European Journal of Chemistry

cis-Bis[4-fluoro-N-(diethylcarbamothioyl)benzamido-κ²O,S]platinum(II), cis-[Pt(L-O,S)₂], was synthesized and characterized by elemental analyses, FT-IR and NMR techniques. The obtained metal complex was also characterized by a single crystal X-ray diffraction study. Molecule formula of the title compound is C₂₄H₂₈F₂N₄O₂PtS₂: tetragonal, space group I4₁/a, a = 19.7530(4) Å, b = 19.7530(4) Å, c = 13.7137(3) Å, V = 5350.83(19) ų, Z = 8, D_calc = 1.742 g/mm³, 22890 reflections measured (3.62 ≤ 2Θ ≤ 52.72), 2733 (R_int = 0.0272), which were used in all calculations. A square-planar coordination geometry is formed around the Pt atom by two S atoms and two O atoms of the N-(diethylcarbamothioyl)-4-fluorobenzamide ligand which are a cis configuration.

(5-Amino-1,3,4-thiadiazole-2-yl)phenol and it derivatives have been synthesized and characterized by spectral methods lik (FT-IR, UV-Vis, and ¹H NMR) and elemental analysis beside the measurements of their physical properties. All the prepared compounds were used as photo stabilizer with polyvinyl chloride. The rate of photo degradation and photo stabilization for PVC films were monitored with irradiation time by measuring the carbonyl (Ico) index values. In addition, the effect of concentrations additives on the rate of photo degradation and photo stabilization process was also studied. We found that the rates were increased with increasing of additives concentrations. Besides, the effect of film thickness is studied and the results showed that the increasing of film thickness will decrease the rate of photo degradation as the following sequences: [5] > [2] > [1] > [3] > [4] > PVC. Degree of deterioration (α), average number of cuts per single polymer chain (s), were calculated for PVC films as a control and that which contains the additives. According to the experimental results obtained several mechanisms were suggested depending on the structure of the additive. Among then UV absorption and radical scavenger for photo stabilizer additive mechanisms were suggested.

Quantum mechanical calculations of geometries, energies and vibrational frequencies of organic mercury and tellurium compounds containing azomethine group, molecules a1-a5 and containing azo group, molecules a6-a10 have been undertaken using density functional theory. The optimized geometrical parameters such as bond lengths, bond angles and dihedral angles showed that only organomercuric compounds have planer structures. The calculation of the total energy and HOMO-LUMO energy gap were showed that organotellurium compounds have higher reactivity than the corresponding organomercuric compounds. As well it showed the HOMO orbitals are localized mainly on tellurium, nitrogen and bromine atoms moieties, while the LUMO of π nature are mostly located on the phenyl ring. The calculated vibrational frequencies of molecules a1 and a7 are in good agreement with experimental frequencies with correlation coefficient r² value is 0.9875 and 0.9987, respectively.

Two series of amino acids conjugated quinazolinones (1a-h and 2a-h) were synthesized by acid-amine coupling and the structures of all the compounds were confirmed through spectroscopic techniques such as IR, NMR and HRMS. The synthesized compounds were evaluated for their antimicrobial, antioxidant and anti-inflammatory activities. Biological evaluation study revealed that, the compounds 1f, 2f, 2g and 1g showed good antioxidant activity with 50% of the inhibition concentration (IC₅₀) values 35, 20, 30 and 40 µg/mL, respectively, much better than the standard BHT (IC₅₀ = 45 µg/mL). The compounds 1g, 2e and 2g found to have promising anti-inflammatory activity and almost all the synthesized compounds exhibited good antimicrobial activities (antibacterial and antifungal) against all the selected pathogenic bacteria and fungi. Conjugates containing Trp, Tyr and Pro have shown better activity than the rest of the analogues in the series. The structure-activity relationship was established for these compounds.

