European Journal of Chemistry

The benzoin condensation was used to evaluate the catalytic activity of different N-heterocyclic carbenes as a function of their structure and N-substituents. There is a correlation between the length of an N-alkyl substituent and its performance as an organocatalyst. Heteroaromatic aldehydes were found to be the most reactive, among the screened substrates, finishing the reaction in 30 minutes, with almost quantitative yields. On the other hand, p-nitrobenzaldehyde, a strongly electrophilic aldehyde, was the least reactive. Electronic effects have little influence on the reaction yield but steric effects can dramatically reduce it. The preformed organocatalyst reacts faster than the generated in situ, with minimum solvent.

In this work, we report that ZnTiO₃/TiO₂ composites, which were synthesized by hydrothermal method possessed photocatalytic and potential spraying properties. The obtained ZnTiO₃/TiO₂ composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction techniques (XRD). Photocatalytic activities of ZnTiO₃/TiO₂ composites were evaluated by using Rhodamine B (RhB) as a model pollutant under visible light irradiation. The experimental results showed that the as-prepared ZnTiO₃ (2%)/TiO₂ composite exhibited better photocatalytic activity than that of pure TiO₂.

An accurate, sensitive and time saving spectrophotometric method has been developed and validated for the determination of two antihypertensive drug mixtures. Mixture 1 contains spironolactone (SPIR), furosemide (FUR) and anthranilic acid (ANTH) (impurity of furosemide) and mixture 2 contains triamterene (TRI), hydrochlorothiazide (HCZ) and chlorothiazide (CZ) (impurity of hydrochlorothiazide). In mixture 1, the determination of drugs depends on dividing the spectrum of ternary mixture by the spectrum of 10 µg/mL of standard furosemide and then spironolactone and anthranilic acid were determined using the difference in amplitude between 242.3 and 254.6 nm, and between 250.8 and 242.4 nm in the ratio spectrum, respectively. On the other hand, furosemide could be determined by dividing the spectrum of ternary mixture by the spectrum of 10 µg/mL of standard spironolactone and then it was determined using the difference in amplitude between 244.8 and 229.7 nm in the ratio spectrum. In mixture 2, the determination of drugs depends on dividing the spectrum of ternary mixture by spectrum of 10 µg/mL of standard triamterene and then hydrochlorothiazide and chlorothiazide were determined using the difference in amplitude between 268.9 and 232.8 nm, and between 292.9 and 250.7 nm in the ratio spectrum, respectively. On the other hand, triamterene could be determined by dividing spectrum of ternary mixture by spectrum of 10 µg/mL of standard hydrochlorothiazide and then triamterene was determined using the difference in amplitude between 230.1 and 244 nm in the ratio spectrum. The developed analytical methods were validated regarding good accuracy and precision according to The International Conference on Harmonisation guidelines, and they were applied to pharmaceutical preparations in addition to laboratory prepared mixtures successfully. Statistically the results were compared with those obtained by reported method and no significant difference was found.

In recent years, nanofibrous materials derived from biopolymers have attracted more interest due to their numerous applications. In our study, a simple composite of cellulose nanocrystals, and cobalt oxide nanoparticles was elaborated using sodium borohydride as a chemical reducer. It has been shown that Co₃O₄ nanoparticles were grown on the surface of cellulose nanocrystals. An important quantity of cobalt oxide nanoparticles was detected using ICP-OES (13.5 g contained in 100 mg of the composite). The size, the morphology and the thermal stability of the composite and the obtained nanoparticles were studied using X-ray powder diffraction, Fourier-transform infrared spectroscopy, Ultraviolet-Visible spectrophotometry, Scanning electron microscopic and Transmission electron microscopic. Our obtained material was used for the degradation of Rhodamine B and it was succeeded in degradation of Rhodamine B within very short period of time (16 min). The catalytic degradation of Rhodamine B was investigated and analyzed with UV-Visible absorption spectra.

