European Journal of Chemistry

The crystal structure of 1,3-diphenyl-propan-2-one oxime, C₁₅H₁₅NO, is described. The compound crystallises in the monoclinic space group C2/c. Centrosymmetrically related molecules are linked to form R₂² (6) dimers. An update, since 2003, of a systematic analysis of the hydrogen bonding patterns in oxime structures with and without competitive O-H...A type acceptors (an acceptor other than the nitrogen of the oxime) functional group is made, taking into account their moieties. The majority of these oximes form dimeric, R₂² (6), structures but R₃³ (8) and R₄⁴ (12) were also found. C3 chains which were classically claimed as the usual oxime H-bond pattern were rarely observed. They are mostly found in aldoxime structures.

The influence of the incorporation of 1,3,4-oxadiazole ring into 2-methyl-1H-benzimidazole derivatives producing a series of substituted 5(6)-(2-methylbenzimidazol-5-yl)-1,3,4-oxadiazoles on the antitumor activity was studied in this study. The antitumor activity of the new compounds was tested against breast cancer cell line MCF-7 and lung cancer cell line A549. S-5-(2-methyl-1H-benzo[d]imidazol-5-yl)-1,3,4-oxadiazol-2-yl 2-nitrobenzenesulfonothioate (9) showed potent activity against both MCF-7 and A549 cell lines. Whereas, compounds 7, 11-13 and 15-17 have moderate growth inhibitory activity on the two cell lines.

An efficient synthesis of the title compound, 1-(4-methylbenzoyl)-3-(4-aminosulfonyl phenyl)thiourea,  was carried out by reaction of 4-methylbenzoyl chloride with potassium thiocyanate in acetone to afford 4-methylbenzoyl isothiocyanate in situ followed by treatment with sulfanilamide. The structure was confirmed by spectroscopic data and elemental analyses. The molecular structure was determined from single crystal X-ray diffraction data. It crystallizes in the monoclinic space group P2₁/n with unit cell dimensions of a = 4.8116(9) Å, b = 17.150(3) Å, c = 18.677(3) Å, γ = 96.487(4) °, and V = 1531.4(5) ų.

A simple and rapid procedure was developed for flotation-separation of toxic metal ions namely Hg²⁺, Mn²⁺ and Cd²⁺ from aqueous solutions. Thiosemicarbazide derivatives such as: 1-(amino-N-phenylmethanethio)-4-(pyridine-2-yl)thiosemicarbazide (H₂PPS), N-phenyl-2-(pyridine-2-ylcarbamothioyl)hydrazinecarboxamide (H₂PBO), 1-(amino(thioformyl)-N-phenylform)-4-(pyridine-2-yl)thiosemicarbazide (H₂APO), and 1-(amino-N-(pyridine-3-yl) methanethio)-4-(pyridine-2-yl)thiosemicarbazide (H₂PPY) have been used as organic chelating agents and oleic acid (HOL) as a surfactant. The different parameters affecting the flotation process namely, metal ion, ligands and surfactant concentrations, foreign ions (which are normally present in fresh and saline waters), pH and temperature are examined. About 100% of mercury, cadmium and manganese ions float at room temperature (~ 25 ^oC), at a metal:ligand ratio of 1:2  and at pH ~5. The procedure was successfully applied to recover Hg²⁺, Mn²⁺ and Cd²⁺ ions spiked into some water samples. The flotation mechanism is suggested based on some physical and chemical studies on the ligands and metal-complexes isolated from the floated layers.

Relying upon the fact that the hardness, like the electronegativity, is a qualitative property and there is commonality in the basic philosophy of the origin and the operational significance of these two fundamental descriptors of atoms in physics and chemistry, we have proposed to use the Gordy's ansatz, modified by Ghosh and Chakraborty, of evaluating electronegativity of atoms as the ansatz of measuring the global hardness of atoms in this work. The ansatz under reference computes the energy of attraction between the screened nucleus of the atoms and its valence electrons. This is our definition of electronegativity and global hardness of atoms. The evaluated new set of global hardness is found to satisfy the sine qua non of a reasonable scale of hardness by exhibiting perfect periodicity of periods and groups and correlating the gross physico-chemical properties of elements. The inertness of Hg and extreme reactivity of Cs and Fr atoms are nicely correlated. The chemical reactivity and its variation in small steps in the series of lanthanide elements are also nicely reproduced. The results of the present semi-empirical calculation find strong correlation with the results of some sophisticated DFT calculations for a set of atoms.

