European Journal of Chemistry

Dibenzoylmethane and six aromatic 1,3-diketones containing a dibenzoylmethane moiety were synthesized from acetophenone and the appropriate ester in crossed-Claisen condensations. The synthesized diketones include derivatives containing carboxyl and ester groups; bis-(1,3-diketones) were also prepared. The absorption of UV radiation of the obtained compounds was investigated in various solvents, and their molar absorption coefficients were calculated. The ratio of tautomers and keto-enol equilibrium constants were calculated using ¹H NMR techniques. Aromatic bis-(1,3-diketones) demonstrated strong hyperchromic effects. The keto-enol equilibrium of the investigated compounds is strongly shifted to the enol form, especially in non-polar solvents.

An efficient synthesis of nitrogen-containing heterocycles pyrazole, triazole,  pyridinone and pyrimidinone derivatives from ethyl 3-(6-dibenzothiophen-2-yl-pyridazin-3-ylamino)-3-oxopropanoate (2) was described. The structures of all products were confirmed and characterized by the elemental analysis and spectroscopic studies (IR, MS, ¹H NMR, ¹³C NMR).

The synthesis of series of 3-aryl-4-dihydrooxazolyl-5-methyl trisubstituted isoxazoles (VI) is reported, both under thermal and microwave conditions starting from various benzaldehydes (I). Benzaldehydes undergo oximation with hydroxylamine hydrosulphate to provide oximes that upon chlorination, followed by condensation with methylacetoacetate, resulted in the formation of esters. Hydrolysis of the esters to acids followed by treatment with PCl₅, resulted in the formation of acid chlorides (III) that upon reaction with hydroxyamines, gave N-β-hydoxyalkyl amides (IV). These on further reaction with SOCl₂, followed by cyclization with 2 N NaOH provided oxazoline substituted isoxazoles (VI) in good yields. The conversion acid chlorides (III) to isoxazoles (VI) was also achieved by microwave irradiation in moderate to excellent yields, with shorter reaction times compared to the conventional thermal method.

Two 1,4-dihydro-Hantzsch pyridine derivatives were synthesized by three steps. In the condensation step, the reaction time can be shortened to 1.5 h through using H₂SO₄-acetic anhydride system as a catalyst rather than the acetic acid-piperidine systemin the cyclization step, the reaction time was shortened from 20 h in ethanol to 15 h in polar aprotic solvent, and the yield of two products also was increased from 43.3% and 39.7% in traditional solvent to 93.2% and 90.1% in polar aprotic solvent.

Reaction of chalcone derivatives 1-4 with hydrazine hydrate in presence of formic acid yielded 2-pyrazolines 5-8. Structures of these compounds have been elucidated by spectroscopic methods; IR, UV, ¹H NMR, ¹³C NMR. Their purities were confirmed by elemental analyses.

N,N,N',N'-tetramethylethylenediammonium dinitrate has been synthesized. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. C₆H₁₈N₄O₆, M =242.24, Triclinic, a = 6.040(2) Å, b = 6.834(3) Å, c = 7.867(2) Å, α = 74.1120(10)°, β = 83.700(2)°, γ = 80.314(2)°, V = 307.12(19) Å³, T = 298(2) K, space group P-1 (no. 2), Z = 1, μ(Mo-K_α) = 0.115, 2383 reflections measured, 1342 unique (R_int = 0.0169) which were used in all calculations. The final wR(F²) was 0.1262 (all data). In the title compound, C₆H₁₈N₂^2+.2NO₃^-, both N atoms of the cationic moiety are protonated and linked via hydrogen bonds to two trigonal planar nitrate anions. Two types of classical hydrogen bonds are observed: N1-H…O1 and N1-H…O2. These bonds link the cations and the anions together, forming a one-dimensional network and reinforcing the cohesion of the ionic structure.