The activation and reaction energies of the C-C and C-H bonds cleavage in pyrene molecule are calculated applying the Density Functional Theory and 6-311G Gaussian basis. Different values for the energies result for the different bonds, depending on the location of the bond and the structure of the corresponding transition states. The C-C bond cleavage reactions include H atom migration, in many cases, leading to the formation of CH₂ groups and H-C≡C- acetylenic fragments. The activation energy values of the C-C reactions are greater than 190.00 kcal/mol for all bonds, those for the C-H bonds are greater than 160.00 kcal/mol. The reaction energy values for the C-C bonds range between 56.497 to 191.503 kcal/mol. As for the C-H cleavage reactions the activation energies range from 163.535 to 165.116 kcal/mol, the reaction energies are nearly constant, 117.500kcal/mol. The geometries of the transition states and reaction products are discussed too.

A series of novel benzimidazole derivatives have been synthesized by the condensation of o-phenylenediamine with 4-bromophenoxy acetic acid and product obtained was alkylated at the benzimidazole -NH with different electrophilic reagents. Subsequent reactions of the products by the Suzuki Coupling between benzimidazole derivatives and phenylboronic acid derivatives were accomplished. All these compounds were characterized by FT-IR, ¹H NMR, MS and elemental analysis. These compounds were screened for their potential antibacterial and antifungal activities. This exhibited some promising results towards testing organism in-vitro.

Self-metathesis of 9-octadecenoic acid methyl ester was carried out with varying the concentration of Grubbs’ second generation catalyst from 0.03 mmol to 0.18 mmol at 40-45 °C for 36 h. Only two products (9-octadecene 30%, and dimethyl-9-octadecene-dienoate 23%) resulted when 0.06 mmol of catalyst was employed, while at other concentrations four metathesized products were observed. 9-Octadecene generated at 0.03, 0.06 and 0.12 mmol completely disappeared and dimethyl-9-octadecene-dienoate (64%) was observed in major amounts at 0.18 mmol concentration.

The electronic properties of α-chlorocurcumin and α-methylcurcumin was theoretically investigated at the B3LYP/6-311++G(d,p) level of theory. The thermodynamics quantities were estimated by calculating the frequencies of the molecules. Three main isomers were predicted after full geometry optimization of various suggested isomers within the tautomeric mixture of each molecule; the cis-enol, trans-enol and the trans-diketo isomers. Their stability was in the sequence: cis-enol > trans-diketo > trans-enol. The stabilization energy for the cis-enol with respect to trans-diketo and trans-enol in chlorocurcumin is 8.44 and 12.59 kcal/mol, respectively, while in methylcurcumin, it is 4.80 and 10.79 kcal/mol, respectively. The fluorescence spectra were recorded for the investigated compounds in several protic and aprotic solvent with different dielectric constants and H-bonding abilities. The emission maxima are within the range 487 to 571 nm in ethylene glycol, while they are within the range 475 to 557 nm in n-hexane. The fluorescence quantum yields of both compounds are low and lower than those of curcumin. The quantum yield of chlorocurcumin ranges from Φ_Fl = 0.008 in MeOH to Φ_Fl = 0.058 in toluene, while for methylcurcumin it ranges from Φ_Fl = 0.007 in DMF to Φ_Fl = 0.0524 in ethylene glycol. The fluorescence of both compounds quenched by water and their fluorescence life times are estimated from the slopes of the linear curves that obtained from Stern-Volmer relationship to be 1.44 and 1.40 psec for chlorocurcumin and methylcurcumin, respectively.

A method for polydimethylsiloxane grafting of alumina powders is described which involves chemical modification of the surface of mesoporous (5 nm) γ-alumina flakes with a linker (3-aminopropyltriethoxysilane: APTES), either by a solution phase (SPD) or a vapour phase (VPD) reaction, followed by PDMS grafting. The systems were analysed by FTIR, gas adsorption/desorption and TGA. Grafting is proven by FTIR for all cases, meaning that a covalent bond exists between inorganic particle and organic moiety. It is demonstrated that the way of applying APTES (by SPD or VPD) has an effect on the morphology of linker as well as of PDMS. A more controlled grafting of the APTES linker on γ-alumina is possible by the VPD method, resulting in efficient grafting and good infiltration of PDMS in the pores of the inorganic system. Stability tests on these PDMS grafted alumina show no degradation after 14 days soaking in a wide range of solvents. Surface modification of metal oxide particles by organic moieties via a chemical reaction can adapt its interfacial properties and renders a high chemical stability of these inorganic-organic hybrids. This validates the use of these materials under severe applications like in membranes for solvent nanofiltration or for protein immobilization and resin modification in e.g. chromatographic applications.