There is an urgent need for the design and development of new and safer drugs, this has attracted organic chemists to synthesize new compounds with potential of biological and chemotherapeutic activities. Here we report, the condensation of phenylethylamine with 2-hydroxy naphthaldehyde yielded Schiff base derivative in good yield. Characterization of synthesized compound was carried by elemental analysis, IR, ¹H-, ¹³C- and HSQC-NMR spectroscopy. The toxicity of the synthesized compound was determined using Balb/c mice model. Dixon’s up and down method was found to have an LD₅₀ of 827.2 mg/kg of body weight, moderate toxicity.

In the present study, a series of new pyrazoline derivatives bearing sulfanilamido moiety were synthesized and obtained in good yields. The chemical structures of the compounds were elucidated by spectral data (FT-IR, MS, UV-VIS and NMR). The synthesized compounds 41-70 were screened for their antimicrobial activity and compared with controls. The in vitro antibacterial activity of compounds 41-45 and 48-57 was checked against two Gram positive microorganisms (S. aureus and S. mutans) and three Gram negative microorganisms (E. coli, K. pneumonia and P. aureginosa), their antifungal activity was checked against C. albicans. The preliminary results showed that these compounds had moderate activity against the tested organisms. Compounds 41, 48, 51 and 56 exhibited promising antimicrobial activity against S. aureus compared to standard drug Ampicilin. Final synthesized compounds 58-70 were tested against two Gram positive (S. aureus and B. subtilis) and two Gram negative (E. coli and P. aureginosa) microorganisms, their activity against C. albicans was also checked and they did not exhibit any antimicrobial activity.

Two bis(8-quinolinolato-N,O)-platinum(II) complexes, C₁₈H₁₂N₂O₂Pt (1) and C₂₀H₁₆N₂O₂Pt (2), were synthesized and characterized by FT-IR, elementary analysis and X-ray single crystal diffraction. Complex 1 crystallizes in monoclinic, space group P2₁/c with a = 9.3413(7), b = 10.3893(9), c = 14.8495(12) Å, β = 100.574(7)°, V = 1416.7(2) ų. Complex 2 crystallizes in monoclinic, space group P2₁/n with a = 9.5115(11), b = 15.5692(18), c = 16.720(2) Å, β = 94.544(2)°, V = 2468.3(5) ų. Intermolecular C-H···O hydrogen bonding interactions, as well as Pt···Pt and π-π stacking interactions, help to stabilize the crystal structures. The preliminary in vitro anticancer activity of complexes 1 and 2 and the corresponding ligands (L1 and L2) were investigated using human cervical (Hela) and hepatocellular carcinoma (Hep-G2) cancer cell lines. The platinum(II) complexes can greatly inhibit the cell proliferation and show stronger cytotoxic activities against the tested cancer cell lines than both ligands.

The current study describes the development of in silico models based on quantitative structure-activity relationship (QSAR) analysis has been performed on 4-quinoline carboxylic acid derivatives as inhibition capacity of vesicular stomatitis virus replication in Madin Darby canine kidney epithelial cells. A highly descriptive and predictive QSAR model was obtained through the calculation of alignment-independent descriptors using MOE 2009.10 software. For a training set of 20 compounds, the partial least squares analyses result in a model which displays a squared correlation coefficient (r²) of 0.913. Validation of this model was performed using leave-one-out (q²) of 0.842. This model gives (r²_pre) of 0.889 for a test set of five compounds. Docking studies were performed for 25 compounds to investigate the mode of interaction between 4-quinoline carboxylic acid derivatives and the active site of the human dihydroorotate dehydrogenase.