2,3-Dihydro-1,3,4-thiadiazoles, and triazolino[4,3-a]pyrimidines containing pyrazole moieties were prepared from the reaction of alkyl 2-[1-(4-cyano-1,5-diphenyl-1H-pyrazol-3-yl)ethylidene]hydrazinecarbodithioate and pyrimidine-2-thione derivatives with appropriate hydrazonoyl halides. The structures of all the newly synthesized compounds were confirmed by elemental analyses, spectral data, and alternative route of synthesis whenever possible.

The complexation behaviour of some salophen,s derivatives with few transition and heavy metal cations in N,N'-dimethyl formamid as nonaqueous solvent at 25 ^oC and 0.05 M tetra ethylammonium perchlorate to investigate the effect of structure were studied by spectrophotometric method. The formation of complexes between ligands and metal ions of the types ML, ML₂ or M₂L was observed. The overall stability constants of such complexes were evaluated by computer refinement of absorption-mole ratio data using the KINFIT program.

A novel series of pyrazolo[1,5-a]pyrimidine-3-carbonitriles substituted with 7-amino, 7-substituted amino and 5-substituted amino groups was synthesized. Some of the newly synthesized compounds were tested in vitro on human colon tumor cell line (HCT116). Compound 14a displayed the highest activity among the tested compounds with IC₅₀ that equals to 0.0020 μM.

Indole-3-acetic acid (1) on reaction with thionyl chloride, afforded 2-(1H-indol-3-yl)acetyl chloride (2), which was further treated with aniline and various substituted anilines through base condensation reaction to obtain respected indole-3-acetic acid derivatives (3-9). The structures of all new compounds were elucidated by elemental analysis, Mass, IR, ¹H NMR and ¹³C NMR and spectroscopic techniques. All the compounds were screened for their antioxidant activities by applying in vitro methods like 2,2-diphenyl-1-picryl hydrazyl (DPPH) free radical scavenging assay and inhibition of microsomal lipid peroxidation (LPO) assay. Butylated hydroxy anisole (BHA) was used as a reference antioxidant compound and the comparative study with newly synthesized compounds was also done. Among the analogues, compound 9 bearing electron donating methoxy substituent in addition to the phenolic moiety showed predominant activity. It is conceivable from these studies that the coupling of aniline and substituted anilines is the most important feature for the significant antioxidant activity of indole-3-acetic acid analogues studied.

The kinetics of oxidation of n-butylamine and 1,3-propanediamine by home-made potassium ferrate(VI) at different conditions has been studied spectrophotometrically in the temperature range of 283.2-298.2 K. The results show first order dependence on potassium ferrate (VI) and on each reductant. The observed rate constant (k_obs) decreases with the increase of [OH^-], and the reaction rate has a negative fraction order with respect to [OH^-]. A plausible mechanism is proposed and the rate equations derived from the mechanism was shown to fit all the experimental results. The rate constants of the rate-determining step and the thermodynamic activation parameters are calculated.

4-Amino-2-(benzylthio)-6-(4-methoxyphenyl)pyrimidine-5-carbonitrile (1) was prepared by treatment of s-benzylthiuronium chloride with 2-(4-methoxybenzylidene)malononitrile in ethanolic sodium hydroxide with hydrazine hydrate to afford the hydrazino derivative 2, which was allowed to react with different electrophilic reagents to give the pyrimidine derivatives 3-12. The proclivity of (E)-2-cyano-3-(4-nitrophenyl)acrylamide (13) towards carbon and nitrogen nucleophiles was also investigated. IR, ¹H NMR and mass spectra for all the synthesized compounds were discussed. All derived compounds were investigated for anti avian influenza (H5N1) virus activity and compared with zanamivir as control drug. All the synthesized compounds didn’t possess any antiviral activity.

Reaction of 2-(oxazolidin-2-ylidene)malononitrile (1) with phosphorus pentasulfide gave the corresponding thioamide derivative (2a) in a regioselective manner. Reaction of this compound with several α-bromocarbonyl compounds gave new 2-(E)-cyano(oxazolidin-2-ylidene)thiazoles (3a-g). The chemical structures of novel compounds were confirmed by ¹H NMR, elemental analysis, FT-IR spectrometry and mass spectrophotometric analyses.

