European Journal of Chemistry

Two new compounds, (E)-2-(3-ethoxy-2-hydroxybenzylidene)hydrazinecarbothioamide (1) and (E)-N-ethyl-2-((2-hydroxynaphthalen-1-yl)methylene)hydrazinecarbothioamide (2) have been synthesized. The prepared compounds have been characterized by CHN analysis, FT-IR, UV-Vis, ¹H and ¹³C NMR spectroscopic techniques as well as the fluorescence emission spectroscopy. The molecular structures of the compounds have also been determined by X-ray single crystal diffraction analysis. The crystal structures revealed that the compounds are remain as a thione form in the solid state and are different in their geometrical, conformational and symmetrical structures. The nuclease activity of compounds to cleave pBR 322 has been investigated using agarose gel electrophoresis assay. The compound 2 revealed a significant nuclease activity which was attributed to the lipophilic properties that provided by substituent moieties of the compound.

An efficient methods has been described for the synthesis of new 2-aminonicotinonitrile derivatives (6a-f) bearing benzothiazole nucleus by solvent free microwave or ultrasound irradiation. The reaction proceeds via one-pot four-component by cyclo condensation reaction of heterocyclic methyl ketones (4a), malononitrile, ammonium acetate and aryl aldehydes. Chalcones intermediate and final compounds were also synthesized by conventional methods, the result confirms that microwave method showed higher yield and purity than conventional one. The synthesized compounds were characterized by FT-IR spectroscopy and ¹H NMR. Antibacterial activities of the synthesized compounds have been tested against four different types of bacteria; most of the tested compounds showed significant biological activities.

The corrosion inhibition of carbon steel was investigated in stagnant naturally aerated chloride solutions using amino acids as environmentally safe corrosion inhibitors. The corrosion rate was calculated in the absence and presence of the corrosion inhibitor using the polarization technique and electrochemical impedance spectroscopy. The experimental impedance data were fitted to theoretical data according to a proposed electronic circuit model to explain the behavior of the alloy/electrolyte interface under different conditions. The corrosion inhibition process was found to depend on the adsorption of the amino acid molecules on the metal surface. Cysteine, histidine, phenylalanine and arginine have shown remarkably high corrosion inhibition efficiency. The corrosion inhibition efficiency was found to depend on the structure of the amino acids. The mechanism of the corrosion inhibition process is based on the adsorption of the amino acid molecules on the active sites of the metal surface. Results obtained from potentiodynamic polarization indicated that the inhibitors are mixed-type inhibitor.

Design and synthesis of some new pyridopyrazinone derivatives as anti-proliferative agents is described. The cytotoxic activities of the synthesized compounds against melanoma cell line (LOXIMVI), ovarian cell line (OVCAR3), thyroid cell lines (CAL62, FTC133, BCPAP and ML1) and colon cell lines (HT29 and HCT116) were investigated. Results revealed that most compounds were active and compound 3d was the most active one. It exhibited promising activity against all tested cell lines. In addition, in vitro kinase assay against both ^WTBRAF and ^V600EBRAF was performed for all synthesized compounds. Furthermore, molecular docking of tested compounds was established with active site of ^V600EBRAF kinase domain. Results of kinase inhibition assay and molecular docking revealed that, compounds 1, 3d, e, h, i, 5d, e and 6b were potent inhibitors for ^V600EBRAF kinase enzyme involved in number of cancer types as melanoma, ovarian and thyroid cancer. The newly synthesized pyridopyrazinones substituted with different substituents at C-3 or fused with triazine heterocycle at C-3 and C-4 afforded potent ^V600EBRAF inhibitors and exhibited promising cytotoxic activities against different cancer types such as melanoma, ovarian, thyroid and colon cancer.

Two accurate, precise, sensitive and selective spectrophotometric methods have been developed and validated for determination of pyridoxine hydrochloride (PYH), cyclizine hydrochloride (CYH) and meclizine hydrochloride (MEH) either in their binary mixtures or in synthetic ternary mixtures. In modified area under the curve method (Method I), PYH has been determined by measuring amplitude value of the plateau at 283 nm (obtained after dividing the ternary mixture by standard spectrum of 20 µg/mL of PYH at which no interference from CYH and MEH) while area under the curve spectrophotometric method (AUC) has been used for calculating CYH and MEH concentrations in the ternary mixture by measuring the area under the curve in the range of 215-228 and 230-243 nm in the obtained division spectrum and after subtraction of the constant value at 283 nm. Method II is mean centering of ratio spectra spectrophotometric method (MCR) at which the mean centered ratio spectra in two successive steps have been used for measuring the amplitudes of the mean centered second ratio spectra amplitudes at 228.8, 262.0 and 270.8 nm for PYH, CYH and MEH, respectively. The proposed methods were successfully applied for determination of the cited drugs in their pharmaceutical formulations. Also they were statistically compared with the reported methods using student's-t and F-tests and there was no significant difference between them regarding both accuracy and precision.