A simple, specific, and precise RP-HPLC method was developed and validated for simultaneous determination of Bisoprolol fumarate (BIS) and Rosuvastatin calcium (ROS) in new formulated tablets. The developed RP-HPLC method depended on chromatographic separation using C₁₈ column (150×4.6 mm, 0.5 μm) with mobile phase consisted of acetonitrile and 0.05 aqueous solution of orthophosphoric acid at the ratio of 65:35 % (v:v) with a flow rate of 1 mL/min and UV detection was carried out at 230 nm. Factors affecting the developed methods were studied and optimized and the retention times for BIS and ROS were found to be 2.758 and 4.974 min, respectively. Linearity of the proposed method was observed over a concentration range 0.2-50 μg/mL for each of BIS (r = 0.9999) and ROS (r = 0.9998). The proposed method was successfully applied for the determination of the studied drugs in their bulk powder, laboratory prepared mixtures and in the formulated tablets. The developed method is the first chromatographic method for determination of those drugs and showed no significant difference when compared with the reported methods.

A synthesis of substituted quinolines has been achieved by the Doebner reaction which is a three component coupling of arylaldehyde, p-amino-acetophenone and phenyl pyruvic acid. The products of 2,3-diary-6-acetyl-quinoline-4-carboxylic acids were obtained by Claisen Schmidt condensation reaction with aldehydes in the presence of sodium hydroxide in order to give the corresponding α,β-unsaturated carbonyls. The substituted α,β-unsaturated carbonyls were condensed with urea, thiourea, hydrazine, phenyl hydrazine, semicarbazide hydrochloride and ethanolamine to synthesized 2-pyrimidinone, 2-pyrimidinethion, pyrazoline-1-phenyl, pyrazoline, pyrazoline-1-carboxamide and 1,4-oxazepines derivatives, respectively, with good yields. The purity and identities of products were elucidated through thin layer chromatography (TLC), melting point and spectroscopic data (IR, ¹H NMR, ¹³C NMR and LC-Mass).

Successful removal of nigrosine, alizarin, indigo and acid fuchsin dyes from aqueous solutions using modified CaO nanoparticles has been investigated. The CaO was obtained from eggshells and modified with AgI. The adsorbents were characterized using X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and transmission electron microscopy. The kinetic studies were also investigated, the results showed that the adsorption of alizarin dye follows the pseudo-first-order model, while the adsorption of the nigrosine, indigo, and acid fuchsin follow the pseudo-second-order model onto modified and unmodified CaO. Moreover, the photocatalytic activity of modified adsorbent was tested under sunlight. The modified adsorbent showed a strong photocatalytic activity, a 0.01 g modified adsorbent was sufficient to absorb 100% of acid fuchsin through only 5 min after exposes to sunlight.

A new compound, spiro-oxindole derivative compound namely ethyl-2ʹ-amino-5ʹ-cyano-6ʹ-(1H-indole-3yl)-2-oxospiro[indoline-3,4ʹ-pyran]-3ʹ-carboxylate (EACIOIPC) has been synthesized and characterized by microanalysis, FT-IR, mass spectrum and NMR (¹H and ¹³C) techniques. The thermal decomposition of the compound was studied by thermogravimetric analysis under dynamic nitrogen atmosphere at different heating rates of 10, 15, 20 and 30 K/min. The kinetic parameters were calculated using model-free (Friedman’s, Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods) and model-fitting (Coats and Redfern (CR)) methods. The decomposition process of EACIOIPC followed a single step mechanism as evidenced from the data. Existence of compensation effect is noticed for the decomposition of EACIOIPC. Invariant kinetic parameters are consistent with the average values obtained by Friedman and KAS in conversional methods.

Although, plenty of photocatalytic approaches have been developed in the past few decades to overcome major drawbacks, such as; wide band gap and fast volume/surface recombination of the charge carriers, the researchers still need to carry out careful systematic studies before conducting experiments based on physicochemical properties of a system. Thus, in this review, a detailed discussion of the band edge positions controlling the migration and charge separation of the produced charged carriers and its impact onto the photocatalytic systems are provided. The knowledge of band edge positions is a crucial prerequisite to a rational design of an efficient photocatalytic system. The enhancement mechanism should match these criteria to be reliable in the field of heterogeneous photocatalysis science.