A facile synthesis of b-lactam derivatives; 3-(1-(4'-(3-chloro-2-(substituted phenyl)-4-oxoazetidin-1-yl)biphenyl-4-yl)-5-oxo-2-phenyl-1H-imidazol-4(5H)-ylidene)indolin-2-ones (6a-e) and 3-(1-(3-chloro-2-(substituted phenyl)-4-oxoazetidin-1-yl)-5-oxo-2-phenyl-1H-imidazol-4(5H)-ylidene)indolin-2-ones (7a-e) is described herein. The title compounds 6a-e and 7a-e were evaluated for their in vitro antimicrobial activity against Candida albicans and Bacillus subtilis respectively using a two fold serial dilution technique. Investigation revealed that 2-hydroxy phenyl function at b-lactam ring in compounds 6d and 7d is a key factor for both antifungal and antibacterial activity, as newly designed compounds 6d and 7d exhibited good biological activity with minimum inhibitory concentration (MIC)12.5 mg/mL against Candida albicans and Bacillus subtilis respectively.

New derivatives of 3,4-dihydroquinoxaline-2(1H)-one were synthesized and characterized. Representative examples were evaluated for their antimicrobial and antifungal activities using Tetracycline and Nystatin as reference compound. One of the tested compounds 10a was found to exhibit slight activity against Staphylococcus aureus. Compounds 10b, 11b and 14b showed slight activity against Escherichia coli. Moreover, nineteen compounds were screened for their inhibition effect on CDK5, CK1, and GSK-3β. None of the tested compounds showed an inhibition activity below 10 µM concentration.

Three simple, sensitive and accurate spectrophotometric methods (A, B and C) were developed to determine doxofylline in bulk and in its dosage forms. Method A is based on charge-transfer complex formation of the drug with p-chloranilic acid. Method B involves the formation of colored chloroform extractable ion-pair complex of the drug with bromophenol blue under acidic condition. Method C is based on ternary complex formation of the drug with molybdenum(V) thiocyanate binary complex. The colored products are quantitated spectrophotometrically at 540, 390 and 690 nm by methods A, B and C, respectively. The variables, which affected the reactions were carefully studied and optimized. The linear ranges for the proposed methods were 4-32 μg/mL (method A & B) and 2-16 μg/mL (method C). Analytical performance of the methods was statistically validated. The proposed methods were successfully applied to the analysis of doxofylline in its dosage forms and were found to be comparable with that of reference method.

Preparation of quinolinyl-3-oxopropanoic acid was accomplished by hydrolysis of pyranoquinolinedione, in aqueous alkaline medium. The chemical behavior of this β-keto acid towards nitrosation, coupling with a diazonium salt, esterification, condensation with 2,2-diethoxyethanamine, hydrazinolysis, Knoevenagel condensation with isatine, salicylaldehyde, 3-formylquinolones, and 3-formylchromone, was investigated. Also many of the products of these reactions were obtained using either pyranoquinolinedione 1 or β-keto acid 2, under the same conditions.

A series of 4-methyl-2-oxo-pyranyl-phenothiazines (IIIa-j) followed by 4-methylpyrano-(2, 3-β)-phenothiazine-2(11H)-one oxime (IVa-j) were synthesized by using 7-hydroxy-4-methylcoumarin (I). Further reaction of (I) was carried out with substituted aromatic amines (a-j) to convert into 7-arylamino-4-methyl-coumarin (IIa-j). Additionally (IIa-j) was treated with sulphur in presence of iodine to obtain a series of novel 4-methyl-2-oxo-pyranyl-phenothiazine (IIIa-j) derivatives, which on treatment with hydroxylamine hydrochloride afforded the title compounds i.e. 4-methylpyrano-(2,3-β)-phenothiazine-2(11H)-one oxime (IVa-j). The structures of these compounds were confirmed by IR, NMR and Mass spectral analysis. The newly synthesized compounds were evaluated for antibacterial and antifungal activity. The results show that compound IIIa, IIIe, IIIh, IIIj, IVa, IVi and IVj exhibited moderate to good antibacterial and antifungal activity at 5-100 mcg/mL.