An accurate, sensitive and selective High Performance Thin Layer Chromatography (HPTLC) method has been developed and validated for determination of carbinoxamine maleate and pseudoephedrine HCl in their binary mixture without previous separation. Chromatographic separation was performed on aluminum plates precoated with silica gel 60F₂₅₄ using acetone: methanol:ethylacetate:triethylamine (5:4:2:0.2, v:v:v:v) as a developing system. The bands were scanned at 215 nm. The proposed method has been validated as per ICH guidelines and its linearity was evident in the ranges of 0.4-8.0 and 4-24 µg/ band for carbinoxamine maleate and pseudoephedrine HCl, respectively. The developed method has been applied for determination of the above mentioned drugs in their pharmaceutical formulation where no interference from methyl paraben present as excipient has been detected. Statistical comparison of the results obtained by the developed HPTLC method and those obtained by the reported HPLC method showed no significant difference between them. The developed method is sensitive, accurate and precise and can be easily used for quality control analysis of the studied drugs.

For the first time, the continuous variation method was applied for the evaluation of the stoichiometry of uranyl phosphate complexes sorbed on bentonite. Sorption of UO₂(CH₃COO)₂⋅2H₂O in the presence of Na₂HPO₄⋅7H₂O from 0.001 mol/L solutions led to the appearance of maxima in the sorption peaks of U(VI) and P(V) ions at molar ratios of [U(VI)]/[P(V)]_s = 1.4, 3.3, 3.6 and 1.2, 1.7. It is suggested, based on complementary XRD and XPS data, that the UO₂HPO₄ complex is located on aluminols (ºAl-OH) whereas the (UO₂)₃(PO₄)₂⋅4H₂O complex is precipitated in the interlamellar space of bentonite. The participation of (UO₂)₃(OH)₅⁺ and (UO₂)₄(OH)₇⁺ species in the formation of U(VI) surface complexes is suggested, based on the deconvolution of sorption spectra of U(VI) on the bentonite in the presence of phosphates.

Novel meso-porphyrins were synthesized via microwave assistance and implemented as centers to polyamide amine (PAMAM) dendrimers. The molecular structures of the porphyrins were characterized by UV-Vis, ¹H and ¹³C NMR spectroscopy. In addition, porphyrin-PAMAM dendrimers were characterized by ¹H and ¹³C NMR spectroscopy. The molecular weight of the prepared dendrimers were confirmed by MALDI-TOF mass spectrometry. These porphyrin-core-PAMAM-modified dendrimers were used as templates to form Ag⁰ species and doped nylon membranes, using the XPS technique to confirm the chemical reduction of the metal cation.

A new Schiff base ligand, 2-(4-(diethylamino)-2-hydroxybenzylidene)-N-(4-phenylthiazol-2-yl) hydrazinecarboxamide (L) and its copper(II), cobalt(II), nickel(II) and zinc(II) complexes were prepared and characterized by analytical and spectroscopic methods. The analytical data suggests the composition of the metal complexes to be 1:2 of the type [ML₂] for copper(II), cobalt(II) and nickel(II) complexes and 1:1 stoichiometry of the type [MLCl] for zinc(II) complex, where L is the deprotonated Schiff base ligand. The conductance measurement data indicates that all the metal complexes are non-electrolytes. The antioxidant activity of all the compounds was evaluated using the DPPH assay. The Schiff base ligand (L) and its copper(II), cobalt(II) complexes are found to be good antioxidants. The antibacterial and antifungal activity was performed by agar diffusion methods. All the metal(II) complexes inhibited the growth of bacteria and fungi. Also, brine shrimp bioassay was also carried out to study the in vitro cytotoxic properties, the copper(II) and zinc(II) complexes showed good cytotoxic property.

