a higher surface area than humic acid and even than the porous carbon in the case of carbon coating. They retain the basic features of the starting materials with lowered functional group content. Moreover, there are interesting new features. NMR relaxometry shows that equilibration of water uptake is very fast, making use in water simple. They have higher adsorption capacities than the pure materials, and they can be applied under a wide range of environmental conditions.

Synthesis, reactions and antimicrobial activities of 8-ethoxycoumarin derivatives.

Condensation of 3-acetyl-8-ethoxycoumarin (3) with thiosemicarbazide gave ethylidenehydrazinecarbothioamide 5, which was transformed into the thiazolidin-4-one derivatives 6,7. Interaction of 3 with DMF/POCl(3) gave b-chloroacroline derivative 8. Treatment of 3 with malononitrile gave benzo[c]chromone and 2-aminobenzonitrile derivatives 9 and 10, respectively with respect to the reaction conditions. Condensation of 3-(2-bromoacetyl)-8-ethoxycoumarin (4) with o-phenylenediamine gave 3-(quioxaline-2-yl)-8-ethoxycoumarin hydrobromide (11), while 4 reacted with 2-aminopyridine to give chromenopyridopyrimidine derivative 12. Condensation of 4 with potassium thio-cyanate/methanol gave an unexpected derivative, 2H-chromeno-3-carboxy(methyl-carbonimidic)thioanhydride 16, which upon treatment with (NH(2))(2)·H(2)O gave 3-ethoxy-2-hydroxybenzaldehyde azine 19. Interaction of 4 with thiourea derivatives gave thiazole derivatives 20a-c. The structures of the newly synthesized compounds were confirmed by their spectra data. The newly synthesized compounds were also screened for their antimicrobial activity.

Synthesis, reactions and biological evaluation of some new naphtho[2,1-b]furan derivatives bearing a pyrazole nucleus.

Vilsmeier formylation of 2-(1-phenylhydrazonoethyl)naphtho[2,1-b]furan (2) gave 3-naphtho[2,1-b]furan-2-yl-1-phenyl-1H-pyrazole-4-carbaldehyde (3), which was reacted with C- and N-nucleophiles to afford naphthofuranpyrazol derivatives 4-8. Treatment of 2-[(3-(naphtho[2,1-b]furan-2-yl)-1-phenyl-1H-pyrazol-4-yl)methylene]-malononitrile (4a) with reactants having active hydrogen and Et3N gave the corresponding pyrazoline, pyran and chromene addition product derivatives 10, 12 and 13, consisting of three different connected heterocyclic moieties. Reaction of 1-((3-(naphtho[2,1-b]furan-2-yl)-1-phenyl-1H-pyrazol-4-yl) methylene)-2-phenylhydrazone (6b) with AcONa and ethyl bromoacetate or chloroacetone afforded the thiazolidinone and methylthiazole derivatives 14 and 15, respectively. In addition, intramolecular cyclization of 6d with Ac2O afford the corresponding 1,3,4-thiadiazol-2-yl acetamide derivative 16. The structures of the synthesized compounds were confirmed by IR, ¹H-NMR/¹³C-NMR and mass spectral studies. Compound 14 showed promising effects against the tested Gram positive and negative bacteria and fungi.

Synthesis and characterization of new diiodocoumarin derivatives with promising antimicrobial activities.

A series of 6,8-diiodocoumarin-3-N-carboxamides (4-11) were prepared. Treatment of ethyl 6,8-diiodocoumarin-3-carboxylate (1) with ethyl cyanoacetate/NH(4)OAc gave ethyl 2-(3-carbamoyl-6,8-diiodocoumarin-4-yl)-2-cyanoacetate (12) and 2-amino-4-hydroxy-7,9-diiodocoumarino[3,4-c]pyridine-1-carbonitrile (13), and treatment with acetone in the presence of NH(4)OAc or methylamine gave the ethyl 4-oxo-2,6-methano-2-methyl-3,4,5,6-tetrahydro-8,10-diiodobenzo[2,1-g]-2H-1,3-oxazocine-5-carboxylate derivatives 14a,b. All compounds were evaluated for their antimicrobial activity and the compounds 12-14a,b exhibited a pronounced effect on all tested microorganisms.

Preparation of 4-aminophenylacetic acid derivatives with promising antimicrobial activity.

Condensation of 4-aminophenylacetic acid with phthalic anhydride gave (dioxoisoindolin-2-yl)phenylacetic acid (1), which was employed as the key intermediate in the synthesis of title compounds 2-8. The products were characterized by analytical and spectral data (IR, 1H NMR, 13C NMR and mass spectra). Antimicrobial activities were studied and some of the compounds showed promising results.