The adsorption of Basic Red 18 (BR 18) from aqueous solution onto KF modified sepiolite was carried out as a function of pH, initial dye concentration, contact time and temperature. The equilibrium data were evaluated according to Langmuir and Freundlich models. The experimental results showed that the best correlation was obtained on Freundlich model. The adsorption kinetics was examined with pseudo-first order, pseudo-second order and intraparticle diffusion models. The result was best fitted for pseudo-second order kinetic model. Thermodynamic investigations were also performed to determine ΔH°, ΔG° and ΔS°. The results indicated that the adsorption of BR 18 was exothermic and spontaneous.

The present study is the first investigation of chemical composition, antioxidant and antimicrobial activities of the volatile oils from Salvia sharifii in Tunisia. The obtained results show that essential oils from Tunis locality were most complex and present 35 compounds representing 96.83% of the total oil composition. The major components of the studied oils in this site are Linalool (32.9%) and the green leaf volatiles; hexyl isolaverate (15.4%) and hexyl-2-methyl butanoate (10.9%) were detected as the major constituents of the oil. Considerable levels of antioxidant activities of the investigated essential oils were highlighted. Variations in antioxidant activities may be attributed to the concentrations of major components and the presence of some phenolic compounds like linalool. Our results showed strong activities of the investigated oils against all tested microorganisms. The antimicrobial test results showed that the oils had a great potential antimicrobial activity against all bacteria and fungal strains. Gram-positive bacteria are more sensitive to the investigated oil, with a range of 0.09 to 6.25 µL/mL than Gram-negative bacteria in the range, which is significantly higher from 1.56 to 25.00 µL/mL. The oil showed moderate antioxidant activities, (IC₅₀ = 16.8 µg/mL) but good to moderate antimicrobial activity against most of the tested microorganisms.

We describe the oxidation of flavanones by employing phenyliodonium diacetate to form the flavone (15), isoflavone (8) and 2,3-dihydrobenzofurane (18) in this study. The oxidative method was found to be regioselective and dependent on the substitution pattern present on the two aromatic rings of the starting flavanone. The structures of products obtained were fully characterized by using IR, ¹H and ¹³C NMR spectroscopy and Mass spectrometry. X-ray crystallography further confirms the structures of flavones and isoflavone. The density field theory calculations have also been performed to get more insight about the structures, electronic and spectroscopic properties of synthetic flavonoid derivatives. The geometrical parameters such as bond lengths and angels showed a good correlation with the values obtained through X-ray crystallography. Moreover, the theoretically simulated vibrational and UV-vis spectral values are in agreement with the experimental results.

Magnesium aluminate nanoparticles have been synthesized by a citrate sol-gel route. X-ray diffraction and IR spectroscopy study confirmed the formation of MgAl₂O₄ cubic spinel structure without presence of any secondary phase. Crystallite size of the synthesized nanoparticles was found to be equal to 24 nm. The ac conductivity of MgAl₂O₄ was studied using complex impedance spectroscopy technique in the frequency range from 5 Hz to 13 MHz and temperature range from 673 to 798 K. The temperature and frequency dependence of ac conductivity were highlighted and the activation energies of, respectively, ac conduction and relaxation processes were also calculated.

Sodium cromoglycate (SCG) and oxymetazoline hydrochloride (OXMT) are administered in combination for effective treatment of nasal congestion and allergy. In this work, SCG was determined using direct spectrophotometry by measuring its zero order absorption spectra at its λ_max 320.6 nm where OXMT showed zero absorbance. On the other hand, four simple, sensitive and precise spectrophotometric methods were developed and validated for the determination of OXMT in the presence of SCG in their laboratory prepared mixtures and pharmaceutical formulation, without preliminary separation; Method A: first derivative spectrophotometric method [¹D], Method B: first derivative of ratio spectra method [¹DD], Method C: ratio difference spectrophotometric method [RDSM] and Method D: ratio subtraction method [RSM]. Ratio manipulating methods (Method B, C and D) were done using divisor of 10.00 µg/mL SCG. Linear correlation was obtained in range 4-22 µg/mL for OXMT by methods A, B and D and 6-22 µg/mL for method C. All methods were validated in compliance with the International Conference on Harmonization (ICH) guidelines and satisfactory results were obtained. No significant difference was noted between the developed methods and the official one with respect to accuracy and precision.