Novel symmetrical and unsymmetrical cyanine dyes, incorporating merocyanine monomethine like, pentamethine cyanine, monomethine-meso-substituted-pentamethine and mono-5[2(4)]-methine cyanine dye have been prepared through the synthesis of new starting compound derivatives named as 1,3-bis-(2-oxo-2H-chromen-3-yl) propane-1,3-dione and (3-oxo1,3-bis(2-oxo-2H-chromen-3-yl)prop-1-enyloxy) copper, cobalt and nickel chloride salt complexes. Structure determination of the new compounds has been characterized on the basis of elemental analysis, IR, ¹H NMR and MS spectra. Structure photosensitization relationship of new dyes have been discussed on the basis of their spectral behavior as criteria of photosensitizing effect through the UV visible-absorption spectra of all synthesized dyes which investigated in 95% ethanol. Antimicrobial properties of some selected cyanine dyes have been investigated against Streptococcus sp, Staphylococcus sp, Salmonella sp. and Shigella sp.

Michael addition reactions of arylhydrazone derivatives with different functionalized α-cyanoacrylamides were conducted and yielded new pyridazine-4-carboxamide compounds. A further reaction with acetic anhydride was investigated resulting in the formation of a 4-deazatoxoflavin analogue. A one step synthesis of 4-deazatoxoflavin was also carried out by reacting azaenamine with N-carbamoyl-2-cyano-3-phenylacrylamide to give deazatoxoflavin. Unambiguous structural elucidation was done using 2D-HMBC spectroscopy.

Single crystal of N'¹,N'⁴-bis((E)-3,4-dihydroxybenzylidene)succinohydrazide (SHBH) was grown by slow evaporation method. Its, Co(II), Ni(II), Cu(II), Zn(II), Co(II)/Zn(II), Ni(II)/Zn(II) and Cu(II)/Zn(II) complexes have been prepared and characterized by elemental analysis, UV-Vis, IR, NMR, MS spectra, thermal and magnetic measurements. The data confirm the formation of tri- and tetra-metallic complexes (homo- and hetero-nuclear). The ligand behaves as a tetranegative hexadentate in the Co(II)/Zn(II) complex; hexanegative hexadentate in the Co(II) complex and hexanegative octadentate in the tetrametallic complexes. A square-planar for [Co₃(SHBH-6H)(H₂O)₆], [Cu₄(SHBH-H)(H₂O)₄(OAc)₂]⋅3H₂O, [Ni₃Zn(SHBH-6H)(H₂O)₆Cl₂]⋅H₂O and [Cu₃Zn(SHBH-6H)(H₂O)₆Cl₂] and tetrahedral for [Ni₄(SHBH-H)(H₂O)₄(OAc)₂]⋅6H₂O, [Zn₃(SHBH-4H)-(H₂O)₄Cl₂]⋅2H₂O and [Co₂Zn(SHBH-6H) (H₂O)₆Cl₂]⋅2H₂O were suggested based on the magnetic and spectral data. The TGA data confirm hydrated and coordinated water as well as the final product. The mass spectra depict their molecular ion peaks and the isotopic species of each complex. It is found that the homometallic complexes are highly stable than the heterometallic complexes. The calculated energies for [Co₂Zn(SHBH-4H)(H₂O)₄Cl₂].2H₂O are higher than [Co₃(SHBH-6H)-(H₂O)₆] indicating that the three Co stabilized the complex.

New classes of natural surfactants have been prepared through the reaction of low molecular weight chitosans (1.3, 6, 10, 18 and 30 kDa) with butyric anhydride in aqueous medium. The new compounds were characterized by ¹H NMR and FT-IR spectroscopy. Their surface tension and particle size were also determined. The degree of substitutions was in the range of 44-57% as confirmed by ¹H NMR spectra. These compounds possess low aggregate size 12-18 nm with higher surface activity on comparison with native chitosan. The prepared compounds are found to be soluble in all pH media in contrast to native chitosan. This may be due to the breaking up of chitosans inter-strand hydrogen bonding upon substitutes.

A simple, precise, accurate and rapid stability indicating liquid chromatography method had been developed for the simultaneous determination of otilonium bromide (OB) and its expected degradation product; p-aminobenzoic acid (PABA) in bulk powder and pharmaceutical preparation. Chromatographic separation was carried out by isocratic elution on Waters Atlantis C18 column (4.6 × 150 mm, 5 µm) using 2 mM ammonium acetate buffer (pH = 2.35) containing 0.05% TFA: acetonitrile (30:70, v:v) as the mobile phase. The flow rate was 0.8 mL/min with UV detection at 290 nm. Linearity was obtained over a concentration range of 0.5-100 μg/mL with regression coefficient of 1 for OB, and over concentration range of 1-50 μg/mL with regression coefficient of 0.9998 for PABA. The values of LOD and LOQ were found to be 0.0665 and 0.2018 μg/mL for OB and 0.1974 and 0.598 μg/mL for PABA, respectively. The method was validated as per ICH guidelines. The method was successfully applied to the determination of the drug in bulk powder and pharmaceutical preparation.