In this report, we explore the DNA binding properties of mixed ligand copper(II)/cobalt(II) complexes of the type [M(bnp)(phen)H₂O].nH₂O, and copper(II)/cobalt(II) complexes of the type [M(Hbnp)₂], where n=0, 1, ..., H₂bnp=3-hydroxy-N'-(2-hydroxybenzylidene)-2-naphtho-hydrazide and phen=1,10-phenanthroline. A host of physical methods like spectral absorption, emission studies and hydrodynamic measurements have been used to probe the effect of ligands on the mode and extent of interaction of the complexes with Calf Thymus DNA. The efficiencies of the complexes to oxidatively cleaved pUC19 DNA was performed in the absence and presence of H₂O₂. Among the compounds tested for antioxidant capacity, H₂bnp displayed excellent activity than its complexes and standards used. It has been observed that Cu(II) and Co(II) complexes exhibited different levels of antibacterial and antifungal effects, with the assays carried out on four pathogenic bacteria and two pathogenic fungi. H₂bnp showed moderate activity against bacteria E. coli, X. vesicatoria and fungi, A. niger and A. flavus, but less than its complexes and standard drugs used for assay.

A number of novel quinazolinone derivatives have been synthesized using the readily obtainable 2-[(1Z,3E)-1-benzamido-4-phenyl-1,3-butadien-1-yl]-3,1-benzoxazin-4(H)one (1) via the reaction with different nitrogen nucleophiles such as azines, Schiff’s base, primary aromatic amines, diamines, hydrazine hydrate and hydroxylamine.

Nine 2,3,5-triphenylimidazole derivatives having nitro and/or OH groups at their phenyl groups as receptors have been designed and synthesized for the colorimetric detection of F- ion, among which receptor (1) having a nitro group at the para position of the 2-phenyl group with respect to the imidazole moiety shows colorimetric responses (yellow to red) in acetonitrile-water (9:1, v:v) mixture towards F- anion selectively among other anions studied. Here nitro group acts as a signaling unit and OH and NH of imidazole moieties act as binding sites respectively.

This paper deals with the up-conversion intrinsic photoluminescence by exciting the Metallo-Phthalocyanine (MPc) prepared by melt method. MPcs were further characterized using UV visible spectrophotometer, FT-IR, and thermal analysis. The magnetic susceptibility, optical absorption and photoluminescence behavior of these compounds were studied. Photocatalytic degradation of amido black 10B dye using different MPcs at varing pH was done to see the efficiency of these compounds. High emission intensity and easy preparation makes these systems potential candidates for application as luminescent material.

The stability studies of biologically active 2,4-dinitrosoresorcinol, o-carboxy phenylazo-dinitrosoresorcinol, N,N`-bis-[4,4`-(1,3-diphenyltriazine)]-diacetamide, 2-amino-6-phenylazo-pyridin-3-ol, 2-amino-3-hydroxy-pyridin-6-ylazo)-benzoic acid, 4-(2-amino-3-hydroxy-pyridin-6-ylazo)-benzoic acid ethyl ester and N-[4-(2-amino-3-hydroxy-pyridin-6-ylazo)-phenyl]-acetamide compounds were studied. The dissociation constants were determined potentiometrically. The thermodynamic parameters of dissociation were evaluated. Regression analysis is applied for correlating the different parameters. The results help to assign the solute-solvent interactions and the solvatochromic potential of the investigated compounds. The electronic character of the substituent and the chemical nature of the solvent are major factors for the observed solvatochromism.