Adenine, thymine and uracil thio-derived acyclonucleosides were synthesized and characterized by UV-Vis, FT-IR, ¹H and ¹³C NMR spectroscopic techniques. The photophysical properties of the derivatives were evaluated in solvents with diverse polarities and at various pH values. The solvent dependent absorbance and emission spectral shifts were analysed using physical parameters of the selected solvents. The regression and correlation coefficients were calculated using multiple regression techniques. The fitting coefficients gave an estimate of the contribution of each interaction to the total spectral shift in various solutions. Multiple linear regression studies, Kamlet-Taft equation and stokes shift correlation with orientation polarizability provide valuable information concerning spectroscopic characteristics of the studied molecules.

The complexation properties of coumarin phthalonitrile derivatives 1-3, towards some transition, heavy and lanthanide metal cations have been investigated in methanol by means of UV spectrophotometry and conductivity experiments. The stoichiometries of the complexes formed and their stability constants were resolved by digital processing of data. A binuclear M₂L (M = Metal, L = Ligand) species were formed and the profiles of affinity of ligands 1-3 towards transition metal cations illustrate their selectivity towards Cu²⁺.

Two pyrazole derivatives, namely 2,4-diamino-5-(5-amino-3-hydroxy-1H-pyrazole-1-carbonyl)thiophene-3-carbonitrile (I) and 1-(2,4-diamino-5-(5-amino-3-hydroxy-1H-pyrazole-1-carbonyl)thiophen-3-yl)propan-1-one (II) were evaluated as a corrosion inhibitors for carbon steel in 1M hydrochloric acid by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy methods. Spectrophotometric and conductometric titration methods were also utilized to investigate the possibilities of chemical adsorption between the steel surface and the compounds under consideration. The results showed that the studied compounds inhibit the corrosion of steel in acidic solution at different temperatures. The adsorption followed the Langmuir isotherm. The thermodynamic and the activation parameters were also determined and discussed.

Three simple, accurate and validated spectrophotometric methods were developed for the determination of pyridostigmine bromide (PB) in presence of its alkaline-induced degradation product, 3-hydoxy-N-methylpyridinium bromide (3-OH NMP) in powder form and in pharmaceutical formulations. Method A, is first derivative method (¹D), which is based on measuring the peak amplitude of the first derivative spectra (¹D) of PB at 260 nm. Method B, is first derivative of ratio spectra (¹DD) which allows the determination of PB at 267.4 nm using (50 µg/mL) of 3-OH NMP as a suitable devisor. Finally, method C depends on mean centering of ratio spectra (MCR) of PB with different concentrations, which were recorded over 200-400 nm and divided by the spectrum of 20 µg/mL of 3-OH NMP as a devisor. The obtained ratio spectra were mean centered and the concentrations of PB were then determined from the calibration graphs obtained by measuring the amplitudes at 338 nm. The proposed methods were successfully applied for assay of PB both in pure form and in pharmaceutical formulations. The proposed methods were validated in compliance with International Conference on Harmonization (ICH) guidelines. The results obtained by the developed methods were statistically compared to those obtained by the reported HPLC method using F- and student's t-tests showing no significant difference regarding both accuracy and precision.

Oxetane ring plays an important role as main core in naturally occurring compounds and has many applications in pharmaceutical industries and synthetic organic chemistry. In this review, we report a brief survey of using the oxetane ring as versatile precursors in the total synthesis of natural products. Many approaches such as cyclization, addition, oxidation, reduction, elimination, protection as well as deprotection reactions utilized to synthesize of most important oxetane-containing natural products involving taxol, (±)-merrilactone A, (±)-oxetin, L-oxetanocin, (+)-(Z)-laureatin and L-oxetanocin are also covered. We describe in this review the most common total synthesis approaches have been yet applied to synthesis of most important oxetane-containing natural products. The review is also included isolation, structure Identification of these oxetane-containing natural products. The biological activity of oxetane-containing natural products due to the oxetane ring is also defined.