The reactions of 2-(benzo[d]thiazol-2-yl)-3-oxopentanedinitrile with a variety of reagents have been investigated aiming to explore the synthetic potentialities of this activated nitrile in heterocyclic synthesis. Several novel pyridopyrimidine, chromenopyridine, oxazole, diazepinone, thiophene and thienopyridine derivatives could be obtained starting from 2-(benzo[d]thiazol-2-yl)-3-oxopentanedinitrile and plausible mechanisms for their formations are reported.

Transparent semi-conducting ZnO thin films with low resistivity and high transmittance in the visible optical region were deposited by the decomposition of bis(2,4-pentanedionate)-bis(aminoethanol) zinc(II) under an atmosphere of oxygen on ceramic, metal and quartz substrates by ultrasonic aerosol assisted chemical vapor deposition. The precursor was synthesized from bis(2,4-pentanedionate) zinc(II) and aminoethanol by sonication in acetonitrile and was characterized by melting point, infrared spectroscopy, CHNS-O elemental, atomic absorption, and single crystal X-ray diffraction analysis. TGA-FTIR was used to identify the cause of the weight losses and evolved gases formed during the breakup of the molecules. Electrical and optical measurements showed that the ZnO film has a band gap of 3.02 eV and typical semiconductor properties with a resistivity that depends on the thickness of the film. Powder XRD, SEM and EDX show that films are uniform, smooth and crystalline in nature, giving particle sizes in the range of 30-60 nm and exhibit a (002) orientation with the c-axis perpendicular to the substrate surface.

Synthesis of a series of 5-aralkyl pyrrolidine-3-carboxylic acid derivatives namely, 1-acetyl-4-hydroxy-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (3a-e), 1-H-4-hydroxy-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (4a-e), 1-acetyl-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (8a-e), 1-H-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (9a-e) have been accomplished. The structures of the new compounds were assigned from IR, ¹H NMR, ¹³C NMR and elemental analyses. Compounds 3a-e, 4a-e, 8a-e and 9a-e were biologically screened for their anticonvulsant potential using the subcutaneous pentylenetetrazole seizures (scPTZ) assay and Gabapentin as reference standard. The 1-H-4-hydroxy-5-benzyl or 5-(4-alkoxy-benzyl)-pyrrolidine-3-carboxylic acids (4a-e) showed the highest anticonvulsant activity. Compound 4b was found to be the most potent one which exhibited 100% protection.

The CHCl₃ and MeOH fractions of the leaves of Linum grandiflorum, showed cytotoxic activity against EL₄ (Murine Leukemia) cell line with IC₅₀ = 60 and 250 mg/mL respectively. Bioassay guided fractionation and isolation (BGFI) of the MeOH fraction resulted in the isolation of two new cytotoxic compounds 1 [luteolin 7-O-α-D-(6```-E-feruloyl)glucopyranosyl (1→2)-β-D-glucopyranoside] and 6 [2-[(3`-isopropoxy-O-β-D-glucopyranosyl)oxy]-2-methylbutane nitrile] against EL₄ with IC₅₀ = 0.2 and 0.3 mM/mL respectively, together with 2 [luteolin 7-O-β-D-glucopyranoside], 3 [vicenin-1], 4 [vicenin-2], 5 [vicenin-3], 7 [linamarin], 8 [lotaustralin], 9 [neolinustatin], and  10 [butan-2-O-β-D-glucopyranoside] which showed cytotoxicity against EL₄ with IC₅₀ = 0.2, 0.9, 0.8, 0.9, 0.4, 0.4, 0.2, 0.4 mM/mL respectively. BGFI of the CHCl₃ fraction revealed the isolation of three cytotoxic aryltetrahydronaphthalene-type lignans identified as 11 [podophyllotoxin], 12 [deoxypodophylotoxin] and 13 [5-methoxypodophyllotoxin] against EL₄ with IC₅₀ = 0.2, 0.09 and 0.2 mM/mL respectively. The isolated compounds were structurally elucidated using 1D, 2D NMR, HR-ESI-MS, and HR-MALDI-MS techniques.