Palladium(II) and cobalt(II) complexes of Schiff base derived from 4-aminobenzene sulfonamide (Sulfonamide drug) were prepared by convenient method. Reaction of sulfonamide with 2-hydroxy-1-naphthaldehyde gave the Schiff base compound 1 in good yield. Treatment of compound 1 with CoCl₂.6H₂O and PdCl₂yielded new metal complexes 2 and 3, respectively. The synthesized compounds were screened for their antibacterial activity against Escherichia coli, Bacillus cereus, Salmonella spp. and Staphylococcus aureus. Additionally, the compounds were tested for antifungal activity against Aspergillus niger and Candida albicans. Some compounds exhibited good antibacterial and antifungal activity. Molecular modeling studies were performed and showed hydrogen binding and hydrophobic interactions.

N-Bis(methylthio)methylenecyanamide (1) was allowed to react with ethylcyanoacetate or malononitrile in the presence of potassium carbonate in dimethylsulfoxide to yield the urea derivatives (3a,b), which on treatment with hydrazine hydrater resulted the corresponding aminopyrazole derivatives (4a,b). The cyclic amidine 5-amino-3-ureido-1H-pyrazole-4-carboxylic acid ethyl ester (4a) is found to be useful intermediate for the synthesis of new pyrazolopyrimidine and pyrazolotriazine derivatives (5-22a,b). The chemical structures of the synthesized compounds (3a,b-22a,b) were characterized by their elemental analyses, FT-IR, ¹H ¹³C NMR and mass spectra.

The synthesis and characterization of two Ag(I)- N-heterocyclic carbene complexes 3 and 4 of imidazole-based NHC proligands 1 and 2, respectively, are described. The findings revealed that the choice of the counter ions is crucial, which can lead to different supramolecular architectures. Complex 3 is a trinuclear, whereas its analogue complex 4 is mononuclear. Despite being structurally different entities, these complexes form cis-palladium-NHC complex 5 by trans-metallation method, which is a cis-platinum analogue. All the reported compounds 1-5 were tested for their anticancer activities, where compounds 2 and 3 found more potent than the rest.

This paper describes one-pot method of the synthesis and properties of composite polymer gel electrolytes based on poly(vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP). As the precursor of the inorganic filler tetraethyl orthosilicate (TEOS) and titanium tetra-n-butoxide (Ti(OC₄H₉)₄) were used. The drying of membranes with fillers was carried out with supercritical CO₂. The membranes and gel electrolytes have been examined structurally and electrochemically, showing favorable properties in terms of electrolyte uptake and electrochemical characteristics in Li-ion cells.

Treatment of chloroquinazoline (2) with primary amines (2-aminothiazoles and sulpha drugs) and secondary amines (morpholine, piperidine, and piperazine) furnished 4-substituted aminoquinazolines (3a,b and 4a,b), 4-aryl quinazolines (5a,b), and bisquinazoline (6). Hydrazinolysis of compound 2 using hydrazine hydrate, phenyl hydrazine, and sulphonyl hydrazine afforded compound 8 and 9a,b. 1,2,4-Trizolo-quinazoline derivatives (7a-c) were obtained via a one-pot reaction of chloroquinazoline (2), hydrazine hydrate, and aromatic aldehydes. Additionally, 1,2,4-trizolo-quinazoline derivatives (10a,b) were furnished when compound 2 was treated with acid hydrazides like acetyl and benzoyl hydrazides. Pyrimidino quinazoline (13) has been constructed via a three-step conversion of chloroquinazoline 2 using interaction with malononitrile followed by partial hydrolysis and hetero-ring cyclization. All the synthesized compounds were fully characterized using physical and spectral data like, FT-IR, ¹H NMR, ¹³C NMR, and HR-MS.

A molecular scaffold containing a furanoquinoline motif that offered a unique molecular architecture for 5-hydroxytryptamine 6 receptor antagonism was generated by a multi-component cyclization reaction.

A hexahydrotriazine derivative was synthesized via a condensation reaction of 4-chloroaniline, propylamine and formalin. The structure of the synthesized compound was confirmed and characterized by using various spectral techniques like FT-IR, ¹H NMR, ¹³C NMR and UV spectroscopy.