New derivatives of thieno[2,3-d]pyrimidin-4-one, 4a-c, and 6 were respectively synthezised based on thiophene derivative, 2c,ortho-disposed amino and ester groups. Carbohydrazide, bearing 7, was obtained by hydrazinolysis of 3-ethoxycabonylmethyl derivative, 4c. Compounds 4b and 7 were used to build up two series of novel 3-substituted-methylthieno[2,3-d]pyrimidin-4-ones, 7-11, and their corresponding 3-substituted-amino analogues 12, 15a,b, 18, which were of significant interest for biological study. The new thieno[2,3-d]pyrimidin-4-one derivatives, with various groups in position 3, were screened for their preliminary antimicrobial activity against a representative panel of Gram-positive and Gram-negative bacteria as well as fungi strains. The compounds tested displayed different levels of antibacterial and antifungal effects, with the assays carried out on six pathogenic bacteria and six pathogenic fungi. Of these compounds, the 3-unsubstituted-thieno[2,3-d]pyrimidin-4(3H)-one, 4a, showed the lowest effect on pathogenic bacteria, while the corresponding 3-substituted analogues produced inhibitory effects against bacteria similar or superior to the reference drug Tetracycline. For those derivatives of thieno[2,3-d]pyrimidin-4-one in which the 3-position contains a methylene moiety, it has been observed that the antibacterial effect was in general found to be significantly higher than the corresponding analogues with a substituted-amino moiety in position 3. Despite promising in vitro antibacterial activity of the new thienopyrimidin-4-ones, only compounds 7, 10 and 11, among the compounds tested, exhibited some kind of antifungal activity. The detailed synthesis and biological screening data were reported.

New series of chromeno[2,3-b]pyridines, 2-8, have been obtained from 1,8-diazabicyclo [5.4.0]undec-7-ene catalyzed Friedländer reaction of 8-allyl-2-aminochromone-3-carboxaldehyde (1) with some carbonyl compounds containing a reactive α-methyl or methylene group namely 2-acetylthiophene, 3-acetylpyridine, 4-chloroacetophenone, 4,6-diacetylresorcinol, acetylacetone, dibenzoyl methane and acetoacetanilide. Heteroannulated chromones, 13-16, were prepared from Friedländer reaction of 1 with some cyclic α-methylene ketones namely 2-phenyliminothiazolidin-4-one, pyrazoline-3,5-dione, 5,5-dimethylcyclohexane-1,3-dione and thiobarbituric acid. Structures of the newly synthesized compounds have been established from elemental analysis and spectroscopic data.

Extract of Bridelia retusa leaves was investigated as corrosion inhibitor of mild steel in 1 N H₂SO₄ using conventional weight loss, electrochemical polarizations, electrochemical impedance spectroscopy and scanning electron microscopic studies. The weight loss results showed that the extract of Bridelia retusa leaves is excellent corrosion inhibitor and electrochemical polarizations data revealed the mixed mode of inhibition. While the results of electrochemical impedance spectroscopy have shown that the change in the impedance parameters, charge transfer resistance and double layer capacitance, with the change in concentration of the extract is due to the adsorption of active molecules leading to the formation of a protective layer on the surface of mild steel. Scanning electron microscopic studies provided the confirmatory evidence of improved surface condition, due to the adsorption, for the corrosion protection.

A number of novel isoquinoline derivatives have been synthesized using the readily obtainable (E)-4-(3,4-dimethoxybenzylidene)-4H-isochromene-1,3-dione, 2, via the reaction with different nitrogen nucleophiles such as cyanoethanoic hydrazide, cyclohexylamine, 2-aminothiophenol and p-toluenesulfonohydrazide. Furthermore, the reactivity of 2 towards thiophenol, and ethylcyanoacetate has been investigated.

Ageratum conyzoides L., is an annual herb with a long history of traditional medicinal uses in many countries in the world, especially in the tropical and subtropical regions. A wide range of chemical compounds including alkaloids, flavonoids, chromenes, benzofurans and terpenoids have been isolated from this species. Extracts and metabolites from this plant have been found to possess pharmacological and insecticidal activities. In continuation of our interest in the Egyptian medicinal plants, the reinvestigation of the methylenechloride extract of the air-dried aerial parts of Ageratum conyzoides afforded a new natural compound 1, pyrrolone, 5-ethoxy-1H-pyrrol-2(5H)-one, together with a known flavonoid. The structures of the compounds were determined by comprehensive NMR studies, including DEPT, COSY, HMQC, HMBC, and MS.

Exponential growth in information technology generates ever increasing amounts of data, making recording density of the storage media crucially important. Two-photon absorption was proposed as a basis for high-density multi-layer technology for optical memory and logic devices. This technology suggests to use polymers, doped with photochromic compounds that undergo a reversible photoinduced isomerization, or photoswitching. In this review we consider recent theoretical works and benchmarking studies of the DFT-based methods, capable to predict two-photon absorption (2PA) and photochemical activity, Next we review the applications of these methods to design a prototype molecule that combines the photon-mode recording property of photochromic compounds with large 2PA cross-section. We conclude that a posteriori Tamm-Dancoff approximation to the second order CEO approach in Density Functional Theory is the powerful tool for both quantitative predictions and qualitative understanding of the excited state processes in photophysics and photochemistry. We also emphasize general principles for the rational design of a two-photon operated photoswitch.